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Simulated organic acid weathering of granodiorite and basalt Aceman, Sheila 1989

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SIMULATED ORGANIC ACID WEATHERING OF GRANODIORITE AND BASALT by SHEILA ACEMAN .Sc., The University of B r i t i s h Columbia, 198 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in THE FACULTY OF GRADUATE STUDIES (Department of S o i l Science) We accept t h i s thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA July, 1989 ® Sheila Aceman In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department of *So ic Sc/ g>\) C-6T The University of British Columbia Vancouver, Canada DE-6 (2/88) ABSTRACT Basalt and granodiorite (medium to f i n e sand p a r t i c l e size) were leached by three low molecular weight a l i p h a t i c organic acids, namely c i t r i c , o x a l i c and a c e t i c acid of . 1M concentration. To evaluate the effectiveness of the organic acids i n d i s s o l v i n g the rock samples, two control solutions, .005M HC1 and d i s t i l l e d water were added to the number of d i s s o l u t i o n treatments. Dissolution of ions from granodiorite, by the leaching treatment shown in parenthesis, decreased i n the following order: Fe(OX) > A1(0X) ~ Si(OX) > Ca(CIT) ~ Mg(OX) - K(OX) > Na(OX) Dissolution of ions from basalt decreased i n the following order: Fe(CIT) > Si(CIT) > Mg(CIT) > Ca(CIT) > Al(OX, ACETIC) > Na(OX) > K(HC1) Oxalic acid e f f e c t i v e l y outcompeted c i t r i c a cid i n the weathering of granodiorite i n s p i t e of having lower s t a b i l i t y constants for certain elements. This was a t t r i b u t e d to differences i n pH of the solutions ( a f f e c t i n g both concentration of IT ions and anionic species), i o n i c competition i n solution for ligand s i t e s and geometry and oxidation state of ions i n the parent mineral. There was no conclusive evidence to indicate that chelation of K* or Na+ took place i n any of the experiments. i i i However, mass balance calculations revealed that o x a l i c acid extracted approximately 40-50% of the K from granodiorite; c i t r i c acid extracted approximately 12%. These l e v e l s were s i g n i f i c a n t l y higher than those extracted by non-sequestering agents. XRD analysis of granodioritic-oxalate p r e c i p i t a t e suggested the possible formation of a K-oxalate s a l t . The chelating acids, c i t r i c and o x a l i c , greatly outcompeted a c e t i c acid and HC1 of s i m i l a r pH for multi-valent cations i n both basalt and granodiorite. Concentrations of Fe, A l , and S i , i n solution were many f o l d higher than calculated concentrations of those ions i n equilibrium with the amorphous oxide i n water. Oxalic acid and c i t r i c d i s s o l u t i o n curves, determined from 11 weeks of leaching, showed i n i t i a l l y increasing rates followed by declining rates which approached steady state towards the eleventh week of the experiment. Declining rates followed by steady-state rates were attributed to the presence of hyperfines the build-up of secondary p r e c i p i t a t e s , the increase of ions i n solutions, and to an eroding leached surface layer. Non-chelating acids namely acetic acid, HC1 and H20 revealed d i s s o l u t i o n curves that were approximately constant (steady-state) throughout the 11 week weathering period. XRD, XRF, SEM, and EDX analyses of weathered basalt and granodiorite as well as AA spectrophotometric solution analyses provided evidence which indicated incongruent i v d i s s o l u t i o n of granodiorite and basalt by a l l 5 leaching treatments. SEM and XRF analyses indicated that c i t r i c a cid was less e f f e c t i v e than o x a l i c acid i n forming p r e c i p i t a t e s from granodiorite. EDX revealed that the amorphous p r e c i p i t a t e which did form i n c i t r i c acid consisted primarily of Fe. EDX analyses of inorganic coatings indicated predominantly S i and Fe i n 1:1 r a t i o . Although c i t r i c acid was able to extract greater amounts of Fe from basalt than granodiorite, extractable Fe, A l and S i analysis and SEM detected no organo-amorphous p r e c i p i t a t e s . Also EDX of inorganic surfaces showed no accumulation of Fe or A l . I t was concluded that the Fe extracted from the basalt remained i n complexed or soluble form due to the higher pH (3-5) of the b a s a l t i c solution. An amorphous p r e c i p i t a t e formed from the leaching of granodiorite with o x a l i c acid. EDX analysis gave evidence that the p r e c i p i t a t e consisted primarily of S i and Fe i n a 1:1 r a t i o . An amorphous p r e c i p i t a t e formed also from the leaching of basalt with o x a l i c acid. EDX analysis gave evidence that the p r e c i p i t a t e consisted primarily of Mg and Fe i n a 1:1 r a t i o . Data from molar oxide r a t i o s and mass balance calculations as well as XRD, XRF, extractable Fe, A l and S i analyses were r e l i e d upon to determine the possible organic and inorganic components of these p r e c i p i t a t e s . V TABLE OF CONTENTS Page i ABSTRACT i i TABLE OF CONTENTS i i LIST OF TABLES v i i LIST OF FIGURES v i i i ACKNOWLEDGEMENTS x i INTRODUCTION 1 MATERIALS AND METHODS 6 LITERATURE REVIEW ' 16 RESULTS AND DISCUSSION 43 A. Section 1 43 B. Section II 68 C. Section III 91 SUMMARY AND CONCLUSIONS 115 BIBLIOGRAPHY 125 APPENDIX A x ' 137 APPENDIX A 2 144 APPENDIX B 148 APPENDIX C 156 APPENDIX D 164 APPENDIX E 17 2 APPENDIX F 176 APPENDIX G 179 APPENDIX H 183 APPENDIX 1 187 APPENDIX J 194 APPENDIX K x 198 APPENDIX K 2 2 03 APPENDIX L 208 APPENDIX M 211 APPENDIX N 214 v i LIST OF TABLES Page Table 1: Chemical Description of C i t r i c , Oxalic and Acetic Acid 7 Table 2: S t a b i l i t y Constants of Oxalate and C i t r a t e Metal Ligands 45 Table 3: Source of Ions From Bas a l t i c and Granodioritic Parents Material 65 Table 4: Composition of Minerals I d e n t i f i e d i n Granodiorite & Basalt by XRD Analyses 66 Table 5: Changes i n XRD Peak Intensities i n Bas a l t i c & Granodioritic Minerals Following 11 Week Batch Dissolution Experiment 67 Table 6: Chemical Description of C i t r a t e and Oxalate Salts 92 v i i LIST OF FIGURES Page Figure 1: Possible pathways of ir o n oxide formation •under near pedogenic conditions 3 0 Figure 2: The a c t i v i t y of F e 3 + maintained by Fe(III) oxides and s o i l - F e 30 Figure 3: Predicted mole f r a c t i o n diagrams f o r c i t r a t e and oxalate i n a nutrient solution i n equilibrium with Fe(OH) 3 (amorph) 4 6 Figure 4: The a c t i v i t y of A l 3 + and i t s hydrolysis species i n equilibrium with g i b b s i t e . . . . 53 Figure 5: The s o l u b i l i t y of various aluminum oxides 53 Figure 6: Hyperfines adhering to g r a n i t i c surface. 71 Figure 7: Hyperfines adhering to b a s a l t i c surface. 71 Figure 8: Ba s a l t i c grain leached by o x a l i c acid for 11 weeks. Note absence of hyperfines and prominent e t c h - p i t t i n g 72 Figure 9: Granodiorite crust materials leached by c i t r i c acid for 11 weeks 76 Figure 10: EDX of sample shown i n Figure 11 76 Figure 11: Granodiorite grain weathered by o x a l i c acid for 11 weeks 77 Figure 12: Mica grain leached by o x a l i c acid - 11 weeks 81 Figure 13: Mica grain leached by ox a l i c acid - 11 weeks. 81 Figure 14: Mica grain leached by o x a l i c acid 11 weeks 82 Figure 15: EDX of sample shown i n Figure 14 82 Figure 16: Granodioritic grain leached by o x a l i c acid 11 weeks 84 Figure 17: EDX of sample shown i n Figure 16 84 v i i i Page Figure 18: Basa l t i c grain leached by o x a l i c a c i d f o r 11 weeks 86 Figure 19: Ba s a l t i c grain leached by o x a l i c a c i d for 11 weeks 86 Figure 20: Granodiorite grain leached i n o x a l i c acid for 11 weeks 87 Figure 21: Granodioritic grain leached i n o x a l i c acid for 11 weeks 87 Figure 22: Basa l t i c grain leached i n o x a l i c a c i d for 11 weeks 88 Figure 23: Ba s a l t i c grain leached i n o x a l i c a c i d f o r 11 weeks 88 Figure 24: Basa l t i c grain leached i n o x a l i c a c i d for 11 weeks 89 Figure 25: Granodiorite grain leached i n o x a l i c acid for 11 weeks 90 Figure 26: EDX of sample shown i n Figure 27 94 Figure 27: Mineral fragments i n g r a n o d i o r i t i c crust found a f t e r 11 weeks of leaching i n oxalic acid 94 Figure 28: EDX of sample shown i n Figure 29 95 Figure 29: Amorphous pr e c i p i t a t e i n g r a n o d i o r i t i c crust found aft e r 11 weeks of leaching i n oxalic acid 95 Figure 30: EDX of sample shown i n Figure 31 99 Figure 31: Amorphous pr e c i p i t a t e i n b a s a l t i c crust formed a f t e r 11 weeks of leaching i n oxalic acid 99 Figure 32: EDX of sample shown i n Figure 33 102 Figure 33: Amorphous pr e c i p i t a t e i n g r a n o d i o r i t i c crust formed afte r 11 weeks of leaching i n c i t r i c acid 102 Figure 34: EDX of sample shown i n Figure 35 104 i x Page Figure 35: Granodioritic "crust" leached i n c i t r i c acid for 11 weeks 104 Figure 36: EDX of sample shown i n Figure 37 106 Figure 37: Ba s a l t i c grains leached i n c i t r i c acid for 11 weeks 106 Figure 38: Ba s a l t i c grain leached i n H 20 for 11 weeks 110 Figure 39: Granodioritic grains leached i n H o0 for 11 weeks 110 X ACKNOWLEDGEMENTS During the course of my research I have received help from many sources. Thanks and appreciation, f i r s t of a l l to Dr. L.M. Lavkulich f o r h i s support and words of encouragement. Thanks also to Dr. L.E. Lowe and Dr. Mary Barnes who always found time to answer any questions and stimulated s c i e n t i f i c enquiry. Dr. Hans Schreier also served on my committee and offered several suggestions regarding t h i s project. Much appreciation i s also extended to those who gave me tec h n i c a l assistance i n the laboratory without whom t h i s t h e s i s would not be completed: Yvonne Duma, Martin Hilmer, Mary Majors, Maureen Soon, Bernie Von Spindler, Lendle Wade, and i n p a r t i c u l a r Eveline Wolterson. I also received academic help from Dr. B. Barnes, Dr. A. Bomke, Dr. T. Brown, Dr. D. Clavette, Dr. J . de Vries, Dr. B. James, and Dr. C. Orvig. 1 I N T R O D U C T I O N Chemical weathering of rocks and minerals i s one of the most important processes by which chemical elements are fractionated at the surface of the earth. Much of the e a r l i e r research on the subject of mineral weathering was based on bulk chemistry or mineralogy of v e r t i c a l p r o f i l e s as a function of geomorphic or c l i m a t i c f actors. Among the most i n f l u e n t i a l concepts to emerge from the early work were the "weathering s e r i e s " of Goldich (1938), the "weathering index" of Jackson and co-workers (Jackson et a l . 1948), and a var i e t y of elemental mobility indices. Goldich's weathering series, perhaps the most well known and quoted i n many books, i s merely the observation that c e r t a i n minerals weather more ra p i d l y than others. However, numerous attempts to unravel the underlying basis of Goldich's weathering series i n terms of thermodynamics (Curtis 1976), or bonding energies i n s i l i c a t e l a t t i c e s (Keller 1954), have s t i l l f a i l e d to produce a sing l e u n i f y i n g t h e o r e t i c a l explanation for the s t a b i l i t y sequence. Weathering sequences of secondary minerals (e.g. Jackson et al.) are also based on observation but f a i l to determine the underlying mineralogical basis f o r the weathering sequence. The most extreme view holds that the weathering sequence: 2 Primary s i l i c a t e > smectite > k a o l i n i t e > gibb s i t e i s i n f a c t a reaction series, brought about by prolonged leaching with the subsequent removal of cations and then , s i l i c a . The duration of leaching dominates t h i s view, with g i b b s i t e seen as the most advanced product of weathering. In 1963 however, Grant (1963, 1964), showed that there i s a d i r e c t transformation of primary feldspars to k a o l i n i t e . Eswaran et a l . (1977), discovered formation of g i b b s i t e from primary minerals and i t s r e s i l i c a t i o n to k a o l i n i t e . Also, as pointed out by Schwertman and Taylor (1977), reduction or chelation-solution and oxidation-precipitation reactions make i t d i f f i c u l t to p o s i t i o n iron oxides i n mineral weathering-s t a b i l i t y sequences. They p a r t i c i p a t e i n nearly a l l stages of weathering and indicate an advanced stage only i f strongly accumulated under aerobic conditions. Cl e a r l y , confusion has resulted from viewing minerals outside of t h e i r environmental context. Although i n 1957 K e l l e r recognized that mineral s t a b i l i t y depends on both the thermodynamic s u s c e p t i b i l i t y of the parent material and the chemistry of the reactant solution, i t i s only i n the l a s t decade that research has focused on the importance of aqueous so l u t i o n chemistry i n the d i s s o l u t i o n of primary and secondary minerals. The l a b i l e aqueous phase undergoes continuous transformation of dissolved constituents into d i f f e r e n t chemical species over a broad range of reaction time scales. 3 This k i n e t i c a l l y complex process i s the e s s e n t i a l force that drives s o i l p r o f i l e development and governs the patterns of chemical weathering (Sposito, 1981). For example, clays, which are non-stoichiometric phases reacting with aqueous solutions cannot be described by one c h a r a c t e r i s t i c formula, for t h e i r composition may change as a function of the composition of the aqueous phase, during or a f t e r t h e i r p r e c i p i t a t i o n . Thermodynamic ca l c u l a t i o n s of e q u i l i b r i a between multi-component s o l i d solutions and aqueous solutions are d i f f i c u l t to i s o l a t e and understand and a general theory i s not yet available. Computer models have, however, recently been developed (e.g. F r i t z , 1985) which allow introduction i n water-rock i n t e r a c t i o n modelling of mineral phases which vary with the composition of the solution. Much remains to be learned regarding the very complex changes i n solution chemistry brought about by weathering of minerals i n the natural environment. In s o i l s , physical, chemical and b i o l o g i c a l factors continually i n t e r a c t making i t d i f f i c u l t to i s o l a t e and quantify the contribution of any one factor at any given time. I t was decided therefore to sim p l i f y a weathering environment by a r t i f i c i a l l y leaching crushed basalt and granodiorite with f i v e d i f f e r e n t extractants comprising both organic and inorganic acids. The focus of the experiment was to study the changes over time i n solu t i o n chemistry for each leaching treatment. P r e c i p i t a t i o n products, which formed as 4 i o n i c species i n solution sought lower free energy l e v e l s , were also analyzed. Physical and chemical changes i n the weathered basalt and granodiorite were only noted i n order to explain c e r t a i n features of s o l u t i o n - p r e c i p i t a t i o n e q u i l i b r i a . Accordingly, three main topics for discussion (sections I, II and III i n Results and Discussion) were chosen i n order to u n i f y the broad scan of information which resulted from the analyses. The f i r s t t o p i c considered the chemical composition of the leaching solutions as influenced by parent rock and acid treatment. The second highlighted the k i n e t i c features of d i s s o l u t i o n , i . e . the r e l a t i v e rates of change of so l u t i o n chemistry over time, and the t h i r d included a discussion on the formation of organo and amorphous p r e c i p i t a t e s from s o l u t i o n products. More s p e c i f i c a l l y the objectives of t h i s study were: 1. To evaluate the effectiveness of two chelating and three non chelating acids i n d i s s o l v i n g basalt and granodiorite. 2. To determine whether the extent of d i s s o l u t i o n i s correlated with s t a b i l i t y constants of organic acids, pH of solution, or type of mineral i n the parent rock. 3. To trace the changes i n rates of d i s s o l u t i o n over time (11 weeks) and propose possible explanations for the k i n e t i c behaviour. 4. To ascertain whether di s s o l u t i o n was incongruent or congruent. 5 5. To analyze p r e c i p i t a t i o n products formed from solution. F i n a l l y , i t was hoped that t h i s experiment would shed l i g h t on further research needed to account for differences i n the d i s s o l u t i o n of minerals by low-molecular-weight a l i p h a t i c acids. 6 MATERIALS AND METHODS 1. EXPERIMENTAL DESIGN B a s a l t i c and g r a n o d i o r i t i c samples were c o l l e c t e d from the Cheakamus and Cypress Bowl Formations located i n the Coastal Mountain Range of B r i t i s h Columbia. The rock samples were then crushed and sieved and the 0.1 mm - 0.5 mm diameter f r a c t i o n (fine-medium sand) was retained for the experiment. P a r t i c l e s i n that s i z e range were considered f i n e enough to react chemically with aqueous solutions but coarse enough that l i q u i d s could be c l e a r l y separated from them by g r a v i t y and centrifugation. Also p a r t i c l e s i n that s i z e range preclude the chances of plugging i n gravity columns. Samples were mixed thoroughly to achieve maximum homogeneity, then weighed to 100 gms, and leached with 400 mis of acid per day. In order to compare the r e l a t i v e d i s s o l u t i o n powers of organic acids i n weathering of minerals, three a l i p h a t i c acids were chosen which are characterized by the number of associated carboxyl and hydroxyl groups. Thus, c i t r i c acid with one hydroxyl and three carboxyl, o x a l i c acid with two carboxyl and a c e t i c acid with one carboxyl group were selected. Each a c i d i c solution was brought to . 1M concentration (see Table 1). To further evaluate the effectiveness of the acids i n d i s s o l v i n g basalt and granodiorite, two control solutions were 7 C i t r i c Acid Oxalic Acid Acetic Chemical Name Chemical Composition Category Type of Complex pKa pH of 10 _ 1M solution 2-Hydroxy propane 1,23-tricarboxylic acid C 6H 80 6 Non-volatile a l i p h a t i c 5 and 6 ri n g 3.14, 4.77, 6.39 2.3 Ethanedioic acid C2 H2°4 Non-volatile a l i p h a t i c 5 ring 1.23, 4.19 1.6 Ethanoic acid C2 H4°2 V o l a t i l e , a l i p h a t i c Monodentate 4.76 2.9 Structures H I H— C—COOH I HOOC —C—OH I . H—C—COOH I H HO 0 / C I ,c 0 OH HO O V I H—C—H I H TABLE 1: CHEMICAL DESCRIPTION OF CITRIC, OXALIC AND ACETIC ACID. 8 prepared - .004M HCL and d i s t i l l e d water. This concentration of HCL produces approximately the same amount of ionized H in sol u t i o n (pH = 2.4) as do .1M c i t r i c (pH = 2.3) and a c e t i c (pH = 2.9) acids. The pH of .1M ox a l i c acid was somewhat lower at pH = 1.6 and d i s t i l l e d water much higher at pH = 5.7. Three r e p l i c a samples of basalt and granodiorite. were leached by the 5 organic and inorganic treatments. Leaching was undertaken by batch and column extraction methods. A summary of the experimental design i s as follows: EXPERIMENT COLUMN/BATCH I PARENT MATERIAL BASALT GRANODIORITE I 1 1 1 1 ' ' i 1 i n TREATMENT c i t r i c O x a l i c A c e t i c HC1 H20 c i t r i c O x a l i c A c e t i c HC1 H20 1 I I I I 1 I ' i 1 — i — i — i — i — i | — i — i 1—i—I 1 — | — | | 1 — | — , 1 1 REPLICAS 1,2,3 1,2,3 1,2,3 1,2,3 1,2,3 1,2,3 1,2,3 1,2,3 1,2,3 1,2,3 The column and batch leaching experiments were carr i e d out over two d i f f e r e n t time periods. In the f i r s t , samples were leached for one month followed by destructive analysis of both solutions and weathered material. Fresh samples and solutions were then reassembled and leached for 11 weeks. Solutions were removed and analyzed a f t e r week 1, 3, 5, 7, 9, and 11. In t h i s way fresh solutions were introduced into the column and batch experiments every two weeks which not only enhanced the rates of dissolution but enabled cal c u l a t i o n s of k i n e t i c features of the experiment. At the end of 11 weeks, the mineral samples were a i r - d r i e d i n preparation for further analysis. 9 2 . D E S C R I P T I O N O F C O L U M N E X P E R I M E N T A L A P P A R A T U S A N D P R O C E D U R E A column extraction procedure was designed which u t i l i z e d the force of gravity to leach the mineral parent material. From top to bottom the apparatus consisted of the following for each sample: (a) One l i t r e polyethylene bo t t l e with tubulation i n which the extracting solution was placed. (b) Polyvinylchloride tubing to connect the b o t t l e to the sample column. (c) Adjustable clamp placed on the tubing to control flow rate. (d) Rubber stopper inserted into the top of the column. A hole bored into t h i s stopper to d i r e c t the PVC tubing into the column. (e) A c r y l i c column 25 cm i n length and 2.5 cm inner diameter to contain 100 gm of sample. (f) 2 mm i n e r t glass beads packed to a depth of 2.5 cm into top of column and resting on rock sample to promote even d i s t r i b u t i o n of leachate. (g) 100 gm of crushed rock sample placed into column. (h) Whatman ashless No. 41 f i l t e r paper beneath rock sample. (i) Rubber stopper inserted into bottom of column to support sample and f i l t e r paper. A hole bored into 10 t h i s stopper directed an a c r y l i c tube into catchment beaker. (j) 600 ml catchment beaker with cellophane cover to i n h i b i t evaporation. The entire assembly was supported on a table i n which holes were bored to enable connecting PVC tubing (from the one l i t r e b o t t l e to the column) to pass through. An e l a s t i c band was pulled around each sample column and attached to n a i l s inserted on a side panel b u i l t on a l l four sides of the table. Solutions from each sample were separated from the parent material for further analysis by removing the contents from the 600 ml catch beaker. Recycling of the solution each day was achieved by pouring the solution captured i n the 600 ml beaker back into the 1 l i t r e polyethylene b o t t l e resting on the table. 3. DESCRIPTION OF BATCH EXPERIMENTAL APPARATUS AND PROCEDURE A batch extraction procedure u t i l i z e d the physical force of shaking sample and solution for 1 hour each day to leach the mineral parent material. An a r b i t r a r y time of one hour was chosen to minimize physical or mechanical breakdown of p a r t i c l e s . 100 gms of sieved granodiorite and basalt were placed i n 500 ml polyethylene bottles with 400 mis of extracting solution and sealed with parafilm and No. 9 rubber stoppers. Each day the seals were removed so that the extracting 11 s o l u t i o n could e q u i l i b r a t e with C02 i n the atmosphere Solutions from each sample were separated from the parent material by centrifugation at 4200 rpm i n order to carry out further analyses. In batch experiments p a r t i c l e size does not have the po t e n t i a l to i n t e r f e r e with leaching rates as i s the case i n gravi t y - column experimental set-ups. I t -was decided therefore to also study, by batch procedure, the leaching of granodiorite and basalt which were sieved and c o l l e c t e d from <.l mm diameter p a r t i c l e s . Samples <.lmm were designated "Granodiorite B" and "Basalt B"; Samples . 1 mm - .5 mm were designated "Granodiorite A" and "Basalt A". Furthermore, a c r u s t - l i k e material s e t t l e d on the top of weathered a i r - d r i e d batch samples following 11 weeks of leaching. I t was thought that t h i s c r u s t - l i k e material might reveal d i s t i n c t i v e chemical features and was therefore separated from the bulk of the sample and analyzed. This material was referred to as "crust". 4. ANALYSES OF SOLUTION EXTRACTS AND WEATHERED MINERAL PARTICLES (a) Solution Extracts Determination of dissolved Ca, Mg, Na, K, Fe, A l , and S i ions was c a r r i e d out with a Perkin-Elmer Model 3 06 atomic absorption spectrophotometer. To overcome possible anionic 12 interference, a nitrous oxide flame was used i n determining l e v e l s of Ca, A l and S i . An acetylene flame was used i n determining l e v e l s Fe, Mg, Na and K. pH of the extracting solutions was determined by an Accumet pH meter, Model 810. (b) Mineral Residues Chemical and physical analyses of the unweathered and weathered granodiorite and basalt included the following: X-ray d i f f r a c t i o n (XRD), X-ray florescence (XRF), SEM (scanning electron microscopy) , l i g h t microscopy, EDX (energy dispersive X-ray) CEC (cation exchange capacity), exchangeable bases, surface area, pH and extractable Fe, A l and S i . C i t r i c and o x a l i c acid c r y s t a l s and c i t r a t e and oxalate s a l t s of K, Na, Mg, K, Fe, A l and S i were prepared i n the laboratory for subsequent XRD analysis. This data was used, i n addition to published data of XRD peaks for organo-metallic s a l t s , to a s s i s t i n the i d e n t i f i c a t i o n of secondary p r e c i p i t a t e s . (i) XRD Analysis Unoriented powder mounts were prepared for XRD examination of the gross mineral d i s t r i b u t i o n s . The sediment samples were packed into a standard P h i l i p s aluminium sample holder and compressed with a piston and a mechanical press. The determinations were a l l made with an automated P h i l i p s PW 1710 Powder 13 Diffractometer using CuK & X-radiation with a curved graphite c r y s t a l (002) monochromator, and an automatically adjusting divergence s l i t (goniometer controlled). The unoriented powder and mineral samples were quickly scanned (,l°2/sec) from 4.2°0 to 60.2°0. ) XRF Analysis For the major elemental determination by XRF, 36 mm diameter glass discs were prepared by fusing, using 0.4 g of sample and 3.6 g of ultra-pure Spectroflux 105 (Johnson-Matthey Chemicals Ltd.) consisting of LigB^Oy, Lag0 3 and Lig0 3. Before weighing, the flux was dried i n a furnace at 500°C for one hour to remove absorbed water. The weighed flux and sample were placed into a platinum c r u c i b l e and fused i n a muffle furnace at 1100°C for 2 0 minutes. After cooling the fused samples, the weight loss r e s u l t i n g from the removal of i n t e r l a y e r water, oxidation of organic matter and v o l a t i l i z a t i o n of some elements, was made up with Spectroflux 100 which contains only Li2B4P 7and thus does not a l t e r the sample/La r a t i o . La i s needed as a heavy absorber i n the glass discs to increase the t o t a l mass absorption of the glass and thereby minimize matrix absorption e f f e c t s between d i f f e r e n t samples. After adding flux 100, 14 the glass was refused on a Meker burner and poured into an Al-mould on a hotplate set at 400°C. The molten sample was then flattened with a brass plunger, and the res u l t i n g disc was l a t e r d i r e c t l y presented to the X-ray beam. An automated P h i l i p s PW 1400 X-ray florescence i n combination with a peripheral d i g i t a l PDT 11 computer was used for c a l c u l a t i n g the elemental concentrations. C a l i b r a t i o n of the analyses was provided by a large number of international rock standards. i) SEM and EDX Analysis Samples to be microanalyzed by SEM were mounted on scanning electron microscope stubs painted with c o l l o i d a l graphite i n an alcohol base. The mounted p a r t i c l e s were then C-coated by a vacuum evaporator and observed using a Hatachi S-570 scanning electron microscope. Polaroid photographs of the electron images were taken at various magnifications and analysis of the sample was carried out with a Kevex 8000 Energy dispersive X-ray spectrometer. Those samples which were not subjected to microanalysis ( i . e . , EDX) were treated with a Hummer gold sputter coater so as to enhance the q u a l i t y i n the photographic image. ) Photographs of mineral samples were taken with a 15 Zeiss dissecting microscope at 50 x magnification. (v) Surface Area Surface area was determined by the ethylene g l y c o l monoethyl ether (EGME) technique (Heilman, M.D; Carter, D.L and Gonzales, C.L. 1965). (vi) Chemical Analyses Cation exchange capacity and exchangeable cations were measured by the ammonium acetate (pH 7.0) method, following the procedure given by Lavkulich (1981). Iron, aluminum and s i l i c o n were extracted by sodium pyrophosphate (pH 10.0) (Bascomb, 1968), acid ammonium oxalate (pH 3.0) (McKeague and Day, 1966) and citrate-bicarbonate s o l u t i o n (pH 7.3) (Weaver et a l , 1968; Mehra and Jackson, 1960). The ppm of each element within each extractant was measured using atomic absorption spectrophotometry on a Perkin-Elmer 306 spectrophotometer. These elements were then calculated as a percent of the t o t a l sample. The pH was determined i n both water (Peech, 1965) using a 1:1 mineral:water suspension, and i n 0.01 M CaCl 2 (Peech, 1965) using a 1:2 mineral:0.01M C a C l 2 suspension. PH measurements were taken on an Accumet pH meter, Model 810. 16 LITERATURE REVIEW A. THE ROLE OF ORGANIC ACIDS IN WEATHERING OF MINERALS 1. Occurence of Natural Organic Acids Natural organic acids i n s o i l s and freshwater environments are derived from plant and animal residues, microbial metabolism and canopy drip (Huang and Violante, 1986). Oxalic and other organic acids can also occur i n rainwater i n concentrations as high as a few micromolar (IO"6 M) (Stumm et a l . , Stumm and Furrer, 1987) . In top s o i l s , the presence of water soluble organic acids, such as malic, malonic, c i t r i c , oxalic, acetic, succinic, t a r t a r i c , v a n i l l i c and p-hydroxybenzoic acids may reach concentrations as high as IO"5 M to 10"3 M, oxalate being the most abundant (Graustein, 1977; Stevenson, 1982). In fungal mats where oxalates are produced, and i n the rhizosphere where root exudates are secreted, as well as l o c a l i z e d microclimates such as c a p i l l a r y water adjacent to a s o i l p a r t i c l e , concentrations of organic acids may be even much higher. In one study of a natural environment, the tcp layer of a forest s o i l contained an average of 7 mg/g oxalate, with the oxalate c r y s t a l s adhering to fungal hyphae demonstrating the source of the organic acid (Graustein et a l . 1977). Ca- and Mg-oxalate c r y s t a l s have also been found i n l i c h e n t h a l l i grown on basalt and serpentine (Jones et a l . 17 1980; Wilson et a l . 1981). The presence of o x a l i c and c i t r i c acids i n the weathering crust of sandstone was demonstrated by th i n layer chromatography (Eckhardt 1978) . Stevenson (1967) has reviewed the d i s t r i b u t i o n and pedogenic a c t i v i t y of organic acids i n s o i l . These acids are chemically polyfunctional i n that they contain more than one carboxyl group (e.g. oxalic) or carboxyl with one or more hydroxyl groups (e.g. c i t r i c ) and can form chelates with inorganic ions. A chelate complex forms when two or more coordinate positions about the metal ion are occupied by donor groups of a single ligand to form an i n t e r n a l r i n g structure. High-molecular-weight organic polymers, such as f u l v i c and humic acids, although less completely characterized, possess carboxyl, hydroxyl and amide groups and also form chelated complexes with metals (Mortenson, 1963). Konova (1961), Ca r o l l (1970), and McKeague et a l . (1986) have discussed the various roles or organic compounds i n pedogenesis. 2. Organic Acids and S o i l Weathering The awareness of an i n t e r a c t i o n between organic and mineral components emerged i n the very early years of s o i l science. Long before Dokuchaiev formulated h i s pedological concept, s o i l organic acids, including humic acids, were thought to play an important r o l e i n the d i s s o l u t i o n of rocks and minerals. Sprengel i n 1826 suggested a key r o l e of organic acids i n mineral weathering (Tan, 1986), followed by 18 Kindler i n 1836 who reported the bleaching of ferruginous sands around decomposing roots (Bloomfield, 1981). Evidence continues to accumulate to t h i s day ind i c a t i n g that organic acids, both aromatic and a l i p h a t i c , accelerate degradation of rocks and minerals due to t h e i r inherent a c i d i t y as well as chelating capacity (e.g. Huang and K e l l e r , 1970; Huang and Kiang 1972; Boyle et a l . 1974; Razzaghe-Karimi 1974; Singer and Navrot 1976; Schnitzer and Kodama, 1976; and Pohlman and McColl 1988) . Debate as to the r e l a t i v e importance of a c i d i t y vs. chelation i n promoting d i s s o l u t i o n of minerals i s evident i n reviewing the l i t e r a t u r e of s o i l science journals. In 1967, Schalsha et a l . studied the e f f e c t of complexing agents on the s o l u b i l i z a t i o n of Fe from granodiorite and postulated that, "the formation of metal complexes may take place simultaneously with acid action, or that chelation may be the sole or major mechanism responsible for some e f f e c t s theretofore a t t r i b u t e d exclusively to H ions." In the same year Boyle et a l . (1967) observed that the greater the chelating a b i l i t y of a biogenic acid the more Fe and A l i t removed from b i o t i t e . Huang and Kiang (1972) found c i t r i c a cid to be more e f f e c t i v e than other acids i n extracting A l and Ca from Ca-rich plagioclase, presumably because of i t s greater complexing a b i l i t y . Strongly complexing organic acids increase the t o t a l weight of clay minerals dissolved by d i s t i l l e d water by factors of 5 to 75 (Huang and K e l l e r , 19 1971), and may a l t e r the r a t i o of S i to other metals, notably Al and Fe, dissolved from some s i l i c a t e minerals (Huang and K e l l e r , 1970) . Indeed, the r e l a t i v e d i s t r i b u t i o n of pH-dependent A l ion species i n aqueous solution i s markedly altered by A l - S a l i c y l a t e complexes within the pH range 1.5 to 7.5 (Huang and K e l l e r , 1972). More recently, Pohlman and McColl (1986) analyzed the moles of metal released from a s o i l by lO'^ M c i t r i c acid at pH 3.25 and 5.65. By c a l c u l a t i n g the r a t i o of number of moles of cations released to H* ions consumed during the leaching process, they concluded that, "the e f f e c t of H+ on the d i s s o l u t i o n process was minimal and d i s s o l u t i o n of metals from the s o l i d phase was mainly by s h i f t i n the anionic species of c i t r i c acid." However, Manley and Evans (1986), concluded from t h e i r ^weathering experiments that the amount of Al released from feldspars by the organic acids appeared to be related more to t h e i r a c i d i c strengths than to t h e i r a b i l i t y to form complexes. They pointed out that i f "complex formation were of paramount importance i n d i s s o l u t i o n , i t would have been expected that protocatechinic, g a l l i c , and, p a r t i c u l a r l y , c a f f e n i c acid would have extracted more A l than the observed amounts". Concurrently Tan, (1986), reported that humic acids with both carboxyl and phenolic functional groups a f f e c t mineral d i s s o l u t i o n by both the a c i d i c e f f e c t and complex formation. He maintained, however, that simple a l i p h a t i c acids including o x a l i c acid a f f e c t mineral 20 decomposition "generally more through the a c i d i c (H* ions) e f f e c t " . Bloom and E r i c h (1987) found that the type of anion i n solution determined the rate and mechanism of gibbsite d i s s o l u t i o n . In solutions containing ions not s p e c i f i c a l l y adsorbed (e.g., NO~and SO? ), proton attack of the surface was the rate-determining step. In solutions containing phosphate which forms inner sphere complexes, anion attack predominated and the rate of the reaction was not dependent on pH. F i n a l l y , i t must be remembered that organic acids may remove metals already released by hydrogen ion attack on s i l i c a t e minerals thereby providing a sink to keep sparingly soluble metals i n solution (Schalscha et a l . 1967). In t h i s way the reaction continually s h i f t s to the r i g h t of equilibrium and the rate of d i s s o l u t i o n i s increased over that of a system where p r e c i p i t a t i o n products b u i l d up. Also, the domain of congruent di s s o l u t i o n of minerals i s extended as higher concentrations of soluble ions can be b u i l t up before a new phase i s formed. b. Geochemistry and Weathering Geochemists have recently begun to apply the p r i n c i p l e s of chemical k i n e t i c s to mineral weathering reactions occurring i n s o i l s . Most of the work done has involved feldspars of d i f f e r e n t composition although pyroxenes, amphiboles, and other minerals have been studied (Berner, 1981; Lasaga, 1981; 21 Holdren and Speyer, 1985; Chow and Wallast, 1985) . In the case of feldspars, many experimental studies of hydrolysis rates have resulted i n compilations of rate c o e f f i c i e n t s f o r d i f f e r e n t experimental conditions (Helgeson et a l . , 1984), yet the actual mechanism of feldspar d i s s o l u t i o n i s s t i l l not c l e a r l y defined (Coleman and Dethier, 1986). Some general theories however have arisen from mineral d i s s o l u t i o n studies. In many d i s s o l u t i o n experiments the release of s i l i c o n and a l k a l i ions are l i n e a r functions of the square root of time and t h i s has been characterized as following "parabolic" rate laws. Some researchers have attributed t h i s parabolic behaviour to the d i f f u s i o n of ions from the fresh mineral through an ever thickening secondary p r e c i p i t a t e (Wollast, 1967; Helgeson, 1971), or through a leached layer formed on the parent material (Luce et a l . , 1972; Paces, 1973; Busenburg and Clemency, 1976). From the work of Petrovic (1976) and Schott & Berner (1983) i t i s l i k e l y that the structure of a hydrous f e r r i c oxide layer, s i m i l a r to that of aluminum hydroxides forming on mineral surfaces i s not protective towards d i s s o l u t i o n . In the leached layer hypothesis, p r e f e r e n t i a l leaching of mobile elements such as a l k a l i s i s thought to occur at the mineral surface and leads to the formation of a residual hydrated layer. Diffusion of reactants through t h i s nonstoichiometric residuum then controls the release of exchangeable cations, while the leached s i l i c a t e or 22 aluminosilicate framework dismantles at a slower rate. As the layer builds up, the rate of d i s s o l u t i o n decreases u n t i l a steady state i s reached when the rate of removal of s i l i c a from the surface keeps pace with the rate of cations from deeper within the s o l i d . F i n a l l y , others have argued that the r a t e - l i m i t i n g step i s , i n contrast to d i f f u s i o n , a surface-controlled reaction (Lagache, 1976; Petrovic et a l . 1976; Holdren and Berner, 1979; Holdren, 1983). This theory envisions weathering as a two stage process: a rapid exchange of H* for a l k a l i s (Garrels and Howard, 1959) followed by the rate determining step controlled by the detachment of s i l i c a t e and aluminate units from the c r y s t a l l i n e framework (Aagaard and Helgeson, 1982). The rate of d i s s o l u t i o n should be constant, as long as parameters such as pH, surface area, ligand concentration do not change (Aagaard and Helgeson, 1982). Schott and Berner (1983) studied the mechanism of iron s i l i c a t e d i s s o l u t i o n during weathering and noted that the hypothetical protonated layer did not continue to grow in thickness during t h e i r experiments. They concluded that t h i s was most l i k e l y a r e s u l t of loss by d i s s o l u t i o n at the layers outer surface at the same rate that i t grew by H* attack at i t s inner surface. Accordingly, the non-linear k i n e t i c s at the beginning of most experiments are attributed to the rapid d i s s o l u t i o n of hyperfine p a r t i c l e s , as i t has been observed i n experimental systems that S i i s released from feldspar i n a l i n e a r fashion following removal of hyperfines by HF-H2-S04 23 treatment (Holdren and Berner, 1979). U n t i l very recently the tendency i n the l i t e r a t u r e has been to consider that the rate l i m i t i n g step during s i l i c a t e d i s s o l u t i o n i s related to surface phenomenon, and the hypothesis of d i f f u s i o n control has been commonly discarded because of the f a i l u r e to i d e n t i f y a residual layer with the a i d of modern spectroscopic methods, such as X-ray photoelectron spectroscopy (XPS) or scanning electron microscopy (SEM). However, as pointed out by Berner et a l . (1985), i f d i s s o l u t i o n occurs along deep cracks, tubes, holes and so on, that intersect only a small portion of the mineral surface, XPS, which samples a large surface area to a small depth, i s l i k e l y to miss cation depletions on the walls of these etch p i t s . Hence, the f a i l u r e to detect cation depletion does not prove absolutely that discontinuous altered layers are not formed. In fact, P e t i t et a l . (1987) have presented the f i r s t d i r e c t evidence of s u r f i c i a l hydration of s i l i c a t e minerals using a resonant nuclear reaction (RNR), which allows d i r e c t hydrogen p r o f i l i n g . The presence of defects, providing points of access surface energy, would l i k e l y f a c i l i t a t e the d i f f u s i o n of molecular water into the c r y s t a l thereby enhancing reactions with the s i l i c a t e net-work. I t should be added that d i f f u s i o n of molecular water had already been detected during the d i s s o l u t i o n of s i l i c a t e glasses and was invoked by Veblen and Busek (198 0) and Eggleton and Boland (1982) as the c o n t r o l l i n g step for the 24 weathering of pyroxenes. I t may be summarized that indeed an a l t e r e d surface layer develops on minerals exposed to solutions. The only question s t i l l unanswered concerns the rate-determining step or the k i n e t i c s of d i s s o l u t i o n . At any rate, i f i t i s true that for most s l i g h t l y soluble minerals the rate of d i s s o l u t i o n i s controlled by reactions at the surface (with or without a leached l a y e r ) , t h i s rate w i l l depend on the coordinative interactions taking place on these surfaces. Furrer and Stumm (1983) have proposed that reaction rates c o n t r o l l i n g d i s s o l u t i o n of most hydrous oxides and aluminum s i l i c a t e s simply depends on the concentration of species i n t e r a c t i n g with the surface. Their study showed that the d i s s o l u t i o n rate of 5-A1203 i n d i l u t e acids (pH 2.5-6) depended d i r e c t l y on both the extent of surface protonation and on the concentration of surface complexes formed i n -the presence of oxalate, s a l i c y l a t e , c i t r a t e and benzoate. Furthermore i t was concluded that the e f f e c t of the ligand became superimposed on that of surface protonation. The t o t a l d i s s o l u t i o n rate can therefore be considered to be composed of two or more additive rates: RTOT = RH + R = t o t a l rate of d i s s o l u t i o n i n mol m"J h"' R „ = rate of proton-promoted d i s s o l u t i o n R,.= rate of ligand promoted d i s s o l u t i o n I t should be noted that the increase i n weathering rate 25 of 5-Al 20 3 upon increase i n proton concentration was not l i n e a r but rather proportional to [H*] to the 0.4 power. Many other common minerals have also been reported to undergo f r a c t i o n a l order d i s s o l u t i o n i n acids, (eg. K-feldspar [H*]033) ; Wallast, 1967; Grandstaff, 1977, and Schott et a l . , 1981). Grandstaff (1986) reported that reaction rates for f o r s t e r i t i c o l i v i n e are f i r s t order with respect to hydrogen a c t i v i t y and approximately proportional to the square root of free-ligand a c t i v i t y . He also comments on the mechanism by which organic ligands may influence the d i s s o l u t i o n rate of o l i v i n e . According to t r a n s i t i o n state reaction theory, a reaction or series of reversib l e reactions occurs, giving r i s e to an activated complex (Aagaard & Helgeson, 1982). The activated complex of undetermined stoichiometry, may then decompose to y i e l d reactants (reverse reaction) or products dissolved i n solution (forward reaction). Organic ligands adsorbed on the surface of the mineral may form metal-organic complexes with ions i n the activated complex, d e s t a b i l i z i n g i t and providing an a l t e r n a t i v e pathway for decomposing the activated complex. The metal-organic complexes then desorb to y i e l d dissolved products. The concepts given for d i s s o l u t i o n of hydrous oxides have been extended to the weathering of k a o l i n i t e (Wieland and Stumm, 1987). Hydrogen ions and ligands may associate with the octahedral (Al-bearing) or tetrahedral (Si-bearing) sheets. Wieland and Stumm (1986), found that oxalate and 26 s a l i c y l a t e accelerated the di s s o l u t i o n reaction of k a o l i n i t e through attack of the A l centers. This f a c i l i t a t e d the (slower) detachment of the A l species, which i s followed by the (faster) detachment of the s i l i c a u n i t s . Robert (1970), and Boyle et a l . (1974) have shown experimentally the d r a s t i c e f f e c t of organic complexing agents on micas and micaceous clays. Not only the i n t e r l a y e r and tetrahedral A l , but even a considerable part of the aluminum of the octahedral layer was complexed. The sheet structure was completely destroyed as the constituents became s o l u b i l i z e d or amorphous. Recent work i n the f i e l d of geochemistry has therefore helped c l a r i f y the debate on the r e l a t i v e importance of proton vs. ligand weathering of aluminosilicates. Whether or not the ligand f a c i l i t a t e s breakdown through attack of octahedral aluminum or raises the concentrations of complexed ions i n solutio n thereby, extending the domain of congruent d i s s o l u t i o n , i t seems certain both proton and ligand attack can occur simultaneously and not one exclusive of the other. B. WEATHERING AND THE FORMATION OF PRECIPITATION PRODUCTS Weathering of rocks and minerals may r e s u l t i n a vast spectrum of p r e c i p i t a t i o n products as ions brought into s o l u t i o n exceed saturation. These inorganic ions also i n t e r a c t with organic ions and depending on such factors as 27 charge and molar r a t i o s of the constituent ions, may form s o l i d s of varying degree of c r y s t a l l i n e order. Much of the research studying these p r e c i p i t a t i o n products has focused on the formation of sesquioxides due to t h e i r common occurrence i n s o i l s . I t was anticipated that due to the high a f f i n i t y of organic acids for Fe and A l , sesquioxide development might occur i n the Batch and Column experiments. A study was undertaken therefore of the l i t e r a t u r e pertaining to sesquioxide development 1 . Forms of Sesquioxides a) Fe oxides Fe oxides, oxihydroxides and hydroxides ( c o l l e c t i v e l y referred to as Fe oxides) are among the most common minerals formed during rock weathering. They vary i n mineral species (goethite, hematite, lepid o c r o c i t e , maghemite, f e r r i h y d r i t e ) and, a d d i t i o n a l l y for any mineral, i n c r y s t a l l i n i t y and A l -for Fe substitution i n the structure. A l l the parameters may r e f l e c t the weathering environment. The various Fe oxides with a high s p e c i f i c surface profoundly influence both chemical and physical properties of s o i l s (e.g. bulk density, porosity, structure, surface charge and anion retention) (Jou,1977).In fact, i t i s now widely believed that oxides of Fe and A l i n s o i l s can provide many more s i t e s for adsorption of a c i d i c organic substances than can clays including smectites ( P a r f i t t et a l . 1977). 28 Forms and formation of Fe oxide minerals i n natural and synthetic environments have been reviewed by Oades and Townsend (1963), and more recently by Schwertmann and Taylor (1977), and Sposito (1984). Among the Fe compounds goethite (FeOOH) i s most often found i n s o i l s as i t i s the most thermodynamically stable (Sposito, 1984). In the presence of Fe-complexing ligands that i n h i b i t c r y s t a l l i z a t i o n , however, f e r r i h y d r i t e (Fe 20 3. 2Fe00H. 2 . 6H20) may p r e c i p i t a t e from s o i l s o l u t i o n (Sposito, 1984), and even the c r y s t a l l i z a t i o n of f e r r i h y d r i t e may be obstructed by the adsorption of s o i l organic matter on i t s surface (Schwertmann, 1966). Cle a r l y the presence of organic ligands i n s o l u t i o n d i r e c t s the transformations of Fe oxides to a remarkable degree. Schwertmann (1966) , investigated the e f f e c t s of a number of low molecular weight a l i p h a t i c carboxylic and hydroxy-carboxylic acids on the c r y s t a l l i z a t i o n of hematite and goethite from freshly p r e c i p i t a t e d f e r r i h y d r i t e . The hydroxy-carboxylic (polybasic) compounds (e.g. c i t r i c acid) i n h i b i t e d c r y s t a l l i z a t i o n whereas the non-hydroxy carboxylic acids (e.g. o x a l i c acid) did not. Furthermore, Fischer and Schwertmann (1975), demonstrated that the addition of oxalic acid to an aqueous system containing f e r r i h y d r i t e (at pH 6 and 70°C) favoured the c r y s t a l l i z a t i o n of hematite over that of goethite. I t was suggested that oxalate accelerated the nucleation of hematite 29 c r y s t a l s by acting as a template, with Fe-Fe distances i n Fe-oxalate (0.56nm) being s i m i l a r to those i n hematite (0.54 nm). On the other hand, where c i t r i c acid provided the organic ligand, oxidation of F e - c i t r a t e yielded pure goethite. In addition to differences i n type of organic ligand, differences i n concentration play a key r o l e on determining which ir o n oxide w i l l form. Schwertmann (1986), concludes, "the higher the concentration of organic compounds compared with the rate of release of Fe from primary s i l i c a t e s , the greater the p r o b a b i l i t y that goethite w i l l be the dominating or only f e r r i c oxide formed." I f the rate of Fe supply i s high along with higher concentrations of organic matter, f e r r i h y d r i t e w i l l form. At s t i l l higher organic matter content a precursor of f e r r i h y d r i t e often occurs and can be considered a young metastable Fe-oxide of low s t r u c t u r a l order and high surface area. Its transformation to more stable forms may be considerably retarded by adsorbed s i l i c a and organics (Schwertmann, 1985). F i n a l l y , even at higher organic matter content, a l l the Fe may be organically complexed such as i n "0" horizons or i n peaty environments and no more Fe oxides w i l l be formed (Schwertmann, 1988). As a r e s u l t of such studies the hematite-goethite r a t i o i n s o i l s has been used to discern the C-regime and, i n turn, the climate. Figure 1 summarizes the possible pathways of Fe oxide formation under near pedogenic conditions. I t should be noted however that amorphous pr e c i p i t a t e s or gels of Fe, i n 30 fast hydrolysis • l idot ion of organic ligands FERRIHYDRITE dohydrof ion • roorrongomsnl d is I 6 Iw* Jon ( pro - J dominonf ly by c o m p U i i o n ) ^ i low hydrolysis, ot idol iow of o r g a n i c l igowds dissolut ion hy reduct ion C O j • procipif a l i en • SIDERITE o i i d o f ion prvcipifofien Fr 3 * r j . d«hydrol ion, lh«n o i ido l ion ( l lew) J I I I I \ • { F ^ ' F e " HYDROXY SALT • i idofion ( fasf) , Ihon part, dohydration -—SLEPIOOCHOCITE l i e n > Figure 1: Possible pathways of iron oxide formation under near pedogenic conditions. Source: Schwertmann, and Taylor, 1977. -6 r-\ Fe(OH)3 (amorp) Fe(OH)3 (Soil-Fe) •y-F*203 (maghemite) •y-FeOOH (lepidocrocite) Source: Lindsay, 1979. Figure 2: The a c t i v i t y of F e 3 + maintained by Fe(III) oxides and soil-Fe. 31 association with organic and inorganic anions, are not d e t a i l e d i n the diagram. To date there appears to be l i t t l e base l i n e data i n s o i l science l i t e r a t u r e chemically characterizing such gels. b) A l oxides A l i n s o i l solutions and freshwater undergoes hydrolysis and may give r i s e to precipitated Al hydroxides (Hsu, 1977). The p r e c i p i t a t e s may c r y s t a l l i z e into 3 polymorphs, namely bayerite, g i b b s i t e or nordstrandite depending on the rate of p r e c i p i t a t i o n , pH of the system, clay surface and nature and concentration of inorganic anions (Hsu, 1977). Also the oxyhydroxides with two polymorphs diaspore and boehmite may form. The mechanisms governing t h e i r development s t i l l remain obscure. A l can also enter the structure of Fe3* oxides and replace Fe3*. Substitution of A l for Fe appears to be widespread i n s o i l s (Schwertmann and Taylor, 1977). In the presence of s i l i c i c acid which has a strong a f f i n i t y for A l (Luciak and Huang, 1974), further hydrolysis and polymerization of the 0H-A1 polymers i s retarded. These counter polyvalent anions tend to l i n k 0H-A1 polymers together but i n d i s t o r t e d arrangements. S i m i l a r l y , many organic acids promote the formation of p r e c i p i t a t i o n products of Al which are non-crystalline to X-rays (Huang and Violante, 1986). As i l l u s t r a t e d i n a study 32 using c i t r i c acid (Kwong and Huang, 1975,1977), the occupation of the coordination s i t e s of A l by c i t r a t e ions, instead of water molecules, disrupts the hydroxyl bridging mechanism indispensible f o r the formation of hydroxy-Al polymers. I t was found i n t h i s study that as l i t t l e as 1 uM c i t r i c acid altered the p r e c i p i t a t i o n behaviour of A l . Due to s t e r i c factors, the perturbing ligands occupying the coordination s i t e s of A l d i s t o r t the arrangement of the unit sheets normally found i n c r y s t a l l i n e A l hydroxides as shown below: Al H ,0v v0 H Al C-0 C-II 0 -CH, Hydroxyl bridging mechanism of _». edge-Al is hampered by the citrate The a b i l i t y of organic ligands to disrupt hydrolysis of A l i s determined lar g e l y by the a f f i n i t y of the acid for Al (reflected i n the s t a b i l i t y constant) and the organic ligand to A l r a t i o (determined by the concentration of acid). 2. Evolution of Sesquioxides Much of the research on formation of sesquioxides has arisen from the study of Podzol development. In p a r t i c u l a r , debate has centered on whether sesquioxides are transported to the Bj horizon by complexing organic compounds (Schnitzer and Kodama, 1977; Buurman and Van Reeuwick, 1984), or whether 33 as short range order s i l i c a t e s upon which organic matter i s subsequently pre c i p i t a t e d (Farmer, 1981; Farmer et a l . 1980; Anderson et a l . 1982; Farmer et a l . 1985). A summary of these arguments sheds some l i g h t on the chemistry of sesquioxide formation from solution, as affected by the presence of organic acids. a) Inorganic Fe-Al-Si Sols During the 1970's, i t was apparent that hydroxyaluminum species react with o r t h o s i l i c i c acid at pH< 5 to give stable sols or solutions; the soluble phase was termed proto-imogolite, since i t s infrared spectrum indicated a close s t r u c t u r a l relationship to imogolite (Farmer and Fraser, 1978; Farmer et a l . 1977,1978,1979). I t i s proposed that there i s ample Si0 2 i n most s o i l solutions ( t y p i c a l l y 10-40 ppm) to ensure that imogolite rather than aluminum hydroxides form when a reactive aluminum species i s l i b e r a t e d by the weathering of minerals (Farmer, 1979). In 1982, Anderson et a l . concluded that imogolite-type materials formed i n the B2 horizons, i n the f i r s t stage, can be deposited only from solutions containing a p o s i t i v e l y charged hydroxy-aluminum s i l i c a t e complex. These solutions cannot, as argued by Farmer et a l . (1980) simultaneously transport negatively charged organic matter except as a minor component sorbed on the po s i t i v e c o l l o i d . Iron was stated to be present almost e n t i r e l y as a separate oxide phase, with 34 very l i t t l e of i t incorporated into imogolite type phases. The idea that Fe and A l are not combined i n a single inorganic complex was based on the findings that although the A l : Fe r a t i o i n B2 horizons l i e s between 1.5 and 2.0, a c e t i c acid extracted about 20% of the oxalate-extractable A l , but less than 1% of the oxalate-extractable Fe. Also Kerndoff and Schnitzer (1980), showed that humic acids have a much greater a f f i n i t y for hydroxy-ferric species than for aluminum ion species i n acid solutions,so i t was argued that any mechanism that generates f e r r i c species, even in low concentration would l i k e l y form f e r r i c organic rather than inorganic species. However, Farmer and Fraser (1982) succeeded in synthesizing at pH 4.5 and 5.0 a stable Al 20 3-Fe 20 3-Si0 2-H 20 sol with Fe: A l molar r a t i o s up to 1.5 (wt/wt) a f t e r which s t a b i l i t y decined rapidly.These results pointed out that mixed Fe-Al hydroxide sols, with or without incorporated s i l i c a , could transport A l and Fe i n podzols and account for the constancy i n oxalate extracts from podzol B2 horizons of the Al:Fe r a t i o s of 1.5-2.0. Hydroxy-Fe species and o r t h o - s i l i c i c acid do not form structures analogous to imogolite (McBride et a l , 1984), although Fe3* has been shown to interact with monomeric s i l i c i c a c id Si(0H) 4 i n d i l u t e acid aqueous solutions to form r e l a t i v e l y stable FeSiO (OH) 32* complexes (Weber and Stumm, 1965). This complex i s monomeric at pH<3.0 and both monomeric and polymeric between between pH 3.0 and 6.0 (Olsen and 35 Omelia, 1973).The extent of Fe substitution f o r Al within imogolite/proto-imogolite structures was investigated by McBride et a l . 1984. ESR spectra indicated that the non-c r y s t a l l i n e precursor of imogolite ( i . e . proto-imogolite) can incorporate Fe3*; Fe3* tended, however, not to substitute randomly i n the s o l i d but segregated into "clustered" Fe 3*-rich phase, even at Al:Fe r a t i o s as high as 40. Segregation was almost complete for Al:Fe r a t i o s of one or l e s s . A mechanism was suggested wherby A l was ejected from an i n i t i a l l y Fe-rich polymer, and then reorganized to form an almost Fe-free proto-imogolite allophane. Such a process, therefore, could account for the high c o l l o i d a l s t a b i l i t y of the mixed AljOj-FejO^-SiOj-H20 so l s , since the dispersed phase could consist of a f e r r i h y d r i t e core protected by a proto-imogolite surface structure. The deposition and p r e c i p i t a t i o n of inorganic sols may occur when the pH r i s e s (>5 for proto-imogolite), or when the p o s i t i v e charges that maintain dispersion at more acid pH values, are neutralized by adsorbed anions, or when these p o s i t i v e c o l l o i d s encounter negatively charged surfaces (Farmer, 1979) . b) Organic Sesquioxide Interaction The formation of sesquioxides in the presence of organic substances was studied over half a century ago by Baudisch and Albrecht (1932), who investigated the oxidation of a mixed 36 s o l u t i o n of ferrous ions and pyridine by a i r , and by Glesmer (1938), who studied the reaction of NaN02 p r e c i p i t a t i n g a mixed so l u t i o n of ferrous ions and hexamethylene tetramine. In 1964 Van Schuylenborgh reported that one mechanism which could account for the formation of sesquioxides from a m e t a l l i c organo-complex was that of hydrolysis. Giving an example of a mononuclear complex, the o v e r a l l equation of such a reaction was presented as: MZ""m + nOH" == M(OH)„ + Z" where M represents the metal Fe or A l , n the valency, Z the organic acid with b a s i c i t y m and MZ""" the complex. The equilibrium constant for t h i s process i s then given by the expression: K= [ M(OH)n ] [ Z-ro ] [ MZ""" ] [ OH"]" As soon as s o l i d M(OH)n exists i n the system, [M(OH)n] becomes constant and the equilibrium (hydrolysis) constant can then be represented by: Kh= [ Z " ] and K— = K„ [ MZ""" ] [ OH" ]" [M(OH)n] Thus an increase i n hydroxyl ion a c t i v i t y ( i . e increase i n pH) tends to s h i f t the equilibrium to the r i g h t , eventually causing p r e c i p i t a t i o n of the hydroxide. Such p r e c i p i t a t i o n can be counteracted, at least i n part, by using an excess of 37 organic ligand. In a much l a t e r study (Farmer, 1979) reported that f u l v i c acid, behaving as a strongly complexing acid, could either decompose proto-imogolite to give a soluble A l - f u l v a t e plus s i l i c i c acid, or co-precipitate a l l A l and fulvate from solution, depending on the molar r a t i o of COOH: metal. S i m i l a r l y , Buurman and Van Reeuijk (1984) , concluded that metal fulvates remain soluble when undersaturated with metals and become insoluble when the metal/fulvate r a t i o r i s e s to saturation. The authors also noted that p r e c i p i t a t e d A l and Fe-saturated organic complexes may be subject to subsequent biodegredation of the organic phase. Thus b i o l o g i c a l oxidation i s another mechanism whereby the inorganic phase i s separated from the ligand. Violante and Huang (1984), suggested that the amounts of organic ligands present i n precipitates of A l depend on the nature and i n i t i a l concentration of the ligands, as well as the aging period. In t h e i r experiment more than 70-80% of t a r t r a t e , c i t r a t e and tannate ligands i n i t i a l l y present i n solution co-precipitated with Al-oxihydroxides. They also observed that the amount of c i t r a t e present i n s o l i d phase decreased during the aging period of 30 days. Violante and Huang (1984) , conclude that i n the. case of ligands such as c i t r a t e , tannate or t a r t r a t e , the anions i n i t i a l l y co-p r e c i p i t a t e d i n the non-crystalline Al gel, may be p a r t i a l l y l i b e r a t e d upon aging, f a c i l i t a i n g the transformation of the 38 non-crystalline material into pseudoboehmite. However, the released ligands which have a strong a f f i n i t y for A l could be readsorbed on the surfaces of the s o l i d phase during aging. The work of Violante and Huang also supports that of Yoldas (1973), who found that during the formation of pseudoboehmite by hydrolysis of aluminum alkoxides, the i n i t i a l noncrystalline materials contained considerable -OR groups (-OC4H,, -OC3H7 etc.) which were responsible for the st r u c t u r a l disorder of the material. During the aging period, the i n i t i a l l y noncrystalline materials were converted into pseudoboehmite with a gradual l i b e r a t i o n of -OR groups. 3. Extraction of Sesquioxides The s e l e c t i v e removal of naturally occurring sesquioxides from s o i l s and clays represents a serious a n a l y t i c a l problem i n that many clay minerals are sensitive to attack under the conditions most conducive to dissolution of Fe, Al and S i oxides, namely at low pH. The methods currently i n popular use re l y upon three extractants, namely a pyrophosphate reagent, an acid-oxalate reagent and a dithionate c i t r a t e reagent. Each reagent i s thought to extract d i f f e r e n t forms of Fe, Al and S i . I t must be reca l l e d , however, that a continuum of c r y s t a l l i n e order exists, ranging from no long-range order to well c r y s t a l l i n e , characterized by 3-dimensional p e r i o d i c i t y over appreciable distances ( F o l l e t , 1965). I t i s , therefore d i f f i c u l t to assess adequately the portion of t h i s continuum 39 that i s being extracted by any p a r t i c u l a r reagent. a) Pyrophosphate Extraction Pyrophosphate reagent has been used for many years to extract organic compounds from s o i l (Bremner and Lees, 1949) . I t i s used at neu t r a l i t y (pH 7) to lessen oxidative breakdown, or at an al k a l i n e pH (pH 10) as organic matter i s more soluble, and c r y s t a l l i n e inorganic Fe compounds les s soluble, at t h i s higher pH (Bascomb, 1968). In recent years, extraction of s o i l s with 0.1M sodium pyrophosphate has been widely used to indicate the amount of Fe and A l associated with organic matter (Farmer et a l . 1983) and as a basis of di s t i n g u i s h i n g spodic and podzolic B horizons from others (McKeague and Schuppli, 1982) . Pyrophosphate i s s p e c i f i c f or Fe-organic complexes and somewhat less s p e c i f i c for Al-organic complexes. The S i l e v e l s extracted by prophosphate are usually very low ( P a r f i t t and Childs, 1988). The o r i g i n a l techniques of extracting Fe and A l from s o i l s by McKeague (1966) , and Bascomb (1968) d i f f e r e d by using Na- and K-pyrophosphate, respectively. McKeague*s method has since been modified by introducing alternative techniques for the c l a r i f i c a t i o n of the suspensions, and by requiring the s o i l to be ground to <150um before analysis (Canada S o i l Survey Committee, 1976). In 1982 McKeague and Schuppli reported that centrifugation for longer times or at higher speeds progressively decreased concentrations of Fe and Al 40 pyrophosphate extracts of s o i l . They concluded that part of the Fe and A l measured i n these extracts was not i n dissolved form but present i n the structure of suspended minerals thereby overestimating l e v e l s at lower centrifugation speeds. This material, amorphous to X-rays, might have been fi n e p a r t i c u l a t e amorphous material present i n the s o i l sample, or i t might have formed by coagulation of solutes i n the pyrophosphate extract. Probably, because of t h i s peptization problem, the pr e c i s i o n of r e p l i c a t e determinations by using pyrophosphate reagent has been found to vary (Loveland and Digby, 1984), and comparison of results cannot be made with confidence. The continued use of the reagent has therefore been questioned (Loveland and Digby, 1984; Schuppli et a l . 1983) . b) Ammonium Oxalate Extraction Acid oxalate reagent (Tamm,1922), i s ammonium oxalate/ o x a l i c acid at pH 3 and t h i s , or s i m i l a r reagents, i s an established extractant for s o i l materials with short-range order. Some laboratories use 4 hour shaking i n the dark (McKeague and Day, 1965), and some 2 hour shaking i n the dark (Schwertmann et a l . 1982). Borggard (1987), has shown that the reaction involves the formation of soluble complexes of Fe and A l with oxalate. Acid oxalate reagent i s known to dissolve, or p a r t l y dissolve, allophane, imogolite, f e r r i h y d r i t e , Fe and A l 41 associated with humus, lepidoc r o c i t e , maghemite, (Borggard, 1982; Farmer et a l . 1983) , and A l from c h l o r i t i z e d vermiculite (Fordham and Norrish, 1983). In p a r t i c u l a r t h i s reagent i s recognized as being f a i r l y s p e c i f i c f or estimating f e r r i h y d r i t e concentrations (Schwertmann et a l . 1982). Childs (1985), has proposed that f e r r i h y d r i t e concentrations (weight %) may be estimated as Fh e s t = 1.7 x Fe% ( o x ). A note of caution: t h i s value may be overestimated by the presence of poorly c r y s t a l l i n e l e p i d o c r o c i t e , magnetite or organic matter complexes, a l l of which may be attacked by acid oxalate (Borgarrd, 1987). Also the value may be underestimated where adsorbed species such as s i l i c a t e i n h i b i t d i s s o l u t i o n ( P a r f i t t and Childs, 1988). The difference between ammonium oxalate and CBD extractable Fe gives a measure of c r y s t a l l i n e inorganic Fe. These two extractants are beleived to be less useful i n distinguishing forms of A l and S i i n s o i l s (Borgaard, 1987), and i n fact Wada (1977) reports that non-crystalline s i l i c a i s not dissolved by ammonium oxalate. c) C i t r a t e Bicarbonate Dithionate Extraction The objectives of the CBD method are pri m a r i l y the determination of free Fe oxides and the removal of amorphous coatings and c r y s t a l s of free Fe oxide acting as cementing agents, for subsequent physical and chemical analyses of s o i l s , sediments and clay minerals (Mehra and Jackson, 1960). 42 Prerequisite to a good method for removal of free i r o n oxides i s a reagent with a high oxidation p o t e n t i a l ( i . e . a good reducing agent). A chelating agent i s also required for sequestering Fe2* and Fe3* ions. The CBD system employs sodium c i t r a t e as a chelating agent, sodium bicarbonate (NaHC03, pH 7.3) as a buffer, and sodium dithionate (Na2S204) for the reduction (Mehra and Jackson, 1960). The reaction i s c a r r i e d out for 15 minutes at 80°C. I t has been claimed that t h i s reagent r e s u l t s i n almost complete solution of Fe oxides, including f e r r i h y d r i t e , without d i f f e r e n t i a t i o n between various c r y s t a l forms (McKeague and Day, 1966). In addition to free Fe oxides, A l -substituted c r y s t a l l i n e hematite and goethite are dissolved by t h i s treatment (Norrish and Taylor, 1961; Fey and Le Roux, 1977). Magnetite and ilmenite, however are not extracted by CBD (Walker,1983). A considerable amount of hydroxy aluminum in t e r l a y e r s of vermiculite c h l o r i t e i s also extracted, but g i b b s i t e i s l i t t l e effected (Dixon and Jackson, 1962). 43 RESULTS AND DISCUSSION; SECTION I A. Dissolution of Ca, Mg, K, Na, Fe, A l and S i by 5 Leaching Treatments The analysis of solution extracts i s given i n Appendix C and depicted graphically i n Appendices B and C. Mass balance calculations, given i n Appendix N, estimate the percentage of each ion from the parent rock brought into solution. Tables 3 and 4 l i s t the source minerals from which each ion originated. Table 5 notes the r e l a t i v e changes i n XRD peak i n t e n s i t i e s i n b a s a l t i c and granodiorite minerals following 11 weeks of weathering. These Tables have been placed at the end of Results and Discussion Section I for reference. For the sake of c l a r i t y , only the key features of the solution analysis are highlighted i n the following discussion. 1. Iron and Magnesium The a b i l i t y of c i t r i c acid and o x a l i c acid to chelate Fe and Mg depended upon the parent material which was subjected to weathering. The graphs i n Appendixes B and C and s t a t i s t i c a l analysis to the 95% confidence l e v e l c l e a r l y show that o x a l i c acid was a more powerful extractant of Fe and Mg from granodiorite than was c i t r i c acid. The complete reversal occurred in' the d i s s o l u t i o n of basalt. In t h i s case c i t r i c 44 acid chelated 3-4 times the amount of Fe and Mg than did o x a l i c acid. According to s t a b i l i t y constants (See Table 2) oxalate i s less e f f e c t i v e than c i t r a t e as an Fe and Mg chelator but i t must be remembered that these values are derived for simple nutrient solutions for the s p e c i f i c metal i n question. However, the a b i l i t y of a ligand to chelate Fe or Mg cannot be determined merely by i t s s t a b i l i t y constant for each cation. Differences between t h i s constant and s t a b i l i t y constants for competing ions must be considered, along with differences i n concentration between Fe 3 + and competing ions. In addition the pH of the solution w i l l determine the charge of the organic ligand, and therefore the s t a b i l i t y of the bond between metal and anion. F i n a l l y , the mineralogical makeup of the parent material as well as i t s active surface area can e f f e c t the degree of extraction. Each of these factors w i l l be considered i n more d e t a i l i n the hope of explaining the experimental r e s u l t s . F i r s t of a l l , reference i s made to the fact that at pH of greater than 4.2, Mg can outcompete Fe i n solution for the oxalate ligand. This competition i s graphically displayed in Figure 3 (Cline et a l . 1982). In contrast Fe can outcompete Mg for the c i t r a t e ligand up to pH 6.4 (See Figure 3). The pH of the o x a l i c solution i n contact with basalt was, on the average, 4.0 or higher. Under these conditions Mg, which was released from basalt i n much greater' amounts than from 45 L ° 9 Coi Equilibrium Reaction Citrate Oxalate Source Ca + L = CaL 4.25 2.64 (3) , (4) Ca + H + L = CaflL 8.71 -Ca + 2L = CaL 2 7.75 3.15 (2) 3.09 3.40 (3) , (4) CaL + L = CaL 2 3.55 - (2) 3.50 - (3) Mg + L = MgL 4.42 3.26 (2) , (4) 4.0 3.20 (3) Mg + H + L = MgHL 7.61 (1) , (2) Mg L + H = MgHL 4.2 (3) Fe + L = FeL 12.62 8.60 (1) , (2) 12.5 8.90 (3) 11.85 9.4 (4) Fe + 2L = FeL 2 15.07 (4) Fe + 3L = FeL 3 19.06 (2) Al + L = AIL 7.26 (4) 9.6 7.30 (3) AIL + L = A1L 2 5.0 (3) Sources: (1) Lindsay, W.L. 1979 Chemical Equilibria in sorts John Wiley & Sons, Inc. New York. (2) Martell, A.E. and Smith, R.M. 1977. C r i t i c a l s t a b i l i t y constants, Vol. 3: other organic ligands. Plenum Press, New York. (3) Norvell W.A. 1972. In Micronutrients in Agriculture, Ed Mortvedt, J.J. Soil Sci. Soc. of Amer. Madison Wisconson, U.S.A. (4) S i l l a n , L.G. and Martell, A.E. 1964 St a b i l i t y constants of metal-ion complexes. 2nd ed. Spec. Pub. no. 17. The Chemical Society, London. TABLE 2: STABILITY CONSTANTS OF OXALATE- AND CITRATE-METAL LIGANDS 46 Figure 3: Predicted mole fraction diagrams for cit r a t e and oxalate in a nutrient solution i n equilibrium with Fe(OH)3(amorph). HL T = sum of a l l chelated species L = free ligand Source: Cline et a l . , 1982. 47 granodiorite, could e f f e c t i v e l y suppress complexation of Fe by oxalate. Conversely, less Mg released from granodiorite could r e s u l t i n l e s s i o n i c competition between the ions for the oxalate ligand; the complexation of Fe by o x a l i c acid was therefore "apparently" more e f f e c t i v e . Ionic competition does not explain why c i t r a t e outcompeted oxalate i n extracting Mg from basalt. One would expect a l l c i t r a t e ligand s i t e s to be taken up by Fe at pH<6.4 leaving l i t t l e or no Mg-citrate complexes. However, a study by Grandstaff (1986) on the d i s s o l u t i o n rate of f o r s t e r i t i c o l i v i n e , established that c i t r a t e was more e f f e c t i v e than oxalate at pH 4.5 i n extracting Mg. Although there was no quantitative analysis to determine the percentage of f o r s t e r i t e i n the b a s a l t i c samples used i n the column and batch studies, XRD analysis determined that f o r s t e r i t e was present and could contribute to the Mg released i n solution. This could explain i n part why the c i t r i c acid solution levels of Mg were higher than o x a l i c acid b a s a l t i c extractions. On the other hand, i t has been shown by Boyle et a l . (1974) , that o x a l i c acid w i l l extract higher l e v e l s of Mg from b i o t i t e than w i l l c i t r i c acid. B i o t i t e was detected i n t h i n section observations of granodiorite and i t s presence was confirmed by XRD. This could explain why the oxalic acid solution l e v e l s of Mg were higher than c i t r i c acid granodiorite extractions. 48 The work of Manley and Evans (1986), studying acid d i s s o l u t i o n of feldspars, also demonstrated that the r e l a t i v e extraction powers of c i t r i c and oxalic acids depends upon the mineral being attacked. The d i f f e r e n t r e a c t i v i t y of the chelating agents and minerals may be due at l e a s t i n part to s t e r i c compatibility or incompatibility. Complexes which may be t h e o r e t i c a l l y possible on the basis of s t r i c t l y chemical considerations may not form because of geometric hindrance. In other words the molecular architecture may prevent ligand groups of a chelating agent from "reaching" metal ions on the surface or within the c r y s t a l l a t t i c e of the mineral. I t may very well be that differences i n size and geometry of c i t r i c and o x a l i c acid i n addition to crystallographic features of the mineral account for differences i n the d i s s o l u t i o n of basalt vs. granodiorite. As yet there appears to be very l i t t l e information i n the s o i l science l i t e r a t u r e on chelate formation which connects the c r y s t a l l i n e c h a r a c t e r i s t i c s of the mineral with morphological features of the acid. A n a l y t i c a l methods of sesquioxide determination have revealed that oxalate extracts much of the Fe from magnetite and ilmenite but l i t t l e from goethite or hematite, while the converse i s true of c i t r a t e d i t h i o n i t e bicarbonate (McKeague et a l . 1971). No mechanistic explanation has been provided. Work with sesquioxides (McKeague and Schuppli, 1985) has also pointed out that the ex a c t a b i l i t y of Fe from minerals i s 49 strongly dependent on p a r t i c l e s i z e . C i t r a t e f a i l e d to dissolve completely c r y s t a l l i n e iron oxide p a r t i c l e s coarser than 50/im. I f c i t r a t e i s more e f f i c i e n t i n attacking f i n e r p a r t i c l e s i t would also be more e f f e c t i v e i n d i s s o l v i n g b a s a l t i c p a r t i c l e s than the coarser granodiorite c r y s t a l l i n e p a r t i c l e s . I t should also be noted that the valence of Fe i n the mineral may influence i t s interaction with solutions. Schott and Berner (1983) , concluded that appreciable F e - c i t r a t e complexes could not have formed i n t h e i r experiments since only Fe (II) rather than Fe (III) which forms strong c i t r a t e complexes was present i n solution and on mineral surfaces. Perhaps t h i s p a r t l y explains why c i t r a t e i s successful i n sequestering Fe (III) from hematite but not the Fe (II) from ilmenite. At any rate, a quantitative determination of the r a t i o of Fe (III) to Fe (II) i n the basalt and granodiorite parent material might c l a r i f y why there was a reversal in extraction powers of the two acids. F i n a l l y , the pH of the extracting solution must be taken into account (See Appendix E) . The pH of o x a l i c acid weathering granodiorite was consistently less than 2 throughout the 11 weeks of the experiment. C i t r i c acid, on the other hand, was consistently greater than pH 2.0. Remembering that the pK for oxalic acid i s 1.23, at pH s l i g h t l y l e s s than 2 approximately 80% of the acid i s i n the dissociated form HL". The pK, for c i t r i c acid i s 3.14 and at 50 pH s l i g h t l y h i g h e r t h a n 2, a p p r o x i m a t e l y 99% o f t h e a c i d i s i n t h e u n d i s s o c i a t e d f o r m H 3 L . The e l e c t r o n s f r o m t h e L e w i s b a s e o f t h e d i s s o c i a t e d o x a l i c a c i d a r e t h e n a v a i l a b l e f o r c o m p l e x a t i o n w i t h a m e t a l L e w i s a c i d o f t h e m i n e r a l , whereas no s u c h e l e c t r o n s a r e a v a i l a b l e f r o m t h e u n d i s s o c i a t e d c i t r i c a c i d . W e a t h e r i n g w i l l p r o c e e d s o l e l y b y a c i d o l y s i s i n t h e c i t r i c a c i d s o l u t i o n , and even s o , t h e o x a l i c a c i d s o l u t i o n , i n a d d i t i o n t o c o m p l e x a t i o n , c o u l d o u t c o m p e t e c i t r i c a c i d t h r o u g h t h e a c t i o n o f a c i d o l y s i s due t o t h e g r e a t e r number o f H + i o n s a v a i l a b l e i n s o l u t i o n a t a l o w e r pH. F u r r e r and Stumm (1983) c o n d u c t e d a s t u d y o f t h e d i s s o l u t i o n o f S - A I 2 O 3 i n d i l u t e a c i d s (pH 2 . 5 - 6 . 0 ) , and t h e i r f i n d i n g s s u p p o r t t h e e x p l a n a t i o n g i v e n a b o v e . I n t h e c a s e o f c i t r a t e , b u t n o t o x a l a t e , t h e r a t e R L I G A N D d e c r e a s e d b e l o w pH=4.5. The a u t h o r s c o n c l u d e d , "most l i k e l y t h i s d e c r e a s e was c a u s e d by t h e p r e s e n c e o f p r o t o n a t e d s u r f a c e l i g a n d s a t l o w e r pH v a l u e s . " I n t h e c a s e o f o x a l a t e , o v e r t h e pH r a n g e i n v e s t i g a t e d t h e d e p r o t o n a t e d s u r f a c e c o m p l e x p r e v a i l e d . T h u s , a m e t a l o r g a n i c complex may h a v e a h i g h s t a b i l i t y c o n s t a n t b u t u n l i k e l y t o form b e c a u s e t h e l i g a n d h a s a g r e a t e r a f f i n i t y f o r H + t h a n f o r t h e m e t a l i o n , and t h e m e t a l i o n may h a v e a g r e a t e r a f f i n i t y f o r OH" t h a n f o r t h e o r g a n i c l i g a n d . F i n a l l y l e v e l s o f Fe e x t r a c t e d f r o m b a s a l t and g r a n o d i o r i t e r e v e a l f o r t h e most p a r t h i g h e r l e v e l s b r o u g h t i n t o s o l u t i o n i n t h e b a t c h e x p e r i m e n t compared w i t h t h e column e x p e r i m e n t . T h i s r e s u l t s u p p o r t s t h e f i n d i n g s o f S i e v e r and 51 Woodford (1979) who observed that the d i s s o l u t i o n of mafic minerals i n buffered solutions was more rapid when a i r was excluded. In the more oxidizing environment of the column experiment, d i s s o l u t i o n i n the presence of oxygen may be slowed by the armoring e f f e c t of a Fe (0H)3 p r e c i p i t a t e . Also the contribution of physical weathering as a r e s u l t of shaking cannot be overlooked. 2 . C a l c i u m Mass balance calculations (Appendix N) and AA spectrophotometry analyses for dissolved Ca, depicted i n Appendix B and C, point to the a b i l i t y of c i t r i c acid over other acids i n extracting Ca, from both basalt and granodiorite. In t h i s case therefore the influence of parent material i s overshadowed by other factors which determine the extracting power of the acids. Also the differences i n s t a b i l i t y constants cannot be used i n the case of c i t r i c and o x a l i c acids as the strength of the Ca-ligand complexes are comparable for both (See Table 2) . I t i s more l i k e l y that the answer presents i t s e l f i n the XRD analyses (Appendix K) of the yellow p r e c i p i t a t e which formed i n the oxalic acid leaching treatments of basalt and granodiorite. The D-spacing peaks of Ca-oxalate appear at 3.19, 2.37 and 1.89 A0 confirming the presence of t h i s s a l t i n the p r e c i p i t a t e . This s a l t i s highly insoluble and although oxalic acid may have e f f e c t i v e l y competed with c i t r i c acid i n detaching Ca from the 52 mineral much less would remain i n soluble form. The formation of a Ca-oxalate p r e c i p i t a t e might also explain why the acetic a c i d solution showed s i g n i f i c a n t l y higher l e v e l s of dissolved Ca f o r b a s a l t i c column samples even though the s t a b i l i t y constant (pK = 1.24) for the Ca-acetic ligand was less than that for the Ca-oxalic ligand (pK =3.4). At the 95% l e v e l there was no s i g n i f i c a n t difference i n s o l u b i l i z e d Ca from o x a l i c and acetic acid leachates i n the batch experiment. 3 . Aluminum The s o l u b i l i t y of Al i n equilibrium with aluminum oxide and hydroxide minerals i s highly pH dependent, decreasing 1000-fold f o r each unit. (See Figure 4). Amorphous A1(0H) 3 i s the most soluble form of aluminum hydroxide expected i n s o i l s ; when the a c t i v i t y of A l 3 + i s controlled by amorphous A1(0H) 3 rather than gibbsite the a c t i v i t y of A l 3 + i s approximately 42 times higher (Lindsay, 1979). Figure 5 shows the a c t i v i t y of A l 3 + and i t s hydrolysis species i n equilibrium with gibbsite. The A l 3 + ion i s predominant below pH 4.7 and i s octahedrally co-ordinated to s i x molecules of water forming A1(H 20) 6 . A1(0H)2+ i s predominant between pH 4.7 and pH 6.5, A1(0H) 3 between pH 6.5 * and 8, and A1(0H) 4 above pH 8. A c t i v i t y of A l 3 + i n solution i s not predictable from pH alone however. For example, the presence of s i l i c a at a c t i v i t i e s above 10"4 decreases the equilibrium of dissolved 2 3 4 5 6 7 8 9 PH F i g u r e 4 : The a c t i v i t y of A l 3 + and i t s h y d r o l y s i s species i n e q u i l i b r i u m with g i b b s i t e . Source: Lindsay, 1979 F i g u r e 5: The s o l u b i l i t y of v a r i o u s aluminum oxides and h y d r i d e s . Source: Lindsay, 1979 54 A l a c t i v i t i e s a t a l l pH v a l u e s ( D r e v e r , 1 9 8 2 ) . The a c t i v i t y o f A l 3 + i n e q u i l i b r i u m w i t h a l u m i n o s i l i c a t e s i n w a t e r i s t h e r e f o r e l e s s t h a n t h a t f o r a l u m i n u m o x i d e s a n d h y d r o x i d e s , a s a r e s u l t o f A l - s i l i c a t e b o n d i n g . A l u m i n u m h a s b e e n c a t e g o r i z e d b y g e o l o g i s t s a s one o f t h e l e a s t s o l u b l e e l e m e n t s r e l e a s e d f r o m a l u m i n o u s r o c k s a n d m i n e r a l s d u r i n g w e a t h e r i n g . B e c a u s e o f i t s r e l a t i v e i m m o b i l i t y i t h a s b e e n u s e d a s a r e f e r e n c e " f i x e d - e l e m e n t " a g a i n s t w h i c h t h e l o s s a n d g a i n o f o t h e r e l e m e n t s h a v e b e e n c o m p a r e d i n s t u d i e s o f r o c k a l t e r a t i o n . The g r a p h s i l l u s t r a t i n g t h e c o n c e n t r a t i o n o f A l 3 + i n s o l u t i o n (See A p p e n d i x B a n d C) f o r b o t h b a t c h a n d c o l u m n e x p e r i m e n t s show a f a i r l y l i n e a r r e l e a s e o f a l u m i n u m f r o m b a s a l t a n d g r a n o d i o r i t e a s a r e s u l t o f a c e t i c a c i d , HC1 and H 20 e x t r a c t i o n . D i s t i l l e d w a t e r was t h e l e a s t e f f e c t i v e i n d i s s o l v i n g A l 3 + a n d s u p p o r t s t h e f i n d i n g s t h a t d i s s o l v e d A l i n n a t u r a l w a t e r s y s t e m s i s l o w e x c e p t i n v e r y a c i d o r a l k a l i n e c o n d i t i o n s . The c o n c e n t r a t i o n o f A l 3 + b r o u g h t i n t o s o l u t i o n b y t h e a c t i o n o f a c e t i c a c i d a n d HC1 on b a s a l t and g r a n o d i o r i t e a t pH 4 showed no s i g n i f i c a n t d i f f e r e n c e a t t h e 9 5 % c o n f i d e n c e l e v e l a n d r a n g e d f r o m a p p r o x i m a t e l y 3.7 t o 7.4 x 10 4 M / l i t e r . T h e s e l e v e l s f a l l b e t w e e n t h e a c t i v i t y o f A l 3 + i n e q u i l i b r i u m w i t h g i b b s i t e a t i o " 4 - 9 6 M a n d a morphous A l ( O H ) 3 a t 10" 3" 3 4 M. Mass b a l a n c e c a l c u l a t i o n s showed t h a t t h e p e r c e n t a g e A 1 2 0 3 e x t r a c t e d f r o m b a s a l t i c a n d g r a n o d i o r i t i c p a r e n t m a t e r i a l was 1% o r l e s s f o r t h e s e 3 e x t r a c t i o n s . 55 The e f f i c a c y of A l extraction from granodiorite was g r e a t l y increased when organic chelating solutions acted as weathering agents. According to mass balance ca l c u l a t i o n s , c i t r i c acid extracted 4-9% and 7.6% of the g r a n o d i o r i t i c AlgC"3 from column and batch experiments respectively. Oxalic acid was even more e f f e c t i v e and extracted 13.2% and 15.8% of the g r a n o d i o r i t i c A I 2 O 3 from column and batch experiments respe c t i v e l y . Again the differences i n d i s s o l u t i o n power may be p a r t l y a t t r i b u t e d to differences i n solution pH of the two acids. The o x a l i c acid solution (pH<2.0) was s l i g h t l y less than c i t r i c acid (pH 2.2). As noted e a r l i e r o x a l i c acid was 8 0% dissociated at that pH forming HL" whereas c i t r i c acid was s t i l l 99% i n undissociated form. Both a c i d i c and chelating factors therefore favored oxalic acid. In addition the mineralogical make-up of granodiorite must be considered. As noted, Boyle et a l . (1974) have shown experimentally the d r a s t i c e f f e c t of oxalic acid treatment on micas and micaceous clays. The sheet structure was completely destroyed as the constituents became soluble or amorphous and at pH 3, the destruction of b i o t i t e was almost t o t a l . The greater attack of b i o t i t e by oxalic acid r e l a t i v e to that by c i t r i c acid was confirmed i n XRD analyses (See Appendix K). This could therefore contribute to higher l e v e l s of s o l u b i l i z e d A l i n the oxalic acid leachate. I t i s i n t e r e s t i n g to note that the graphs fo r A l extraction from b a t c h granodiorite show a constant l i n e a r 56 re l a t i o n s h i p of ion extracted versus time. This suggests that physical weathering from shaking not only broke down a cation depleted layer but opened up new surfaces to further weathering. Also, concentrations of A l 3 + dissolved i n both o x a l i c and c i t r i c acid solutions were i n approximately a 1:1 r a t i o with that of S i extracted by the same acids i n the batch experiment. A l : S i r a t i o s were <1 i n the column experiment and both o x a l i c A l and S i curves showed declining rates. Also the l e v e l s of A l extracted were lower than that for batch. A l l three observations suggest that an altered surface was not as e a s i l y detached, that p r e c i p i t a t e s may have formed and remained i n l o c a l i z e d microenvironments, or that preferred channelling through the column could have contributed to lower and d e c l i n i n g rates of dissolution, as well as incongruent weathering. The e f f i c a c y of A l extraction from basalt by c i t r i c and o x a l i c acid exceeded that of the non-chelating acids i n the f i r s t week of the experiment but quickly dropped o f f . In fact the graph (Appendix C) showing d i s s o l u t i o n of Al from basalt i n the batch experiment reveals that acetic acid and HC1 were more successful i n d i s s o l v i n g A l throughout several weeks. Examination of batch solution pH's (Appendix E) quickly point to the greater a c i d i t y of acetic acid and HC1 (pH<3.5) in contrast to c i t r i c acid (pH=4.0) and oxalic acid (pH 4.5-5.0). Differences i n pH however, do not d i r e c t l y explain why the 57 more a l k a l i n e oxalic acid solution extracted higher l e v e l s of Al than did the c i t r i c acid solution. At the respective pH's,1 the chelating e f f e c t of the oxalic L2" anion could possibly have outcompeted the H2L- anion of c i t r i c acid. F i n a l l y i t i s important to highlight the fact that soluble A l le v e l s for a l l treatments were far les s i n basalt experiments than for granodiorite experiments. This i s i n spi t e of the fact that the % A1 20 3 i n basalt as determined by XRF was 15.17%, only s l i g h t l y less than 16.61% i n granodiorite. Again i t i s to be noted that pH of extracting solutions was much higher af t e r weathering basalt than granodiorite. As pointed out by Manley and Evans (198 6), the t o t a l amount of Al released from feldspars by d i f f e r e n t organic acids was s i g n i f i c a n t l y correlated (r=.95) with the pH of solutions. Such could be the case i n the weathering of mixed minerals. Secondly, very high l e v e l s of S i which were not bound up i n quartz were released from basalt. The s i l i c a t e anion as explained e a r l i e r could have p r e c i p i t a t e d any released A l cations thereby suppressing l e v e l s of soluble A l . Also at pH < 5 hydroxyaluminum species may react with o r t h o s i l i c i c acid to give stable sols or solutions (proto-imogolite) . Thirdly, much of the A l released from granodiorite originated from b i o t i t e . The XRD peak i n t e n s i t i e s f or b i o t i t e showed the greatest decrease of any mineral subsequent to weathering by c i t r i c and o x a l i c acids. B i o t i t e was therefore less resistant to acid attack than were 58 any of the Al-bearing minerals comprising the b a s a l t i c parent material. 4. S i l i c o n The s o l u b i l i t y of s i l i c a minerals i n terms of H 4Si0 4 i s expected to range from 10"2-74M (amorphous s i l i c a ) to 10"4M (quartz) and i s determined for equilibrium i n water. This corresponds to a range of 6 to 60 ppm. Other minerals have intermediate s o l u b i l i t i e s including Si0 2 (soil) which has been estimated to have a s o l u b i l i t y i n water of 10'3'10M. The l e v e l s of s i l i c a brought into solution by d i s s o l u t i o n of basalt and granodiorite by acetic acid, HC1 and H20 were well below 60 ppm. The solutions were therefore undersaturated with respect to amorphous s i l i c a . However, the l e v e l s of s i l i c a brought into solution as a r e s u l t of o x a l i c and c i t r i c acid d i s s o l u t i o n were exceedingly high. (See Appendix N). For example, basalt leached i n the batch experiment by c i t r i c acid released approximately 2 00 x the amount s i l i c a i n water in equilibrium with amorphous s i l i c a . Oxalic acid released a l i t t l e more than 100 x the amount of s i l i c a i n equilibrium with amorphous s i l i c a i n water. No analyses were carr i e d out to discriminate what percentage of t h i s s i l i c a was i n either complexed or c o l l o i d a l form. I t i s quite l i k e l y that c o l l o i d a l p a r t i c l e s contributed to the very high readings. Elgawhary and Lindsay (1972) proposed extracting s o i l s with 0.02 M Ca i n order to keep 59 c o l l o i d a l s i l i c a flocculated during extraction, as well as f i l t r a t i o n of samples i n which s i l i c a i s measured. When t h i s procedure was used, they found that measured s i l i c a i n s o i l s o l u t i o n corresponded more nearly to the l e v e l s of H 4Si0 4 expected from s o l u b i l i t y predictions. In the case of the batch and column experiments, f i l t r a t i o n of the extraction sample should have been car r i e d out, as a f i r s t step i n segregating d i f f e r e n t forms of s i l i c a i n s o l u t i o n . I f i n fact much of the s i l i c a detected by AA spectrophotometry was c o l l o i d a l i t may be surmised that these p a r t i c l e s were brought into solution subsequent to the extraction of more e a s i l y dissolved ions such as Fe, Mg, Na, Ca or K. This unstable cation depleted al t e r e d zone, according to Berner and Schott (1982), could then break down as d i s s o l u t i o n proceeds releasing the s i l i c a t e framework. This phenomenon would explain why s i l i c a released form basalt was the highest. In the weathering experiments of Smith et a l . (1982) , the ferromagnesium minerals such as f a y a l i t e , f o r s t e r i t e and o l i v i n e , having Mg and Fe as the metaloxy groups separating Si-O-tetrahedra, offered least resistance to acid attack and released substantial amounts of monomeric s i l i c a . In contrast, much of the s i l i c a i n the granodiorite samples was bound i n the quartz f r a c t i o n , a t e c t o s i l i c a t e highly r e s i s t a n t to weathering. Again, the p o s s i b i l i t y of proto-imoqolite e x i s t i n g i n solution also cannot be overlooked as t h i s species i s soluble 60 at pH <5. As discussed e a r l i e r , investigations to determine i o n i c speciation i n chelating solutions are s t i l l i n t h e i r infancy. So far, thermodynamic data describing composition and s t a b i l i t y of organic complexes i n aqueous solut i o n are very scarce i n the l i t e r a t u r e . Henderson and Duff (1963) d i f f e r e n t i a t e d 3 d i f f e r e n t forms of s i l i c a released from minerals by the action of an oxalic-producing s t r a i n of fungi as follows: ammonium-molybidate-reactive (AMR) s i l i c a corresponding to t o t a l s i l i c a , c o l l o i d a l polymerized (CP) s i l i c a and amorphous s i l i c a . Huang and K e l l e r (1971) noted that dissolved S i i n .01 M complexing acid solutions exceeded 2-35 times i t s concentration i n d i s t i l l e d water. They did not however determine the various forms of s i l i c a brought into s o l u t i o n . Some f i n a l points are worth noting: (1) Although the curves for b a s a l t i c s i l i c a extraction by c i t r i c and o x a l i c acid intersected at week 5 i n the column experiment, the t o t a l amounts of s i l i c a extracted i n 11 weeks were equal. Mass balance calculations (See Appendix N) indicate that t o t a l dissolved s i l i c a accounted for 8.52% of the b a s a l t i c parent material i n b o t h c i t r i c and o x a l i c acid treatments. (2) In the batch experiment c i t r i c acid extracted 11.62% and o x a l i c acid 7.52% s i l i c a from basalt. Dissolution of granodiorite showed a reversed trend. Oxalic acid extracted 61 2.24 and 2.86% of the parent material s i l i c a from column and batch respectively. C i t r i c acid on the other hand extracted 0.88% and 1.52% of the parent material s i l i c a from column and batch respectively. This reverse trend may be due to differences i n pH of the solutions, although generally, S i di s s o l u t i o n i s thought to be fa r less s e n s i t i v e to pH changes than that for other ions. In fac t the log a c t i v i t y of H 4Si0 4 i n equilibrium with various forms of Si0 2 i s constant i n the range pH 2 to pH 9, and only at pH values above 9 does the s o l u b i l i t y of s i l i c a increase sharply because of the formation of s i l i c a t e ions (Elgawhary and Lindsay 1972). However, several studies have reported that the release of H 4Si0 4 by s o i l s and many s i l i c a t e minerals greatly increased as pH changed from 7.0 to 4.0 (McKeague and Cline, 1963; Beckworth and Reeve, 1964; Huang and Jackson, 1968 and Weaver et a l . , 1968). 5 . Sodium and Potassium Hydrated metal cations such as Na+ and K+ are extremely weak acids (pKa=15) which f a i l to dissociate a proton from t h e i r enveloping sheath of water molecules u n t i l extremely high pH values are reached. Because the water molecules of the hydration sheath are doubly protonated at normal s o i l pH value, there i s l i t t l e tendency for these a l k a l i metal cations to co-ordinate with e l e c t r o p h i l i c centers on mineral surfaces. Therefore they act as i n d i f f e r e n t ions and over the pH range 62 commonly met i n s o i l s , the predominant hydration state of the ions i s constant. Thus sodium and potassium are present only as the Na+ and K+ ions i n solution. a) Sodium I t i s apparent from the mass balance c a l c u l a t i o n s and the graphs of sodium in solution vs. time (Appendices B and C) that the two chelating acids were at best only s l i g h t l y more e f f e c t i v e i n extracting Na from basalt and granodiorite than were acetic acid, HC1 or H20. In f a c t at the 95% confidence l e v e l there was no s i g n i f i c a n t difference between the concentrations of s o l u b i l i z e d Na i n the 5 extracting solutions weathering b a s a l t i c parent rock. This i s i n agreement with the finding of Huang and K e l l e r (1970) who reported that the dissol ution of a l k a l i ions from muscovite and microcline i n organic acids was found to be the same order of magnitude as deionized water or C0 2-charged water. The authors concluded that " i t i s u n l i k e l y that monovalent cation chelates are formed during organic acid d i s s o l u t i o n of minerals". The solution curves also point to a rapid early release of sodium followed by declining rates approaching steady state towards Week 11 of the experiment. This i s a t t r i b u t e d to either d i s s o l u t i o n of hyperfines or to the rapid exchange of H+ ions for the Na+ ion (hydrolysis). The l e v e l s of Na extracted were the highest for c i t r i c and o x a l i c acid -63 granodiorite d i s s o l u t i o n . At the 95% confidence l e v e l c i t r i c and o x a l i c acid dissolved s i g n i f i c a n t l y higher l e v e l s of Na than did the other acids. This may be due to the fa c t that c i t r i c and ox a l i c acid were the most e f f e c t i v e i n attacking hornblende, pyroxene and plagioclase, which served as sources of the Na ion. b) Potassium Mass balance calculations and solution graphs of K extracted from basalt show s i m i l a r trends to those noted for Na. F i r s t of a l l , non-chelating acids are as e f f e c t i v e i n extracting K as the chelating acids. Secondly, there occurred a rapid release of K i n the f i r s t week followed by sharply d e c l i n i n g rates of release u n t i l Week 3 of the experiment. Rates then gently increased for 1 to 2 weeks, then decreased u n t i l the end of week 11. The curves for a l l extraction treatments approached 0 at the end of the experiment suggesting that the number of active surface s i t e s of b i o t i t e or muscovite were declining. Mass balance cal c u l a t i o n s show that only a very small percentage (<2%) of the K was removed from the b a s a l t i c parent material through leaching. Evidently what remained, l i k e l y i n the muscovite, was not accessible to further i o n i c exchange with H+. Mass balance calculations and solution graphs of K extracted from granodiorite show that o x a l i c acid was successful i n extracting as much as 40% (column) and 50% 6 4 (batch) of the K contained i n the parent material. In the batch experiment t h i s amounted to approximately 5 times that of acetic acid, 12 times that of HCl, and 29 times that of H20. C i t r i c acid extracted 13% (column) and 22% (batch) of the K contained i n the parent material, also well ahead of the other three extracting acids. Does t h i s mean that the chelating acids were indeed able to complex K? The XRD analysis of weathered crust material (Appendix K2) suggests the p o s s i b i l i t y of a K-oxalate per hydrate s a l t having formed; however, a more l i k e l y clue i s given i n the X-Ray d i f f r a c t i o n analyses (Appendix I) which shows a dramatic drop i n i n t e n s i t y for the b i o t i t e peak weathered by o x a l i c and c i t r i c acid. As noted e a r l i e r , o x a l i c acid i s extremely e f f e c t i v e i n d i s s o l v i n g b i o t i t e through attack of Mg and Fe i n the octahedral layer. Subsequent oxidation of octahedral Fe i s associated with ejection of octahedral cations, loss of i n t e r l a y e r K, and a contraction of the b-dimension of the b i o t i t e sheet (Gilkes, R.J. and Suddhiprakarn, A. 1979). The K detected i n AA solution analyses could have been s o l u b i l i z e d i n d i r e c t l y following the i n i t i a l attack of Mg and Fe by the chelating acid. 65 Ion Mineral Calcium - Hornblende, Pyroxene, Plagioclase Magnesium - Olivine, Biotite, Hornblende, Pyroxene Sodium - Hornblende, Plagioclase {albite), Pyroxene Potassium - Biotite, Muscovite, K-Feldspar Iron - Pyroxene (Pigeonite, Augite, Hypersthene) - Fe(II) Hornblende - Fe(III):Fe(II) ratio often high Biotite - Fe(III):Fe(II) ratio approximately equal Olivine - Fe(II) Magnetite - Fe(III),Fe(II); Ilmenite - Fe(II), Hematite - Fe(II) Aluminium - Feldspars, Pyroxene, Hornblende, Micas Sil i c o n - Feldspars, Pyroxene, Hornblende, Quartz, Micas, Olivine TABLE 3: SOURCE OF IONS FROM BASALTIC AND GRANODIORITIC PARENT MATERIAL 66 Name Group Composition K-Feldspar Tectosilicate (orthoclase, Microcline) Plagioclase (oligoclase, Labradorite, anorthite) Plagioclase (Albite) Pyroxene (Pigeonite) (Hypersthene) (Enstatite) (Augite) Hornbelende (amphibole) Olivine (Fayalite) (Forsterite) Biotite Muscovite Quartz Ilmenite Hematite Magnetite Anatase Periclase Tectosilicate r Tectosilicate Inosilicate Single chain Inosilicate Double chain Nesosilicate Phyllosilicate Phyllosilicate Tectosilicate Iron Titanate Iron Oxide Iron Oxide Titanium Oxide Magnesium Oxide K Al S i 3 0 8 (Na, Ca) Al Si,0 3U8 Na A l S i 3 0 8 (Ca, Mg, Fe)Si0 3 Mg2 S i 2 0 6 (Ca,Na)(Mg,Fe,Al,Ti) ( S i A l ) 2 0 6 ( C a ' N a 2 ? " 3 3+ (Mg,Fe 2*,Fe 3 +,Al) 5 (Al, S i ) 8 0 2 2 (0H) 2 (Mg,Fe)2 Si 0 4 4 (Fe 2Si 0 4) 4[(Mg,Fe) 2 Si0 4] K(Mg,Fe 2 +) 3 ( A l , F e 3 + ) S i 3 0 1 0 (OH,F)2 K,A12(A1 S i 3 ) 0 1 Q (OH)2 X-Si0 2 FeOTiO, F e2°3 Fe 20 4 B-TiO-MgO TABLE 4 : COMPOSITION OF MINERALS IDENTIFIED IN GRANODIORITE fi BASALT BY XRD ANALYSES. 67 A. G r a n o d i o r i t e C i t r i c A c i d O x a l i c A c i d A c e t i c & HC1 HOH 0 (+) (-) 0 (+) (-) 0 ( + ) (-) 0 ('+) (-) K - F e l d s p a r P l a g i o c l a s e H o r n b l e n d e P y r o x e n e M i c a s P e r i c l a s e I l m e n i t e M a g n e t i t e H e m a t i t e Q u a r t z ** ** ** ** ** ** ** *** *** *** ** ** *** ** * * ** * * ** * B. Ba s a l t P l a g i o c l a s e H o r n b l e n d e P y r o x e n e F a y a l i t e F o r s t e r i t e M i c a s M a g n e t i t e H e m a t i t e Q u a r t z *** *** *** *** * ** *** ** ** * * ** N o t e : (0) = No change (+) = i n c r e a s e (-) ** = l a r g e c hange *** = v e r y l a r g e change. d e c r e a s e * = s m a l l change TABLE 5 : CHANGES IN XRD PEAK INTENSITIES IN BASALTIC & GRANODIORITIC MINERALS FOLLOWING 11 WEEX BATCH DISSOLUTION EXPERIMENT. 68 R E S U L T S & D I S C U S S I O N ; S E C T I O N I I B . D i s s o l u t i o n o f B a s a l t a n d G r a n o d i o r i t e b y 5 L e a c h i n g T r e a t m e n t s 1. T h e I n f l u e n c e o f K i n e t i c F a c t o r s o n t h e D i s s o l u t i o n o f B a s a l t a n d G r a n o d i o r i t e The d i s t r i b u t i o n for the concentration of i o n i c species i n s olution vs. time shown i n Appendices B and C reveal several i n t e r e s t i n g features regarding the k i n e t i c s of di s s o l u t i o n i n both batch and column experiments. The slopes of each curve indicate immediately whether or not the rate of di s s o l u t i o n i s increasing, d e c l i n i n g or l i n e a r , i e . approaching steady state. On the whole, two tendencies are apparent. F i r s t l y , the curves for c i t r i c and ox a l i c acid extractions for Fe, Mg and K, are characterized by an i n i t i a l increase i n rate, followed by dec l i n i n g rates which approached l i n e a r i t y towards the 11th week. In a l l other instances, the curves for c i t r i c and oxalic acid declined from the s t a r t and subsequently l e v e l l e d out. This i s to say that the curves for the two complexing agents suggest rapid, perhaps even parabolic d i s s o l u t i o n followed by steady-state d i s s o l u t i o n . Secondly, the curves for aceti c , HC1 and H20 extractions are l i n e a r and approximately constant, with the exception of Na+ and K+ curves, i n both basalt and granodiorite. A possible explanation for the constant l i n e a r rates over the period of 69 11 weeks may be found i n considering the r e l a t i v e extraction powers of the d i f f e r e n t acids. I t i s obvious from the atomic absorption data as well as mass balance c a l c u l a t i o n s and s t a t i s t i c a l analysis that acetic acid, HC1 and H20 weathered both basalt and granodiorite to a much l e s s e r extent than did the chelating acids. Consequently, maximal concentrations of ions brought into solution were fa r from reaching a l e v e l where p r e c i p i t a t e s might form. The reactions are f a r from equilibrium and as such represent an open system where rates of d i s s o l u t i o n of elements from minerals have been determined to be l i n e a r (Kodama et a l . 1983). In contrast, the rate of release of constituent elements i n a closed system decreases exponentially with time (Kodama et a l . 1983). Several factors could contribute to the d e c l i n i n g rates of ions brought into solution by c i t r i c and o x a l i c acid. F i r s t of a l l , a cation depleted surface layer may have developed according to the theory mentioned e a r l i e r (Correns and von Engelhardt 1938). Accordingly, as t h i s a l t e r e d layer b u i l t up, the rate of d i s s o l u t i o n decreased. Eventually, however, the depleted surface layer broke down, being unstable chemically, u n t i l i t reached an equilibrium thickness, being destroyed at the layer-solution interface at the same rate i t was formed at the layer-mineral surface. EDX analysis of weathered surfaces revealed depletion of a l k a l i and a l k a l i earth cations r e l a t i v e to S i . See Figures 16 and 17. Also analysis of the solutions, i n d i c a t i n g high l e v e l s of c a t i o n i c 70 extraction, suggest that such a leached layer possibly developed. The high l e v e l s of S i and A l both c o l l o i d a l and soluble, detected through AA spectrophotometry analysis of the solutions, are consistent with the concept that detachment of s i l i c a t e and aluminate units from the c r y s t a l l i n e framework follows the exchange of H + for a l k a l i s (AAgaard and Helgeson, 1982). Interestingly, a comparison of the d i s s o l u t i o n graphs for S i and A l i n batch and column experiments reveals a f a i r l y l i n e a r rate i n the batch experiment but d e c l i n i n g rates for the column experiment. This suggests that indeed a protective as well as a l t e r e d layer had b u i l t up i n the column experiment. In the case of the batch experiment, however, physical grinding, through shaking of samples could co n t i n u a l l y a s s i s t i n the breakdown of the chemically unstable surfaces, leading to steady-state d i s s o l u t i o n . Where the a l t e r e d surface i s not broken down, as i n the column experiment, decreasing rates of d i s s o l u t i o n occurred. There i s on the other hand, d i r e c t evidence from SEM observations that i n i t i a l weathering of superfines adhering to the surface of unweathered mineral grains could account for both the rapid r i s e then f a l l i n rates during the f i r s t few weeks of weathering. Figures 6 and 7 show the existence of hyperfine p a r t i c u l a t e matter, an a r t i f a c t of grinding, adhering e l e c t r o s t a t i c a l l y to the outer surface of the mineral. A f t e r 11 weeks of weathering the surfaces of mineral grains were clean as shown i n Figure 8. The d i s s o l u t i o n of F i g u r e 6: Hyperfines adhering to g r a n i t i c s u rface. 600 x m a g n i f i c a t i o n F i g u r e 7: Hyperfines adhering to b a s a l t i c s u r f a c e . 600 x m a g n i f i c a t i o n 72 Figure 8: Basaltic grain leached by oxalic acid for 11 weeks. Note absence of hyperfines and prominent etch-pitting. 600 x magnification 73 these p a r t i c l e s occurred more ra p i d l y than that of the bulk mineral due to greater surface area, exposed edges and the large abundance of strained or broken bonds. With time, as the p a r t i c l e s were destroyed, the d i s s o l u t i o n rate may have tapered o f f to the l i n e a r rate of destruction of the bulk mineral. Holdren and Berner (1979) demonstrated c l e a r l y that adhered f i n e p a r t i c l e s could, i n fact, be responsible for the pseudo-parabolic stage of laboratory d i s s o l u t i o n experiments. Freshly ground unwashed a l b i t e exhibited high i n i t i a l d i s s o l u t i o n rates which did not appear i f the f i n e p a r t i c l e s were f i r s t removed by HF-H2S04. Si m i l a r l y , non-linear rates of d i s s o l u t i o n may be at t r i b u t e d to the presence of edges, corners, cracks, holes etc. and at a smaller scale, point defects, i n boundaries and d i s l o c a t i o n s (Schott & P e t i t , 1987). Furrer and Stumm (1983), noted, " I f heterogeneities of surface properties (different phases, d i f f e r e n t p a r t i c l e s i z e , d i f f e r e n t surface energies) e x i s t , parabolic d i s s o l u t i o n rates are t y p i c a l l y observed. Linear rate laws are usually obtained i f the pretreatment renders the surface properties s u f f i c i e n t l y homogenous." 2 . Incongruent vs. Congruent Dissolution Congruent d i s s o l u t i o n , or a close approach to i t , has been demonstrated i n determinations of s o l u b i l i t i e s from undersaturation of simple s i l i c a t e minerals in d i l u t e aqueous 74 solutions at low to moderate temperatures when enough time has passed for equilibrium to be reached. Examples of such studies are: k a o l i n i t e 25°C, 2 years (Polzer and Keirt, 1965) ; c h r y s o t i l e 90°C, 2 months (Hostetler and Christ, 1968) magnesium s i l i c a t e s , 100 hrs. (Luce et a l . 1971) ; and o l i v i n e , 2 months (Grahdstaff, 1986). Yet many f i e l d studies have shown that s i l i c a t e s weather incongruently i n nature (Loughman, 1969). The laboratory d i s s o l u t i o n of feldspars by inorganic and organic acids has generally been observed to be incongruent (Correns, 1963; Huang and Ke l l e r , 1970 and Gardner, 1983). Usually, a l k a l i s and a l k a l i n e earths are released i n excess of s i l i c a and dissolved alumina i s least abundant. Cle a r l y i n a system whereby the parent material such as basalt and granodiorite was comprised of mixed mineral assemblages of undetermined stoichiometry, incongruent weathering was expected to take place. I t was impossible to trace the o r i g i n of ions brought into solution, so that stoichiometries of ions from mineral to s o l u t i o n could be compared. I t was however possible to draw some conclusions i n d i r e c t l y from the experimental data regarding p r e f e r e n t i a l d i s s o l u t i o n of cert a i n elements. This data supported the fact that incongruent weathering had indeed taken place, a) F i r s t of a l l , congruent d i s s o l u t i o n may be indicated by constant rates of ion released into solution. For the most part of the experiment, rates of d i s s o l u t i o n for the seven 75 ions measured by spectrophotometry were variable, generally slowing down with time. This behaviour i n part r e f l e c t s the build-up of reaction products which changes the ion a c t i v i t y product of the solut i o n with respect to the parent material. The formation of secondary prec i p i t a t e s of any kind within the system conceals the actual stoichiometry of the d i s s o l u t i o n reaction and precludes, by d e f i n i t i o n , congruent weathering taking place. The presence of both amorphous and c r y s t a l l i n e secondary p r e c i p i t a t e s was revealed by Fe, A l , and S i oxide extraction analysis, scanning electron microscopy and EDX. For example, Figure 9 shows an electron micrograph of granodiorite grains weathered by c i t r i c acid. The accompanying EDX graph shows a major peak for S i and a very minor peak f o r A l suggesting the development of an amorphous s i l i c a or alumino-silica surface. Figure 11 features a granodiorite grain weathered by oxalic acid showing a rounding and coalescence of the surface t y p i f y i n g a g e l . b) X-ray fluorescence analysis measuring the percentages of oxides i n unweathered and weathered samples may be used to determine chemical losses and gains. In p a r t i c u l a r , comparison of changes i n molar r a t i o s of the oxides, subsequent to leaching over time, provides a strong t o o l to assess whether weathering has i n fact proceeded incongruently. The following i s a summary highlighting key features which became apparent i n comparing molar r a t i o s of unweathered to weathered mineral following eleven weeks of leaching. See 76 Figure 9: Granodiorite crust materials leached by c i t r i c acid for 11 weeks. 800 x magnification C i t r i c a c i d 5000 countl I'ltp. 1 cm. Elapsed* 200 at e * ZOO ate* Rang? » 10.230 keV I n t e g r a l 0 • 1 8.?30 -» 129315 Figure 10: EDX of sample shown in Figure 9 . Note prominent Si peak. 77 Figure 1 1 : Granodiorite grain weathered by oxalic acid for 1 1 weeks N o t e c o a l e s c i n g s u r f a c e s 2 5 0 x m a g n i f i c a t i o n 78 tables i n Appendix J which give numerical values for calculated molar r a t i o s . A. Granodiorite 11 weeks - Column and Batch Experiments 1. SiOa/Al^ s r a t i o s increased s l i g h t l y for a l l treatments (Oxalic acid - greatest change) 2. Si02/R2°3 r atios increased for a l l treatments (Oxalic acid - greatest change). 3. AlgOs/FegOs r a t i o s remained the same except for ox a l i c acid which showed a very high increase. 4. Bases/Al20 3 r a t i o s decreased very s l i g h t l y for a l l treatments except HC1 and HgO column experiment which showed a s l i g h t increase. 5. Bases/Si0 2 r a t i o s remained the same except for ox a l i c and c i t r i c acid which showed s l i g h t decrease. I t may therefore be concluded f i r s t of a l l that Fe and Al were removed p r e f e r e n t i a l l y to s i l i c a . Secondly, except for the o x a l i c acid treatment Fe and A l were removed i n a 1:1 r a t i o . Oxalic acid extracted Fe to a much greater extent than A l . The removal of the sum of Ca, Mg, K and Na was roughly 79 equal to that of A l or S i , except for o x a l i c and c i t r i c acid where removal of the bases s l i g h t l y exceed A l and S i . 8. Basalt - 11 weeks - Column and Batch Experiments 1. Si0 2/Al 20 3 r a t i o s decreased for c i t r i c and o x a l i c acid and increased for acetic acid, HC1, and H20. 2. Si0 2/R 20 3 r a t i o s increased for a l l treatments ( C i t r i c a c i d - greatest change). 3. Al 20 3/Fe 20 3 r a t i o s increased for a l l treatments with a very great change shown for c i t r i c acid. 4. Bases/Al 20 3 r a t i o s decreased for a l l treatments ( C i t r i c acid - greatest change). 5., Bases/Si0 2 r a t i o s decreased s l i g h t l y for a l l treatments except H20 ( C i t r i c acid - greatest change). The most apparent feature i s that of the extraction power of c i t r i c acid i n leaching S i , Fe, and Mg. In fact, s h i f t s i n weathering r a t i o s for both weathered basalt and granodiorite were greatest for the strongly complexing acids namely o x a l i c and c i t r i c acid. These r e s u l t s support the work of Huang and K e l l e r (1970), who concluded that incongruent 80 weathering of s i l i c a t e minerals i s brought about through d i s s o l u t i o n by chelating acids. The decrease i n bases/Al 20 3 and bases/Si0 2 r a t i o s may be explained either by the greater r e l a t i v e extraction of the bases or by the scavenging of Al and S i by an Fe-oxide coating. However, the Al2Oz/'R203 and Si0 2/R 20 3 r a t i o s increased, thus refuting the l a t t e r explanation. c) Incongruent weathering may also arise due to the presence of d i s l o c a t i o n s commonly manifested by etch p i t s on reacted mineral grains. S t r a i n energy associated'with dislocations may catalyze the breaking of bonds by either a hydronium ion or organic ligand and accelerate formation of the c r i t i c a l activated complex (Aagaard and Helgeson 1982). Also, detachment of the activated complex may occur at d i f f e r e n t rates i n d i f f e r e n t c r y s t a l l o g r a h i c directions. S i t e - s e l e c t i v e attack implies a surface-controlled reaction and contradicts the notion of a protective surface layer as a mineral being dissolved by di f f u s i o n - c o n t r o l l e d reaction should possess smooth, rounded surfaces. Extensive e t c h - p i t t i n g and s i t e s e l e c t i v e d i s s o l u t i o n were observed i n weathered b a s a l t i c and gra n o d i o r i t i c grains under the scanning electron microscope. Figures 12 to 14 show increasing magnification of a mica grain leached by oxalic acid for 11 weeks and dramatically i l l u s t r a t e that the grains are anisotropic with respect to dissolution and that Figure 12: Mica grain leached by oxalic acid -200 x magnification 11 weeks. Figure 13: Mica grain leached by oxalic acid - 11 weeks Note exfoliation. 1100 x magnification F i g u r e 14: M i c a g r a i n l e a c h e d by o x a l i c a c i d 11 weeks 2200 x m a g n i f i c a t i o n "3T-TfcT r^WT77T9~7ul P r e s e t -V e r t - 396 c o u n t s D l s p - 1 Comp. 3 E l a p s e d . S l fll »9 —~Xt3U\ Fe T i 200 sees 200 s e e s i- 0.000 Rang-. 10.230 keV 10.110 - f I n t e g r a l 0 • 25201 F i g u r e 15: EDX o f s a m p l e shown i n F i g u r e 14. N o t e K and Fe p e a k s . 83 d i s s o l u t i o n occurs at much greater rates on some surfaces than others. The EDX analysis (Figure 15) taken at 2200X magnification suggests the removal of K and Fe from interlamellae regions of the p a r t i c l e , and l i k e l y a delayed release of s i l i c a . Figure 16 exemplifies more advance etch-p i t t i n g of a granodiorite grain also leached by o x a l i c acid for 11 weeks. The accompanying EDX analysis confirms the incongruent removal of bases leaving a strong s i l i c a peak. I t i s possible that further d i s s o l u t i o n could break down the remaining alumino-silicate l a t t i c e releasing a l l constituents to solution. I t has been suggested by Holdren and Berner (1979) that t h i s stage of the reaction i s most l i k e l y congruent for a p a r t i c u l a r mineral, providing no secondary p r e c i p i t a t e s on the surface act as a scavenging armour for ions i n solution. It should be further noted that the e t c h - p i t t i n g observed i n the micrographs may also be due to d i f f e r e n t i a l d i s s o l u t i o n of two d i s t i n c t phases as commonly found, for example, i n microperthitic exsolution features of feldspars (Gardner 1983) . Gardner (1983) postulated that congruent d i s s o l u t i o n of two d i s t i n c t but intimately intergrown phases at d i f f e r e n t rates may appear to be incongruent d i s s o l u t i o n of the bulk phase. The presence of etch p i t s i n addition to p r e c i p i t a t i o n of authigenic phases on grain surfaces accounted for the increase i n s p e c i f i c surface of the weathered minerals. (See 84 Figure 16: Granodioritic grain leached by oxalic acid 11 weeks. Note preferential dissolution following crystallographic features (honeycomb etching) 1200 x magnification l l . - i u r .'JUS / e r t « 1' PfiC ['t*p> P r e s v t • E l s e c » c l . 2tt0 sees I ?1 sees Ml : n* o.ooe C» ; Par.g't™ i 0. 23(Tk c V I n t e g r a l 0 Figure 17: EDX of sample shown i n Figure 16. 85 Appendix L) . A f t e r 11 weeks, the surface area of granodiorite increased 4-5 f o l d and that of basalt 4-7 f o l d . Holdren and Speyer (1986) found i n t h e i r study of the stoichiometry of a l k a l i feldspars d i s s o l u t i o n that as the grain s i z e became smaller, the reaction became more nearly congruent. This could p a r t l y explain why di s s o l u t i o n approached l i n e a r i t y towards the end of the 11 week experiment. Figures 18 to 25 show other types and stages of etch-p i t t i n g . VO CO Figure 18: B a s a l t i c g r a i n leached by o x a l i c a c i d f o r 11 weeks Note smooth vs a c t i v e l y eroding s u r f a c e 1200 x m a g n i f i c a t i o n Figure 19: B a s a l t i c g r a i n leached by o x a l i c a c i d f o r 11 weeks 600 x m a g n i f i c a t i o n F i g u r e 20: G r a n o d i o r i t e g r a i n leached i n o x a l i c a c i d f o r 11 weeks Note c o n t r a s t i n rough surface f e a t u r e s t o th a t of u n d e r l y i n g smooth f e a t u r e s 800 x m a g n i f i c a t i o n Figure 21: G r a n o d i o r i t i c g r a i n leached i n o x a l i c a c i d f o r 11 weeks Note a c t i v e l y eroding s u r f a c e i n foreground 1500 x m a g n i f i c a t i o n Figure 2 2 : Basaltic grain leached in oxalic acid for H K i g u r e 2 3 : Basaltic grain leached in oxalic acid for 11 800 x magnification m a g n i f i c a t i o n 89 Figure 24: Basaltic grain leached in oxalic acid for 11 weeks. Note prominent etch p i t 600 x magnification 90 Figure 25: Granodiorite grain leached in oxalic acid for 11 weeks. Note contrast in actively eroding surface in centre to smoother striated surfaces i n foreground 400 x magnification 91 RESULTS AND DISCUSSION: SECTION III C. Formation of Organo and Amorphous P r e c i p i t a t i o n Products The r e s u l t s of the analyses to determine the extent of Fe, A l , and S i oxide formation on the g r a n o d i o r i t i c and b a s a l t i c surfaces i s summarized i n Appendix A 2 . Graphic depiction of t h i s data i s shown i n Appendix A-|. I t i s immediately apparent that the FepyRO l e v e l s for both basalt and granodiorite leached by o x a l i c acid are remarkably high. The l e v e l s for granodiorite ranged between 2.0-2.4% and for basalt between 4.7-6.5%. To gain an appreciation of the r e l a t i v e magnitude of these l e v e l s to those found i n s o i l s , i t i s noted that the percentage of FepyRO extracted from an Ortho Humic F e r r i c Podzol on Vancouver Island reached a maximum of .50% i n the B horizon (G. Singleton, 1978). As noted e a r l i e r , research (e.g. Schuppli et al.1983; Loveland and Digby,1984) has given evidence that conventional centrifugation i s inadequate to sediment suspended material completely i n pyrophosphate extracts at a pH of 10. Jenroy and G u i l l e t (1981), found ferruginous p a r t i c l e s >100 nm diameter s t i l l present i n Na-pyrophosphate solutions centrifuged at RCF 40,000, whilst McKeague and Shuppli (1982), found that stepwise centrifugation up to RCF 120,000 progressively decreased amounts of Fe and A l i n solutions. Name Formulae Crystalline Form Solubility Cold Water ' gms/100 Hot g Water Fe (II) Oxalate FeC 20 4.2H 20 pale yellow, rhomb 0.022 0.026 Fe (III) Oxalate Fe 2(C 20 4) 3.5H 20 Yellow micro crystalline powder V.S. V.S. Mg oxalate MgC204.2H20 White powder .07 0.08 Ca Oxalate CaC 20 4 Colorless, cubic 0.00067 0.0014 Ca Oxalate hydrate CaC 20 4H 20 Colorless, cubic i 1 Al Oxalate A1 2(C 20 4) 3.4H 20 White powder i i Fe (II) citrate FeC 6H 60 ?.H 20 White micro phomb s l . s — ( I l l ) c i t r a t e FeC 6H 50 7.5H 20 Red-brown scales s l . s soluble Mg.citrate, mono-H MgHC6H507.5H20 White granular powder 20 2 5 soluble Ca-citrate Ca 3(C 6H 50 7) 2 4H20 White needles 0. 085 0.096 Al-citrate not given — — --Source: Handbook of Chemistry & Physics , 1984. T A B L E 6: C H E M I C A L D E S C R I P T I O N OF C I T R A T E AND O X A L A T E S A L T S 93 The laboratories i n the s o i l science department at UBC are not equipped with a high-speed centrifuge (6000-8000 RCF Max.). The Fe measured i n the pyrophosphate extracts therefore was not e n t i r e l y i n dissolved form but present also i n the , strucure of suspended materials, thereby overestimating the values. Mass balance calculations (Appendix N) , d i f f e r e n t i a t i n g % Fe i n the unweathered sample v.s. Fe i n the dissolved and precipitated form give values which exceeded that of the s t a r t i n g material. Evidently c o l l o i d a l material was measured i n the AA spectrophotometric solution analyses thereby introducing inaccuracy. I t i s possible that the source of some of t h i s c o l l o i d a l material originated from a yellow p r e c i p i t a t e which was observed forming i n both granodiorite and basalt parent material leached, by oxalic acid. These p r e c i p i t a t e s were examined i n more d e t a i l with the help of a scanning electron microscope and chemically analyzed by EDX, XRD and XRF. A chemical description of c i t r a t e and oxalate s a l t s i s given i n Table 6 to a s s i s t i n the i d e n t i f i c a t i o n of the p r e c i p i t a t e s . A discussion of those findings follows. 1. Granodiorite Oxalic P r e c i p i t a t e Magnification under the electron microscope revealed 2 d i s t i n c t components of the p r e c i p i t a t e which formed from g r a n o d i o r i t e . F i r s t l y , very small (<5 um) fragmented mineral grains were c l e a r l y v i s i b l e . See Figure 27. EDX of these 31-Oct-lSiiJB ICslt'J: lb V e r t - £14 counts P i s p - 1 H I M9" P r e s e t -E lops?d= 20U iec< 28B tecs •}- O.uUU R . M . y e , 10.338 keV l n t r c i r a I 0 F i g u r e 26: EDX of sample shown i n Figure 27. F i g u r e 27: Mine r a l fragments i n g r a n o d i o r i t i c c r u s t found a f t e r 11 weeks of l e a c h i n g i n o x a l i c a c i d . Figure 28: EDX of sample shown in Figure 29. Figure 29: Amorphous precipitate in granodioritic crust found after 11 weeks of leaching in oxalic acid. 1200 x magnification 96 grains (Figure 26) determined the presence of S i , A l , Ca, Fe and K, indi c a t i n g a mafic material. XRD of the p r e c i p i t a t e confirmed the presence of hornblende as well as plagioclase. The second component appeared to be a short range ordered " f l u f f y " p r e c i p i t a t e which exhibited very high surface area. (Figure 29). The EDX analyses , (Figure 28), determined the presence of S i and Fe, i n approximately 50% r a t i o , with lesser peaks of A l and Ca. XRD analyses confirmed the presence of Fe-oxalate hydrate, calcium oxalate and oxa l i c acid.In fact, the yellow colour i s in d i c a t i v e of the Fe-oxalate hydrate (Handbook of Chemistry and Physics, 1986). To date there i s neither any reported evidence of a S i -oxalate complex (Drs. Barnes,W. and Clavette,D. pers. comm.), nor any reported s t a b i l i t y constants to match. In addition, XRD peak data for such. a compound was not found i n the l i t e r a t u r e . I t i s l i k e l y that i n an ox a l i c acid s o l u t i o n of pH <2, protonation of the g r a n i t i c surface (and cleavage of the siloxanol bond),took place with subsequent release of Si(0H) 4 into solution. With a Saturation Index of greater than 0, pre c i p i t a t e s w i l l form, and i n fact the f l u f f y appearance shown i n the photograqph (Figure 29), i s t y p i c a l of the metal hydroxide Si(0H) 4 (Dr. Orvig, C.E. pers. comm.). Although no s t a b i l i t y constants are to date given i n the l i t e r a u r e for a Si-oxalate complex i t can be predicted that Fe w i l l e f f e c t i v e l y compete with the S i for the oxalate anion. 97 This competition may preclude the chances of S i combining with oxalate. On the other hand the p o s s i b i l i t y of a Si-oxalate complex cannot be ruled out (Dr. Clavette,D. pers. comm.). The i n t e r a c t i o n of s i l i c i c acid and s i l i c a t e s with organic components of b i o l o g i c a l systems i s thought to involve several types of chemical bonding such as Si-O-C, Si-N-C, Si-C,as well as hydrogen-bonded complexes ( I l e r , 1979).Furthermore, not only 4-but also 5- and 6- co-ordinated s i l i c o n have been iso l a t e d and characterized (Weiss and Herzog, 1978) . Weiss and Herzog (1978), were able to p r e c i p i t a t e an organic S i - s a l t , [ S i ( t h p l ) 3 ]PF 6by tr e a t i n g f i n e l y ground s i l i c a ( s i l i c a gel or quartz), i n an aqueous suspension at pH= 3.5 with a tropolone derivative. Tripolones are abundant i n higher plants and are s i m i l a r to oxalic acid i n e x h i b i t i n g bidentate character with a delocalized Pi-system i n the anionic form. Subsequent work i n Sweden (Sjoberg et. a l . 1985), has investigated complex formation of s i l i c i c a cid and s i l i c a t e s with polyols (mannitol), saccarides (glucose), 1,2- diphenols 29 (pyrocatechol), and tropolones. The authors report S i - NMR chemical s h i f t values which showed that, at pH < 3, a hexa-coordinated s i l i c o n tropolone (SiLjyr-) complex was promoted. However, no such complex occured i n neutral and a l k a l i n e aqueous solutions. But i t remains possible that given the low pH conditions of the batch and column experiment, ox a l i c acid may have formed a complex with s i l i c o n s i m i l a r i n nature 98 to the s i l i c o n - tripolone bond. F i n a l l y , an F e - s i l i c a t e complex, known to form at low pH's (Dr. Clavette,D. pers. comm.), may have contributed to the observed p r e c i p i t a t e . Although the EDX analysis gives no s t r u c t u r a l information, the height of the peaks i n the graph did indicate that Fe and S i were i n approximately 1:1 r a t i o , thereby pointing to the p o s s i b i l i t y of such a compound exist i n g . XRD peaks f o r Fe2Si0 4 did not appear at the diagnostic 2.49 or 1.78 A but the presence of these peaks may have been overshadowed by peaks from other minerals or s a l t s occuring i n higher concentration. The accumulation of Fe i n the " f l u f f y " p r e c i p i t a t e i s c l e a r l y shown from the XRF data, (Appendix I ) , whereby the l e v e l s of Fe20 3 rose as high as 16.22% i n contrast to 5.21% i n the unweathered granodiorite. Also the SiO ^ R g O a^nd A l ^ ^ / F e ^ s r a t i o s (Appendix J) dropped from 5.52 and 5.33 respectively in the unweathered material to 3.26 and 0.90 i n the p r e c i p i t a t e . I t i s i n t e r e s t i n g to note that the S i O ^ R ^ s and Al2°3/ F e2°3 r a t i o s show j u s t the opposite trend for the weathered granodiorite grains which were analyzed separately from the p r e c i p i t a t e . These r a t i o s were the highest f o r a l l the recorded values for the 5 leaching treatments both i n batch and column experiments. This shows a strong depletion of Fe from the parent material. I t may be concluded therefore, that Fe leached from the granodiorite into solution i s to a large extent reappearing i n the p r e c i p i t a t e . For t h i s reason, • 2 a-0ct-i9o& a s : a n y * cn 0> V e r t . B a s a l t O x a l i c C r u s t 2317 c o u n t s b l i p * 1 Na P r e s e t • (.lapsed-' s i ; : ; - : * :'::':::':::i-:::::::::.r«:>:::::' I-:::-:::-. rtf ™ ! : ; : . ; . . . . . . . . . i.:....w ° Ti Mn Fe ,0.000 Range* 10.230 keV I n t e g r a l 0 • 200 s e e s 200 s e e s 10. 110 -> 215599 Figure 30: EDX of sample shown in Figure 31. Figure 31: Amorphous precipitate in basaltic crust formed after 11 weeks of leaching i n oxalic acid. 1800 x magnification 100 mass balance cal c u l a t i o n s (Appendix N) itemizing Fe brought into s o l u t i o n and subsequently precipitated, may t o t a l greater than 100% as the Fe extracted i s e f f e c t i v e l y measured twice i n two d i f f e r e n t forms. 2. Basalt Oxalate Pr e c i p i t a t e Magnification under the scanning electron microscope of the p r e c i p i t a t e formed from oxalic acid leaching of basalt i s shown i n Figure 31. EDX analyses produced major peaks for Mg and Fe. XRF analysis (Appendix I) of the p r e c i p i t a t e indicated the highest accumulation of Fe 20 3 (14.63%), of any weathered product under a l l experimental conditions. Sesquioxide analysis (summarized i n the bar graph i n Appendix A.,) , also show the highest l e v e l of extractable Fe p y R 0 (25%) for any sample and r e f l e c t s the fact that the Fe i s bound in organic complexes with o x a l i c acid. Surprisingly, the Fe C B 0 l e v e l s (5.5%) are greater than the Fe Q X l e v e l s (2.0%) pointing to the presence of some c r y s t a l l i n e Fe. XRD analysis (Appendix K2) i d e n t i f i e d major peaks for Fe-oxalate hydrate, Mg-oxalate hydrate, calcium oxalate, oxalic acid as well as pyroxene and f a y a l i t e . Once again, the yellow colour of the p r e c i p i t a t e i s also i n d i c a t i v e of the Fe-oxalate hydrate (Handbook of Physics and Chemistry, 1986). 101 3a. Granodiorite C i t r a t e P r e c i p i t a t e The c r u s t - l i k e material which s e t t l e d out upon drying i n the granodiorite batch sample a f t e r 11 weeks of weathering was examined under the scanning electron microscope (Figure 33). At 700 and HOOx magnification an amorphous material, " f l u f f y " i n appearance, i s seen to adhere to mineral p a r t i c l e s . EDX at 8000x magnification, (Figure 32) revealed that the material consisted of Fe and a minor amount of S i . This formation l i k e l y accounts for the fact that Fe p Y R 0 l e v e l s were s l i g h t l y higher than other forms of extractable Fe i n the crust material (Appendix A. 2) . XRF analysis of t h i s material showed an accumulation of Fe 20 3 (6.5%) compared with that of unweathered granodiorite (5.21%). In contrast the p r e c i p i t a t e from oxalic acid leaching contained 16.22% Fe 20 3. Thus the c i t r a t e p r e c i p i t a t e , although predominantly Fe, developed to a much lesser extent or at a slower rate than that developed under o x a l i c acid and formed only a small part of the crust. In addition, the XRD analysis did not produce any peaks for c a t i o n - c i t r a t e complexes which may have existed but were below detectable l i m i t s . There was a s l i g h t increase i n i n t e n s i t y for the hematite peak (Appendix K2) , but the hematite i s l i k e l y of lithogenic o r i g i n and not a secondary product. 3b. Granodiorite C i t r a t e Inorganic Surface Coatings Coatings on the surface of granodiorite p a r t i c l e s weathered by c i t r i c acid, d i f f e r i n g i n appearance from the 7-hov-19Se 11 :41 . lb C i t r i c a c i d " C r u s t " V e r t - 500 c o u n t s D i s p - 1 P r e s e t • E 1 a p s e d • 200 s e e s 200 s e e s (N O Tt-/ S l : i 0.000 Range• 10.230 keV " 9.750 -> 15825 I n t e g r a l 0 F i g u r e 32: EDX o f sam p l e shown i n F i g u r e 33. F i g u r e 33: Amorphous p r e c i p i t a t e i n g r a n o d i o r i t i c c r u s t f o r m e d a f t e r 11 weeks o f l e a c h i n g i n c i t r i c a c i d . 1100 x m a g n i f i c a t i o n I 103 sample noted above, were also observed i n the f i n e r "crust" material which s e t t l e d out upon drying.This second type of coating was photographed under the scanning electron microscope and i s shown i n Figure 35. Both 500 and 800x magnification revealed amorphous surface material coalescing between p a r t i c l e s . EDX analysis at 800x magnification and penetrating 2um into the surface showed major peaks for S i , Al and Fe. The r a t i o of Fe: Al as given by the r e l a t i v e heights of the peaks i s approximately 1.4. In view of the fact that Farmer and Fraser (1982), were succesful i n synthesizing a stable Al 20 3-Fe 20 3-Si0 2-H 20 s o l (pH 4.5-5.0) with Fe:Al molar r a t i o s up to 1.5, i t i s possible that the amorphous material (See area A i n the photo) could be s i m i l a r i n make-up. As reported however , by McBride et a l . (1984), Fe 3 + tends not to substitute randomly i n an A l - S i l i c a gel but rather aggregates into clustered F e 3 + - r i c h phase i n the form of f e r r i c oxihydroxide within the g e l . The Fe-rich phase forms a precursor to f e r r i h y d r i t e and the A l - S i r i c h phase a precusor to proto-imogolite. The formation of t h i s gel l i k e l y occurred subsequent to the removal of the .1M c i t r i c acid s o l u t i o n (pH 2.5) from the sample. A small unit of r e s i d u a l c i t r i c a cid dried on the mineral p a r t i c l e s and may be observed i n Area B of the photo. At f i r s t , the presence of a strong chelator, such as c i t r i c a c i d i n such high concentration, would seem to preclude the chances of sesquioxides forming at a l l . Note that A l i n F i g u r e 34: EDX of sample shown i n Figure 35. F i g u r e 35: G r a n o d i o r i t i c " c r u s t " leached i n c i t r i c a c i d f o r 11 weeks. 500 x m a g n i f i c a t i o n 105 organic complexes, for example, i s more stable than i n o r t h o s i l i c a t e (Buurman and Vav Reeuwijk, 1984). But bearing i n mind that most of the solution was removed and the samples were l e f t to a i r - d r y over the course of several weeks, i t i s , possible to trace the formation of these p r e c i p i t a t e s . As noted by Farmer (1979), metal fulvates remain soluble when undersaturated with metals but become insoluble when the metal:fulvate r a t i o r i s e s to saturation. Removal of so l u t i o n through centrifugation followed by . a i r - d r y i n g may have e f f e c t i v e l y separated much of the organic phase from the ligand by reducing the ligand:metal r a t i o . Secondly, the amount of c i t r a t e , at f i r s t co-precipitated with a metal, w i l l decrease upon aging (Violante and Huang, 1984). The l i b e r a t i o n of the organic anions with time i n the laboratory experiments of Violante and Huang (1984), resulted i n the formation of an inorganic p r e c i p i t a t e . Thirdly, under f i e l d conditions, b i o l o g i c a l oxidation w i l l separate the organic from inorganic phase (Buurman and Van Reeuwijk, 1984). This, of course was not a factor i n the batch and column laboratory experiments. 4. Basalt C i t r a t e Precipitate No " f l u f f y " p r e c i p i t a t e was detected from the weathering of basalt with c i t r i c acid under the scanning electron microscope (Figure 37). Rather, the r e l a t i v e EDX analysis of crust material showed an accumulation of s i l i c a with only a B a s a l t g r a i n under c i t r i c a c i d c r u s t P rese t * Vcr t= 3t,U"5 counts [ ' i s p . 1 E l a p s e d Sl ; i : ^ : : : : : ; . : i : : : : . : : i : i : - ! ' i : : i : ! . - i::.!:t ; : i : i W g MjNa . 211. L! i l . L - l l i : . • F e i - r » — r ~ — — l a . a r i u kt-v i n t e g r a l 0 F i g u r e 36: EDX of sample shown i n Figure 37. F i g u r e 37: B a s a l t i c g r a i n s leached i n c i t r i c a c i d f o r 11 weeks. 150 x m a g n i f i c a t i o n 107 minor Fe peak (Figure 36) .The r e l a t i v e accumulation of S i over that of Fe i s r e f l e c t e d i n the SiOjj/RgOs r a t i o which increased from 3.61 i n the unweathered basalt to 4.05 i n the weathered cr u s t . S i m i l a r l y , Percentage of Fe^G^in weathered crust dropped ., to 7.04% for Basalt A and even lower to 3.69% f o r Basalt B, compared with 12.4 6% for the unweathered basalt. I t might be added that the l e v e l s of a l l forms of p r e c i p i t a t e d Fe as measured i n CBD, oxalate, and pyrophosphate extractions, as well as t o t a l Fe i n the p r e c i p i t a t e as measured by XRF were the lowest of a l l 5 leaching treatments for both column and batch t r i a l s . (Conversely, SiO^R^sand AljOg/FegO^ratios were the highest.) The amount of dissolved Fe, on the other hand exceeded a l l leaching treatments. Clearly, the Fe leached into solution, for the most part, remained i n soluble form. The a b i l i t y of c i t r a t e to maintain Fe i n s o l u t i o n leached from basalt i s f a r greater than the a b i l i t y of oxalate of s i m i l a r molar concentration. Therefore, although c i t r i c acid was able to extract greater amounts of Fe from basalt than from granodiorite the development of p r e c i p i t a t e s occured only i n the granodiorite samples. As c i t r i c acid weathered the granodiorite, the pH of the solution rose only to approximately 2.3. At t h i s pH c i t r i c a cid remains undissociated and d i s s o l u t i o n of Fe i s brought about more through a c i d o l y s i s ( i . e . H + attack) than through chelation. In contrast, as c i t r i c a c i d weathered the 108 basalt, the pH of the solution rose to approximately 3-5. At these higher pH's the Fe may be complexed to eithe r HjjL'or to 2- . . . . . HL as each ligand comprises roughly 50% of the c i t r i c acid. The complexed Fe therefore remained i n soluble form. 5. Granodiorite - Acetic acid, HCl and HgO Leaching Treatments Granodiorite leached i n acetic and hydrochloric acid as well as d i s t i l l e d water were examined for sesquioxide development. XRF data showed a drop i n Fe20 3 l e v e l s i n weathered grains but to a much lesser extent than eit h e r c i t r i c or o x a l i c acid treatments. EDX analyses of the crusts r e s u l t i n g from a c e t i c acid and d i s t i l l e d water treatments showed only a minor Fe peak of lesser i n t e n s i t y than those for S i , A l , Ca or K. XRD analyses of crusts from a l l 3 treatments indicated new peaks appearing at 2.50, 2.21 and 1.96A0. These coincide with the peaks of f e r r i h y d r i t e . I t i s tempting to conclude that, i n the absence of stronger organic acids such as .1M o x a l i c and c i t r i c acids which may i n h i b i t the c r y s t a l l i z a t i o n of Fe and A l oxides, f e r r i h y d r i t e could indeed form. However, Schwertmann et a l . (1982), reported that because of i t s poor c r y s t a l l i n i t y f e r r i h y d r i t e can only be recognized e a s i l y by routine XRD i f i t i s reasonably pure. To i d e n t i f y i t i n lower concentrations as found i n s o i l s or i n mixtures with other minerals (e.g. quartz, micas, goethite), s p e c i a l procedures such as DXRD and Mossbauer spectroscopy 1 0 9 must be applied. The authors found that the lower l i m i t of f e r r i h y d r i t e detection l i e s somewhere between 13.3% Fe o x and 2.9% Fe o x. Fe o x l e v e l s recorded f o r the weathered residues including crust were appriximately 1% or l e s s for a l l 3 inorganic treatments. The photograph i n Figure 39, taken under the l i g h t microscope, c l e a r l y shows some form of Fe oxide development as indicated by the darker orange areas i n tha grains of a g r a n o d i o r i t i c sample leached i n water. These coatings were not , however, analyzed i n further d e t a i l . 6. Basalt - Acetic acid, HC1 and H20 Leaching Treatments XRF data for basalt leached by the 3 non-chelating acids gave only a s l i g h t drop i n Fe 20 3 i n the weathered residues. Levels for Si02 and A1 20 3 remained about the same following leaching. In addition, XRD analyses did not detect the development of any new peaks.This i s consistent with the very low s o l u b i l i t y of Fe, S i and A l oxides , even at low pH, in an aquatic environment deplete of strongly complexing organic acids. XRF analyses of the crust material gave a s l i g h t increase i n % A1 20 3 and a s l i g h t decrease i n % Fe 20 3 compared with both the unweathered and weathered residues. Data for extractable Fe and A l showed Fe o x C B D and A l o x C 8 D l e v e l s higher than those for the c i t r i c and oxalic acid treatments. This i s su r p r i s i n g i n l i g h t of the f a c t that 110 Figure 39: Granodioritic grains leached in H20 for 11 weeks. Note Fe oxidation in centre of photograph 200 x magnification I l l c i t r i c and o x a l i c acid have a much higher extraction capacity for Fe and A l than do ac e t i c acid, HCl and HgO. These higher than expected values may be due to an error i n measurement due to the presence of c o l l o i d a l p a r t i c l e s as discussed e a r l i e r . Also, much of the Fe and A l extracted by the chelating acids may be t i e d up i n organic association either i n solution as with c i t r i c acid or i n p r e c i p i t a t e as with oxalic acid. On the other hand, any Fe or A l , however l i t t l e , extracted from non-chelating agents may have adsorbed and oxidized very quickly onto the mineral surface. The photograph i n Figure 38 shows areas of dark orange where Fe has oxidized onto the surface of a b a s a l t i c grain leached i n water. 7. Fe 0x" F e C B D Ratios The graphic display of data showing the percentage extractable Fe reveals immediately a surprising relationship between F e g x a n d F e C B D l e v e l s ' f ° r both basalt and granodiorite samples i n a l l 5 leaching treatments: Feox leve l s were higher than FecBD l e v e l s i n the majority of samples. Since CBD removes both poorly and well c r y s t a l l i z e d Fe oxides, Feox : F eCBD r a t i o s normally should not exceed unity, Data from Mckeague and Day (1966), and Singleton (1978) , have revaled t y p i c a l ranges f o r the main types of s o i l horizons between 0 and 1. Several factors could account for the r a t i o of Feox : F eCBD exceeding unity i n the batch and column weathering experiments. F i r s t of a l l , Feox : F eCBD r a t i o s may be greater 112 than unity due to the presence of c r y s t a l l i n e magnetite. B a r i l and Bitton (1969), and McKeague et a l , (1971a), have shown that ammonium oxalate solution releases Fe from magnetite which i s Known to be only sparingly soluble i n CBD (Gamble and Daniels, 1972). Results of more recent work by Chao and Zhou (1983), confirmed the observations made by e a r l i e r investigators that oxalic acid i s p a r t i c u l a r l y e f f e c t i v e i n bringing magnetites into solution. The in c l u s i o n , therefore, of d e t r i t a l magnetites with amorphous ir o n oxides could confound the use and interpretation of data on active iron r a t i o s . The presence of magnetite i n both basalt and granodiorite was confirmed by XRD analyses. Secondly, CBD dissolves Fe from fi n e p a r t i c l e s of l a b i l e s i l i c a t e s but f a i l s to dissolve completely some c r y s t a l l i n e iron oxides p a r t i c l e s coarser than approximately 50 um (Pawluk, 1972; McKeague and Schuppli, 1985). For t h i s reason Schwertmann and Taylor suggest that coarse samples may require several treatments of CBD extractant. Considering that samples were leached from crushed basalt and granodiorite whose p a r t i c l e s i z e lay between 100 and 500um i t i s possible that FecBD l e v e l s were underestimated. Thirdly, acid ammonium oxalate can diss o l v e s i g n i f i c a n t amounts of Fe from organic complexes (McKeague, 1967; McKeague et a l . 1971; Schwertmann, 1973). There i s , therefore, a tendency for the Feox* F eCBD r a t i o to increase with increasing C content (Campbell and Schwertmann, 1984). Research has shown 113 that oxalate-extractable Fe and Al commonly exceed CBD-extractable Fe and A l i n B horizons of Orthic Humic Podzols (McKeague and Day, 1966; Singleton, 1978). Accordingly, the presence of metal organic complexes could have weighted the r e s u l t s , i n the batch and column experiments, for those samples leached by organic acids i n contrast to those samples leached by HC1 and H20. A fourth factor to consider i s that of time. Aging as an important parameter i n the c r y s t a l l i z a t i o n of sesquioxide compounds has been established by Hsu and Ragone (1972). In a chronological sequence, amorphous forms precede those of more long-range order, and could have accounted, i n t h i s experiment, for a large component of the sesquioxides which formed. In addition, as with other d i f f e r e n t i a l d i s s o l u t i o n methods used i n s o i l s work, both oxalate and CBD methods are l a r g e l y emperical. In fact, they cannot be expected to separate sharply Fe i n iron oxides from Fe i n other combinations and p a r t i c u l a r l y amorphous from c r y s t a l l i n e forms because they are a l l part of a continuum. The r e s u l t s , therefore, may not have given a "true " i n d i c a t i o n of the r e l a t i v e ,amounts of each Fe form. F i n a l l y , as mentioned previously, the introduction of c o l l o i d a l material into solution may have overestimated the atomic absorption spectrophotometric readings. I t i s 114 recommended therefore that extractants be passed through a 20 um f i l t e r paper p r i o r to AA analyses. 8. Additional Notes a) Sesquioxide formation a f t e r 4 weeks of leaching was as high or higher than a f t e r 11 weeks of leaching for most samples, basalt and granodiorite, for both column and batch experiments. According to Schwertmann (1973), Fe on freshly ground and exposed surfaces i s more e a s i l y dissolved than from weathered surfaces commonly present i n s o i l s . I t appears that the rate of formation decreased with time as the surface became coated with the oxides. b) I t i s generally acknowledged that the addition of sesquioxide coatings to a mineral p a r t i c l e w i l l a l t e r the surface charge of that p a r t i c l e . The pH dependent charge developed l a r g e l y by amorphous coatings may reduce the CEC of the underlying permanent negatively charged surface (Hendershot and Lavkulich, 1983). This phenomena was not apparent i n CEC data for basalt and granodiorite which showed a steady increase up to 11 weeks. c) In the batch and column d i s s o l u t i o n studies, granodiorite and basalt of heterogenous mineral composition were leached i n solutions whose chemical make-up varied as weathering 115 proceeded. The formation of amorphous p r e c i p i t a t e s i n t h i s environment could not be modelled i n a simple fashion. As pointed out by Holden (1983), the bulk compositions of p r e c i p i t a t e s formed i n simulated mineral d i s s o l u t i o n experiments are very complex and continually evolve during the course of a reaction as pH and redox conditions s h i f t . The presence or absence of s a l t and other nucleation s i t e s on the mineral surface may be important i n i n i t i a t i n g p r e c i p i t a t i o n and the number of such s i t e s i s not fixed over time. Competition between ions for reactive s i t e s or i n other words the competition between Lewis acids for Lewis bases and vice versa, further complicates any attempt to model p r e c i p i t a t e formation from a very mixed ionic solution. In f a c t , previous studies of alumino-silicate p r e c i p i t a t i o n which have been used to suggest that precipitates should form with fixed compositions, ( K i t t r i c k , 1970;Bussenburg, 1978), or with compositions which are determined solely by the pH of the surrounding medium (Paces, 1978) have been thrown into question i n l i g h t of Holdren's more recent work. In t h i s current study, further a n a l y t i c a l work i s needed to f i r s t of a l l determine quantitatively the precise chemical make-up of the p r e c i p i t a t e s including the molar r a t i o s of each element and organic ligand. Only then can further steps be taken to the s o l u b i l i t y product constant which, i n addition to the ion a c t i v i t y product (IAP) can be used to formulate the Saturation Index for each compound. This i s not such an easy task as 116 r e l i a b l e aqueous a c t i v i t i e s of ions must f i r s t be calculated. This involves corrections for ion pairing and complexing as well as a c t i v i t y - c o e f f i c i e n t calculations. These corrections can be very d i f f i c u l t , requiring the use of a large computor system. 117 S U M M A R Y A N D C O N C L U S I O N S Two simulated weathering experiments, namely batch (shaking) and column (gravity) were designed to study the ., d i s s o l u t i o n of crushed basalt and granodiorite i n the presence of 3 organic and 2 inorganic acids. Chemical and morphological changes i n the mineral residues a f t e r 4 weeks and 11 weeks of weathering were examined. Changes i n both leachate chemistry and rates of dis s o l u t i o n , as revealed by solution analyses were also noted, as well as the formation of p r e c i p i t a t i o n products. 1. Chelation and S t a b i l i t y Constants F i r s t of a l l , solution analyses show that the d i s s o l u t i o n of ions from granodiorite, by the leaching treatment shown i n parentheses, decreased i n the following order: Fe(OX) > A1(0X) ~ Si(OX) > Ca(CIT) - Mg(OX) ~ K(OX) > Na(OX) Dissolution of ions from basalt decreased i n the following order: Fe(CIT) > Si(CIT) > Mg(CIT) > Ca(CIT) > A1(0X, ACETIC) > Na(OX) > K(HC1) In the weathered granodioritic solutions, s t a t i s t i c a l analysis revealed s i g n i f i c a n t difference, at the 95% confidence l e v e l between c i t r i c and ox a l i c acid solutions as well as between the chelating and non-chelating acids for multi-valent s o l u b i l i z e d ions. Also l e v e l s of s o l u b i l i z e d 118 ions i n water were s i g n i f i c a n t l y lower than for a l l other treatments. There was no s i g n i f i c a n t difference between ac e t i c acid HCl treatments for dissolved Ca, Mg, Na, K and Fe. In the weathered b a s a l t i c solutions, there was at the 95% confidence l e v e l , s i g n i f i c a n t difference between c i t r i c and o x a l i c acid solutions for Ca, Mg, Fe, Al and S i . In addition s i g n i f i c a n t differences occurred between a l l 5 leachates for dissolved Fe and Mg. Also there were s i g n i f i c a n t differences between ox a l i c and acetic acid solutions for dissolved Ca, between ox a l i c , acetic acid and HCl for dissolved Al and between ac e t i c acid and HCl for dissolved S i . As was the case with granodiorite levels of s o l u b i l i z e d ions i n water were s i g n i f i c a n t l y lower than for a l l other treatments. There were however i n s i g n i f i c a n t differences for dissolved Na amongst a l l leachates except water. The same held true for K+ except i n the case of granodiorite where c i t r i c and o x a l i c acid leachates revealed high levels of s o l u b i l i z e d K. Oxalic acid e f f e c t i v e l y outcompeted c i t r i c acid i n the weathering of granodiorite i n spite of having lower s t a b i l i t y constants for most ions. This r e s u l t was somewhat su r p r i s i n g as many weathering experiments reported i n the l i t e r a t u r e , point to a c o r r e l a t i o n between the e f f i c a c y of an organic acid i n extracting ions from a mineral to i t s s t a b i l i t y constant with that ion. A closer inspection of a l l available data from both batch and column experiments showed that for the two chelating acids, the a b i l i t y of the acid to extract an ion 119 ultimately depend on solution pH and on the pKa's of the acids. Formation curves were used i n estimating the degree of d i s s o c i a t i o n (and percentage of each ligand formed) for the pH of the leaching solution. I t was shown that at pH of approximately 2.2, c i t r i c acid (pK1 = 3.14) was undissociated. In other words the H+ ion could outcompete any metal cation from the mineral surfaces for Lewis base c i t r a t e ligand. Oxalic acid (pK, = 1.23), on the other hand, was approximately 80% dissociated at pH < 2 and the c i t r a t e anion was available to form chelates. I t i s concluded, therefore, that acid d i s s o c i a t i o n constants may be more important than s t a b i l i t y constants per se i n determining the r e l a t i v e d i s s o l u t i o n power of an organic acid at a p a r t i c u l a r pH. Evidence from solution AA analyses and XRD indicated that the effectiveness of o x a l i c acid i n weathering granodiorite might also be explained on the basis of ion competition in solution for ligand s i t e s , geometry and oxidation state of ions i n the parent material as well as p a r t i c l e s i z e and active surface area of the parent material. I t i s concluded that for any p a r t i c u l a r weathering environment both the physical and chemical components of the mineral(s) and the chemical make-up of the s o l u t i o n must be s c r u t i n i z e d i n order to explain d i s s o l u t i o n i n the presence of organic acids. 120 2. Chelation and A l k a l i Metals There was no conclusive evidence to indicate that chelation of K + or Na + took place i n any of the experiments. In fact, i n the weathering of basalt, HCl extracted more K into s o l u t i o n than did any other leaching treatment. The a b i l i t y of c i t r i c and oxalic acid to extract the highest l e v e l s of K from granodiorite was, on the basis of SEM, EDX and AA solution analyses, attributed to the breakdown of b i o t i t e i n i t i a t e d by chelation of organic acid to Mg and Fe, with subsequent release of K from the i n t e r l a y e r s . 3 . Chelation vs. Acid Dissolution Molar oxide r a t i o s , mass balance c a l c u l a t i o n s , XRF and EDX of unweathered and weathered rock as well as AA s o l u t i o n analyses showed that strongly chelating acids such as c i t r i c and o x a l i c acid greatly outcompeted acetic acid and HCl of s i m i l a r pH for multi-valent cations. This was p a r t i c u l a r l y evident for A l , Fe and S i whose concentrations i n s o l u t i o n were many-fold higher than concentrations i n water i n equilibrium with the amorphous oxides. This i s a t t r i b u t e d to the a b i l i t y of c i t r i c and oxalic acids to complex metals and therefore increase the domain of weathering. However, the extent of complexation for any given chelate i s also determined by pH. As noted above, depending on the pH of the solu t i o n and pKa of the chelating acid both a c i d attack of a mineral surface through ion exchange and complexation between 121 mineral and anion may occur concurrently. I t i s rather s i m p l i s t i c to r e l y on the use of complexation index as introduced by Razzaghi-Karimi and Robert (1979) whereby values greater than 1 for R R _ Amount of element released by organic acid Amount of element released by HC1 indicate chelation. There i s a need to determine more qu a n t i t a t i v e l y the extent of d i s s o c i a t i o n of the chelating acid and therefore the extent to which chelation competes with or i s superimposed on a c i d o l y s i s . 4. K i n e t i c s of Dissolution A study of k i n e t i c s of weathering of both basalt and granodiorite showed that oxalic and c i t r i c acid d i s s o l u t i o n curves were characterized by i n i t i a l l y increasing rates followed by declining rates which approached steady state towards the eleventh week of the experiment. Electron microscopic (SEM) evidence of hyperfine p a r t i c l e s adhering to mineral surfaces supported the theory that rapid i n i t i a l rates of weathering were due to the breakdown of these very small a r t i f a c t s of grinding. Evidence of a leached surface layer, from EDX analyses of basalt and granodiorite, might explain the approach towards steady state k i n e t i c s a f t e r 11 weeks of d i s s o l u t i o n . This cation depleted layer with i t s imbalance of charge and s t r u c t u r a l s t r a i n may have broken down into sol u t i o n exposing a fresh surface to repeat the cycle of 122 events. The very high l e v e l s of S i brought into solution by the d i s s o l u t i o n of basalt by o x a l i c and c i t r i c acid provide, i n d i r e c t l y , additional evidence to support t h i s theory. F i n a l l y the build-up of ions i n solu t i o n as well as pr e c i p i t a t e s , i s c h a r a c t e r i s t i c of a closed weathering system approaching equilibrium with the s o l i d state whereby rates of d i s s o l u t i o n decline. Non-chelating acids such as a c e t i c acid, HCl and H20 revealed d i s s o l u t i o n curves that were approximately constant (steady state) throughout the 11 week weathering experiments. This i s c h a r a c t e r i s t i c of an open system i n which the solution i s greatly undersaturated with respect to the s o l i d phase. 5. Incongruent Dissolution Incongruent d i s s o l u t i o n was observed for granodiorite and basalt weathered by a l l 5 leaching treatments. Incongruent d i s s o l u t i o n was noted i n p a r t i c u l a r f o r c i t r i c acid treatments as evidenced by the following: a) variable but predominantly de c l i n i n g rates of dis s o l u t i o n (AA solution analysis) b) changes i n molar r a t i o s of elements from unweathered to weathered sample (from XRF data) c) mass balance calculations showing p r e f e r e n t i a l leaching of c e r t a i n elements by chelating acids (from AA solution analyses) d) b u i l d up of pr e c i p i t a t e d reaction products (XRD, 123 SEM, EDX, XRF and extractable Fe, A l , S i analyses) e) leached mineral surface layers with predominantly S i residue (EDX) f) etch p i t s and other d i s c o n t i n u i t i e s on mineral surfaces (SEM) 6 . The Formation of P r e c i p i t a t i o n Products C i t r i c acid was less e f f e c t i v e than o x a l i c acid i n forming p r e c i p i t a t e s from granodiorite. However, EDX analysis of an amorphous (possibly organo) p r e c i p i t a t e which d i d form showed that i t consisted of primarily Fe. EDX analysis of a second morphological d i s t i n c t type of amorphous ( l i k e l y inorganic) coating indicated predominantly S i and Fe i n a 1:1 r a t i o . Although c i t r i c acid was able to extract greater amounts of Fe from basalt than granodiorite and even exceed a l l extraction treatments no inorganic or organic-amorphous p r e c i p i t a t e s were detected. In fact extractable Fe, A l and si(CIT)(PYRO)(OX) w e r e the lowest of a l l 5 leaching treatments. I t i s concluded that the Fe extracted remained i n complexed or soluble form due to the higher pH (3-5) of the b a s a l t i c solution. At the lower pH (2-3) of the granodiorite solution the undissociated c i t r i c acid was unable to form F e - c i t r a t e chelates. What appeared under the scanning electron microscope to be an amorphous p r e c i p i t a t e formed from the leaching of granodiorite with o x a l i c acid. EDX analysis indicated that 124 i t consisted primarily of S i and Fe i n a 1:1 r a t i o . Possible inorganic and organic components of t h i s p r e c i p i t a t e were discussed i n some d e t a i l . An amorphous p r e c i p i t a t e also formed from the leaching of basalt with o x a l i c acid which consisted primarily of Mg and Fe i n a 1:1 r a t i o . Under the experimental conditions given with both batch and column procedures, o x a l i c acid was more e f f e c t i v e than c i t r i c acid in promoting the early stages of sesquioxide development. The d i s s o l u t i o n of Fe, A l and S i from basalt and granodiorite by hon-chelating agents such as acetic acid, HCl and H20 was s i g n i f i c a n t l y lower (within 95% confidence l i m i t s ) . 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Biotechnol.23: 803-809. 137 Appendix A ^ Extractable Fe and A l from Weathered Basalt and Granodiorite E x t r a c t a b l e Fe and Al Basalt — Column — 4 Weeks X p N X U><-Citric Oxalic \//\ Pyro Fe R\W1 Pyro Al Acetic l \ XI Ox Fe IXX1 Ox Al HC1 ^ CBD Fe g>553 CBD Al HOH s x u 2.6 2.4 2.2 2 1.8 -1.6 1.4 -1.2 -1 -0.8 0.6 -0.4 -0.2 -0 139 E x t r a c t a b l e " Fe a n d Al Granodiorite — Column — 11 weeks \ \ \ \ 2 Citric Oxalic Acetic Treatment HCl HOH 3 E x t r a c t a b l e Fe a n d Al Basalt — Column — 11 week Citric Oxalic Pyro Fe Acetic rxXI Ox Fe HCl HOH CBD Fe KS>s^ l Pyro Al [XX] Ox Al CBD Al 2.2 2 -1.8 1.6 -1.4 -1.2 1 0.8 0.6 0.4 -0.2 -0 E x t r a c t a b l e Fe a n d Al Basalt — Batch — 4 weeks Citric \ \ \ \ \ \ V; Oxalic Acetic \ / XI Pyro Fe l^\>3 Pyro Al I X X l Ox Fe CXX3 Ox Al HCl HOH Y77Z\ CBD Fe CBD Al r 141 E x t r a c t a b l e Fe Granodiorite — Batch — and Al 11 weeks o a> 3 a o a u X w 0.2 -0.1 Citric Oxalic Acetic HC1 HOH Treatment E x t r a c t a b l e Fe and Al Basalt — Batch — 11 weeks 3 4.5 -4 3.5 H 3 2.5 2 -1.5 1 -0.5 PI / / / / / / / / / / / / / / / / / / /• 0 \ \ \ \ \ \ \ \ \ \ \ \ \2I 2 es_ Citric Oxalic Acetic HC1 HOH Pyro Fe l\M Ox Fe CBD Fe KW\1 Pyro Al [XXI Ox Al C B D AI E x t r a c t a b l e Fe a n d Al < . l m m B a s a l t B a t c h —11 w e e k s 7 - r - : P y r o A l I X X l Ox A l C B D A l V 3 143 E x t r a c t a b l e F e a n d Al Granodiorite Crusts— 11 weeks Citric HOH Basalt Crusts-11 Weeks 2. s x IX XI Pyro Fe KS^Xl Pyro Al CBD Al 144 Appendix A 2: Tables of Data from Extractable Fe and A l and S i from Weathered Basalt and Granodiorite Extractable Iron. Aluminum and Silicon 1% by wt. I PARENT MATERIAL PYROPHOSPHATE OXALATE DITHIONATE Fe Al Si Fe Al Si Fe Al Si Granodiorite A 0.00 0.00 0.00 0.32 0.08 0.00 0.28 0.01 0.00 Granodiorite B 0.00 0.00 0.00 1.32 0.05 0.00 1.38 0.01 0.00 Basalt A 0.00 0.00 0.00 . 1.31 0.07 0.52 0.18 0.01 0.00 Basalt B 0.00 0.00 0.00 1.92 0 . H 0.84 0.61 - 0.01 0.00 Hawaiin Basalt 0.00 0.00 0.00 0.77 0.24 0.36 0.25 0.00 0.00 *A :.lmm-.5mm *B:<. 1mm EXPERIMENT 1: COLUMN STUOY-4 WEEKS PYROPHOSPHATE OXALATE OITHIONATE PARENT MATERIAL TREATMENT Fe Al Si Fe Al Si Fe Al Si GrDio. A Citric 0.13 0.03 0.11 0.97 0.18 0.00 0.65 0.15 0.20 GrDio. A Oxalic 0.03 0.01 0.19 0.74 0.24 0.24 0.83 0.09 0.18 GrDio. A Acetic 0.04 0.01 0.05 0.74 0.17 0.12 0.30 0.10 0.18 GrDio. A HCl .0.10 0.02 0.07 0.79 0.16 0.12 0.30 0.09 0.10 GiDio. A HOH 0.02 0.01 0.06 0.94 0.24 0.20 0.48 0.10 0.18 Basalt A Citric 0.15 0.00 0.30 1.28 0.22 0.52 0.70 0.04 0.28 Basalt A Oxalic 1.50 0.01 0.32 1.64 0.17 0.92 0.90 0.06 0.25 Basalt A Acetic 0.03 0.00 0.25 1.84 0.24 1.32 0.45 0.06 0.25 Basalt A HCl 0.02 0.01 0.15 1.72 0.17 1.00 0.38 0.05 0.25 Basalt A HOH 0.02 0.01 0.10 1.80 0.22 1.08 0.55 0.05 0.20 EXPERIMENT 2 BATCH STUDY-4 WEEKS PARENT MATERIAL TREATMENT PYROPHOSPHATE OXALATE DITHIONATE Fe Al Si Fe Al Si Fe Al Si GrDio. A Cilric 0.06 0.01 0.26 0.72 0.13 0.00 0.18 0.04 0.10 GrDio A Oxalic 0.52 0.01 0.24 0.90 0.12 0.00 0.45 0.06 0.13 GrDio A Acetic 0.09 0.01 0.06 0.72 0.09 0.00 0.30 0.06 0.10 GrDio A HCl 0.01 0.01 0.00 1.05 0.12 0.00 0.40 0.06 0.13 GrDio. A HOH 0.01 0.00 0.00 1.00 0.19 0.24 0.48 0.09 0.10 Basalt A Citric 0.15 0.01 0.54 1.60 0.12 0.72 0.38 0.03 0.25 Basalt A Oxalic 0.88 0.01 0.25 1.60 0.08 0.60 0.68 0.04 0.18 Basalt A Acetic 0.05 0.01 0.07 0.91 0.14 0.00 0.35 0.07 0.10 Basalt A HCl 0.01 0.01 0.16 2.20 0.17 0.92 0.45 0.05 0.20 Basalt A HOH 0.01 0.01 0.26 1.80 0.10 0.76- 0.40 0.04 0.15 EXPERIMENT 3= COLUMN STUDY-11 WEEKS PARENT MATERIAL TREATMENT PYROPHOSPHATE Fe Al GrDio. A Citric 0.07 0.03 GrDio. A Oxalic 2.42 0.02 GrDio. A Acetic 0.02 0.01 GrDio. A HCI 0.01 0.01 GrDio. A HOH 0.01 0.00 Basalt A Citric 0.12 0.00 Basalt A Oxalic 6.50 0.01 Basalt A Acetic 0.45 0.01 Basalt A HCI 0.01 ' 0.00 Basalt A HOH 0.00 0.00 EXPERIMENT 4= BATCH STUDY-11 WEEKS PARENT MATERIAL TREATMENT PYROPHOSPHATE GrDio.A GrDio.A GrDio.A GrDio.A GrDio.A Basalt A Basalt A Basalt A Basalt A Basalt A Citric Oxalic Acetic HCI HOH Citric Oxalic Acetic HCI HOH Fe 0.13 2.00 0.04 0.02 0.01 0.20 4.70 0.02 0.01 0.00 Al 0.05 0.02 0.02 0.02 0.00 0.00 0.00 0.01 0.01 0.00 Hawaiin Hawaiin Citric Oxalic 0.32 3.00 0.01 0.01 OXALATE DfTHIONATE Fe Al Si Fe Al Si 0.53 0.07 0.00 1.28 0.06 0.18 0.78 0.04 0.00 0.35 0.08 0.10 0.82 0.12 0.00 0.35 0.08 0.10 0.64 0.12 0.00 0.30 0.07 0.08 0.48 0.10 0.00 0.30 0.07 0.08 0.58 0.08 0.00 0.15 0.02 0.18 1.05 0.00 0.00 2.43 0.01 0.20 1.39 0.08 0.52 0.40 0.04 0.13 1.35 0.08 0.52 0.38 0.05 0.13 1.56 0.10 0.60 0.35 0.04 0.13 OXALATE DfTHIONATE Fe Al Si Fe Al Si 0.51 0.09 0.00 0.25 0.07 0.15 0.87 0.06 0.00 1.00 0.06 0.23 0.72 0.14 0.00 0.33 0.08 0.08 0.64 0.14 0.00 0.33 0.08 0.08 0.70 0.14 0.00 0.25 0.08 0.05 0.66 0.09 0.12 0.19 0.02 0.20 0.68 0.00 0.00 0.25 0.05 0.20 1.60 0.09 0.68 0.35 0.03 0.13 1.10 0.06 0.44 0.35 0.04 0.10 1.60 0.10 0.68 0.38 0.04 0.13 1.09 0.23 0.16 0.60 0.06 0.25 0.88 0.06 0.00 1.43 0.03 0.20 EXPERIMENT 5= BATCH STUDY-11 WEEKS PARENT MATERIAL TREATMENT PYROPHOSPHATE OXALATE DITHIONATE Fe AL Si Fe Al Si Fe Al Si GfDio.B Citric 0.95 0.00 0.89 1.30 0.09 0.28 0.58 0.03 0.25 GrDio.B Oxaic 5.10 0.04 0.43 1.64 0.04 0.00 3.38 0.05 0.23 GfDio.B Acetic 0.11 0.03 0.07 1.40 0.06 0.00 1.15 0.05 0.08 Basalt B Citric 0.19 0.06 0.24 1.09 0.09 0.00 0.58 0.09 0.18 Basalt B Oxaic ' 6.50 0.02 0.62 1.40 0.03 0.20 2.63 0.02 0.23 Basalt B Acetic 0.12 0.03 0.08 1.60 0.03 0.28 2.63 0.02 0.20 EXPERIMENT 6= BATCH-II WEEKS Analyses of Crust Formations PARENT MATERIAL TREATMENT PYROPHOSPHATE OXALATE DITHIONATE Fe Al Si Fe Al Si Fe Al Si GrDio.A Crtric 2.60 1.00 0.70 1.64 0.62 0.00 1.23 0.70 0.28 GrDio.A Oxaic 19.00 0.14 0.50 2.88 0.33 0.12 8.30 0.42 0.25 GrDio.A Acetic 0.16 0.11 0.08 0.54 0.20 0.00 0.83 0.14 0.15 GrDio.A Ha 0.26 0.10 0.07 0.88 0.31 0.20 0.99 1.80 0.19 GrDio.A HOH 0.28 0.06 0.08 1.14 0.46 0.32 0.72 1.38 0.21 Basalt A Citric 0.90 0.01 0.61 0.53 0.06 0.16 0.53 0.02 0.25 Basalt A Oxaic 25.00 0.01 0.54 2.04 0.00 0.24 5.53 0.01 0.33 Basalt A Acetic 0.25 0.05 0.07 0.42 0.25 0.80 0.43 0.04 0.13 Basalt A HCt X X X X X X X X X Basalt A HOH X X X X X X X X X Hawaiin Citric 2.70 0.04 0.86 1.16 0.10 0.24 1.03 0.08 0.30 Ha wain Oxaic 25.20 0.03 0.70 2.04 0.00 0.24 4.10 0.05 0.43 GrDio.B Citric 5.60 0.03 1.52 1.48 0.05 0.28 2.08 0.04 0.45 GrDio.B Oxaic 31.00 0.03 0.53 2.52 0.07 0.00 11.55 0.09 0.25 GrDio.B Acetic 0.61 0.11 0.08 8.20 0.42 0.60 0.88 0.05 0.08 Basalt B Citric 1.38 0.70 0.71 0.92 0.44 0.16 0.90 0.48 0.23 Basalt B Oxaic 21.00 0.02 1.40 3.20 0.00 0.12 2.53 0.02 0.28 Basalt B Acetic 0.38 0.03 0.20 2.08 0.24 1.12 0.85 0.07 0.13 148 Appendix B: Solution Analyses of 5 Leaching Treatments Granodiorite and Basalt Column Study *Data i s average of 3 r e p l i c a t e samples 2 0. a. u z o o z o p 3 o 149 G R A N O D I O R I T E C A L C I U M CITRIC W E E K 9 WEEK 1 1 H 2 0 B A S A L T C A L C I U M 120 - i — W E E K 1 W E E K 3 W E E K 5 W E E K 7 W E E K 9 • CITRIC + OXALIC O A C E T I C * H C L 1 5 1 BASALT SODIUM 11 -, BASALT SODIUM WEEK 1 WEEK 3 WEEK 5 WEEK 7 WEEK 9 • CITRIC + OXALIC o ACETIC A HCL • CITRIC + OXALIC o ACETIC A HCL x H20 s a. a. xj z o C_> Z o • 3 c 7} 400 350 H 300 H 250 200 -\ 150 H 100 50 H WEEK 1 154 G R A N O D I O R I T E • CITRIC * WEEK 3 OXALIC ALUMINIUM * WEEK 5 * WEEK 7 o ACETIC WEEK 9 A HCL WEEK 1 1 x 1120 c c <J z o u z o O C/3 60 50 40 H 30 H 20 H 10 - i WEEK 1 B A S A L T ALUMINIUM D CITRIC WEEK 1 1 H20 155 G R A N O D I O R I T E SILICON 450 - i WEEK 1 WEEK 3 WEEK 5 WEEK 7 WEEK 9 WEEK 11 O CITRIC ' + OXALIC o ACETIC A HCL x H20 156 Appendix C: Solution Analyses of 5 Leaching Treatments Granodiorite and Basalt Batch Study *Data i s average of 3 r e p l i c a t e samples s a. a. o Z O u z o 3 o in WEEK 1 157 G R A N O D I O R I T E CALCIUM • CITRIC WEEK 3 OXALIC WEEK 5 WEEK 7 WEEK 9 © ACETIC A HCL WEEK 1 1 H20 a. a. o z o o z o •3 o to B A S A L T CALCIUM CITRIC WEEK 11 H20 158 G R A N O D I O R I T E M A G N E S I U M 50 -40 -30 -20 -W E E K 1 W E E K 3 W E E K 5 W E E K 7 W E E K 9 W E E K 1 1 O CITRIC + OXALIC o A C E T I C A H C L >: H 3 0 3 OL 0. U z o . o z o D ' O W E E K 1 159 G R A N O D I O R I T E S O D I U M CITRIC W E E K 3 OXALIC W E E K 5 W E E K 7 O A C E T I C W E E K 9 H C L WEEK 1 1 H 2 0 B A S A L T S O D I U M 160 G R A N O D I O R I T E POTASSIUM 280 - | : ~~ B A S A L T POTASSIUM B A S A L T IRON 2.B - j -s a. c o z o v z o p D _l o 1/5 350 300 250 200 H 150 100 -\ 162 G R A N O D I O R I T E A L U M I N I U M W E E K 9 W E E K 1 1 • CITRIC + OXALIC o A C E T I C A HCL >: 1120 B A S A L T A L U M I N I U M a. c u z o z o p -J O t/3 n CITRIC 163 G R A N O D I O R I T E SILICON WEEK 11 H20 2 0. ^ (fi U T3, z c © a o »• Z o H 3 o 1.4 1.3 1.2 -1.1 - * 1 -0.9 -O.B 0.7 0.6 0.5 -0.4 ~ 0.3 -0.2 -0.1 -0 -1 WEEK 1 B A S A L T SILICON CITRIC WEEK 3 OXALIC WEEK 5 o ACETIC WEEK 7 WEEK 9 & HCL WEEK 11 H20 164 Appendix D: Solution Analyses of 5 Leaching Treatments Granodiorite "B" and Basalt "B" Batch Study *Data i s average of 2 r e p l i c a t e samples • CITRIC + OXALIC o A C E T I C a 0- ^ w CO CJ T> z c o « w 3 2 2 3 J O 7) 2.4 1 6 6 < , 1 m r n G R A N O D I O R I T E M A G N E S I U M W E E K 1 W E E K 3 W E E K 5 W E E K 7 W E E K 9 W E E K 11 CITRIC O X A U C A C E T I C <, 1 m m B A S A L T M A G N E S I U M 160 - i W E E K 1 W E E K 3 W E E K 5 W E E K 7 WEEK 9 W E E K 1 1 • CITRIC + OXALIC o A C E T I C 167 <.1 m m G R A N O D I O R I T E S O D I U M 80 W E E K 1 W E E K 3 W E E K 5 W E E K 7 W E E K 9 WEEK 1 1 • CITRIC + OXALIC o A C E T I C < . 1 m m B A S A L T S O D I U M 55 - | o H 1 1 1 1 1 W E E K 1 W E E K 3 W E E K 5 . W E E K 7 W E E K 9 WEEK 1 1 • CITRIC OXALIC o A C E T I C 168 <.1 m m G R A N O D I O R I T E P O T A S S I U M W E E K 1 W E E K 3 W E E K 5 W E E K 7 W E E K 9 W E E K 11 • CITRIC + OXALIC o A C E T I C • CITRIC + OXALIC o A C E T I C CITRIC + OXALIC A C E T I C 170 <.1 m m G R A N O D I O R I T E ALUMINIUM 400 - i — WEEK 1 WEEK 3 WEEK 5 WEEK 7 WEEK 9 WEEK 11 n CITRIC + OXALIC o ACETIC • CITRIC + OXALIC o ACETIC 1 7 1 < . 1 m m G R A N O D I O R I T E SILICON W E E K 1 W E E K 3 W E E K 5 W E E K 7 W E E K 9 W E E K 11 • CITRIC + OXALIC o A C E T I C S Pu OH O z o t_> z o 3 O' t/1 <. 1 m m B A S A L T SILICON 900 W E E K 1 W E E K 3 W E E K 5 W E E K 7 WEEK 9 WEEK 11 CITRIC OXALIC A C E T I C 172 Analyses of Solution pH from 5 Leaching Treatments Granodiorite and Basalt-Column and Batch Studies *Data i s average of 3 r e p l i c a t e samples 1 7 3 S o l u t i o n p H — 4 W e e k s B a t c h — G r a n o d i o r i t e 6 7 6 5 3 2 < c > — • — - - " " ~~ ——• " " ' ~ ~ 1 Q — . £ ] — j , — W E E K 1 + O x a l i c o A c e t i c A HCI x H O H S o l u t i o n p H — 4 W e e k s B a t c h - B a s a l t 7.5 - i — W E E K 1 C i t r i c + O x a l i c © A c e t i c A HCI x H O H 174 S o l u t i o n p H C o l o m n — G r a n o d i o r i t e g C i t r i c S o l u t i o n p H C o l u m n — B a s a l t 1 ~ l 3 C i t r i c C i t r i c O x a l i c A c e t i c H C l H O H S o l u t i o n p H B a t c h — B a s a l t W E E K 1 W E E K 3 W E E K 5 W E E K 7 W E E K 9 WEEK 11 C i t r i c + O x a l i c o A c e t i c A H C l x H O H 176 Appendix F: Table of Data from Solution Analyses of 5 Leaching Treatments Granodiorite and Basalt - Column and Batch 1 Month Study COLUMN STUDY- 4 WEEK WEATHERING EXPERIMENT ANALYSES OF SOLUTION EXTRACTS Ippm I PARENT MATERIAL TREATMENT Ca Mg Na K Fe Al Si GRANODIORITE CITRIC 195.0 106 0 17.2 74.0 860.0 209.0 170.0 GRANODIORITE CITRIC 206.0 1250 17.0 85.0 480.0 234.0 190.0 GRANODIORITE CITRIC 143.0 84.0 16.9 61.0 430.0 216.0 190 0 GRANODIORITE OXALIC 49.5 159 0 9.7 192 0 310 0 312.0 340:0 GRANODIORITE OXALIC 40 0 149 0 18 9 162 0 230.0 375 0 340 0 GRANODIORITE OXALIC 410 163.0 19 3 195 0 3100 370.0 350.0 GRANODIORITE ACETIC 68.5 4 7 9 3 23.0 250.0 16.0 40.0 GRANODIORITE ACETIC 65.5 4.4 8.6 27.2 130.0 13.0 300 GRANODIORITE ACETIC 67.0 5.4 8.8 25.5 280 0 12.0 30.0 GRANODIORITE HCI 89 0 68.0 18.4 62 0 360.0 147.0 140.0 GRANODIORITE HCI 100.0 44 0 14.9 52.0 370.0 115.0 130.0 GRANODIORITE HCI 114 0 54 0 12.8 54 5 220.0 112 0 110 0 GRANODIORITE HOH 10.8 09 4.7 6.5 0 0 0.0 0.0 GRANODIORITE HOH 5,0 04 6.5 51 0.0 0.0 00 GRANODIORITE HOH 8.2 0.8 4.1 5.6 0.0 0.0 0.0 BASALT CITRIC 109.0 1180 0 8.3 1.8 2310 0 20.0 100.0 BASALT CITRIC 75.0 11200 11.0 2.4 2100 0 20.0 80.0 BASALT CITRIC 102 0 1550 0 10 9 2 8 34000 30 0 950 BASALT OXALIC 26.5 200 0 10.3 1.0 370.0 44 0 59 0 BASALT OXALIC 26.5 207.0 10 4 1.2 3200 41 0 61.0 BASALT OXALIC 35 3 ?06 0 10 3 1.4 350 0 4 4 0 59 0 BASALT ACETIC 34 0 10 0 5.8 2 3 . 620 12 0 40 0 BASALT ACETIC 56.0 12 6 9.9 3.2 85 0 11.0 30 0 BASALT ACETIC 46 0 19.4 10.1 3 6 97 0 13 0 50.0 BASALT HCI 65 0 375 0 12.9 2 9 520 0 31.0 54.0 BASALT HCI 48 0 3350 16.6 5.1 630 0 34.0 58.0 BASALT HCI 57 0 204.0 14:7 5.0 430.0 35.0 62 0 BASALT HOH 0.8 00 4.2 12 0 0 0 0 0.0 BASALT HOH 0 9 00 2 9 0 8 0 0 0 0 0 0 BASALT HOH 16 00 3.3 0 8 .0 0 0.0 00 BATCH STUDY- 4 WEEK WEATHERING EXPERIMENT ANALYSES OF SOLUTION EXTRACTS Ippm I PARENT MATERIAL TREATMENT Ca Mg Na K Fe Al Si GRANODIORITE CITRIC 214.0 142.0 33.5 90.0 930.0 345.0 270.0 GRANODIORITE CITRIC 192.0 145.0 27.7 92.0 990.0 278.0 240.0 GRANODIORITE CITRIC 201.0 129.0 34.0 940 780.0 359.0 290.0 GRANODIORITE OXALIC 42.0 193 0 33.2 155.0 147.0 368.0 325.0 GRANODIORITE OXALIC 34.0 . 187.0 28 5 145.0 142.0 315.0 350.0 GRANODIORITE OXALIC 39.5 184 0 33.0 123.0 181.0 . 379:0 362.0 GRANODIORITE ACETIC 62 0 17.0 17 5 50.0 310.0 45.0 70.0 GRANODIORITE ACETIC 510 12.0 14 6 45.0 290.0 32.0 40.0 GRANODIORITE ACETIC 62.9 1 7.0 19.5 52.0 278.0 38.0 50.0 GRANODIORITE HCl 120.0 70.0 19 0 64.0 310.0 125.0 125.0 GRANODIORITE HCl 143.0 75.0 21.0 52.0 325.0 132.0 134.0 GRANODIORITE HCl 134.0 85 0 24.0 56.0' 340.0 128.0 137 0 GRANODIORITE HOH 7 4 6.8 10.3 14.2 0.0 0.0 0.0 GRANODIORITE HOH 7.8 6 2 10.3 . 14.2 0.0 0.0 0.0 GRANODIORITE HOH 2.0 6.9 10.7 15.0 0.0 0.0 00 BASALT CITRIC 110 0 999.0 25.6 7 0 2710.0 65.0 89 0 BASALT CITRIC 130.0 1090.0 24 0 8.0 2432.0 49.0 110.0 BASALT CITRIC 120.0 1020.0 28.0 7.8 2980 0 58.0 98.0 BASALT OXALIC 30 0 110.0 22.3 2.0 420.0 54.0 70.0 BASALT OXALIC 28 0 120.0 23.0 1.8 452.0 52.0 50.0 BASALT OXALIC 29.0 158.0 22.5 . 2.5 480.0 57.0 54.0 BASALT ACETIC 55 0 16.0 17.5 47.0 220.0 16.0 45.0 BASALT ACETIC 86.0 21.0 19.0 .61.0 210 0 28.0 42.0 BASALT ACETIC 75.0 23.0 21.0 58.0 198.0 24.0 42.0 BASALT HCl 16 4 300.0 11.6 3.7 410.0 35.0 48.0 BASALT HCl 15.0 320.0 1 1.8 2.9 390.0 36.0 56.0 BASALT HCl 18 3 326.0 11.2 2 2 345.0 34.0 57.0 BASALT HOH 5.5 2 0 13.2 1.0 0.0 0.0 0.0 BASALT HOH 5.2 2.5 10 5 1.3 0.0 0.0 0.0 BASALT HOH 6.2 2.1 11.6 1.7 0.0 2.0 0.0 179 Appendix G: Tables of Data from Solution Analyses of 5 Leaching Treatments Granodiorite and Basalt - Column and Batch 11 Week Study *Data i s average of 3 r e p l i c a t e samples COLUMN STUDY SOLUTION EXTRACTS I p p m ) GRANITE BASALT GRANITE BASALT CALCIUM WEEK 1 WEEK 3 WEEKS WEEK 7 WEEK 9 WEEK 11 MAGNESIUM WEEK 1 WEEK 3 WEEK 5 WEEK 7 WEEK 9 WEEK II CITRIC 188.33 103.00 29.00 16.17 12.03 9.33 41.73 70.33 53.33 54.00 48.00 30.67 OXALIC 43.83 50.30 32.70 21.50 15.33 9.67 94.67 159.00 158.67 113.33 104.33 47.67 ACETIC 45.17 37.33 33.73 •33.47 22.50 23.33 32.33 3.07 3.60 4.47 4.30 4.70 HCL 74.00 48.83 34.60 31.00 26.83 25.33 56.00 6.27 6.57 6.53 8.13 9.17 H20 4.23 5.53 2.80 1.70 1.17 0.00 0.40 0.40 0.00 0.00 0.00 ' 0.00 CITRIC 113.67 94.33 43.67 32.67 29.77 14.00 637.67 1443.33 1223.33 573.33 430.00 176.33 OXALIC 36.00 25.33 13.50 11.00 3.53 5.00 204.33 296.67 536.67 336.67 131.33 100.67 ACETIC 35.83 23.00 17.23 11.63 13.17 9.67 7.53 13.40 17.00 17.67 21.50 17.37 HCL 42.01 33.00 14.50 4.43 23.00 15.00 9.67 16.37 14.07 9.47 20.47 18.60 H20 0.00 0.00 0.90 0.40 0.43 0.00 0.00 0.00 0.00 0.00 0.00 0.00 SODIUM WEEK 1 WEEK 3 WEEK 5 , WEEK 7 WEEK 9 WEEK 11 POTASSIUM WEEK 1 WEEK 3 WEEK 5 WEEK 7 WEEK 9 WEEK II CITRIC 12.63 4.87 2.70 2.57 2.07 1.93 40.17 62.87 48.80 49.57 56.00 48.37 OXALIC 16.17 8.97 6.47 5.17 4.37 3.53 124.67 228.67 222.67 146.00 132.00 81.50 ACETIC 5.67 2.83 1.60 1.20 0.47 0.57 14.70 15.20 11.00 8.37 5.47 5.27 HCL 6.23 3.03 2.07 1.03 0.77 0.67 18.83 19.93 13.57 9.33 8.43 7.50 H20 2.70 1.37 0.80 0.60 0.20 0.07 3.33 3.63 3.07 2.30 1.23 0.33 CITRIC 10.10 3.67 3.27 2.67 1.53 0.83 3.17 1.07 1.67 1.57 0.50 0.43 OXALIC 10.60 5.97 5.80 3.60 4.43 4.67 1.00 0.67 0.70 1.77 0.87 0.20 ACETIC 6.07 2.60 2.00 1.30 1.23 1.07 2.73 1.27 1.33 0.83 0.20 0.27 HCL 6.30 3.40 2.30 1.10 2.67 2.67 1.90 1.30 1.07 0.50 0.40 0.00 H20 1.83 0.67 0.60 0.13 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 o GRANITE BASALT IRON WEEK 1 WEEK 3 WEEK 5 WEEK 7 WEEK 9 WEEK II ALUMINIUM WEEK 1 WEEK 3 WEEKS WEEK 7 WEEK 9 WEEK II CITRIC 346.67 206.67 117.67 143.33 100.00 109.67 130.33 111.33 73.33 79.00 81.00 65.33 OXALIC 596.67 713.33 653.33 406.67 260.00 141.33 258.67 363.00 280.00 222.67 193.33 131.00 ACETIC 41.00 23.33 12.33 14.00 11.33 9.33 14.33 11.33 12.00 10.00 13.33 5.67 HCL 39.67 35.67 21.00 19.00 20.00 19.33 9.00 14.67 17.67 11.67 13.00 12.67 H20 4.00 0.00 0.00 0.00 0.00 0.00 3.67 0.00 0.00 0.00 0.00 0.00 CITRIC 1813.33 2533.33 1533.33 1533.33 653.33 243.33 43.33 14.67 6.33 7.00 7.67 3.33 OXALIC 426.67 656.67 613.33 613.33 113.00 64.00 55.00 35.33 28.67 23.00 22.33 24.33 ACETIC 26.33 44.00 56.67 56.67 55.33 44.33 11.00 8.33 9.67 8.00 7.67 3.67 HCL 33.00 69.33 54.00 54.00 54.33 44.33 7.33 5.00 5.67 5.33 0.73 11.33 H20 3.67 0.00 0.00 0.00 0.00 0.00 5.00 0.00 000 0.00 0.00 0.00 SILICON WEEK I WEEK 3 WEEK 5 WEEK 7 WEEK 9 WEEK 11 GRANITE BASALT CITRIC 120.00 126.67 80.00 93.33 133.33 106.67 OXALIC 263.33 410.00 340.00 250.00 243.33 160.00 ACETIC 21.67 0.00 0.00 0.00 0.00 0.00 H HCL 13.33 0.00 0.00 0.00 0.00 0.00 03 H20 0.00 0.00 0.00 0.00 0.00 0.00 H CITRIC 1253.33 1366.67 1016.67 673.33 486.67 176.67 OXALIC 510.00 853.33 1 106.00 803.33 1020.00 683.33 ACETIC 10.00 20.00 20.00 10.00 43.33 23.33 HCL 20.00 30.00 6.67 0.00 20.00 26.70 H20 0.00 0.00 0.00 0.00 0.00 0,00 BATCH STUDY SOLUTION EXTRACTS (ppm) CALCIUM WEEK 1 WEEK 3 WEEK 5 WEEK 7 WEEK 9 WEEK 11 GRANITE CITRIC 26.03 183.33 215.00 64.67 39.33 19.26 OXALIC 45.83 44.67 56.00 43.90 38.17 33.83 ACETIC 48.17 29.67 18.17 16.47 12.17 12.17 HCL 25.67 30.00 17.17 14.00 • 6.43 5.47 HOH 4.23 4.17 3.73 2.03 3.73 4.17 BASALT CITRIC 80.50 • 58.33 49.03 47.93 38.33 34.50 OXALIC 10.53 9.83 1 1.83 28.50 11.40 23.83 ACETIC 29.67 13.33 11.83 12.07. 10.07 12.50 HCL 42.20 28.17 18.83 17.17 7.73 10.33 HOH 1.43 1.90 1.33 1.57 1.53 1.13 SODIUM WEEK 1 WEEK 3 WEEK 5 WEEK 7 WEEK 9 WEEK 11 GRANITE CITRIC 13.33 9.50 6.80 5.70 5.07 4.40 OXALIC 17.90 10.50 7.57 8.50 7.67 7.30 ACETIC 6.50 4.90 2.60 2.67 1.60 1.30 HCL' 3.87 4.03 2.70 1.83 1.07 1.17 H20 3.07 2.67 1.47 1.97 0.67 0.83 BASALT CITRIC 10.57 5.60 4.00 4.27 3.10 2.77 OXALIC 11.00 7.07 5.20 4.73' 3.53 4.10 ACETIC 8.20 4.10 3.73 .4.40 3.50 3.40 HCL 8.80 5.63 4.43 4.70 2.37 3.17 H20 2.43 2.90 1.63 1,60 1.07 0.90 MAGNESIUM WEEK I 58.33 157.67 6.33 •4.83 2.27 936.67 191.00 7.17 10.00 0.37 POTASSIUM WEEK I 46.33 146.00 24.17 12.90 7.07 3.33 1.77 4.00 3.03 0.53 WEEK 3 96.67 133.33 6.57 11.60 3.47 746.67 -38.87 3.60 9.23 0.00 WEEK 3 81.00 178.33 24.00 21.50 8.83 1.17 0.83 1.17 1.67 0.00 WEEK 5 145.33 189.00 7.97 9.00 2.83 1190.00 140.67 4.40 9.23 0.00 WEEK 5 133.67 268.00 20.97 19.97 7.20 1.47 1.13 1.43 2.00 0.77 WEEK 7 116.00 175.33 12.67 10.83 2.37 1300.00 143.00 7.37 1 1.23 0.00 WEEK 7 86.33 239.33 26.03 •21.20 6.07 1.53 1.10 1.60 1.87 1.13 WEEK 9 97.33 155.33 9.43 8.03 2.77 836.67 111.67 7.27 5.30 0.40 WEEK 9 95.67 196.33 19.93 12.97 5.50 1.13 0.77 1.00 0.83 0.63 WEEK 11 93.67 1 14.33 9.13 9.37 4.60 756.67 139.33 9.77 8.60 0.00 WEEK 11 83.67 174.67 15.53 14.37 6.87 0.40 0.20 0.00 0.00 0.40 IRON WEEK 1 WEEK 3 WEEK 5 WEEK 7 WEEK 9 WEEK 11 GRANITE CITRIC 616.67 336.67 373.33 256.67 270.00 233.53 OXALIC 683.33 600.00 860.00 740.00 680.00 525.33 ACETIC 203.00 88.67 58.67 63.33 48.00 37.00 HCL 31.33 84.33 71.00 54.33 34.33 36.67 H20 14.33 28.00 13.33 0.00 • 9.33 28.67 BASALT CITRIC 2346.67 1996.67 . 2666.67 1666.67 1200.00 1 113.33 OXALIC 296.67 173.33 306.67 263.33 193.33 246.67 ACETIC • 36.67 14.00 17.67 20.00 21.67 19.67 HCL 65.33 50.67 36.00 19.00 13.33 1 1.67 H20 14.67 8.67 2.67 0.00 4.67 1.00 SILICON WEEK 1 WEEK 3 WEEK 5 WEEK 7 WEEK 9 WEEK 1 1 GRANITE CITRIC 140.00 196.70 203.30 206.00 190.00 196.67 OXALIC 323.33 373.30 350.00 380.00 370.00 336.67 ACETIC 33.33 50.00 13.30 30.00 26.70 30.00 HCL 0.00 23.30 0.00 20.00 6.70 13.33 H20 16.67 23.30 0.00 0.00 0.00 0.00 BASALT CITRIC 1113.33 1080.00 1323.30 1346.00 1016.00 903.33 OXALIC 693.33 643.00 763.30 820.00 753.00 760.00 ACETIC 26.67 30.00 46.67 40.00 30.00 40.00 HCL 33.33 36.70 43.30 33.00 0.00 26.00 H20 23.33 20.00 3.33 0.00 0.00 0.00 WEEK 1 WEEK 3 WEEK 5 WEEK 7 WEEK 9 WEEK II 149.33 169.00 162.35 140.67 154.67 142.55 325.00 335.33 290.00 558.67 . 326.67 518.55 12.00 21.67 18.00 26.00 25.00 18.55 0.00 2.67 9.55 10.67 10.35 12.55 5.00 9.67 5.67 0.00 6.35 1 1.00 42.33 20.00 15.00 15.00 15.00 12.00 53.67 30.67 20.55 . 18.67 21.00 19.67 12.33 18.35 19.55 ' 19.55 21.53 18.00 4.67 22.00 25.00 17.33 15.00 17.35 6.67 9.33 5.55 0 00 7.35 0.00 00 U) BATCH SOLUTION EXTRACTS I p p m ) Particles <» 1 mm CALCIUM WEEK I WEEK 3 WEEK 5 WEEK 7 WEEK 9 WEEK I I GRANITE CITRIC OXALIC ACETIC 330.00 8.00 50.00 75.00 24.75 46.25 60.20 33.50 53.00 37.13 28.25 30.50 48.50 23.20 22.25 39.00 19.00 21.00 BASALT CITRIC OXALIC ACETIC 275.00 8.10 31.20 96.00 6.00 18.00 141.00 9.75 17.00 135.00 10.00 16.25 115.00 6.70 14.50 1 14.00 7.75 17.00 SODIUM WEEK I WEEK 3 WEEK 5 WEEK 7 WEEK 9 WEEK 11 GRANITE CITRIC OXALIC ACETIC 77.50 ' 23.50 18.50 15.35 16.55 15.25 8.65 17.70 11.80 4.55 10.80 5.45 3.90 8.50 3.65 2.75 7.25 3.50 BASALT CITRIC OXALIC ACETIC 50.50 33.25 12.75 14.45 23.50 10.00 9.60 24.80 14.50 6.20 13.10 7.85 3.75 5.25 5.55 5.10 3.20 5.70 MAGNESIUM WEEK I WEEK 3 WEEK 5 WEEK 7 WEEK 9 WEEK 11 GRANITE CITRIC OXALIC ACETIC 2260.00 9.80 10.90 1315.00 64.00 8.70 1260.00 136.00 8.20 735.00 97.50 6.10 975.00 69.50 3.55 635.00 51.50 "4.15 BASALT CITRIC OXALIC ACETIC 69.00 18.00 15.20 92.00 21.95 4.30 70.00 154.00 16.50 63.50 130.00 2.75 61.00 1 13.00 2.40 85.00 82.50 2.85 POTASSIUM WEEK I WEEK 3 WEEK 5 WEEK 7 WEEK 9 WEEK 11 H CO GRANITE CITRIC OXALIC ACETIC 13.90 29.75 43.75 3.85 89.50 58.50 2.65 240.00 50.00 0.45 145.00 18.45 0.80 110.00 13.00 0.80 72.50 12.50 BASALT CITRIC OXALIC ACETIC 169.00 3.75 3.00 52.45 2.75 2.50 54.50 3.10 3.85 59.75 2.10 2.35 50.70 1.20 1.55 73.50 0.55 0.35 IRON WEEK I WEEK 3 WEEK 5 WEEK 7 WEEK 9 WEEK 11 GRANITE CITRIC OXALIC ACETIC 9 1 5 0 . 0 0 7 . 5 0 1 6 5 0 . 0 0 1 0 3 0 . 0 0 5 7 . 0 0 6 6 0 . 0 0 2 2 5 0 . 0 0 2 8 0 . 0 0 6 1 5 . 0 0 1 2 5 0 0 0 2 5 0 . 0 0 1 9 0 . 0 0 1 3 0 0 . 0 0 2 0 0 . 0 0 1 0 5 . 0 0 1 3 2 5 . 0 0 1 7 0 . 0 0 1 2 0 . 0 0 BASALT CITRIC • OXALIC ACETIC 1 3 4 0 0 . 0 0 1 2 . 5 0 7 9 0 . 0 0 ; 9 3 0 0 0 0 3 9 . 0 0 1 5 5 . 0 0 3 9 0 0 0 2 6 0 . 0 0 2 0 5 . 0 0 2 0 0 . 0 0 1 7 5 . 0 0 7 6 . 0 0 1 1 0 . 0 0 1 7 5 . 0 0 3 4 0 0 2 0 0 0 0 1 5 0 . 0 0 2 0 . 0 0 SILICON WEEK I WEEK 3 WEEK 5 WEEK 7 WEEK 9 WEEK 11 . GRANITE CITRIC OXALIC • ACETIC 1 4 8 5 . 0 0 1 1 5 . 0 0 0 . 0 0 7 2 0 . 0 0 2 3 0 . 0 0 2 0 . 0 0 5 2 5 . 0 0 3 7 5 . 0 0 6 5 . 0 0 5 3 5 . 0 0 2 3 0 . 0 0 2 0 . 0 0 6 1 0 . 0 0 1 6 0 . 0 0 2 0 . 0 0 5 9 0 . 0 0 1 5 5 . 0 0 2 0 . 0 0 BASALT CITRIC OXALIC ACETIC 2 3 0 . 0 0 4 7 5 . 0 0 2 5 0 0 1 3 5 . 0 0 8 1 5 . 0 0 3 0 . 0 0 1 2 0 . 0 0 8 8 0 . 0 0 2 5 . 0 0 1 3 5 . 0 0 8 1 5 . 0 0 2 5 . 0 0 9 5 . 0 0 5 7 0 . 0 0 0 . 0 0 . 1 2 0 . 0 0 5 5 0 . 0 0 0 . 0 0 ALUMINIUM WEEK I WEEK 3 WEEK 5 WEEK 7 WEEK 9 WEEK II GRANITE CITRIC 2 3 0 . 0 0 5 0 . 0 0 ' 2 8 . 0 0 1 5 . 5 0 4 . 5 0 6 . 5 0 OXALIC 3 8 0 . 0 0 2 4 8 . 0 0 3 5 5 . 0 0 2 6 4 . 0 0 1 9 9 . 5 0 2 1 5 . 0 0 ACETIC 0 . 0 0 8 . 5 0 3 1 . 0 0 3 0 . 0 0 2 4 . 0 0 2 1 . 0 0 BASALT CITRIC 1 9 8 . 0 0 1 9 7 . 0 0 1 5 1 . 0 0 1 3 6 . 0 0 9 6 . 5 0 " 1 1 1 . 5 0 OXALIC 8 8 . 0 0 9 7 . 0 0 1 1 0 . 0 0 6 4 . 0 0 2 7 . 0 0 1 4 . 0 0 ACETIC 0 . 0 0 2 4 . 0 0 3 9 . 0 0 2 7 . 0 0 2 7 . 5 0 2 5 . 5 0 186 Tables of Data from pH Analyses of Weathered Granodiorite and B a s a l t i c Residues and Solution Extracts *Data i s average of 3 r e p l i c a t e samples pH OF UNWEATHERED AND WEATHERED RESIDUES PARENT MATERIALS HOH CaCI (.OIM) Granodiorite A Granodiorite B Basalt A Basalt B 7.10 7.30 6.60 7.00 6.55 5.70 5.00 5.83 *A:.1 m m - . 5 m m *8:<.1mm EXPERIMENT 1: COLUMN STUDY-4 WEEKS PARENT MATERIAL TREATMENT HOH CaCI 1.0 IMI EXPERIMENT 3= COLUMN STUDY-11 WEEKS PARENT MATERIAL TREATMENT HOH CaCI 1.0 IM) GrDio. A GrDio. A GrDio. A GrDio. A GrDio. A Basalt A Basalt A Basalt A Basalt A Basalt A Citric Oxalic Acetic HCL HOH Citric Oxalic Acetic HCL HOH 3.08 5.20 4.83 2.93 5.49 5.84 6.30 4.60 3.07 4.92 2.99 4.20 4.82 3.16 5.80 5.70 4.40 4.18 3.34 5.47 GrDio. A GrDio. A GrDio. A GrDio. A GrDio. A Basalt A Basalt A Basalt A Basalt A Basalt A Citric Oxalic Acetic HCL HOH Citric Oxalic Acetic HCL HOH 2.94 4.50 4.53 4.00 5.40 4.25 4.81 4.83 4.23 5.26 2.73 3.56 4.06 3.60 5.82 3.48 4.17 4.61 3.96 5.08 00 -0 EXPERIMENT 2= BATCH STUDY-4 WEEKS PARENT MATERIAL TREATMENT HOH CaCII.OlM) EXPERIMENT 4= BATCH-11 WEEKS PARENT MATERIAL TREATMENT HOH CaCI (.OIM) GrDio. A GrDio. A GrDio. A GrDio. A GrDio. A Citric Oxalic Acetic HCL HOH 3.35 5.00 4.45 6.1 1 6.65 3.18 4.40 4.40 6.09 6.40 GrDio. A GrDio. A GrDio. A GrDio. A GrDio. A Citric Oxalic Acetic HCL HOH 2.82 4.32 4.49 3.80 5.35 2.88 3.84 4.36 4.26 6.10 Basolt A Bosalt A Basolt A Basalt A Basalt A Citric Oxalic Acetic HCL HOH 5.84 6.20 4.51 5.40 5.53 5.80 5.35 4.30 5.02 5.72 Basalt A Basalt A Basalt A Basalt A Basalt A Citric Oxalic Acetic HCL HOH 5.57 5.13 4.51 3.50 5.50 5.50. 4.42 4.15 3.95 5.80 188 BATCH and COLUMN STUDY- 4 WEEK WEATHERING EXPERIMENT PH ANALYSES OF SOLUTION EXTRACTS (Average of 3 replicates I COLUMN TREATMENT TIME 0 WEEK 1 WEEK 3 WEEK 4 GRANODIORITE GRANODIORITE GRANODIORITE GRANODIORITE GRANODIORITE CITRIC OXALIC ACETIC HCl HOH 2.2 1.6 2.9 2.3 5.8 2.3 1.9 3.1 2.3 6.0 2.3 2.8 3.8 2.4 7.1 2.3 4.4 3.8 2.4 7.2 BASALT BASALT BASALT BASALT BASALT CITRIC OXALIC ACETIC HCl HOH 2.2 1.6 2.9 2.3 5.8 4.1 4.5 3.5 2.3 6.7 5:2 5.5 3.5 3.0-6.7 6.4 •6.7 3.5 3.2 6.8 BATCH TREATMENT TIME 0 WEEK 1 WEEK 3 WEEK 4 GRANODIORITE GRANODIORITE GRANODIORITE GRANODIORITE GRANODIORITE CITRIC OXALIC ACETIC HCl HOH 2.2 1.6 2.9 2.3 5.8 2.5 2.7 3.8 2.4 6.8 2.5 3.4 4.0 2.5 7.0 2.6 4.4 4.1 2.5 7.2 BASALT BASALT BASALT BASALT BASALT CITRIC OXALIC ACETIC HCl HOH 2.2 1.6 2.9 2.3 5.8 4.0 5.0 3.5 2.3 6.6 4.1 5.3 3.9 2.4 6.7 4.1 6.6 4.0 2.6 7.0 189 pH OF SOLUTON EXTRAC TS COLUMN EXPERIMENT - 11 WEEKS PARENT MATERIAL TREATMENT TIME 0 Gr.Dio. A Gr.Dio. A Gr.Dio. A Gr.Dio. A Gr.Dio. A Basalt A Basalt A Basalt A Basalt A 8asalt A Citric Oxolic Acetic HCL HOH Citric Oxalic Acetic HCL HOH 2.2 1.6 2.9 2.3 5.8 2.2 1.6 2.9 2.3 5.8 WEEK 1 WEEK 3 WEEK 5 WEEK 7 WEEK 9 WEEK 11 2.2 1.8 3.4 3.7 6.7 •3.9 5.0 3.3 3.4 4.5 2.3 1.6 3.2 3.2 •7.3 5.1 5.2 3.4 3.7 6.5 2.4 1.5 3.2 3.0 6.9 3.8 4.9 3.2 3.4 6.8 2.3 1.5 3.0 3.0 6.3' 3.3 3.7 3.3 3.6 5.7 2.2 1.4 2.9 2.9 6.6 2.8 3.0 3.3 3.1 5.8 2.2 1.4 2.9 2.8 6.3 2.6 1.7 3.2 3.1 5.5 BATCH - 11 WEEKS PARENT MATERIAL TREATMENT TIME 0 WEEK I WEEK 3 WEEK 5 WEEK 7 WEEK 9 WEEK 11 Gr.Dio. A Gr.Dio. A Gr.Dio. A Gr.Dio. A Gr.Dio. A Basalt A Basolt A Basalt A Basolt A Bosolt A Cilric Oxalic Acetic HCL HOH Citric Oxalic Acetic HCL HOH 2.2 1.6 2.9 2.3 5.8 2.2 1.6 2.9 2.3 5.8 2.3 1.8 3.6 4.1 6.3 3.8 4.5 3.3 3.8 6.6 2.4 1.8 3.4 4.2 7.5 4.1 4.6 3.2 3.3 6.8 2.4 1.8 3.6 3.9 7.2 4.4 5.2 3.2 3.3 6.7 2.4 1.8 3.5 3.9 7:1 4.2 5.0 3.3 3.4 ' 5.9 1 7 3.3 3.9 6.9 3.9 5.1 3.2 3.4 6.7 2.3 1.7 3.4 3.9 6.8 3.8 5.1 3.2 3.4 6.5 190 Appendix I: Tables of Data from XRF Analyses of Unweathered and Weathered Granodiorite and Basalt XRF DATA FOR MAJOR ELEMENTAL ANALYSIS (expressed as % weight oxide I P A R E N T . M A T E R I A L S Si02 A I 2 0 3 Fe203 C o O G r a n o d i o r i t e A G r a n o d i o r i t e 8 B a s o l t A B o s a l t B H o w o i i n B a s a l t 6 3 . 8 0 6 3 . 5 5 4 9 . 9 6 5 1 . 0 2 5 0 . 7 6 1 6 . 6 1 1 6 . 4 3 1 5 . 1 7 1 5 . 4 1 1 2 . 7 5 5 . 2 1 5 . 5 3 1 2 . 4 6 1 2 . 4 0 1 2 . 9 2 4 . 9 3 4 . 9 9 8 . 4 1 8 . 3 9 1 0 . 9 0 • A : . 1 - . 5 m m * B . < . 1 m m EXPERIMENT I: COLUMN STUDY-4 WEEKS P A R E N T M A T E R I A L T R E A T M E N T Fe203 . G r D i O - A G r O i o . A G r D i o . A G r O i o A G r 0 i o . A C i t r i c O K O l i c A c e t i c H C I H O H 6 2 . 1 3 6 4 . 9 0 6 3 . 8 1 6 2 . 1 8 6 2 . 3 0 1 5 . 2 8 1 6 . 8 1 1 6 . 8 3 1 7 . 1 1 1 7 . 2 2 4 . 9 5 . 4 . 4 2 4 . 8 8 4 . 9 7 4 . 7 7 4 . 6 6 4 . 9 5 4 . 9 2 4 . 8 2 4 . 9 5 B a s a l t A B a s a l t A B o s a l t A B o s a l t A B a s a l t A C i t r i c O x a l i c A c e t i c H C I H O H 5 2 . 2 4 5 1 . 0 6 5 0 . 3 6 5 0 . 0 0 5 0 . 3 6 1 6 . 4 8 1 5 . 9 0 1 5 . 3 6 1 5 . 5 5 1 5 . 4 3 9 . 8 6 1 1 . 0 8 1 1 . 3 9 1 1 . 3 0 1 1 . 7 1 9 . 2 3 8 . 8 2 8 . 6 3 8 . 7 5 8 . 7 8 EXPERIMENT 2 BATCH STUDY - 4 WEEKS P A R E N T M A T E R I A L T R E A T M E N T A I 2 0 3 G r D i o A G r O i o . A G r D i o . A G r D i o . A G r D i o . A C i t r i c O x o l i c A c e t i c HCI H O H 6 2 . 7 8 6 2 . 4 9 6 5 . 8 4 6 4 . 6 8 6 3 . 4 2 1 7 . 0 5 1 6 . 5 1 16 . 8 4 1 6 . 3 1 1 6 . 7 3 4 . 2 8 4 . 7 1 5 . 1 6 5 . 3 7 4 . 9 6 4 . 8 8 4 . 8 9 4 . 9 5 4 . 8 4 4 . 8 5 B a s a l t A B a s a l t A B a s a l t A B o s a l t A B a s a l t A C i t r i c O x a l i c A c e t i c H C I H O H 5 2 . 0 8 4 8 . 6 5 5 0 . 3 2 4 9 . 0 0 5 0 . 9 3 1 6 . 2 2 1 5 . 0 6 1 6 . 0 5 1 4 . 9 3 1 5 . 7 3 1 0 . 4 9 1 1 . 4 1 1 1 . 3 2 1 1 . 2 2 1 1 . 6 2 8 . 9 4 8 . 3 5 8 . 6 3 8 . 4 4 8 . 7 4 M g O K 2 0 N a 2 0 M n 0 2 . T i 0 2 P 2 0 5 . S 0 2 T o t a l 2 . 1 5 . 2 . 3 1 3 . 7 7 0 . 1 1 0 . 5 0 0 . 1 1 0 . 0 2 9 9 . 5 2 2 . 2 7 2 . 1 4 3 . 6 8 " 0 . 1 3 0 . 5 4 0 . 1 0 0 . 0 2 9 9 . 3 8 9 . 0 4 0 . 5 4 - 3 . 3 8 0 . 1 6 1 . 5 1 0 . 2 5 0 . 0 2 1 0 0 . 9 0 9 . 1 3 0 . 5 9 " 3 . 4 1 0 . 1 8 1 . 5 0 0 . 2 5 0 . 0 2 1 0 2 . 3 0 1 0 . 0 4 . • 0 . 4 5 2 . 3 3 0 . 1 6 2 . 3 8 0 . 2 3 0 . 0 2 1 0 2 . 9 4 M g O K 2 0 N a 2 0 M n 0 2 T i 0 2 P 2 0 5 S 0 2 T o t a l 1 . 9 8 2 . 0 9 3 . 7 6 0 . 1 1 0 . 4 8 0 . 0 6 0 . 0 2 9 5 . 5 2 1 . 9 5 2 . 2 1 4 . 0 4 0 . 1 0 0 . 5 1 0 . 0 5 0 . 0 2 9 9 . 9 6 M 2 . 1 2 2 . 3 3 4 . 0 8 0 . 1 1 0 . 5 2 0 . 1 2 0 . 0 2 9 9 . 7 4 VO 2 . 1 9 2 . 4 0 3 . 9 3 0 . 1 1 0 . 5 8 0 . 0 8 0 . 0 2 9 8 . 3 9 H 2 . 0 9 2 . 3 3 3 . 9 9 0 . 1 0 0 . 5 1 0 . 1 1 0 . 0 2 9 8 . 3 9 6 . 1 7 0 . 6 5 3 . 7 2 0 . 1 3 1 . 6 8 0 . 2 2 0 . 0 2 1 0 0 . 4 0 7 . 0 7 0 . 5 9 3 . 6 0 0 . 1 5 1 . 5 3 0 . 2 0 0 . 0 2 1 0 0 . 0 2 7 . 2 0 0 . 5 9 3 . 5 9 0 . 1 5 1 . 5 6 0 . 2 6 0 . 0 2 9 9 . 1 1 7 . 2 8 • 0 . 5 8 3 . 4 7 0 . 1 5 1 . 5 8 0 . 2 6 0 . 0 2 9 8 . 9 4 7 . 6 1 0 . 6 0 3 . 6 3 0 . 1 5 1 . 5 6 0 . 2 6 0 . 0 2 1 0 0 . 1 1 M g O K 2 0 N a 2 0 M n 0 2 T i 0 2 P 2 0 5 S 0 2 T o t a l 1 . 8 9 2 . 2 8 . . 3 . 9 4 0 . 0 9 0 . 4 8 • 0 . 0 9 0 . 0 2 5 7 . 7 8 2 .13 2 . 3 4 3 . 9 4 0 . 0 9 0 . 5 2 0 . 1 1 . 0 . 0 2 9 7 . 7 5 2 . 2 0 2 . 2 7 4 . 2 3 0 . 1 1 0 . 5 2 0 . 1 2 0 . 0 2 1 0 2 . 2 6 2 . 1 3 2 . 2 4 4 . 0 8 • 0 . 1 1 0 . 5 0 0 . 1 2 0 . 0 2 1 0 0 . 4 0 2 . 1 1 2 . 2 8 3 . 9 1 0 . 1 1 0 . 5 1 0 . 1 1 0 . 0 2 9 9 . 0 1 7 . 3 9 0 . 5 9 4 . 0 S . ' 0 . 1 3 1 . 5 4 . 0 . 2 5 0 . 0 2 1 0 1 . 7 3 7 . 8 9 0 . 5 6 3 . 5 2 0 . 1 4 1 . 4 8 0 . 2 6 0 . 0 2 9 7 . 3 4 7 . 4 6 0 . 5 9 3 . 4 6 0 . 1 4 1 . 5 1 0 . 2 6 0 . 0 2 9 9 . 7 6 7 . 6 3 0 . 5 6 3.31 0 14 1 . 5 1 0 . 2 6 0 . 0 2 9 7 . 0 2 7 . 4 9 0 . 6 2 3 . 6 6 • 0 . 1 5 1 . 5 6 0 . 2 7 0 . 0 2 1 0 0 . 8 1 EXPERIMENT 3: COLUMN STUDY-II WEEKS P A R E N T M A T E R I A L T R E A T M E N T G r D i o . A G r O i o . A G r D i o . A G r D i o . A G r O i o . A C i t r i c O x a l i c A c e t i c H C l H O H 6 4 . 7 3 6 5 . 1 1 6 3 . 8 1 6 3 . 7 0 . 6 3 . 2 8 1 6 . 7 5 1 6 . 2 4 . 1 6 . 7 3 1 6 . 7 1 1 6 . 9 0 4 . 3 5 3 . 3 2 4 . 6 9 4 . 7 6 4 . 7 8 4 . 8 1 4 . 9 4 4 . 8 3 4 . 7 9 4 . 9 7 B a s a l t A B a s a l t A B a s a l t A B a s a l t A B a s a l t A C i t r i c O x a l i c A c e t i c H C l H O H 5 4 . 3 5 4 5 . 1 9 4 9 . 8 9 5 0 . 9 9 4 9 . 7 3 1 8 . 1 1 1 4 . 6 9 1 5 . 5 0 1 5 . 6 3 1 4 . 9 7 6 . 8 2 9 . 2 8 1 1 . 2 6 1 1 . 5 0 1 1 . 8 2 9 . 9 2 8 . 3 1 8 . 6 7 8 . 6 8 8 . 4 4 EXPERIMENT + BATCH-11 WEEKS P A R E N T M A T E R I A L T R E A T M E N T A I 2 0 3 G r D i o . A G r D i o . A G r D i o . A G r D i o . A G r D i o . A C i t r i c O x a l i c A c e t i c H C l H O H 6 3 . 9 4 6 1 . 7 8 6 3 . 7 2 6 4 . 6 1 6 4 . 0 5 1 6 . 8 0 1 5 . 6 4 1 6 . 7 7 1 7 . 0 2 1 6 . 8 0 4 . 1 5 3 . 6 5 4 . 9 3 4 . 6 5 4 . 9 4 4 . 8 3 4 . 7 9 4 . 8 8 4 . 9 2 4 . 8 7 B a s o l t A B a s a l t A B a s a l t A B a s a l t A B o s a l t A C i t r i c O x o t i c A c e t i c . H C l H O H 5 4 . 4 9 4 5 . 1 8 5 0 . 9 3 4 8 . 3 9 5 0 . 5 0 1 7 . 9 8 1 4 . 3 8 1 5 ' 7 0 1 4 . 6 3 1 5 . 6 3 7 . 5 0 1 0 . 5 4 1 1 . 7 6 1 1 . 2 5 I i : 9 8 9 . 7 3 8 . 0 6 8 . 6 5 ' 8 . 2 8 8 . 1 3 M q O K 2 0 N a 2 0 M n 0 2 " T i 0 2 P 2 0 5 S 0 2 T o t a l 1 . 7 3 . 2 . 0 9 3 . 7 1 0 . 0 9 0 . 4 4 0 . 0 0 0 . 0 2 9 8 . 7 2 1 . 3 6 1 . 7 8 4 . 0 6 0 . 0 8 ' 0 . 3 2 0 . 0 4 0 . 0 2 9 7 . 2 7 1 . 9 8 2 . 1 6 4 0 4 6 .09 0 . 4 8 0 0 7 0 . 0 2 9 8 . 9 0 1 . 9 1 2 . 1 8 4 . 2 6 0 . 1 1 0 . 4 8 0 . 0 5 0 . 0 2 9 8 . 9 7 2 . 0 5 2 . 2 9 4 . 6 5 0 . 1 1 0 . 4 9 0 ) 1 0 . 0 2 9 9 . 6 5 3 . 1 1 0 . 6 9 4 . 6 2 0 . 1 0 1 . 6 2 0 . 1 7 0 . 0 2 9 9 . 5 3 5 . 3 4 0 . 5 7 . 3 . 5 1 . 0 . 1 3 • 1 . 1 5 0 . 1 0 0 . 0 2 8 8 . 2 9 , 7 . 2 6 0 . 5 6 3 . 6 0 0 . 1 4 1 . 5 7 0 . 2 6 0 . 0 2 9 8 . 7 3 7 . 6 3 0 . 5 9 3 . 8 8 0 . 1 5 1 . 5 8 0 . 2 4 0 . 0 2 . . . 1 0 0 . 8 9 7 . 9 5 0 . 5 8 3 . 5 5 . 0 . 1 4 1 . 5 2 0 . 2 6 0 . 0 2 9 8 . 9 8 M g O 1 .73 - 2 . 0 B 4 . 1 7 0 . 0 8 0 . 4 4 0 . 0 2 0 . 0 2 . 9 8 . 2 6 • 1 . 2 8 I B ? . 4 . 0 2 0 . 0 8 0 . 3 2 • 0 . 0 ? 0 .02 9 3 . 4 2 2 . 0 8 2 .20 4 . 0 7 0 . 1 0 . 0 . 5 0 0 . 1 1 0 . 0 2 . 9 9 . 3 8 1 . 8 7 2 . 2 3 4 . 0 2 0 . 0 9 0 . 4 5 0 . 1 2 0 . 0 2 • 1 0 0 . 0 0 2.02 2 . 2 8 3 . 9 5 0 . 1 1 0 . 5 0 0 . 1 2 0 . 0 2 9 9 . 6 6 4 . 0 9 0 : 6 4 4 . 2 0 0 . 1 1 1 . 6 4 0 2 4 • 0 . 0 2 1 0 0 . 6 4 7 . 2 9 ' • 0 . 5 1 3 . 4 2 0 . 1 5 . 1 . 3 1 0 1 6 0 . 0 2 9 1 . 0 2 7 . 8 7 0 . 5 8 ' 3 . 5 7 0 . 1 5 1 . 5 6 0 ? 6 0 . 0 2 ' 1 0 1 . 0 5 7 . 2 9 0 . 5 6 3 . 3 5 0 . 1 4 1 . 4 6 0 . 2 5 0 0 2 9 5 . 6 2 8 . 1 3 0 . 5 8 3 . 6 8 0 . 1 5 1 . 5 6 0 . 2 6 0 . 0 2 1 0 0 . 6 2 LO to EXPERIMENT 5; BATCH STUDY -I I WEEKS PARENT MATERIAL TREATMENT Gr.Dio. 8 Gr.Dio. B Gr.Dio. B Citric Oxolic Acetic 62.77 60.12 63.90 14.15 13.01 14.91 5.11 7.52 6.69 4.64 4.64 4.96 Bosolt 8 Bosolt B Bosolt B Citric Oxalic Acetic 51.03 45.84 45.06 15.94 14.60 14.25 8.08 11.17 11.19 9.14 B.39 8.29 Hawoiin Howaiin Citric Oxolic 52.48 46.25 14.08 11.57 12.32 11.47 11.78 10.10 EXPERIMENT 6 CRUST ANALYSES BATCH EXPERIMENT -11 WEEKS PARENT MATERIAL Gr.Dio. A Gr.Dio. A Gr.Dio. A Gr.Dio. A Gr.Dio. A Citric Oxalic Acetic HCl HOH 39.97 37.09 63.33 62.70 63.83 11.45 9.13 16.88 16.83 16.81 6.57 16.22 4.79 5.52 4.37 2.58 3.66 4.61 4.61 4.72 Basalt A Basalt A Basalt A Basolt A Basolt A Citric Oxalic Acetic HCl HOH 51.33 50.43 50.65 17.05 16.08 16.36 7.04 11.51 10.51 9 31 8.65 8.98 Gr.Dio. B Gr.Dio. B Gr.Dio. B Citric Oxalic Acetic 41.63 35.06 46.69 12.23 8.11 11.96 6.20 20.21 23.17 5.43 3 79 3.49 Basalt B Basalt B Basolt B Citric Oxolic Acetic 52.47 24.26 51.51 13.68 6.00 17.86 3.69 14.63 9.21 3 93 4.30 9.05 MqO K20 1.87 1.87 1.90 1.63 2.24 2.01 5.69 0.53 7.57 0.47 7.35 0.48 8.83 0.40 9.81 0.43 6.49 0.10 3.20 0.13 3.72 0.12 3.59 0.10 3.39 0.15 3.13 0.14 2.15 0.17 2.06 0.16 Ti02 P205 0.39 0.02 0.34 0.01 0.45 0.21 1.43 0.19 1.20 0.10 1.19 0.1! 2.10 0.23 1.90 0.17 502 Total 0.02 97.43 0.02 92.52 0.02 99.23 0.02 95.74 0.02 92.90 0.02 91.21 0.02 104.56 0.02 93.94 MqO K20 Na20 Mn02 Ti02 P205 S02 Total H 3.99 3.07 1.87 0.16 1.31 0.02 0.02 71.01 VO 2.79 1.97 1.60 0.23 0.97 0.02 0.02 73.70 W 2.36 2.44 3.88 0.10 0.63 0.11 0.02 99.15 2.35 2.38 3.70 0.10 0.68 _ 0.14 0.02 99.03 2.05 2.39 3.86 0.10 0.51 0.10. 0.02 98.76 4.24 0.65 4.29 0.08 1.60 0.23 0.02 95.84 6.46 0.69 3.78 0.15 1.58 0.27 0.02 99.62 6.01 0.61 3.95 0.13 1.56 0.27 0.02 99.05 5.18 0.45 2.82 0.09 0.97 0.08 0.02 75.10 1.52 1.27 1.68 0.17 0.41 0.00 0.02 72.24 1.98 1.90 2.47 0.08 0.54 0.41 0.02 92.71 2.42 2.39 2.95 0.12 0.66 0.15 0.02 82.48 7.43 0.26 2.47 0.19 1.15 0.28 0.02 60.99 4.79 0 54 4.03 Oil 1.31 ' 0.25 0.02 98.68 194 Tables of Calculations of Molar Oxide Ratios of Unweathered and Weathered Granodiorite and Basalt •Calculations determined from XRF data EXPERIMENT I: COLUMN STUDY-4 WEEKS PARENT MATERIAL TREATMENT Si02/AI2O3 GrDioA Cilric ~ 6.87 GrOio.A Oxalic 6.75 GrDio.A Acetic 6.56 GrDio.A HCI 6.06 GrDioA HOH 6.12 Basalt A Citric 5.44 Bosolt A Oxalic 5.31 Basolt A Acetic 5.60 Bosolt A "HCI 5.53 Basalt A HOH 5.60 EXPERIMENT 2 BATCH STUDY- 4 WEEKS PARENT MATERIAL TREATMENT SJ02/AI203 GrDio.A Citric 6.18 GrDioA Oxalic 6.50 GrDio.A Acetic 6.47 GrDioA HCI 6.69 GrDioA HOH 6.63 Basolt A Citric 5.44 Bosalt A Oxalic 5.40 Bosolt A Acetic 5.25 Bosolt A HCI 5.47 Bosolt A HOH 5.67 Si02/R203 AI203/Fe203 BaserAlumina Ba»e*Silica 5.72 5.68 5.53 5.15 5.20 3.95 3.70 3.82 3.82 3.82 5.00 5.33 5.33 5.67 5.67 2.67 2.67 2.14 2.14 2.14 1.40 1.44 1.44 1.35 1.29 2.31 2.50 2.60 2.67 2.73 0.20 0.21 0.22 0.22 0.21 0.42 0.47 0.46 0.48 0.49 Si02/R203 5.25 5.47 5.50 5.63 5.58 3.7B 3.68 3.65 3.73 3.86 AI203/Fe203 5.67 5.33 5.67 5.33 5.33 2.29 2.14 2.29 2.14 2.14 Ba»erAtumirta 1.29 1.44 1.35 1.44 1.38 2.56 2.73 2.50 2 60 2.83 Ba»ea:Silica 0.21-0.21 0.21 0.21 0.21 0.47 0.51 0.48 0.48 0.48 EXPERIMENT 3: COLUMN STUOY-1 I WEEKS PARENT MATERIAL TREATMENT Si02/AI203 GrDio.A Citric 6.75 GrDio.A Oxolic 6.75 GrDio.A Acetic 6.63 GrDio.A HCl 6.63 GrDio.A HOH 6.56 Bosolt A Citric 5.00 Basalt A Oxolic 5.36 Basalt A Acetic 5.53 Bosalt A HCl 5.67 Bosolt A HOH 5.53 EXPERIMENT 4: BATCH- I I WEEKS PARENT MATERIAL TREATMENT Si02/AI203 GrDio.A _ Citric 6.63 GrDio.A O.ulic 6.87 GrDio.A Acetic 6.63 GrDio.A ' HCl 6.29 GrOio.A HOH 6.69 Bosalt A Citric 5.06 Basalt A Oxalic 5.36 Basalt A Acetic 5.67 Basalt A HCl 5.79 Basalt A HOH 5.60 Si02/R203 AI203/Fe203 Ba*e*Alumina BaaeeSilka 5.68 6.00 5.58 5.58 5.53 4.09 3.75 3.77 3.86 3.77 5 33 8.00 5 33 5.33 5.33 4.50 2.33 2.14 2.14 2.14 1.31 1.25 1.37 1.44 1.50 1.89 2.50 2.67 2.73 2.80 0.19 0.18 0.21 0.22 0.23 0.38 0.47 0.48 0.48 0.51 Si02/R203 5.58 6.06 5.58 5.35 5.63 3.96 3.57 3.86 3.86 3.65 AI203 -Fe203 5.33 7.50 533 5.67 5.33 3.60 2.00 2.14 2.00 1.88 . Ba»ct Akjmrva 1.37 1.33 1.37 1.29 1.37 3.50 2.79 2.73 2.79 2.80 BaaerSilica 0.21 0.19 0.21 0.21 0.21 0.38 0.52 0.48 0.48 0.50 EXPERIMENT S BATCH STUDY-11 WEEKS PARENT MATERIAL TREATMENT Si02/AI203 Gr.Dio. B Citric 7.43 Gr.Dio. B Oxalic 7.69 Gr.Oio. B Acetic . ' 7.07 Basalt B Citric 5.31 Basalt B Oxalic 5.43 Basolt B Acetic 5.54 Hawaiin Citric 6.21 Hawaiin Oxalic 7.06 EXPERIMENT 6= CRUST ANALYSES BATCH EXPERIMENT-11 WEEKS PARENT MATERIAL TREATMENT Si02/AI203 Gr.Dio. A Citric 6.09 Gr.Dio. A Oxalic 6.89 Gr.Dio. A Acetic 6.18 Gr.Dio. A HCI 6.12 Gr.Dio. A HOH 6.63 Basalt A Citric 5.00 Basolt A Oxalic * Basolt A Acetic 5.25 Basalt A HCI 5.25 Bosolt A HOH x Gr.Oio. B Citric 5.75 Gr.Dio. B Oxalic 7.25 Gr.Dio. B Acetic 6.50 Basolt B Citric 6.69 Basolt B Oxalic 6.67 Bosalt B Acetic 4.78 Hawaiin Citric 6.64 AI203/Fe203 Bases^Alumina BaserSiltca 4.67 2.60 3.75 3.20 2.00 2.00 1.75 1.75 1.79 1.54 1.53 2.31 2.44 2.71 3.29 4.09 0.24 0.20 0.22 0.43 0.51 0.51 0.53 0.58 AI203/Fe203 2.75 0.90 5.66 5.66 5.33 4.25 x ' 2.29 2.29 x 3.00 0.62 0.80 6.50 0.67 3.00 Bases: Alumina 1.90 2.11 1.35 1.35 1.37 2.00 X 2.31 2.31 2.25 1.87 1.42 1.62 5.00 1.89 3.55 Bases^Silica 0.31 0.31 0.22 0.22 0.21 0.40 0.44 0.44 0.39 0.26 0.22 0.24 0.70 0.40 0.53 1.83 198 Appendix : Tables of Data from XRD Analyses of Unweathered and Weathered Granodiorite and Basalt. X-RAY DIFFRACTION ANALYSES GRANODIORITE- COLUMN EXPERIMENT MINERAL ANGLE 20 D-SPACE INTENSITY CITRIC ACID UNWEATHERED WKS- 4 WKS- 1 Micas 8.885 9.5220 598 62 115 Hornblende 10.557 8.3794 121 57 N.D. K-Spar 20.973 4.2356 220 167 155 . Plagioclase 22.071 4.0272 92 155 180 K-Spar 22.943 3.8761 108 55 65 Ilmenite 23.798 3.7388 59 125 106 Plagioclase 24.445 3.6413 94 117 111 Quartz/ Micas 26.711 3.3373 1340 1222 1222 Plagioclase 28.061 3.1758 1194 407 598 Hornblende 28.365 3.1463 118 137 206 Pyroxene/Magnetite 29.788 2.9992 57 67 92 Pyroxene 30.537 2.9273 112 129 133 Fe- silicate 31.605 2.8308 55 136 77 Biotite 33.951 2.6404 72 67 59 Magnetite/Hematite 35.692 2.5155 126 115 116 Quartz 36.702 2.4485 91 104 137 Titanite/ Hematite 39.586 2.2766 62 98 126 Periclase 42.513 2,1263 128 104 68 Micas 45.084 • 2.0109 93 47 N.0. Quartz 50.283 1.8145 248 140 176 Fe- silicate 51.525 1.7736 128 90 73 Magnetite/Hematite 54.944 1.6711 73 58 66 OXALIC ACID ACETIC ACID HCl HOH VKS- 4 WKS- 11 WKS- 4 WKS- 11 WKS- 4 WKS- 11 •WKS- 4 WKS -1 64 143 116 109 107 129 105. 159 73 104 60 69 N.D. N.D. 61 68 170 194 176 140 175 199 129 148 156 155 . • 136 157 149 168 178 149 77 N.0. 79 NO. 66 66 73 N.D. 106 111 119 136 131 96 104 143 138 139 107 112 119 105 154 120 1026 1186 1254 768 1240 1158 776 1272 760 1027 1130 591 748 818 540 467 N.D. N.D. 151 141 N.D. 175 120 132 101 80 103 116 84 137 93 61 160 137 130 134 140 143 132 148 86 106 120 103. 97 ' 87 90 108 61 61 N.D. N.D. 65 N.D. 58 N.D. 115 108 ' 103 204 108 122 104 100 100 110 114 130 76 108 100 65 125 142 100 . 111 71 106 92 96 97 • . 123 78 99 73 88 71 114 54 55 68 N.D. 57 N.D. N.D. N.D. 82 203 169 83 168 124 89 118 55 68 . 66 81 69 74 81 66 60 73 62 62 N.D. 67 63 N.D. GRANODIORITE- BATCH EXPERIMENT MINERAL ANGLE 20 D-SPACE INTENSITY CITRIC ACID UNWEATHERED WKS- 4 WKS - 11 Micas 8.885 9.5220 598 105 105 147 Hornblende 10.557 8.3794 121 55 65 K-Spar 20.973 4.2356 220 220 167 Plagioclase 22.071 4?0272 92 150 157 K-Spar 22.943 3.8761 108 92 66 Ilmenite 23.798 3.7388 59 145 117 Plagioclase 24.445 3.6413 94 154 160 Quartz/ Micas 26.711 3.3373 1340 1189 999 Plagioclase 28.061 3.1758 1194 563 813 Hornblende 28.365 3.1463 118 96 166 Proxene/ Magnetite 29.788 2.9992 57 78 88 Pyroxene 30.537 2.9273 112 144 124 Fe- silicate 31.605 2.8308 55 97 117 Biotile 33.951 2.6404 72 77 58 Magnetite/Hematite 35.692 2.5155 126 114 125 Quartz 36.702 2.4485 91 87- 127 Tilan i t e / Hematite 39.586 2.2766 62 89 113 Perictase 42.513 2.1263 128 67 113 Micas 45.084 2.0109 93 N.D. NO. Quartz 50.283 1.8145 248 92 117 Fe- silicate 51.525 1.7736 128 75 83 Magnetile/Hematile 54.944 1.6711 73 39 62 OXALIC ACIO ACETIC ACID HCl HOH WKS- 4 WKS- 11 WKS- 4 WKS- 11 WKS- 4' WKS- 11 WKS- 4 WKS -1 N.D. N.0. 162 126 161 150 85 166 N.D. N.D. 79 61 81 60 76 48 114 121 159 226 182 174 167 167 81 99 158 133 158 133 145 127 N.D. N.D. 83 55 81 55 62 N.D. 65 64 98 198 94 57 108 148 57 62 118 124 123 110 120 119 611 616 1061 1295 1524 1295 869 887 488 496 587 688 710 687 521 1013 81 79 161 203 107 101 84 154 68 72 94 78 92 78 72 100 107 60 153 135 170 135 133 187 60 N.D 90 92 67 92 77 80 66 N.D. NO. N.D. N.D. N.D. N.D. N.D. 79 61 97 99 101 99 131 92 89 63 98 220 175 150 109 95 96 61 89 104 69 98 95 105 69 87 69 118 83 67 107 52 N.D. NO. 54 N.0. 80 56 N.D. N.D. 110 76 145 237 166 116 167 119 72 NO. 51 83 79 98 • 60 92 50 52 66 56 68 70 N.D N.D. BASALT- COLUMN EXPERIMENT MINERAL ANGLE 20 0-SPACE INTENSITY CITRIC ACID OXALIC A C D ACETIC ACS) HCI HOH UNWEATHERED WKS- 4 WKS- 11 WKS- 4 WKS- 11 WKS- 4 WKS- 11 WKS- 4 WKS- 11 WKS- 4 WKS -Ox-Precipitate 18.290 4.8503 N.D. N.D. N.D. N.D. 132 N.D. N.D. N.D. N.D. N.D. N.D. Plagioclase 22.120 4.0184 t51 190 157 143 129 152 . 133 161 138 155 163 Forsterite 22.952 3.8746 69 65 62 72 96 94 74 60 121 56 63 Plagioclase 23.770 3.7431 227 376 310 ' 220 189 166 172 178 189 173 220 a 1 Plagioclase 24.562 3.6242 1 1 6 . 139 115 123 113 116 101 H 2 133 118 96 b 1 Fayalite " " " " *' " " " " " " " " M i c a s / Ouartz 26.554 3.3567 72 92 76 82 N.D. 66 N.D. 67 N.D. 60 72 a) Plagioclase 27.908 3.1968 425 '645 298 433 507 425 342 421 337 254 470 b l Hypersthene " " " " " " " " " " " " " Hornblende 28.508 3.1309 164 126 69 150 168 157 140 121 116 N.D. N.D. Pyroxene 29.858 2.9923 161 197 , . 139 168 162 194 133 191 163 150 176 Pyroxene 30.440 2.9364 161 165 158 150 142 140 152 156 167 119 150 Hypersthene 30.827 2.9004 73 64 62 70 N.D. 54 79 77 107 68 64 Fayalile 31.602 2.8310 94 91 88 90 70 79 74 74 98 69 100 Hornblende 32.199 2.7799 N.D. N.D. N.D. ' 82 N.D. 80 59 59 N.D. 121 110 a 1 llmentte 35.008 2.5630 61 71 66 90 81 73 61 61 69 63 75 b 1 Fayalite " " " " " " " " " " " " a 1 Magnetile 35.659 2.5177 175 . 165 144 170 133 167 158 170 173 233 156 b l Fayalite " " " " " c 1 Hematite " " " " " " " " Ouarlz 36.448 2.4650 N.D. 57 34 79 96 160 89 84 62 87 112 Periclase 42.376 2.1329 87 125 76 81 102 99 77 78 80 77 71 Ox- Precipitate 44.840 2.0213 N.D. N.D. N.D. N.D. N.D. N.D. N.D. N.D. " N.D. N.D. N.D Hematite 49.828 1.8300 N.D. 75 66 73 62 69 68 63 68 67 68 Fayalite 51.608 1.7710 150 86 61 N.D. 58 57 73 61 66 N.D. 84 llmenile 52.286 1.7496 60 53 47 54 89 59 74 73 64 81 76 BASALT- BATCH EXPERIMENT MINERAL ANGLE 20 D-SPACE INTENSITY CITRIC ACID OXALIC ACID ACETIC ACD HCI HOH UNWEATHERED WKS- 4 WKS-,11 WKS- 4 WKS- 1 1 WKS- 4 WKS- 11 WKS- 4 WKS- 11 ' WKS- 4. WKS -Ox-Precipitate 18.290 4.8503 N.D. N.D. . N.D. N.D. 117 N.D. N.D. N.D. N.D. N.D. N.D. Plagioclase 22.120 4.0184 151 185 152 116 199 160 141 157 168 127 129 Forsterite 22.952 3.8746 69 70 71 73 55 68 62 69 52 70 52 Plagioclase 23.770 3.7431 227 238 186 230 144 225 223 179 212 172 153 a l Plagioclase 24.562 3.6242 116 158 116 112 154 150 146 107 130 107 96 b l Fayalite " " " " " " " " " " Micas/ Quartz 26.554 3.3567 72 75 65 75 77 76 86 78 75 60 • 71. a 1 Plagioclase 27.908 3.1968 425 406 295 380 300 411 354 308 465 345 435 b l Hypersthene " " " " " " " " " Hornblende 28.508 3.1309 164 160 59 98 N.D. • 123 86 116 129 90 55 Pyroxene 29.858 2.9923 161 217 124 196 172 159 150 161 207 126 150 Pyroxene 30.440 2.9364 161 140 146 136 143 164 173 161 126 168 139 Hypersthene 30.827 2.9004 73 64 N.D. 70 57 N.D. N.D. N.D. N.D. N.D. 66 Fayalite 31.602 2.8310 94 84 56 90 63 97 104 79 85 88 81 Hornblende 32.199 2.7799 " N.D. 61 N.D. N.D. N.D. N.D. N.D. 93 87 83 60 a i llmenite' 35.008 2.5630 61 68 56 71 76 72 78 65 83 88 53 b l Fayalite " " " " " " " " " " " a) Magnetite 35.659 2.5177 175 , 188 161 223 • 123 181 181 222 179 157 . 219 b l Fayalite " " " " " " " c 1 Hematite " " " " " " Quartz' 36.448 2.4650 N.D. 95 N.D. 87 64 70 66 77 69 97 92 Periclase 42.376 2.1329 87 87 82 85 81 89 99 78 97 79 149 Ox-Precipitate 44.840 2.0213 N.D. N.D. N.D. N.D. 83 N.D. N.D. N.D. N.D. N.D. N.D. Hematite 49.828 1.8300 N.D. 76 72 N.D. 79 81 100 • - 57 64 59 58 Fayalite 51.608 1.7710 150 64 N.D. 60 N.D. 103 86 64 89 N.D. 83 llmenite . 52.286 1.7496 60 ., 56 N.D. 94 67 60 59 64 ' 50 62 107 Appendix K 2: Tables of Data from XRD Analyses of Granodiorite and B a s a l t i c "crust". 204 Angle 20 D-Spacing Intensity Mineral 18.616 4.7661 195 Fe (II) Oxalate Dihydrate 21.037 4.2229 55 Quartz 22.127 4.0173 60 a) Plagioclase b) Fe (II) Oxalate 23.055 3.8575 83 Oxalic Acid 23.907 3.7220 62 a) K-Feldspar b) Plagioclase 24.563 3.6241 82 Plagioclase 26.734 3.3345 367 a) Micas b) Quartz 28.051 3.1808 229 Plagioclase 28.385 3.1442 71 a) Plagioclase b) Hornblende 29.677 3.0102 83 a) Plagioclase b) Pyroxene 30.498 2.9310 63 a) Pyroxene b) K-oxalate 31.594 2.8317 85 a) Ca-oxalate hydrate b) Na-oxalate 34.502 2.5994 82 Mica 35.618 2.5205 53 K-oxalate per hydrate 36.803 2 .4421 54 a) o x a l i c Acid b) K-oxalate 39.610 2.2752 58 a) Hematite b) K-oxalate 50.308 1.8136 86 Quartz Table: I d e n t i f i c a t i o n of XRD peaks for Granodiorite/Oxalic Acid Crust. Source: Batch experiment - 11 week weathering study. 205 Angle 20 D-Spacing Intensity Mineral 22.120 4.0184 196 Plagioclase 22 .945 3.8758 77 F o r s t e r i t e 23.824 3.7347 257 a) Plagioclase b) Ilmenite 24-577 3.6221 140 F a y a l i t e 25.744 3.4604 66 a) Titanium Oxide b) K, A l , S i l i c a t e hydrate 26.577 3.3538 95 a) Quartz b) Mica 27.912 3.1964 586 Plagioclase 29.832 2.9949 135 a) Pyroxene (Augite) a) Plagioclase b) Pyroxene b) Plagioclase 30.801 2.9028 81 Pyroxene (Pigeonite) 31.671 2.8250 100 Fa y a l i t e 32.749 2.7345 60 a) Ilmenite b) Ca 2 S i 0 4 c) K ? Mg S i 0 4 33.912 2.6433 65 Hematite 35.112 2.5557 64 a) Magnetite b) Ilmenite 35.735 2.5125 190 Hematite 42.312 2.1360 105 a) P e r i c l a s e b) Quartz 48.570 1.8744 80 Titanium Oxide 49.873 1.8284 66 a) Quartz b) Hematite 51.628 1.7703 83 F a y a l i t e / F o r s t e r i t e 52.300 1.7491 55 Ilmenite Table: I d e n t i f i c a t i o n of XRD peaks f o r B a s a l t / C i t r i c Acid Crust. Source: Batch experiment - 11 week weathering study. 206 Angle 20 D-Spacing Intensity Mineral 8.719 10.1411 117 Mica 20.856 4.2592 91 a) K-Feldspar b ) Quartz 21.954 4.0486 112 Plagioclase 23.724 3.7503 74 a) Feldspar b ) Ilmenite 24.299 3.6628 76 Plagioclase 26.563 3.3555 422 Quartz and Mica 27.869 3.2013 195 Plagioclase 29.697 3.0082 64 a) K-Feldspar b ) Plagioclase 30.346 2.9454 108 a) Plagioclase b ) K-Feldspar c) Pyroxene 33.997 2.6369 131 Hematite 35.432 2.5333 73 Magnetite 36.003 2.4945 58 a) F e - s i l i c a t e b ) Hematite 36.640 2.4526 103 Quartz 39.403 2.2867 72 a) Nutile/Anatase 41.305 2.1857 74 Hematite 45.003 2.0143 61 Mica 49.825 1.8301 54 Quartz 51.391 1.7779 82 a) Ilmenite b ) F e - s i l i c a t e 54.622 1.6801 54 a) Hematite b ) Magnetite Table: I d e n t i f i c a t i o n of XRD peaks f o r G r a n o d i o r i t e / C i t r i c Acid Crust. Source: Batch experiment - 11 week weathering study. 207 Angle 20 D-Spacing Intensity Mineral 18.336 4.8382 822 23.226 23.849 28.404 34.946 37.969 43.178 44.724 48.794 3.89295 130 3.7310 3.1421 2.5674 2.3697 2.0951 2.0262 1.8663 76 356 153 93 124 179 109 a) Mg - oxalate hydrate b) Fe - oxalate hydrate c) Na-Fe (II) Oxalate Nona Hydrate a) Oxalic a c i d b) F a y a l i t e A l b i t e a) Ca-Oxalate b) Pyroxene F a y a l i t e a) Ca-oxalate b) Mg - oxalate hydrate U n i d e n t i f i e d a) Mg-oxalate hydrate b) Fe-oxalate hydrate a) Ca-oxalate b) Fe-Oxalate hydrate Table I d e n t i f i c a t i o n of XRD peaks f o r Basalt/Oxalic Acid Crust Source: Batch Experiment - 11 week weathering study. 208 Appendix L: Tables of Data from CEC and Surface Area Analyses of Unweathered and Weathered and Unweathered Granodiorite and Basalt. 2 0 9 GRANODIORITE AND BASALT UNWEATHERED AND WEATHERED RESIDUES: CEC. SPECIFIC SURFACE AND SURFACE CHARGE DENSITY PARENT MATERIALS CEC UNWEATHERED (me/lOOg) Granodiorite A 0.6 Granodiorite ite B 1.1 Basalt A 0.7 Basalt B 1.1 Hawaiin Basalt 0.3 *A:. 1 mm-.5mm «B:<.lmm SPECIFIC SURFACE CHARGE DENSITY (Tl (m l/g) (me/m 1) ) x 10"' 2.0 3.2 2.8 3.9 1.5 4.9 1.9 5.5 2.0 1.7 EXPERIMENT 1 = COLUMN STUDY-4 WEEKS PARENT MATERIAL TREATMENT CEC SPECIFIC SURFACE CHARGE DE (me/IOOg) (m l/9) (me/m 2 ] GrDio. A Citric 1.0 3.1 3.2 GrDio. A Oxalic 1.5 4.5 3.2 GrDio. A Acetic 1.0 3.1 3.2 GrDio. A HCL 1.0 5.2 1.8 GrDio. A HOH 1.9 14.1 1.3 Basalt A Citric 1.8 3.9 4.7 Basalt A Oxalic 3.9 5.2 7.4 Basalt A Acetic 2.2 3.5 6.3 Basalt A HCL 1.2 4.2 3.0 Basalt A HOH 1.1 2.1 5.2 EXPERIMENT 2' BATCH STUDY-4 WEEKS PARENT MATERIAL TREATMENT CEC SPECIFIC SURFACE CHARGE DE (me/100g) (m*/9) (me/m2; GrDio. A Citric 2.2 5.2 4.3 GrDio. A Oxalic 2.7 4.6 5.9 GrDio. A Acetic 1.8 4.3 4.3 GrDio. A HCL 0.8 4.9 1.7 GrDio. A HOH 0.9 12.9 1.0 Basalt A Citric 3.5 9.8 3.6 Basalt A Oxalic 2.3 8.1 2 S Basalt A Acetic 1.4 3.5 4.0 Basalt A HCL 1.0 4.5 2.3. Basalt A HOH 1.9 7.3 2.6 210 EXPERIMENT 3: COLUMN STUDY-1 1 WEEKS PARENT MATERIAL TREATMENT GrDio. A GrDio. A GrDio. A GrDio. A GrDio. A Basalt A Basalt A Basalt A Basalt A Basalt A Citric Oxalic Acetic HCL HOH Citric Oxalic Acetic HCL HOH CEC (me/ lOOg) 2.6 2.8 1.0 'l.O 1.8 3.9 2.9 5.0 7.9 2.7 SPECIFIC SURFACE . (m»/g) 8.0 . S.5 2.8 3.5 5.9 6.5 4.6 9.0 1 1.5 . 6.0 CHARGE DENSITY (T I (me/m ^ ) x 10" 3 3.5 3.0 3.0 6.0 6.3 5.5 6.5 4.5 EXPERIMENT 4:BATCH-lt WEEKS PARENT MATERIAL TREATMENT GrDio. A GrDio. A GrDio. A GrDio. A GrDio. A Basalt A Basalt A Basalt A Basalt A Basalt A \ Citric Oxalic Acetic HCL HOH Citric Oxalic Acetic HCL HOH CEC (me/ lOOg) 1.1 • 4.1 2.7 1.9 2.0 • 3.9 3.1 • 4.0 3.5 3.2 SPECIFIC SURFACE (mVg) 4.2 9.8 8.0 7.8 6.9 6.2 6.0 9.1 4.2 7.6 CHARGE DENSITY (Tl ( m e / m 1 ) » 10" J 2.6 4.2 3.4 2.4 2.9 6.3 5.2 4.5 8.4 4.2 EXPERIMENT 5: BATCH-1 I WEEKS PARENT MATERIAL TREATMENT GrDio. B GrDio. B GrDio. B Basalt B Basalt B Basalt B Hawaiin B Hawaiin B Citric Oxalic Acetic Citric Oxalic Acetic Citric Oxalic CEC (me/ lOOg) 2.3 2.4 1.7 . 3.9 3.6 2.1 1.0 2.5 SPECIFIC SURFACE (mVg) 11.2 1.2.1 10.3 7.8 13.1 3.1 ' 4.0 •  10.9 CHARGE DENSITY (Tl (me/m 2 ) 2.1 2.0 4.9 2.8 6.7 2.5 2.3 10 •3 211 Appendix M: Tables of Data from Exchangeable Bases Analyses of Unweathered and Weathered Analyses. 212 EXCHANGEABLE BASES OF UNWEATHERED AND WEATHERED RESIDUES Imeq/lOOg PARENT MATERIALS Calcium 0.53 0.70 0.24 0.39 0.14 EXCHANGEABLE BASES (meq/IOOgl Magnesium Sodium Potassium Granodiorite A Granodiorite B Basalt A Basalt B Hawaiin Basalt *A:. l-.Smm *B:< 1 mm EXPERIMENT 1: COLUMN STUDY-4 WEEKS PARENT MATERIAL TREATMENT Gr.Dio. A Gr.Dio. A Gr.Dio. A Gr.Dio. A Gr.Dio. A Basalt A Basalt A Basalt A Basalt A Basalt A' Citric Oxalic Acetic HCL HOH Citric Oxalic Acetic HCL HOH EXPERIMENT 2- BATCH STUDY-4 WEEKS PARENT MATERIAL TREATMENT 0.03 0.09 0.11 0.27 0.06 Calcium 0.06 0.24 0.36 0.37 0.54 0.05 0.49 0.10 0.22 0.36 Calcium 0.11 0.18 0.12 0.20 0.04 0.25 0.20 0.10 0.09 0.03 EXCHANGEABLE BASES (meq/10Og I Magnesium Sodium 0.44 0.25 0.02 0.03 0.28 1.14 1.16 0.04 0.51 0.12 0.04 0.08 0.04 0.06 0.05 0.63 0.03 0.03 0.06 0.04 EXCHANGEABLE BASES (meq/1 OOg I Magnesium Sodium Potassium 0.14 0.22 0.12 0.1 1 0.1 1 . 0.16 0.05 0.04 0.05 0.04 Potassium Gr.Dio. A Citric 0.10 Gr.Dio. A Oxalic 0.22 Gr.Dio. A Acetic 0.23 Gr.Oio. A HCL 0.56 Gr.Dio. A HOH 0.61 Basalt A Citric 0.06 Basalt A Oxalic 0.44 Bosalt A Acetic 0.14 Bosalt A HCL 0.34 Basolt A HOH 0.29 0.40 0.04 0.13 0.59 0.05 0.23 0.07 0.07 0.15 0.12 0.07 0.17 0.08 0.09 0.13 0.07 0.02 0.03 1.18 0.04 ' 0.06 0.07 0.06 0.06 0.17 0.08 0.09 0.18 0.08 0.06 213 EXPERIMENT 3: COLUMN STUDY-11 WEEKS PARENT MATERIAL TREATMENT Gr.Dio. A Gr.Dio. A Gr.Dio. A Gr.Dio. A Gr.Dio. A Citric Oxolic Acetic HCL HOH Calcium 0.03 0.07 0.17 0.13 0.58 EXCHANGEABLE BASES (meq/ 1 OOg 1 Magnesium Sodium Potassium 0.62 1.02 0.13 0.14 0.05 0.06 0.07 0.05 0.04 0.06 0.25 0.59 0.06 0.07 0.26 Basalt A Basalt A Basalt A Basalt A Basalt A Citric Oxalic Acetic HCL HOH 0.02 0.29 0.09 0.08 0.32 1.16 1.41 0.27 0.19 0.14 0.10 0.15 0.09 0.10 0.06 0.20 0.10 0.08 0.0S 0.08 EXPERIMENT 4> BATCH STUDY-11 WEEKS PARENT MATERIAL TREATMENT Gr.Dio. A Gr.Dio. A Gr.Dio. A Gr.Dio. A Gr.Dio. A Citric Oxalic Acetic HCL HOH Calcium 0.03 0.14 0.23 0.19 0.42 EXCHANGEABLE BASES Magnesium Sodium 0.87 0.06 0.98 0.06 0.12 , 0.04 0.09 0.04 0.14 0.05 (meq/10Og I Potassium 0.39 0.58 0.10 0.33 0.12 Basalt A Bosolt A Basalt A Basalt A Basalt A Citric Oxolic Acetic HCL HOH 0.00 0.27 0.09 0.10 0.35 6.46 10.13 0.12 0.07 0.16 0.05 0.05 0.05 0.05 0.05 0.05 0.15 0.67 0.29 0.93 EXPERIMENT S< BATCH STUDY-11 WEEKS PARENT MATERIAL Gr.Dio. B Gr.Dio. B Gr.Dio. B TREATMENT Citric Oxalic Acetic Calcium 0.19 0.11 0.43 EXCHANGEABLE BASES Magnesium Sodium 1.18 0.14 0.95 0.14 0.13 0.05 'meq/1 OOg 1 Potassium 0.35 0.51 0.11 Bosalt B Basolt B Basalt B Citric Oxalic Acetic 0.02 0.45 0.06 1.10 1.36 0.19 0.09 0.15 0.09 0.50 0.07 0.77 Hawaiin Hawaiin Citric Oxolic 0.06 0.20 1.22 0.88 0.07 0.16 0.08 0.23 214 A p p e n d i x N : M a s s B a l a n c e C a l c u l a t i o n s Note: The values may be used only f o r the basis of approimate comparisons f o r the following reasons: 1. C o l l o i d a l material may overestimate values from s o l u t i o n and extractable Fe, A l , and S i analyses. 2. Values f o r extractable Fe, A l , and S i are not additive but i n f a c t overlap. 3. Concentrations of ions i n solutions may l a t e r form p r e c i p i t a t e s and contribute to both s o i i d and s o l u t i o n analyses. 4. Values f o r extractable A l and S i are l e s s accurate than f o r extractable Fe. 215 M A S S B A L A N C E C A L C U L A T I O N S B A T C H A N D C O L U M N E X P E R I M E N T C a 2 + , M g 2 + , Na +, K + I . G R A N O D I O R I T E - % C a O TREATMENT A BBCH CBCH DCOL ECOL C i t r i c 4.93 0.77 20.20 0.51 10.30 Oxalic 4.93 0.37 7.45 0.24 4.92 Ac e t i c 4.93 0.19 3.89 0.27 5.55 HCL 4.93 0.14 2.80 0.34 6.83 HOH 4.93 0.03 0.63 0.02 0.44 I I . B A S A L T -% C a O C i t r i c 8.41 0.43 5.15 0.46 5.46 Oxalic 8.41 0.13 1.60 0.13 1.57 Ac e t i c 8.41 0.12 1.49 0.15 1.84 HCL 8.41 0.17 2.07 0.18 2.20 HOH .8.41 0.01 0.15 0.00 0.00 I . G R A N O D I O R I T E - % M g O C i t r i c 2.15 0.40 18.76 0.20 9.20 Oxalic 2.15 0.61 28.57 0.45 20.93 Ac e t i c 2.15 0.03 1.61 0.03 1.62 HCL 2.15 0.04 1.66 0.06 2.86 HOH 2.15 0.01 0.57 0.00 0. 00 I I . B A S A L T - % M g O C i t r i c 9.04 3.83 42.36 2.98 32.93 Oxalic 9.04 0.51 5.62 1.07 11.80 Ace t i c 9.04 0.03 0.29 0.06 0. 69 HCL 9.04 0.04 0.39 0.06 0.69 HOH 9.04 0.00 0.00 0.00 0.00 A = % Oxide i n unweathered material BBCH = T o t a l % oxide i n 11 wks batch leachate CBCH = % B of A DCOL = T o t a l * oxide i n 11 wks batch leachate Eorvr = % D O f A 216 M A S S B A L A N C E C A L C U L A T I O N S B A T C H & C O L U M N E X P E R I M E N T I . G R A N O D I O R I T E - % N a 2 0 T R E A T M E N T A BBCH CBCH DCOL ECO] C i t r i c 3.77 0.05 1.33 0.03 0.77 Oxalic 3.77 0.06 1.70 0.05 1.28 Ac e t i c 3.77 0.02 0.56 0.01 0.35 HCL 3.77 0.02 0.42 0.01 0.39 HOH 3.77 0.01 0.31 0.01 0.16 I I . B A S A L T - % N a 2 0 C i t r i c 3.38 0.03 0.97 0.03 0.70 Oxalic 3.38 0.04 1.14 0.04 1.40 Ace t i c 3.38 0.03 0.87 0.01 0.17 HCL 3.38 0.03 0.93 0.02 0.59 HOH 3.38 0.01 0.34 0.00 0.00 I . G R A N O D I O R I T E - % K 2 0C i t r i c 2.31 0.51 21.98 0.29 12.76 Oxalic 2.31 1.16 50.19 0.90 39.04 Ac e t i c 2.31 0.13 5.45 0.06 2.50 HCL 2.31 0.10 4.30 0.07 3.10 HOH 2.31 0.04 1.74 0.01 0.58 I I . B A S A L T - % K 2 0 C i t r i c 0.54 0.01 1.61 0.01 1.50 Oxalic 0.54 0.01 1.03 <0.01 1.00 Acet i c 0.54 0.01 1.64 0.00 0.00 HCL 0.54 0.01 1.68 0.00 0.00 HOH 0.54 0.00 0.00 0.00 0.00 A = % Oxide i n unweathered material BBCH = T o t a l % oxide i n 11 wks Batch leachate CBCH = % B °f A DCOL = T o t a l % oxide i n 11 wks Batch leachate E C 0 L = % D of A M A S S B A L A N C E C A L C U L A T I O N S C O L U M N E X P E R I M E N T I . G R A N O D I O R I T E % F e ~ 0 A B C TREATMENT C i t r i c 5.21 1.17 0.20 Oxalic 5.21 3.17 6.92 Acetic 5.21 . 0.13 0.06 HCL 5.21 0.19 0.03 HOH 5.21 0.00 0.03 I I B A S A L T -• % F e 2 0 3 C i t r i c 12.46 9.51 0.34 Oxalic 12 .46 2.85 18.59 Acetic 12.46 0.32 1.29 HCL 12.46 0.35 0.03 HOH 12.46 0.00 0.00 A = % Oxide i n unweathered material B = Total % oxide i n 11 wks leachate C = Pyrophoshate extractable % oxide D = Ammonium Oxalate extractable % oxide E = CBD extractable % oxide F = % B of A G = % E of A D E F G H 1. 52 3. 66 22.48 70.26 92.74 2. 23 1. 00 60.85 19.21 80.06 2. 34 1. 00 2.49 19.21 21.70 1. 83 0. 86 3.61 16.47 20.08 1. 37 0. 86 0.00 16.50 16.50 1. 66 0. 43 76.30 3.44 79.74 3. 00 6. 95 22.83 55.78 78.61 3. 98 1. 14 2.60 9.18 11.78 3. 86 1. 09 2.80 8.72 il . 5 2 4. 46 1. 00 0.00 8.03 8.03 ^4 M A S S B A L A N C E C A L C U L A T I O N S C O L U M N E X P E R I M E N T I . G R A N O D I O R I T E % A1 203 A B C D E F G H C i t r i c 16.61 0.82 0.11 0.26 0.23 4.91 1.37 6.28 Oxalic 16.61 2.19 0.08 0.15 0.30 13.19 1.82 15.01 Acetic 16.61 0.10 0.04 0.45 0.30 0.60 1.82 2.42 HCL 16.61 0.12 0.04 0.45 0.26 0.71 1.59 2.30 HOH 16.61 0.00 0.00 0.38 0.26 0.00 1.59 1.59 I I . B A S A L T % A1 20 3 C i t r i c 15. ,17 0. .12 0. .00 0. .30 0. .08 0. .82 0. ,53 1. .35 Oxalic 15. ,17 0. ,29 0. .04 0. ,00 0. ,04 1. ,88 0, ,25 2. ,13 Acetic 15. ,17 0. ,07 0. .04 0. .30 0. ,15 0. .48 1. ,00 1. .48 HCL 15. ,17 0. .05 0. .00 0. .30 0. ,19 0. .35 1, ,25 1. .60 HOH 15. .17 0. .00 0. .00 0. .38 0. ,15 0. .00 1. ,00 1. .00 A = % Oxide i n unweathered material B = Total % oxide i n 11 wks leachate C = Pyrophoshate extractable % oxide D = Ammonium Oxalate extractable % oxide E = CBD extractable % oxide F = % B of A G = % E of A H = % t o t a l oxide removed (F + G) to M CO M A S S B A L A N C E C A L C U L A T I O N S C O L U M N E X P E R I M E N T 1. G R A N O D I O R I T E % 8i0 2 A B C D E F G H C i t r i c 63 .80 0. .56 0. .38 0. ,00 0. 38 0. ,88 0. ,60 1. .40 Oxalic 63 .80 1. .42 0. .79 0. .00 0. 21 2. .24 0. ,34 2. .58 Acetic 63 .80 0. .02 0. .09 0. .00 0. 21 0. .03 0. .34 0. .37 HCL 63 .80 0. .01 0. , 00 0. ,00 0. 17 0. .02 0. ,27 0. .29 HOH 63 .80 0. .00 0. .00 0. ,00 0. 17 0. .00 0. .27 0. .27 I I . B A S A L T -% s i o 2 C i t r i c 49 .96 4. .26 1. .01 0. .00 0. 38 8. .52 0. .60 9. .12 Oxalic 49 .96 4. .26 0. .96 0. .00 0. 43 8. .52 0. .86 9. .38 Acetic 49 .96 0. .10 0. .13 1. ,11 0. 28 0. ,20 0. .56 0. .76 HCL 49 .96 0. .09 0. .09 1. .11 0. 28 0. .18 0. .56 0. .74 HOH 49 .96 0. ,00 0. ,00 1. ,28 0. 28 0. .00 0. ,56 0. .56 A = % Oxide i n unweathered material B = Total % oxide i n 11 wks leachate C = Pyrophoshate extractable % oxide D = Ammonium Oxalate extractable % oxide E = CBD extractable % oxide F = % B of A G = % E of A H = % t o t a l oxide removed (F + G) M A S S B A L A N C E C A L C U L A T I O N S B A T C H E X P E R I M E N T I . G R A N O D I O R I T E - % F e 2 0 3 TREATMENT A B C C i t r i c 5.21 2.37 0.37 Oxalic 5.21 4.68 5.72 Acetic 5.21 0.57 0.11 HCL 5.21 0.34 0.14 HOH 5.21 0.11 0.31 I I . B A S A L T % F e 2 0 3 C i t r i c 12. .46 4. ,40 0. 57 Oxalic 12. .46 1. .69 13 .44 Acetic 12. .46 0. .15 0. 06 HCL 12. .46 0. .30 0. 13 HOH 12. .46 0. .04 0. 03 D E F G H 1. 43 0. 72 45.49 13.81 59.70 2. 43 2. 86 89.83 54.89 144.70 2. 06 0. 94 10.94 18.04 28.98 1. 83 0. 94 6.52 18.04 24.56 2. 00 o. 72 2.11 13.82 15.93 1. 89 0. 54 35.31 4.33 39.64 1. 89 0. 72 13.56 5.78 19.34 4. 58 1. 00 1.21 8.02 9.22 3. 15 1. 00 2.40 8.02 10.42 4. 58 1. 07 0.32 8.59 8.91 A = % Oxide i n unweathered material B = Total % oxide i n 1 1 wks leachate C = Pyrophoshate extractable (% oxide) D = Ammonium Oxalate extractable (% oxide) E = CBD extractable (% oxide) F = % B of A G = % E O f A H = % t o t a l removed (F + G) MASS B A L A N C E C A L C U L A T I O N S B A T C H E X P E R I M E N T I . G R A N O D I O R I T E % A1 20 3 TREATMENT A B C D C i t r i c 16.61 1. 26 0. 18 0.30 Oxalic 16.61 2. 63 0. 05 0.20 Acetic 16.61 0. 17 0. 06 0.48 HCL 16.61 0. 06 0. 06 0.48 HOH 16.61 0. 05 0. 00 0.48 I I . B A S A L T % A1 20 3 TREATMENT A B C D C i t r i c 15.17 0. 16 0. 00 0.00 Oxalic 15.17 0. 22 0. 00 0.09 Acetic 15.17 0. 15 0. 00 0.09 HCL 15.17 0. 14 0. 00 0.06 HOH 15.17 0. 04 0. 00 0.10 A = % Oxide i n unweathered material B = Total % oxide i n 11 wks leachate C — Pyrophoshate extractable % oxide D = Ammonium Oxalate extractable % oxide E = CBD extractable % oxide F = % B of A G = % E of A H = % t o t a l oxide removed (F + G) E F G H 0.24 7.58 1.44 8.02 0.20 15.83 1.20 16.03 0.27 1.02 1.62 2.64 0.27 0.36 1.62 1.98 0.27 0.30 1.62 1.92 E F G H 1.18 0.02 1.47 0.13 1.60 0.03 0.99 0.20 1.19 0.03 0.92 0.20 1.12 0.04 0.26 0.26 0.52 M A S S B A L A N C E C A L C U L A T I O N S B A T C H E X P E R I M E N T I . G R A N O D I O R I T E - % 8 i 0 2 A B C D TREATMENT % S i 0 2 C i t r i c 63.80 0.97 0.38 0.00 Oxalic 63.80 1.83 0.62 0.00 Acetic 63.80 0.16 0.00 0.00 HCL 63.80 0.05 0.00 0.00 HOH 63.80 0.03 0.00 0.00 I I . B A S A L T -% S i 0 2 C i t r i c 49.96 5.80 0.75 0.26 Oxalic 49.96 3.79 0.75 0.43 Acetic 49.96 0.18 0 1.63 HCL 49.96 0.15 0 0.94 HOH 49.96 0.04 0 1.63 A = % Oxide i n unweathered material B = Total % oxide i n 11 wks leachate C = Pyrophoshate extractable (% oxide) D = Ammonium Oxalate extractable (% oxide) E = CBD extractable (% oxide) F = % B of A G = % E of A H = % t o t a l removed (F + G) E F G H 0.32 1.52 0.50 2.02 0.48 2.86 0.75 3.61 0.16 1.56 0.25 1.81 0.16 0.08 0.25 0.33 0.11 0.05 0.17 0.22 0.43 11.62 0.86 12.48 0.60 7.59 1.20 8.79 0.54 0.37 1.08 1.45 0.21 0.30 0.43 0.73 0.54 0.08 1.08 1.16 

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