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Aspects of the inorganic amorphous system of humo ferric podzols of the Lower Main Land [sic] of British… Visentin, Girolamo 1973

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c'  ASPECTS OF THE INORGANIC AMORPHOUS SYSTEM OF HUMO FERRIC PODZOLS OF THE LOWER MAIN LAND OF BRITISH COLUMBIA by Girolamo V i s e n t i n B.S.A.,  U n i v e r s i t y of Padua - I t a l y , 1 9 6 6  A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n the  Department of  Soil  Science  We accept t h i s t h e s i s as the  conforming  r e q u i r e d standard  THE UNIVERSITY OF BRITISH COLUMBIA October, 1 9 7 3  to  ii In presenting  t h i s thesis i n p a r t i a l f u l f i l m e n t of the  requirements for an advanced degree at the University of B r i t i s h Columbia, I agree that the L i b r a r y s h a l l make i t f r e e l y available f o r reference  and study.  I further agree  that permission f o r extensive copying of t h i s thesis for scholarly purposes may  be granted by the Head of  Department or by his representatives.  my  I t i s understood  that copying or duplication of t h i s thesis for f i n a n c i a l gain s h a l l not be allowed without my written permission.  Department of S o i l Science  The University of B r i t i s h Columbia Vancouver 8, Canada.  * • •  111  ABSTRACT A study was made t o j and  the s t r u c t u r a l o r g a n i z a t i o n  ( i ) i n v e s t i g a t e the nature o f the i n o r g a n i c  system i n p o d z o l s o i l s o f B r i t i s h Columbia,  amorphous  ( i i ) evaluate  the r e l a t i o n s h i p s between t h i s n a t u r a l system and a r t i f i c i a l amorphous i r o n - a l u m i n o s i l i c a t e systems. study ,are d e s c r i b e d  Results  of t h i s  i n a s e r i e s of three papers, each des-  c r i b i n g phases o f t h i s study. The  successive  selective dissolution analysis,  combined with i n f r a r e d spectroscopy technique proved t o be s u i t a b l e f o r q u a l i t a t i v e as w e l l as q u a n t i t a t i v e a t i o n o f the i n o r g a n i c  determin-  amorphous system o f the s o i l s  studied. A s t r u c t u r a l model f o r a r t i f i c a l aluminosilicate  systems i s d i s c u s s e d  amorphous i r o n -  and although not  considered t o be p e r f e c t , p r e s e n t s a u s e f u l p i c t u r e o f iron-aluminosilicate structures for  as i t o f f e r s an  some o f the experimental f i n d i n g s  explanation  recorded.  S t r o n g c o r r e l a t i o n s have been found through chemical and p h y s i c a l a n a l y s e s between the amorphous inorganic  system o f the s o i l s s t u d i e d  and a r t i f i c i a l l y -  prepared i r o n - a l u m i n o s i l i c a t e systems, and c l o s e s t r u c t u r a l organization  between the two systems i s i n f e r r e d .  iv  ACKNOWLEDGEMENTS  The  author wishes t o express h i s s i n c e r e  a p p r e c i a t i o n t o Dr, L.M. L a v k u l i c h , Department o f S o i l Science,  for his interest,  direction,  and a s s i s t a n c e  throughout the p r o j e c t and i n the p r e p a r a t i o n  of this  thesis. Appreciation  i s a l s o expressed t o Mr. B, von  S p i n d l e r , Miss S. McMeekin, and Mr. W. Cheang f o r a s s i s tance..with l a b o r a t o r y work d u r i n g v a r i o u s stages o f the study, and t o Miss Beth Loughran f o r a s s i s t a n c e with the draughting of f i g u r e s f o r t h i s The  thesis.  author would l i k e t o extend deep a p p r e c i a t i o n  to h i s w i f e , Maria L u i s a , f o r her a s s i s t a n c e , encouragement, and many s a c r i f i c e s d u r i n g the course o f t h i s study.  V  TABLE OF CONTENTS Page INTRODUCTION I  -  AN EVALUATION OF THE AMORPHOUS INORGANIC SYSTEM OF SELECTED BRITISH COLUMBIA PODZOL SOILS Introduction  2  The importance of the i n o r g a n i c amorphous system i n s o i l s  4  The pedogenesis o f the i n o r g a n i c ' amorphous system  7  Methods o f removal o f the i n o r g a n i c amorphous system  8  M a t e r i a l and Methods  17  The s o i l s used  17  Chemical c h a r a c t e r i z a t i o n  21  Aluminum and i r o n d e t e r m i n a t i o n  26  Preparation extraction  26  o f the s o i l  R e s u l t s and C o n c l u s i o n Procedures  samples f o r -  on the E x t r a c t i o n  32  Mineralogical Studies  37  S u c c e s s i v e E x t r a c t i o n Experiment and I n f r a r e d Spectroscopy f o r C h a r a c t e r i z a t i o n of the Amorphous Inorganic System i n S o i l Clays  38  R e s u l t s and D i s c u s s i o n E x t r a c t i o n Experiment  48  on S u c c e s s i v e  I n f r a r e d Spectroscopy S t u d i e s  59  Conclusion  67  Literature Cited  69  vi II  - STRUCTURE AND PROPERTIES OF AMORPHOUS 'IRON-  P  a  g  S  ALUMINOSILICATE SYSTEMS Introduction  73  M a t e r i a l s and Methods  80  R e s u l t s and D i s c u s s i o n  82  S t r u c t u r a l Model  97  Conclusion  101  Literature Cited  103  I I I - THE AMORPHOUS INORGANIC SYSTEM OF SOIL COMPARED TO AN ARTIFICIAL AMORPHOUS IRONALUMINOSILICATE SYSTEM Introduction  105  M a t e r i a l s and Methods  106  R e s u l t s and D i s c u s s i o n  110  Conclusion  126  Literature Cited  1  2  8  vii LIST OF TABLES Table  Page - 1.  2.1  E x t r a c t i o n a b i l i t y o f sodium pyrophosphate, ammonium o x a l a t e , and sodium dithionite  15  Abbotsford S e r i e s , podzol  17  A m i n i humo-ferric  2.2  Marble H i l l .  2.3  Ryder S e r i e s ,  2.4  Summer s e r i e s . f e r r i c podzol  3.1  Abbotsford - S e l e c t e d P r o p e r t i e s  22  3.2  Marble H i l l  23  3.3  Ryder - S e l e c t e d P r o p e r t i e s  24  3.4  Summer - S e l e c t e d P r o p e r t i e s  25  4.1  Comparison o f S i data (from the s o i l as a whole) g i v e n by e x t r a c t i o n withs o x a l a t e , pyrophosphate, and d i t h i o n i t e  29  Comparison o f Fe d a t a (from the S o i l as a whole) g i v e n by e x t r a c t i o n w i t h : o x a l a t e , pyrophosphate, and d i t h i o n i t e  30  Comparison o f A l data (from the s o i l as a whole) g i v e n by e x t r a c t i o n w i t h : o x a l a t e , pyrophosphate, and d i t h i o n i t e  31  D i f f e r e n c e s between o x a l a t e - and pyrophosphate-extracted Fe and between d i t h i o n i t e - and o x a l a t e - e x t r a c t e d Fe  35  Main m i n e r a l s p r e s e n t i n Ryder, Summer Abbotsford, and Marble H i l l as d e t e r mined by X-ray d i f f r a c t i o n  38  Ryder - S u c c e s s i v e e x t r a c t i o n s on <Z/K c l a y  49  Summer - S u c c e s s i v e e x t r a c t i o n s on <2p c l a y  50  4.2  4.3  5.  6.  7. 8.  A mini humo-ferric p o d z o l A m i n i humo-ferric p o d z o l A gleyed o r t h i c humo-  - Selected Properties  18 19 20  viii Table  9.  Page Ryder - Amorphous m a t e r i a l e x t r a c t e d from < 2/4 c l a y by s u c c e s s i v e e x t r a c tions: 5% Na CCU + Na pyrophosphate + a c i d ammonium o x a l a t e . Included a r e : % l o s s , % c l a y content, molar r a t i o o f amorphous oxides, sum of amorphous oxides, s u r f a c e area, % amorphous oxides i n s o i l  52  Summer - Amorphous m a t e r i a l e x t r a c t e d from < 2 p c l a y by s u c c e s s i v e e x t r a c tions: Na CCU + a c i d NHj, oxalate + dithionite. The table also includes: molar r a t i o o f amorphous o x i d e s , % sum of amorphous o x i d e s , fo c l a y content, % amorphous oxides i n s o i l , % l o s s , surface area  53  Surface a r e a (m /g) o f Bf3 Ryder h o r i z o n c l a y and the s u r f a c e o f the same a f t e r : sodium carbonate, a c i d ammonium o x a l a t e , and d i t h i o n i t e treatments.  °2  2  10.  2  J  11.  II  - 1.  Chemical composition, elemental and oxide r a t i o s , s p e c i f i c surface area, C E„C., X-ray d i f f r a c t i o n e  2.  III  Dry f i x a t i o n o f potassium s i l i c a gels  by iron-alumino"  8  6  8  8  3.  A S - 2 s u c c e s s i v e treatments d a t a and r a t i o s  90  4.  Comparison between data obtained a f t e r s u c c e s s i v e (a+b+c) e x t r a c t i o n and d a t a a f t e r a c i d d i g e s t i o n procedure on A S - 2 sample  91  - 1.  2.  Percent amorphous AlpO^o Fe CU, S i 0 ~ . i n Clay-R3, AC-R3 and i n •'AS-2* as e x t r a c t e d by s u c c e s s i v e s e l e c t i v e d i s s o l u t i o n s and d i t h i o n i t e only; amorphous oxides molar ratio ?  T o t a l p e r c e n t o f amorphous m a t e r i a l i n Clay-R3, AC-R3» and AS-2 as e x t r a c t e d by s u c c e s s i v e s e l e c t i v e d i s s o l u t i o n s and d i t h i o n i t e only; p e r c e n t l o s s a f t e r treatments, s u r f a c e area o f the untreated samples and a f t e r treatments  1  1  2  114  ix Table  Page 3.  T o t a l elemental a n a l y s i s of AC-R3» A S - l , AS-2 and AS-3  118  4„  T o t a l percent of A l , Fe, S i oxides r e c a l c u l a t e d from Table 3 on a i r - d r y b a s i s .  118  5.  Atomic r a t i o s A l / A l + S i , oxides molar r a t i o s , p e r c e n t oxides i n AC-R3* AS-1, AS-2 and AS-3 c a l c u l a t e d from the data of t o t a l elemental a n a l y s i s and the data of s u c c e s s i v e e x t r a c t i o n s  119  X LIST OF FIGURES Figure  Page  - 1.  2,  3o  4.  5.  6  0  7.  8.1  8.2  9a»  b.  Comparison of aluminum e x t r a c t i o n methods. Oxalate v e r s u s c i t r a t e - b i e a r b o n a t e dithionite  33  Comparison of i r o n e x t r a c t i o n methods. Oxalate v e r s u s c i t r a t e - b i c a r b o n a t e dithionite  34  Amorphous e x t r a c t e d i r o n (by d i f f e r e n c e between oxalate and pyrophosphate e x t r a c t e d i r o n ) , and c l a y content i n Ryder  36  Amorphous e x t r a c t e d i r o n (by d i f f e r e n c e between oxalate and pyrophosphate e x t r a c t e d i r o n ) , and c l a y content i n Summer  36  A schematic r e p r e s e n t a t i o n o f s u c c e s s i v e e x t r a c t i o n s of i n o r g a n i c amorphous system and c o r r e s p o n d i n g analyses  43  D i s t r i b u t i o n along the Ryder p r o f i l e of A l , Fe and S i oxides e x t r a c t e d by s u c c e s s i v e treatments j < 2/u c l a y content  55  D i s t r i b u t i o n along the Summer p r o f i l e of A l , Fe and S i oxides e x t r a c t e d by success i v e t r e a t m e n t s ; < 2^ c l a y content  55  Ryder - D i s t r i b u t i o n a l o n g the p r o f i l e t o t a l amorphous oxides e x t r a c t e d by s u c c e s s i v e treatments? % <2j* c l a y  of 56  Summer - D i s t r i b u t i o n a l o n g the p r o f i l e of t o t a l amorphous oxides e x t r a c t e d by successive treatments; fo<2j* c l a y  56  Comparison between i n f r a r e d s p e c t r a of u n t r e a t e d Clay-R3 and the Clay-R3 a f t e r (a+b) e x t r a c t i o n  63  D i f f e r e n t i a l i n f r a r e d s p e c t r a between u n t r e a t e d Clay-R3 ( i n sample-beam) and the Clay-R3 a f t e r (a+b) e x t r a c t i o n ( i n reference-beam).  63  xi Figure  Page 10a„  b.  11a.  b.  12.  13.  14.  II  -  1. 2.  Comparison between i n f r a r e d s p e c t r a of u n t r e a t e d Clay-R3 and the Clay-R3 a f t e r (a+b+c) e x t r a c t i o n  64  D i f f e r e n t i a l i n f r a r e d s p e c t r a between u n t r e a t e d Clay-R3 ( i n sample-beam) and the Clay-R3 a f t e r (a+b+c) e x t r a c t i o n ( i n reference-beam)  64  Comparison between i n f r a r e d s p e c t r a of the untreated Clay-R3 and the C l a y R3 a f t e r (a+b+c+d) e x t r a c t i o n  65  D i f f e r e n t i a l i n f r a r e d s p e c t r a o f the u n t r e a t e d Clay-R3 ( i n sample-beam) and the Clay-R3 a f t e r (a+b+c+d) e x t r a c t i o n ( i n reference-beam)  .  4.  5  D i f f e r e n t i a l i n f r a r e d s p e c t r a o f Clay-R3 a f t e r (a+b) e x t r a c t i o n ( i n sample-beam) and Clay-R3 a f t e r (a+b+c+d) e x t r a c t i o n ( i n reference-beam)  66  D i f f e r e n t i a l i n f r a r e d s p e c t r a of Clay-R3 a f t e r (a+b+c) e x t r a c t i o n ( i n sample-beam) and Clay-R3 a f t e r (a+b+c+d) e x t r a c t i o n ( i n reference-beam)  66  Comparison between i n f r a r e d s p e c t r a o f u n t r e a t e d Clay-R3 and Clay-R3 a f t e r f o u r successive extractions  66  Schematic s t r u c t u r a l r e l a t i o n s h i p s i n silicoaluminas  78  C a t i o n exchange c a p a c i t y and s u r f a c e area of s y n t h e t i c i r o n - a l u m i n o s i l i c a t e hydrogels as determined at pH 7.0 i n f u n c t i o n of % AlgOyAlgO-j + S i 0  85  Schematic r e p r e s e n t a t i o n and s t r u c t u r a l formulas of i r o n - a l u m i n o s i l i c a t e core-phase and p o l y h y d r o x y - i r o n and -aluminum phases with v a r y i n g A l / A l + S i atomic r a t i o  100  2  3.  6  Comparison o f i n f r a r e d s p e c t r a of i r o n a l u m i n o s i l i c a t e standards AS-1, AS-2, and AS-3  93  xii Figure  Page 5.  III  -  1.  Infrared spectra of i r o n - a l u m i n o s i l i c a t e standards A S - 1 , AS-2 and AS-3 a f t e r dehydration ( a t 300 C)  94  Comparison "between i n f r a r e d s p e c t r a of AC-R3 (amorphous concentrate o f Ryder Bf3 h o r i z o n ) and AS-2 (amorphous i r o n a l u m i n o s i l i c a t e standard)  121  2.1  AC-R3 i n f r a r e d s p e c t r a a f t e r extractions  122  2.2  AC-R3 i n f r a r e d s p e c t r a a f t e r s u c c e s s i v e e x t r a c t i o n s and h e a t i n g at 300 C  3.1  AS-2 i n f r a r e d s p e c t r a a f t e r extractions  3.2  successive  successive  AS-2 i n f r a r e d s p e c t r a a f t e r s u c c e s s i v e e x t r a c t i o n s and h e a t i n g at 300 C  123 124 125  1.  INTRODUCTION  The  importance of the s o i l  i n o r g a n i c amorphous  system f o r the c h a r a c t e r i z a t i o n of chemical and  the p h y s i c a l  p r o p e r t i e s o f s o i l has been e s t a b l i s h e d by much r e s e a r c h even though the amount o f amorphous m a t e r i a l p r e s e n t be o n l y . a few .  percent.  T h i s system i s d e s c r i b e d  as a complex p o l y m e r i c  system composed of d i f f e r e n t i n t e r a c t i n g phases; has  may  an  attempt  been made i n t h i s study t o d i s t i n g u i s h among these  v a r i o u s phases because t h e i r r e l a t i v e d i s t r i b u t i o n w i t h i n the s o i l p r o f i l e i s f e l t  to have an important b e a r i n g  p h y s i c o - c h e m i c a l p r o p e r t i e s of the s o i l , ation,of s o i l the  genesis,  i n t e n s i t y and The  and  the  on the i n t e r p r e t -  on the s t u d i e s connected w i t h  c o n d i t i o n of weathering.  other o b j e c t i v e of t h i s t h e s i s was  gate the nature of the component phases o f the i n o r g a n i c amorphous system and of the system i t s e l f . phases and  on  to  investi-  natural  the s t r u c t u r a l o r g a n i z a t i o n  For t h i s purpose, the nature of  the  the s t r u c t u r e o f a r t i f i c i a l amorphous i r o n -  a l u m i n o s i l i c a t e systems have been s t u d i e d on the b a s i s they could have t h e i r c o u n t e r p a r t  i n the n a t u r a l environment.  In seeking r e l a t i o n s h i p s between n a t u r a l and systems, s u c c e s s i v e  that  artificial  s e l e c t i v e d i s s o l u t i o n a n a l y s i s combined  with i n f r a r e d s p e c t r o s c o p y has been shown to be s u i t a b l e f o r the purpose of t h i s study.  2.  AN EVALUATION OP THE AMORPHOUS INORGANIC SYSTEM OF SELECTED BRITISH COLUMBIA PODZOL SOILS  INTRODUCTION The f i n e s t p a r t i c l e s c o n t a i n e d i n the c l a y f r a c t i o n o f most s o i l s are amorphous t o X-ray and  often  c o n t r i b u t e s i g n i f i c a n t l y t o the bulk o f s o i l s .  Their  h i g h r e a c t i v i t y has i n v i t e d i n v e s t i g a t i o n s i n t o  their  q u a n t i t a t i v e d e t e r m i n a t i o n and t h e i r c o m p o s i t i o n .  Any  attempt a t d e f i n i n g t h i s amorphous system other than by an o p e r a t i o n a l means would be naive because  the system  l a c k s f u n c t i o n a l homogeneity and,, consequently, l a c k s unique r e a c t i o n s whereby i t may guished.  be unambiguously, d i s t i n -  I t i s i n f a c t a complex system i n which v e r y  o f t e n d i f f e r e n t i n t e r a c t i n g phases  occur  contemporaneously,  i n d i f f e r e n t p r o p o r t i o n s , depending upon the type of p a r e n t m a t e r i a l undergoing weathering and the e v o l u t i v e dynamics of the  soil. Another concept seems t o be i n h e r e n t t o t h i s  polyphase system*  i t appears, i n f a c t  to assume there e x i s t s a continuum  0  t o be q u i t e  realistic  from t o t a l l y d i s o r d e r e d to  p o o r l y ordered phases i n t h i s systemj  i n the d i s o r d e r e d  phases atoms or molecules o f a s o l i d d e v i a t e from those o f c o r r e s p o n d i n g c r y s t a l l i n e s o l i d s due t o d e f e c t s such as v a c a n c i e s , i n t e r s t i t i a l atoms and g r a i n boundaries (Fieldes,;,.,  1966).  A high p r o p o r t i o n of d e f e c t s r e s u l t s i n a h i g h l y  disordered  s t a t e which l n extreme cases c o u l d approach complete randomness . I f a p r e c i s e d e f l n a t i o n of the amorphous polyphase system i s p o s s i b l e , the system could, be d e f i n e d i n terms of p h y s i c a l and chemical p r o p e r t i e s of the s o i l m a t e r i a l , which are conveyed to the s o i l by the i n o r g a n i c amorphous system. Amorphous m a t e r i a l s are known to be common i n podz o l i c o r spodic h o r i z o n s of Podzol s o i l s . The adopted  crite-  r i a f o r spodic h o r i z o n s by the U.S.D.A. S o i l Survey S t a f f are h i g h C.E.C. (150 meq/100 g c l a y ) , high 15-bar water  retention  a pH of more than 9.k i n NaF, more than \% of o r g a n i c matter, and the presence of a low-temperature endotherm ( S o i l Survey S t a f f et a l . ,  i n D.T.A.  I 9 6 7 ) .  Even w i t h the term " a l l o p h a n e " there i s d i s a g r e e ment among authors who  have t r i e d to d e f i n e i t ;  them ( F i e l d e s , 1966; F l e l d e s and F u l k e r t , 1966)  some of recognize  a l l o p h a n e , i n g e n e r a l , as having many q u a l i t a t i v e  similari-  t i e s i n chemical behaviour that depend upon t h e i r nature as random-structured hydrous a l u m i n o s i l i c a t e s and t h a t  differ-  ences among a l l o p h a n e s a r e , i n g e n e r a l , due to c o m p o s i t i o n . On the o t h e r hand, L a i and Swindale (I969) have more r e c e n t l y d e f i n e d a l l o p h a n e s hydrated a l u m i n o s i l i c a t e miner a l s , amorphous to X-ray and without ordered c r y s t a l l i n e s t r u c t u r e , i m p l y i n g w i t h the term '•mineral" a more d e f i n i t e composition and a more c h a r a c t e r i s t i c arrangement  of atoms.  4.  THE  IMPORTANCE OF THE INORGANIC AMORPHOUS SYSTEM  IN SOILS. S o i l c l a y m i n e r a l o g i s t s and p e d o l o g i s t s , supporting  while  the view t h a t the c l a y f r a c t i o n may c o n t a i n an  appreciable  amount o f amorphous i n o r g a n i c m a t e r i a l ,  still  have some r e s e r v a t i o n s as t o i t s importance i n determining and governing the chemical and p h y s i c a l p r o p e r t i e s o f associated c r y s t a l l i n e clay  minerals.  From the s t u d i e s o f many authors ( F i e l d e s , e t a l . , 1951; 1963?  M i t c h e l l and Farmer, I 9 6 0 } Greenland and Oades, 1 9 6 9 ;  Yuan, 1 9 6 8 j 1969i  De Mumbrum, I 9 6 0 }  Deshpande e t a l , , 1 9 6 8 $  B r i n e r and Jackson, 1 9 6 9 ;  P a r f i t t , 1972)  Sumner,  Raman and Mortland,  i t appears t h a t numerous c o r r e l a t i o n s  e x i s t between p a r t i c u l a r macromorphological f e a t u r e s o f the s o i l p r o f i l e and the nature and amount, o f the i n o r g a n i c amorphous system, as w e l l as the i n t e r r e l a t i o n s h i p s between t h i s system and the physico-chemical line clay.  properties of c r y s t a l -  I n f a c t , evidence i s a v a i l a b l e t o show t h a t  p r o p e r t i e s such as anion a b s o r p t i o n , area, are modified  s w e l l i n g , and surface  by the presence o f amorphous i r o n  oxides  even though few thorough i n v e s t i g a t i o n s have been undertaken. Sumner (1963) has demonstrated t h a t i r o n behave a m p h o t e r i c a l l y  i n s o i l and c o n t r i b u t e  oxides  significantly  to the b u f f e r c a p a c i t y o f t r o p i c a l s o i l s r i c h i n i r o n  oxides.  5.  Deshpane e t a l , (1968) examining i n r e l a t i o n t o aggregate  the r o l e of i r o n oxides  s t a b i l i t y , paying p a r t i c u l a r  a t t e n t i o n t o the r e l a t i v e importance  of Fe and A l , r e p o r t e d  s i g n i f i c a n t evidence of the p a r t p l a y e d by "free** aluminum oxides i n enhancing aggregates.  the s t a b i l i t y of micro- and macro-  The degree o f s t r u c t u r e and c o n s i s t e n c e of some  s o i l s has been r e l a t e d t o the bonding  a c t i o n of f r e e s e s q u i -  oxides on. the s u r f a c e of the primary p a r t i c l e s .  These  authors p o s t u l a t e i n t e r a c t i o n of the p o s i t i v e charges Al  of  oxides, with the n e g a t i v e l y - c h a r g e d c l a y p a r t i c l e s .  also, concluded  t h a t most of the i r o n was  They  present i n small,  d i s c r e t e , n e g a t i v e l y - c h a r g e d p a r t i c l e s which had  relatively  little  e f f e c t on the p h y s i c a l and p h y s i c o - c h e m i c a l p r o p e r t i e s  of  soil.  the  Greenland  and Oades (19&9) i n t h e i r work on changes  i n p h y s i c a l p r o p e r t i e s a s s o c i a t e d with the removal of f r e e i r o n oxides from d i f f e r e n t s o i l s a r r i v e d at d i f f e r e n t l u s i o n s than those of Deshpane e t a l , ( 1 9 6 8 ) ,  conc-  Aluminum  oxides and hydroxides, and a s m a l l p a r t . o f the f r e e  iron  c o u l d be p r e s e n t i n an a c t i v e form as c o a t i n g on c l a y p a r t i c l e s , and these a c t i v e oxides are b e l i e v e d t o be r e s p o n s i b l e f o r most, of the p o s i t i v e charges developed  by the s o i l .  The  reduction, of exchange negative charges a c c e s s i b l e to hydrogen ions, c r e a t e s an important  immunity t o a c i d weathering,  pro-  v i d e s pH f u n c t i o n a l C.E.C., l a t e n t or t i t r a t a b l e  acidity,  and s i t e s , with s t r o n g a f f i n i t i e s f o r phosphorus,  boron,  6.  molybdenum, and  other metals important i n p l a n t n u t r i t i o n .  F r e s h l y formed i r o n hydroxides are knownto be a c t i v e i n the sense t h a t they have high i s o e l e c t r i c and  points  are t h e r e f o r e predominantly p o s i t i v e l y charged up  about pH  8 . 0 and  have v e r y l a r g e s u r f a c e  F i e l d e s et a l .  (1951)  to  areas.  d u r i n g a survey o f the  islands  of Lower Cooks Group have observed t h a t the oxides of A l , Fe, and T i appeared to be the only p o s s i b l e sources of the C.E.c.,  and  high  s i n c e c r y s t a l l i n e forms o f these oxides have  c a p a c i t i e s they f e l t t h a t the amorphous oxides could  low  be  responsible. i Phosphate r e t e n t i o n s t u d i e s on n a t u r a l s o i l s as , w e l l as on s y n t h e t i c i r o n and  aluminum oxides and  C l o o s et a l . ,  hydroxides  (Gastuche e t . a l . ,  1963;  that, i n general,  the i n o r g a n i c amorphous system e x h i b i t s  a high p o t e n t i a l o f phosphate a b s o r p t i o n a v a i l a b i l i t y , whereas the r e v e r s e was  have shown  1968),  and  a low degree of  observed f o r c r y s t a l r  line material.  ,  , S p e c i f i c exchange e f f e c t s shown by s o i l s , p r e f e r e n t i a l r e t e n t i o n and NH^». Rb,  including  f i x a t i o n of c a t i o n s such as  K,  and Cs, have been almost e x c l u s i v e l y a s c r i b e d  to  c r y s t a l l i n e p h y l l o s i l i c a t e s i n the c l a y f r a c t i o n . Van Reeuwijk and  De V i l l i e r s  a l u m i n o s i l i c a t e gels to provide n a t u r a l allophane and  (1967)»  using  synthetic  a model f o r at l e a s t some  the c l a y m i n e r a l  formation  reactions  i n which these g e l s are i n v o l v e d , i n v e s t i g a t e d the  cation  7.  exchange s p e c i f i c i t y with p a r t i c u l a r reference to potassium. They f e l t i t was premature to accept t h e i r p o s i t i v e r e s u l t s • of K - f i x a t i o n by s o i l s , although i t i s possible they may have some relevance to that kind of f i x a t i o n which occurs in certain s o i l s i n the moist state.  THE PEDOGENESIS OF THE INORGANIC AMORPHOUS SYSTEM. The d i f f e r e n t phases of the system are believed to be transient products of the weathering of primary minerals, and of random-structured aluminosilicates.  The  next, step, i n the process which i s most l i k e l y to occur i s an h y d r o l i t i c polymerization of aquo-ions present i n solut i o n or a, r e l a t i v e l y rapid p r e c i p i t a t i o n at low temperatures and pressures giving r i s e to disordered hydroxy polymers„ The p a r t i c u l a r polyphase formations are believed to occur only^where s p e c i f i c weathering conditions are consistently establish,ed, such as a uniformly d i s t r i b u t e d r a i n f a l l , of 1200.mm or more annually, , The fundamental mechanism of decomposition i n the pedological neoformations i s that of hydrolysis which brings about a depolymerization of the orderly arranged iron.and aluminosilicate frameworks, with release i n the medium of the constituents i n the form of S i (OH)^ monomer acids, insoluble A l ( 0 H ) y and hydrated iron oxides, a l l lackingorderly  arrangement.  8. Subsequent l e a c h i n g o f bases and accesses t o G 0 would 2  lower the pH and l e a d t o c o p r e c i p i t a t i o n o f a f e r s i a l l i t i c amorphous phase a l o n g with p r e c i p i t a t i o n o f hydrous aluminum and hydrous i r o n amorphous p o l y m e r i c  phases  e  The nature o f these neogenic polyphases i s such t h a t i t allows them t o a s s o c i a t e i n d i f f e r e n t ways with the components o f the c o l l o i d a l f r a c t i o n o f the s o i l j hydroxy-Al and Fe ( I I I ) polymers  can be a s s o c i a t e d with  n e g a t i v e l y charged c r y s t a l l i n e p h y l l o s i l i c a t e s , o r i n t i m a t e l y a s s o c i a t e d w i t h each o t h e r .  A l and Fe can a l s o  be complexed w i t h organic matter or s u b s t i t u t e d i s o m o r p h o u s l y  i for  S i i n SiOg-Alg G^-FegO^ c o p r e c i p i t a t e s .  METHODS OF REMOVAL OF THE INORGANIC AMORPHOUS SYSTEM. " ;  The e a r l y r e s e a r c h e r s were p r i m a r i l y with the removal  1  concerned  o f the i n o r g a n i c amorphous system and i n  p a r t i c u l a r o f t h e i r o n o x i d e s , i n o r d e r t o improve the r e s o l u t i o n o f the c r y s t a l l i n e m i n e r a l s by X-ray  diffraction.  When they found changes i n the c l a y a f t e r the e x t r a c t i o n they began t o r e a l i z e t h a t these amorphous m a t e r i a l s might be important soils.  There  i n the c h a r a c t e r i z a t i o n and development o f i s now evidence t h a t s o i l  forming processes,!  as w e l l as parent m a t e r i a l s , are important i n the kinds and s t a b i l i t y o f the amorphous m a t e r i a l s o c c u r r i n g in, s o i l . As mentioned i n the i n t r o d u c t i o n , the c l a y t i o n of s o i l  frac-  c o n t a i n s the f i n e s t and t h e r e f o r e the most  9* s u r f a c e - r e a c t i v e p a r t i c l e s and as can be a p p r e c i a t e d many of the p r o p e r t i e s o f s o i l a r e determined by the nature o f these  f r a c t i o n s even when the amount p r e s e n t may be merely  a few p e r c e n t . treatment  Although  i t i s i n e v i t a b l e the chemical p r e -  w i l l r e s u l t i n some a l t e r a t i o n ' o f these p r o p e r t i e s ,  these need not n e c e s s a r i l y be disadvantageous and a c a r e f u l and c o n t r o l l e d d e g r a d a t i o n  o f the c l a y f r a c t i o n should  vide valuable information concerning properties.  pro-  i t s composition and  S t u d i e s based upon the r e l a t i v e s t a b i l i t y o f  a component o r a group o f components i n c l a y s t o s p e c i f i c chemical reagents p r o v i d e a u s e f u l approach t o t h e i d e n t i f i c a t i o n and e s t i m a t i o n o f the c o n s t i t u e n t s o f such complex systems. The more r e c e n t e f f o r t s o f r e s e a r c h e r s have been towards the r a p i d and e f f i c i e n t removal o f s e s q u i o x i d e s and the d i f f e r e n t i a t i o n and c h a r a c t e r i z a t i o n o f t h e amorphous s e s q u i o x i d e s as d i f f e r e n t i a t e d from c r y s t a l l i n e Tamm  sesquioxides,  (1932) was among the f i r s t t o propose a method  of removing s e s q u i o x i d e s from s o i l as a means o f d i s t i n g u i s h i n g between p o d z o l s and brown e a r t h s ,  Muir  (1961), u s i n g  Tamm's a c i d NH^ oxalate procedure f e l t t h a t the method's primary  use was t o determine the r a t e o f s o i l development  and t o d i s t i n g u i s h between types o f s o i l s , r a t h e r than as a method t o c l e a n up c l a y s f o r m i n e r a l o g i c a l a n a l y s i s .  10.  Other r e s e a r c h e r s were more concerned with the removal o f the s e s q u i o x i d e s Deb  (1950),  B  especially iron  oxides  6  i n s t u d y i n g the importance o f i r o n oxides i n  p o d z o l i z a t i o n , l a t e r i z a t i o n and phosphate  fixation,  compared Tamm's procedure w i t h a procedure u t i l i z i n g Nad i t h i o n i t e as a r e d u c i n g agent, w i t h a sodium a c e t a t e t a r t r a t e buffer»  Deb concluded  e x t r a c t e d by Tamm's procedure, uncovering  t h a t the s e s q u i o x i d e s i n c r e a s e d the C.E.C. by  a d d i t i o n a l exchange s i t e s on the c l a y , while  h i s procedure lowered the C.E.C. and removed amorphous as w e l l as c r y s t a l l i n e s e s q u i o x i d e s which possess c a t i o n exchange c a p a b i l i t y o r destroyed Mehra and Jackson  some  some o f the c l a y .  ( i 9 6 0 ) t e s t e d s e v e r a l methods  of e x t r a c t i o n a g a i n s t one proposed by them which was a sodium c i t r a t e system b u f f e r e d with sodium b i c a r b o n a t e and c o n t a i n i n g sodium d i t h i o n i t e .  The sodium c i t r a t e a c t s  as a c h e l a t i n g agent h e l p i n g t o remove some aluminum c o a t ings and s i l i c a cements.  The Na-bicarbonate kept the pH  w i t h i n a narrow range where there would be l e s s problems with p r e c i p i t a t i o n , as was the case with Deb's s u n l i g h t oxalate  procedure. Gorbunov e t a l . ( 1 9 6 1 ) ,  i n comparing a l l the  methods d i s c u s s e d above, as w e l l as o t h e r s  e  found  none o f the methods removed a l l the s e s q u i o x i d e s treatment.  that i n one  They found t h a t Tamm's o r Mehra and Jackson's  methods appeared more s p e c i f i c f o r amorphous s e s q u i o x i d e s .  11.  while Deb's procedure was  most s p e c i f i c f o r hydrated  iron  oxides. C o f f i n (1961) d e f i n e d " f r e e " i r o n to i r o n oxides and not  as p a r t  present.  other forms of i r o n found i n s o i l s  of the  The  include but  c r y s t a l l i n e l a t t i c e of other m i n e r a l s  purpose of h i s s t u d i e s was  to evaluate  the  e f f i c i e n c y of some of the more w i d e l y used h y d r o s u l p h i t e methods, and  to determine the r o l e of such f a c t o r s  temperature, and free  reagent c o n c e n t r a t i o n i n the  i r o n from s o i l s .  c a r r i e d out  He  at 50°C and  proposed j u s t one  e x t r a c t i o n •.. solution  sodium h y d r o s u l p h i t e i n a 0 „ 2 M c i t r a t e b u f f e r . r e p o r t e d an average standard d e v i a t i o n for duplicate  of  pH,  removal of  with a 5%  at pH 4 . 7 5  as  of  Coffin  0„034?S i r o n  +  values.  Franzmeier et a l , (1963) have c o n s i d e r e d the of sodium pyrophosphate as a c h e l a t i n g s t u d i e s of spodic h o r i z o n s and Mehra and  Jackson's method.  i t s a b i l i t y to e x t r a c t as i r o n .  minerals.  7.3  Their  agent i n t h e i r  compared t h e i r r e s u l t s with  Pyrophosphate was  organic matter and  They found that the maximum  occurred at pH  use  aluminum as  for well  extraction-efficiency  with l e s s d i s s o l u t i o n  of  r e s u l t s showed that m u l t i p l e  with p y r o p h o s p h a t e - d i t h i o n i t e and  selected  silicate extractions  citrate-dithionite  removed s i m i l a r amounts of i r o n and  extraction  of  p y r o p h o s p h a t e - d i t h i o n i t e removed about 75% as much i r o n  as  multiple  extractions  that  one  of c i t r a t e - d i t h i o n i t e .  12. More aluminum was  e x t r a c t e d by  pyrophosphate-dithionite  than c i t r a t e - d i t h i o n i t e r e g a r d l e s s of the number of t r e a t ments. McKeague and Day  (1966) t e s t e d Mehra and  Jackson's  c i t r a t e - d i t h i o n i t e procedure i n comparison with a c i d  NH^-  oxalate u s i n g a wide range of i r o n - e n r i c h e d h o r i z o n s Canadian s o i l s , i r o n and pH,  as w e l l as prepared amorphous and  aluminum oxides»  to propose  e x t r a c t i o n method u t i l i z i n g o x a l a t e .  t i o n at pH  3.0  with a f o u r hour shaking  An  extrac-  little  They r e p o r t e d t h a t both procedures  e x t r a c t e d more i r o n and  aluminum from f r e s h l y prepared amor-  phous aluminum m a t e r i a l than from s i l i c a t e m i n e r a l s . o x a l a t e - e x t r a c t a b l e aluminum exceeded aluminum i n most cases and  These authors claimed  t h a t some i r o n and  t h a t the  aluminum complexes.  oxalate values give  an  of the amorphous m a t e r i a l s formed by weathering  p r o c e s s i n g r e g a r d l e s s of the s o i l parent organic matter content  material,  or amount of t o t a l i r o n  They concluded t h a t t h e i r procedure was as an i n d i c a t o r of development of podzol soils  Also,  citrate-dithionite  d i s s o l v e d by the oxalate occur as metal-organic  estimate  an  time and c a r r i e d  out i n darkness gave the best r e s u l t s , with v e r y s i l i c a dissolution.  crystalline  They a l s o t e s t e d the e f f e c t s of  time of e x t r a c t i o n , e t c . , i n attempting  efficient  of  d e r i v e d from parent  oxides.  especially useful B horizons  m a t e r i a l high i n i r o n  as w e l l as b e i n g a b e t t e r e x t r a c t o r of  pH,  in  content,  13. aluminum than The  citrate-dithionite. o x a l a t e - e x t r a c t a b l e Fe and A l served i n  differentiating  c e r t a i n c l a s s e s of s o i l t h a t are d e f i n e d  i n the Canadian System of C l a s s i f i c a t i o n  (C.S.S.C. 1970).  They a l s o found that a l l podzol B h o r i z o n s had  distinct  accumulation of o x a l a t e - e x t r a c t a b l e aluminum and t h a t the o x a l a t e - i r o n and aluminum v a l u e s were a s s o c i a t e d w i t h h o r i z o n s h a v i n g a high pH dependent C.E.C. and h i g h phosphorus f i x i n g c a p a c i t y . (1967)  t  McKeague, i n a l a t e r r e p o r t  i n an e v a l u a t i o n of 0.1M  pyrophosphate  p y r o p h o s p h a t e - d i t h i o n i t e i n comparison  and  with o x a l a t e as  e x t r a c t a n t s of the accumulation products i n p o d z o l s and some other s o i l s , concluded t h a t the procedure was  Franzmeier.'s  not s p e c i f i c enough i n e x t r a c t i n g i r o n  i s l e s s s u i t a b l e f o r e s t i m a t i n g the accumulation  products  i n p o d z o l - l i k e B h o r i z o n s than a c i d NH^-oxalate and pyrophosphate.  and  0.1M  Although the d i s t i n c t i o n between amor-  phous and more or l e s s . c r y s t a l l i n e forms of e x t r a c t a b l e Fe i n s o i l s  i s useful, a further d i f f e r e n t i a t i o n  amorphous f r a c t i o n i s necessary.  Some s o i l s  of the .  developed  i n v o l c a n i c ash and some prominently mottled cambic h o r i z o n s c o n t a i n h i g h amounts of i n o r g a n i c Fe and  they  cannot be d i s t i n g u i s h e d by t h e i r content o f o x a l a t e e x t r a c t a b l e Fe from spodic h o r i z o n s i n which Fe i s u s u a l l y a s s o c i a t e d with organic matter. have proposed  a differentiation  McKeague et a l , (1970) of forms of e x t r a c t a b l e  14.  i r o n and  aluminum i n s o i l s by a f u r t h e r c h a r a c t e r i z a t i o n  of the form of Fe and A l e x t r a c t e d from known t>y pyrophosphate i n r e l a t i o n to o x a l a t e and They concluded  substances  dithionite.  t h a t t h e i r d a t a p r o v i d e d evidence  t h a t an  approximate d i f f e r e n t i a t i o n can be made among o r g a n i c complexed Fe, amorphous i n o r g a n i c Fe, and more or l e s s c r y s t a l l i n e Fe by s e l e c t i v e e x t r a c t i o n s o f s o i l s with phosphate, oxalate and d i t h i o n i t e .  Data f o r s y n t h e t i c  Fe- and A l - f u l v i c a c i d complexes, Fe- and oxides, and  pyro-  Al-hydrous  f o r spodic h o r i z o n s i n r e l a t i o n to other  i n d i c a t e t h a t pyrophosphate i s r e a s o n a b l y  soils  specific for  Fe o r g a n i c complexes and'somewhat l e s s s p e c i f i c f o r A l organic  complexes. The  d i f f e r e n c e between o x a l a t e and pyrophosphate  e x t r a c t a b l e Fe g i v e s a measure of amorphous i n o r g a n i c Fe and d i t h i o n i t e minus o x a l a t e - e x t r a c t a b l e Fe p r o v i d e s estimate  of more or l e s s c r y s t a l l i n e Fe oxides„  an  These  e x t r a c t a n t s are b e l i e v e d t o be l e s s u s e f u l i n d i s t i n g u i s h i n g forms of A l i n s o i l s . A summary of the e x t r a c t i n g a b i l i t y of the d i f f e r e n t reagents following table.  f o r Fe and A l i s presented  i n the  15.  TABLE 1. E x t r a c t i o n a b i l i t y o f sodium pyrophosphate, ammonium oxalate  and sodium d i t h i o n i t e f o r  i r o n and aluminum i n s o i l s *  INORGANIC IRON AND ALUMINUM COMPOUNDS  Silicates  Well c r y s tallized oxides  ORGANIC COMPLEXES  Amorphous hydroxides  (pH 3.8) N a - d i t h i o n i t e  (pH3.0) A c i d NH^-oxalate  (pH 10.0)  Na-pyrophosphate  good e x t r a c t i o n poor e x t r a c t i o n  * Modified  from Bascomb,  I968.  Acid soluble fulvate  Acid insoluble humate  16.  The purpose  of t h i s study was t o compare the  v a r i o u s e x t r a c t i o n procedures on s e l e c t e d s o i l s from the Lower F r a s e r V a l l e y and t o e l u c i d a t e the e f f e c t s o f the extractants  on s o i l c l a y s by means of X-ray  and i n f r a r e d spectroscopy.  diffraction  17.  MATERIALS AND METHODS Four podzol s o i l s representative of four s o i l series of B r i t i s h Columbia were considered i n t h i s studyt Abbotsford,  Marble H i l l , Ryder and Summer s e r i e s .  Brief  descriptions of these s o i l p r o f i l e s are given i n Tables 2.1,  2 , 2 , 2 . 3 , and 2 . 4 . TABLE 2 . 1 ABBOTSFORD SERIES: A MINI HUMO-FERRIC PODZOL  HORIZON Ap  DEPTH cm 0-15  Bf^hcc  15-25  Bf-cc  25-50  Bf^cc  50-68  J  DESCRIPTION Raw to p a r t i a l l y decomposed, mainly deciduous materials,; abrupt boundary. Dark reddish brown (5YR 3 / 4 M ) j gravelly sandy loam; weak, f i n e , subangular blockyj very f r i a b l e when moist5 numerous hard concretions; clear to gradual boundary. Brown reddish (5YR 4/4M); loamy sand; weak, f i n e , subangular blocky; f r i a b l e when moist, numerous concretions; gradual boundary, Reddish brown (5YR 4 / 4 M ) ; loamy sand; weak, f i n e , subangular blocky; f r i a b l e when moist, scattered fine concretions5 clear boundary.  BI1C  68-?5  Dark yellowish-brown (10YR 4/4M): gravelly loamy sand; firm i n place, breaking to single grain when disturbed? loose when moist; diffuse boundary.  IIC  75 +  Grayish-brown (10YR 5/3M): the same as above f o r the r e s t .  The parent material of t h i s podzol, collected i n the Abbotsford  area (along Hamm street, one mile from the  intersection of Hamm and Huntingdon Roads) at 67 meters elevation (A.S.L.) on a gentle slope, i s shallow aeolian deposits over g l a c i a l outwash. as well to rapid?  The drainage  i s classified  no ground water was present i n the cont-  r o l section with good moisture r e l a t i o n s h i p s . d i s t r i b u t i o n i s good.  The root  18.  TABLE 2 . 2 MARBLE HILLs  HORIZON  A MINI HUMO-FERRIG  DEPTH (cm)  PODZOL  DESCRIPTION ;  ,  L-H  0-15  Bf  1  15-65  Dark yellowish-brown (10 YR k/kM) t s i l t loam; weak, medium, subangular b l o c k y , s c a t t e r e d s o f t t o hard concret i o n s ; f r i a b l e when moist and abundant r o o t s ; gradual boundary.  Bf  2  65-80  Yellowish-brown (10 YR 5 A M ) ; s i l t loam; weak, medium, subangular b l o c k y , s c a t t e r e d s o f t t o hard c o n c r e t i o n s ; f r i a b l e when moist, abundant r o o t s ; c l e a r boundary.  80-90-  Brown t o yellowish-brown (10 YR 5/3.5M); g r a v e l l y sandy loam; weak, medium, subangular b l o c k y b r e a k i n g t o s i n g l e g r a i n ; very f r i a b l e when moist, common r o o t s 5 gradual boundary.  B II C  IIC  90-105  Raw t o w e l l decomposed mixture o f deciduous and c o n i f e r o u s m a t e r i a l s ; abrupt boundary.  Grayish-brown (10 YR 5/3M) t o v a r i e g a t e d ; g r a v e l l y sand; s i n g l e - g r a i n e d ; l o o s e when moist, o c c a s i o n a l r o o t s ; g r a d u a l boundary.  The Marble H i l l podzol samples were c o l l e c t e d i n the Abbotsford-Clearbrook area a t an e l e v a t i o n o f 50 meters (A.S.L.) with 2 - 5 % g e n t l e s l o p e s , on Clearbrook road a t the C.D.A. s m a l l f r u i t - t r e e Experimental Farm. ial  The parent mater-  i s a s i l t y a e o l i a n d e p o s i t over g r a v e l l y and sandy  g l a c i a l outwash d e p o s i t s .  The drainage i s c l a s s i f i e d as w e l l .  No ground water was p r e s e n t i n the c o n t r o l s e c t i o n and the moisture s t a t u s was good.  The s u r f a c e t e x t u r e s are e i t h e r  loam or s i l t y loam, which remain constant towards the lower h o r i z o n s i n the p r o f i l e where a coarse u n d e r l a y i s encountered.  19. TABLE RYDER SERIES s  HORIZON .  2.3  A MINI HUMO-FERRIC  DEPTH (cm)  PODZOL  DESCRIPTION  Ap  0-10  Bf-  10-30  D a r k r e d d i s h - b r o w n (5 YR 3AM); silt l o a m ; weak, f i n e , s u b a n g u l a r b l o c k y ; f r i a b l e when m o i s t , a b u n d a n t r o o t s ; g r a d u a l boundary.  Bf  30-60  R e d d i s h - b r o w n t o d a r k - b r o w n (5 YR 4/4 7.5 YR 4 / 4 M ) ; s i l t l o a m ; weak, f i n e , s u b a n g u l a r b l o c k y ; f r i a b l e when m o i s t ; a b u n d a n t t o common r o o t s ; g r a d u a l boundary.  Bfo  60-90  D a r k brown (7.5 YR 4 / 4 M ) 1 s i l t l o a m ; weak, f i n e , s u b a n g u l a r b l o c k y ; f r i a b l e when m o i s t , common r o o t s ; g r a d u a l boundary,  BIIC  90-105  D a r k y e l l o w i s h - b r o w n (10 YR 4/4M); g r a v e l l y s a n d y loam; m a s s i v e ; f r i a b l e when m o i s t ; g r a d u a l b o u n d a r y .  ?  C  105-140  V e r y d a r k g r a y i s h - b r o w n (10 YR 3 / 2 M ) ; s i l t loam? weak, f i n e , s u b a n g u l a r b l o c k y , b r e a k i n g t o weak, f i n e g r a n u l a r s t r u c t u r e ; f r i a b l e when m o i s t , a b u n d a n t r o o t s 5 abrupt boundary.  O l i v e brown ( 2 . 5 YR 4 / 4 M ) ; g r a v e l l y . loamy s a n d ; m a s s i v e ; f r i a b l e when m o i s t ; g r a d u a l boundary.  The R y d e r p o d z o l was c o l l e c t e d ford  area,  elevation  on a g e n t l e  slope  i n the Abbots-  ( 1 0 - 1 2 % ) , a b o u t 80 m e t e r s  (A.S.L.) a l o n g McCallum r o a d  ( h a l f mile  i n t e r s e c t i o n o f M c C a l l u m and M c C o n n e l l r o a d ) . material  is a silty  The d r a i n a g e present;  aeolian material  i s classified  from t h e  The p a r e n t  over g l a c i a l  till.  a s w e l l w i t h no g r o u n d w a t e r  good m o i s t u r e c o n d i t i o n s  and r o o t  penetration.  20. TABLE 2.4 SUMMER SERIES:  HORIZON  L-F-H  A GLEYED ORTHIC HUMO-FERRIC  DEPTH (cm) 0-15  PODZOL  DESCRIPTION  Moderately t o w e l l decomposed f o r e s t l i t t e r containing pieces of charcoal; abundant r o o t s .  Ae  15-22  Gray 9 (10 YR 6/2M); medium t o f i n e sand; very weak, f i n e subangular b l o c k y , breaking t o s i n g l e grains; very f r i a b l e t o loose when moist; c l e a r boundary.  Bf  22-50  D a r k - r e d d i s h brown (5 YR 2.5/2.5M); mottles are many, prominent, y e l l o w i s h red t o dark-red (5 YR 4-/6 - 2.5 YR 3/6) moist; sandy loam; m a i n l y massive, but some s t r o n g , medium b l o c k y s t r u c t u r e i n l o c a l i z e d pockets; f r i a b l e t o f i r m when moist, o c c a s i o n a l r o o t s ; diffuse boundary.  Bfcg  50-90  Grayish-brown (10 YR 5/2M); m o t t l e s common, d i s t i n c t , dark r e d d i s h brown (5 YR 3/4 m o i s t ) ; medium sand; massive; f r i a b l e t o f i r m when moist, s c a t t e r e d , dark r e d d i s h brown c o n c r e t i o n s up t o one inch i n diameter.  BC  90-110  WW  Cg  110-120  HCg  120-135  11*11*  NS  A  t|  X A J. W V  Vf  f  • \JL  talJL  JTL  XC U U  1 D J 1  U  (5 YR 3/4 m o i s t ) ; medium sand; mi very f r i a b l e when moist; d i f f u s e boundary. G r a y i s h brown (10 YR 5/2M); mottles; common, d i s t i n c t , reddish-brown (5 YR 5/3)5 sand and s i l t y c l a y ; massive; f i r m when moist; d i f f u s e boundary. G r a y i s h brown (10 YR 5/2M); common, d i s t i n c t , r e d d i s h brown m o t t l e s (5 YR 5/3)i s i l t y c l a y ; massive; p l a s t i c and s t i c k y when moist; d i f f u s e boundary.  J  21.  The Summer was c o l l e c t e d i n the U.B.C. campus a l o n g C h a n c e l l o r Boulevard a t an e l e v a t i o n o f about 18 meters (A.S.L.) and slope not over 2% . The parent m a t e r i a l i s sandy, r a i s e d l i t t o r a l  and beach d e p o s i t s over marine and  g l a c i a l - m a r i n e d e p o s i t s . The i n t e r n a l drainage I s impeded by the impermeable g l a c i o - m a r i n e underlay and cemented o r s t e i n h o r i z o n s . The r e s u l t i s a perched water t a b l e . Rooting depth i s r e s t r i c t e d by the cemenfced of  s u b s o i l . The p r o f i l e  consists  w e l l developed e l u v i a l and cemented i l l u v i a l h o r i z o n s w i t h  m o t t l e s i n the lower p a r t . CHEMICAL CHARACTERIZATION Chemical c h a r a c t e r i z a t i o n o f these f o u r s o i l s was done on the s o i l as a whole by r o u t i n e l a b o r a t o r y procedures and the r e s u l t s a r e r e p o r t e d i n T a b l e s ; 3 « 1 . 3 . 2 , 3 « 3 . and 3 • 4 . The o r g a n i c matter was determined a c c o r d i n g to the p r o cedure o u t l i n e d by A l l i s o n  (1965);  t o t a l N i t r o g e n was d e t e r -  mined f o l l o w i n g the procedure suggested by Bremner  (1965);  C.E.C. was determined by NH^OAc s a t u r a t i o n and semi-micro K j e l d a h l procedure (Chapman, 1 9 6 5 ) ; and the pH was determined w i t h the procedure o u t l i n e d by Peech  (I965).  The chemical d i s s o l u t i o n procedures which were used a r e : (a) 5% sodium  carbonate, b a s i c a l l y as o u t l i n e d by F o l l e t  (b) sodium pyrophosphate (c)  as proposed by Bascomb  (I965K  (1968),  a c i d ammonium o x a l a t e as proposed by Tamm ( 1 9 3 2 ) and r e v i -  ewed by McKeague and Day ( I 9 6 6 ) , (d) c i t r a t e - b i c a r b i n a t e - d i t h i o n i t e as suggested by Mehra and Jackson  (i960).  22. TABLE  3.1  ABBOTSFORD - SELECTED PROPERTIES  Sample  PH (O.OlM Ca C l )  pH (H 0)  Horizon  9  :  z  9  O.M. %  N (total)  C/N  %  Al  Ap  5.96  4.97  3.27  0.09  21.00  A2  Bfjhcc  5.89  5.00  3.53  0.11  18.54  A3  B  f  c  c  6  ,  0  7  5  ,  4  7  2  °*^  8  0  ,  0  14.00  2  A4  Bf cc  5.95  5.46  0.97  0.03  18.66  A5  BIIC  5.92  5.43  0.37  0.02  10.50  A6  IIC  5.72  5.57  0.08  0.01  5.00  Sample  3  Horizon  Exchangeable C a t i o n s (me/100 g of s o i l ) — — r — Ca K Mg Na  C.E.C. (me/lOOg of s o i l )  B.S. %  Al  Ap  3.38  0.31  0.28  0,07  14.47  27,92  A2  Bfjhcc  3.55  0,42  0.16  0.08  14.23  29.59  A3  BfgCC  1.25  0.23  0.12  0,08  12.77  13.16  A4  Bf^cc  1.03  0.23  0,09  0,08  14.37  9.95  A5  BIIC  0.65  0,15  0,09  0,09  10.19  9,62  A6  IIC  0,28  0.03  0,03  0.08  9.28  4„53  23.  TABLE 3.2 MARBLE HILL - SELECTED PROPERTIES  Sample  Horizon  pH (H 0) 2  pH (0.01M CaCl )  P.M.  N (total)  2  C/N  % Ml,  L-H  M2  B  M3  Bf  M4*  M5  5.32  4.70  15.04  0.50  17.40  5.33  4,78  2.63  0.10  15.20  5.33  4.88  2.65  0.10  15.20  BIIC  5.35  4.95  0.96  0,04  14.00  IIC  5.1?  4.95  0.32  0.02  9.00  l  f  2  Exchangeable C a t i o n s imple  Horizon  Ml  L-H  M2  Bf  M3  Bf  M4 M5  (i/looK  Ca  g o f Mg soil)  n  Na  „  n  of s o i l ) Ui/lboe B.S.  14.00  0.&2  1.26  0.22  37.90  42.48  2.00  0.34  0.09  0,08  20.23  12.31  1.16  0,20  0.12  0,09  19.64  8.01  BIIC  0,6:6  0.09  0.11  0.24  8.25  13.41  IIC  0.46  0.03  0.03  0.09  5.07  12.20  t  2  TABLE 3 . 3 RYDER - SELECTED PROPERTIES  Sample  Horizon  pH (H 0) 2  pH (O.Ol M. Ca C l ) 2  O.M. %  N (total) $  C/N  Rl  Ap  5.82  5 . 10  15.38  0.31  28.71  R2  Bfl  5. 95  5 . 15  2.77  0,10  16.00  R3  Bf2  5. 95  5.26  I.89  0.08  13.62  R4  Bf3  5. 95  5.26  1.06  0.04  15.25  R5  BIIC  5 . 90  5.  30  0.59  0.03  11.33  R6  C  5.94  5. 35  0.49  0.03  9.33  imple  Horizon  Exchangeable C a t i o n s (me/100 g o f s o i l ) Ca Mg Na K  C ,E ,C e (me/100 g of s o i l )  B.S.  % t  17.50  2.00  1.10  0.14  51.20  39.88  Bfl  1.98  0.38  0.41  0,06  29,10  9.76  R3  Bf2  1.40  0.35  0.23  0.08  25.70  8,24  R4  Bf3  1.13  0.33  0.25  0.10  19.35  9.53  R5  BIIC  0.43  0.08  0.14  0.06  12.61  5.92  R6  C  0.33  0.10  0.15  0.07  10.53  6.50  Rl  Ap  R2  25. TABLE 3.4 SUMMER - SELECTED PROPERTIES  PH (0,01 M. Ca C l )  O.M.  N (total)  Horizon  PH (H 0)  SI  L-F-H  3.60  3.10  49.00  loOl  28,04  S2  Ae  4.35  3.94  1.20  0.05  13.80  5.62  5.25  .1.33  0.05  15.40  imple  S3  2  2  %  C/N  %  S4  Bfcg  5.90  5.56  0.49  0.02  14.00  S5  BC  6.20  5.80  0.19  0.01  11.00  S6  Cg  5.94  0.16  0.01  '  S?  HCg  6.55 6.30  5.85  0.13  0.01  Sample  Horizon  SI  L-F-H  S2  Ae  S3  Exchangeable C a t i o n s (me/100 g o f s o i l ) Ca K Mg Na  10.50  9.00 7.00  CE.C. (me/100 g of s o i l )  B.S. fo  0.36  0.81  0.60  137.50  8.92  0,45  0.03  0.04  0.11  12,50  5.04  Bfh ;  1.30  0.05  0.24  0.17  13.75  12.80  S4  Bfcg  0.78  0.03  0.18  0.14  8.75  12,91  S5  BC  0.80  0.05  0.15  0,14  15.00  7.60  S6  Cg  4.08  0.17  1,08  0,34  11.25  50.40  S7  IlCg  8.00  0,16  0.95  0.26  15.00  62.47  26.  ALUMINUM AND  IRON DETERMINATION  Atomic a b s o r p t i o n s p e c t r o s c o p y  (A.A.) was  used  f o r aluminum d e t e r m i n a t i o n because of i t s r a p i d i t y and Pawluk ( 1 9 6 ? ) has demonstrated the a c c u r a c y  precision.  the method by comparison w i t h an a c c e p t e d The  of  g r a v i m e t r i c method.  g r e a t e s t s e n s i t i v i t y from e x p e r i m e n t a l work i s 0 . 5  p e r c e n t a b s o r p t i o n , from 0 t o kO ppm  ppm  aluminum.  I n o r d e r t o have good r e s u l t s f o r A l a n a l y s i s u s i n g c i t r a t e - d i t h i o n i t e and pyrophosphate e x t r a c t e d samples i t i s necessary  t o t r e a t the s t a n d a r d s  the unknown samples.  The  low i n o r d e r t o p r e v e n t  e x a c t l y the same as  s a l t c o n t e n t must a l s o be k e p t  f o u l i n g o f the b u r n e r head.  Atomic a b s o r p t i o n spectophotometry was f o r i r o n determination.  a l s o used  Pawluk ( 1 9 6 7 ) u s i n g a P e r k i n -  Elmer 303t determined a s e n s i t i v i t y t o i r o n of 0 , 3 Fei p e r c e n t 0.05ppm  those  ppm  of a b s o r p t i o n and c o u l d d e t e c t as l i t t l e  Fe,  He  as  compared the r e s u l t s o b t a i n e d by A.A.  o b t a i n e d by the a c c e p t e d  u t i l i z i n g O-phenanthroline,  colorimetric  with  procedure  The r e s u l t s o b t a i n e d by  the  two p r o c e d u r e s were i n c l o s e agreement, and he found t h a t the r e p r o d u c i b i l i t y of r e s u l t s were b e t t e r w i t h atomic a b s o r p t i o n t h a n w i t h c o l o r i m e t r i c . method.  PREPARATION OF THE  SOIL SAMPLE FOR  EXTRACTION  To p r e p a r e t h e s o i l samples f o r the  selective  .  27.  d i s s o l u t i o n p r o c e d u r e , o r g a n i c m a t t e r was d e s t r o y e d sodium h y p o c h l o r i t e The  by  (NaOCl) a t pH 9 . 5 (Anderson 1 9 6 3 ) .  method has been t e s t e d by L a v k u l i c h and Wiens (1970)$  t h e i r r e s u l t s suggested a b e t t e r d e s t r u c t i o n o f o r g a n i c m a t t e r t h a n w i t h hydrogen p e r o x i d e and l e s s d e s t r u c t i o n o f mineral  fraction. No sample g r i n d i n g was done f o r any o f t h e  e x t r a c t i o n procedure i n order t o avoid l o s s of f i n e c l a y w i t h a consequent l o w e r i n g o f t h e r e s u l t a n t v a l u e s .  After  s i e v i n g (100 mesh s i e v e ) and m i x i n g a l a r g e sample, a " r e p r e s e n t a t i v e " subsample was withdrawn and served as sample s o u r c e f o r t h e l a b o r a t o r y a n a l y s i s o f i r o n , aluminum, and s i l i c o n .  The major source o f e r r o r i s i n o b t a i n i n g a  sample t h a t r e p r e s e n t s in,the  an average o f t h e h o r i z o n as i t . o c c u r s  field. The  follows«  o r g a n i c m a t t e r removal p r o c e d u r e was as  20 g o f s o i l , p r e p a r e d as d e s c r i b e d  above,  were p u t i n t o a 250 ml c e n t r i f u g e p l a s t i c b o t t l e j  4-0 ml  of NaOCl s o l u t i o n (minimum 6% a v a i l a b l e c h l o r i n e ) , which was a d j u s t e d  t o pH 9 . 5 i m m e d i a t e l y p r i o r t o use, was added.  A f t e r mixing thoroughly,  t h e b o t t l e s were p u t i n a b o i l i n g  wa^erbath f o r 15 minutes ( w i t h a second s t i r r i n g the b o i l i n g p e r i o d ) .  during  C e n t r i f u g a t i o n f o r 10 minutes a t  2200 rpm was c a r r i e d out f o l l o w e d by d e c a n t a t i o n  of the  s u s p e n s i o n and t h e d e c a n t a t e was saved f o r s e l e c t i v e  28.  elemental a n a l y s i s (Mn.  Fe, A l , S i ) .  The  above  treatment  was  repeated f i v e times, each time the supernatant  was  collected after  liquid  centrifugation.  Elemental a n a l y s i s on the NaOCl-decantate r e v e a l e d the presence  of t r a c e s of Fe, A l and S i only i n  the sample with the h i g h e s t percent (over 1 0 % ) o r g a n i c matter. For the s e l e c t i v e e x t r a c t i o n s of i r o n , aluminum and s i l i c o n , accepted l a b procedures were f o l l o w e d as out' l i n e d by Bascomb ( 1 9 6 8 ) ,  f o r O.lM  e x t r a c t i o n ; ? by McKeague and Day  sodium pyrophosphate (1966)  f o r a c i d ammonium  oxalate e x t r a c t i o n , and by Mehra and Jackson citrate-dithionite The  (i960)  for ,  extraction.  c a l c u l a t e d r e s u l t s are r e p o r t e d i n Tables  4 . 1 , 4.2, and 4.3 i n which a comparison of the data  from  the three d i f f e r e n t e x t r a c t i o n s f o r each element ( S i , Fe, A l ) are g i v e n i n p e r c e n t .  29. TABLE 4.1 COMPARISON OF S I DATA (from whole s o i l ) e x t r a c t e d b y s OXALATE Si  SOIL  HORIZON  RYDER Rl R2  Ap  R3  Bf  R4  Bfj  R5  BIIC C  0.11 0.70 1.25 0.85 0.20 0.10  MARBLE HILL Ml M2  L-H  -  M3  Bf  M4  BIIC IIC  R6  M5 SUMMER  B  l  f  2  ±  2  SI S2  L-F-H Ae  S3  Bf>.  S4  Bfcg  S5 s6  BC  S7  —  Cg HCg  A4  Ap Bf-jhcc Bf cc Bf^cc  A5 A6  BIIC IIC  A2 A3  2  0,09 0.10 0.09 O 09 0,15 0.11 e  •  -  -  -  0.10 1,20  0.07 0.09 0.10  0,80 0,40  -  0.50 1.30 0*90 1,00 o.4o  DITHIONITE Si  %  1*37 0,98 0.20  ABBOTSFORD Al  —  0,12 0 12 0.10 0.11  0,62  Bf  PYROPHOSPHATE Si  0  0.07 0.23 0.25 0,28  0,20 0.15  0,43 0,40  0,23 0,18  0,12  0,35 0,25 0.25 0,20 0,15 0.23  -  -  0,10 0,07 0,06 0.07 0.07  0.25 0.23 0,23 0,20 0.10  0.08 0,14  30. TABLE 4.2 COMPARISON OF FE DATA (from whole s o i l ) e x t r a c t e d by*  OXALATE Fe —  PYROPHOSPHATE Fe %  DITHIONITE Fe  SOIL  HORIZON  RYDER RI R2  Ap .  1.40  0.08  1.84  1.54  0.13  R3 R4  l Bf Bf^  1.50 1.40  0.07  1.93 ,1.76  0,04  1.63  R5  BIIC  0.99  0.03  1.03  R6  C  0.99  0,02  0.75  MARBLE HILL Ml M2  L-H  -  -  -  1,62  0,25 0.16  M3 M4 M5 SUMMER SI S2  B  f  2  l Bf  B  f  2  BIIC IIC  S3  L-F-H Ae Bfh'  s4  Bfcg  S5  BC Cg IlCg  s6 S7 ABBOTSFORD Al A2 A  3  A4 A5 A6  Ap B^hcc Bf cc Bf^cc 2  BIIC IIC  1.40 1.0? 1.06  2.16  0.05 0.03  1.96 1.28 0.84  -  -  -  0,08 0.61  0.05 0.09 0.06  0.18  0.04  0.65 0.56  0.95 0.43 0,26  0.94  1.29  0,51  0.02 0.02  -  -  -  0.88 0,80  0.15  1.57  0,03  1,65  0.98  0.03 0.01 0.01  1.76  0.56 0^22  0,85  1.28  0,66  31.  TABLE 4 . 3 COMPARISON OP AL DATA (from whole s o i l ) e x t r a c t e d b y j  SOIL  HORIZON  OXALATE Al  PYROPHOSPHATE Al  0  DITHIONITE Al  RYDER  1.05 1.90 1.90  Bf^ BIIC  Rl  Ap  R 2  B  R3 R4 R5 R6  l Bf f  2  C  0.55  0 . 4 5  0.55  0.95  0 , 4 1  0 . 8 2  1.50  0.32  0,68  1.45 1.45  0.33  0.53 0.43  2.20 2.10 1.60 1.20  0.80 0.62  0.29  MARBLE HILL Ml  L-H  M 2  B  M3  l Bf f  2  M 4  BIIC  M5  IIC  -  0 . 4 0  1.25 1.10 0.68  0.30  0 . 4 0  SUMMER SI  L-F-H  S 2  Ae  S3  Bfh  S 4  0.30  *m  -  0 , 1 9  0 . 1 8  0,47  0.88  Bfcg  2.15 1.20  0 , 2 8  0.55  S5  BC  0 . 8 0  0,21  s6  eg  0.20  0 . 0 8  0.35 0.13  S7  HCg  0,20  0,06  0.13  •1.50 2.00  -  0.90  ABBOTSFORD Al A 2  .- Ap Bf hcc 1  0.51  Bf^CC  1 . 8 1  0.31 0.32  A 5  BIIC  A6  IIC  1,65 0.90  0.25 0.17  A3 A4  • BfgCC  0.78 0 , 8 0 0 . 4 8  0.25  32. RESULTS AND CONCLUSIONS OF THE EXTRACTION PROCEDURES  The a b i l i t y of the oxalate procedure to remove more aluminum than the citrate-bicarbonate-dithionite procedure i s r e a d i l y evident and Figure 1 shows t h i s r e l a tionship.  On the other hand, the citrate-bicarbonate-  d i t h i o n i t e procedure extracts s l i g h t l y higher quantities, of iron than the oxalate procedure?  of course, the c i t r a t e -  bicarbonate-dithionite method extracts amorphous as well,as c r y s t a l l i n e forms of i r o n ; while the oxalate method reportedly extracts only the amorphous i r o n compounds. This explains the differences i n the values.  Only two  oxalate iron values exceeded the citrate-bicarbonated i t h i o n i t e values. these two procedures  The d i f f e r e n t extraction a b i l i t y of i s i l l u s t r a t e d i n Figure 2,  As reported previously, the difference between oxalate and pyrophosphate - extractable Fe gives a measure of amorphous inorganic Fe? while the difference between d i t h i o n i t e and oxalate - extractable Fe provides an estimate of more or l e s s c r y s t a l l i n e Fe - oxides (McKeague et a l 1 9 7 1 ) . e  In Table 5B an account of these differences i s given f o r the four s o i l s .  Figures 3 and k i l l u s t r a t e the  d i s t r i b u t i o n of the amorphous extractable A l and Fe as i t r e s u l t s from Table 5» f o r the Ryder and Summer s o i l s only. The d i s t r i b u t i o n of clay i s also provided along with the amorphous Fe distribution? the two d i s t r i b u t i o n s down the p r o f i l e appear to be quite c l o s e l y r e l a t e d .  33.  0  0.4 PERCENT  FIGURE 1.  0.8  1.2  C I T R A T E - B I C A R B . - D I T H I O N I T E EXTRAC.  COMPARISON OF  ALUMINUM EXTRACTION METHODS:  CITRATE-BICARBONATE-DITHIONITE,  1.6 ALUMINUM OXALATE  VS  34  1  1  r  O  PERCENT FIGURE 2,  OXALATE  EXTRACTABLE  IRON  COMPARISON OF IRON EXTRACTION METHODS: •DITHIONITE.  OXALATE VS  35-  TABLE 5" D i f f e r e n c e s Between Oxalate-  and P y r o p h o s p h a t e - E x t r a c t e d Fe and  D i t h i o n i t e - and O x a l a t e -  SAMPLE  HORIZON  E x t r a c t e d Fe  OXAL - PYROPH (amorphous i r o n ) % Fe  DITH - OXAL (+ c r y s t . i r o n ) " fo Fe •  RYDER RI R2 R3 R4 R5 R6  Ap i 4i 9  0.38  1A3  0 26  Bfj  1.36  0.23  BIIC C  0.96  0.04  l Bf B  f  2  MARBLE H I L L Ml M2 M3 M4 M5  L-H Bf  t  2 BIIC  B f  IIC  SUMMER  0.97  -  9  -  -  1.37  0.54  1.24  0.56  1.02  0.21  1.03  -  -  -  SI  L-F-H  S2  Ae  0.03  0.10  S3 S4  Bf;>  0.52  0.33  Bfcg  0.89  0.34  S5  BC  0.39  0.22  S6  Cg  0.24  0,30  S7  HCg  0.48  0.34  ABBOTSFORD Al  -  -  A2  Ap Bf hcc 1  0.73  0.69  A3  Bf cc 2  0.77  0.85  A4  Bf^CC  0.95  0.78  A5  BUG  0.55  0.72  A6  IIC  0.21  0.44  FIGURE 3,  AMORPHOUS EXTRACTED AND  IRON "(BY D I F F E R E N C E BETWEEN  PYROPHOSPHATE EXTRACTED  OXALATE  I R O N ) , AND CLAY CONTENT IN  RYDER.  %  FIGURE 4,  Elemental  AMORPHOUS AND  Fe  EXTRACTED  1  IRON  <2 p. C L A Y  (BY D I F F E R E N C E BETWEEN  PYROPHOSPHATE EXTRACTED  SUMMER.  %  I RON), AND CLAY  OXALATE  CONTENT IN  3?» . MINERALOGIGAL STUDIES X-ray d i f f r a c t i o n a n a l y s i s o f the< 2^ c l a y f r a c t i o n from the d i f f e r e n t h o r i z o n obtained  o f the f o u r s o i l s were  on a P h i l l i p s X-ray d i f r a c t o m e t e r  9  u s i n g Cu K<<  radiation. The and  samples were s i m i l a r i n showing only weak  d i f f u s e r e f l e c t i o n s i n the c l a y m i n e r a l  appears  9  range.  It  i n f a c t , t h a t an amorphous c o a t i n g on the c r y s -  t a l l i n e p h y l l o s i l i c a t e minerals  p r e v e n t s the l a t t e r t o  become o r i e n t e d on t h e i r b a s a l p l a n e s so as t o mask o r s c a t t e r the d i f f r a c t i o n peaks.  Occurrence o f the amorphous  phase as d i s c r e t e p a r t i c l e s or as an e x t e r n a l c o a t i n g  could  not o n l y prevent the l a y e r s from assuming p a r a l l e l o r i e n t a t i o n , but a l s o absorb some o f the d i f f r a c t i o n from w e l l crystallized i  clay,  Treatment with oxalate  improved d r a m a t i c a l l y the  r e s o l u t i o n o f the peaks, so t h a t i t was p o s s i b l e t o i d e n t i f y the main m i n e r a l s  present  which are p r e s e n t e d i n Table 6 ,  38.  TABLE 6 Dominant m i n e r a l s p r e s e n t i n R y d e r , Summer, A b b o t s f o r d , as d e t e r m i n e d  by X-ray  S O I L SERIES PROFILE  and M a r b l e  Hill  diffraction.  MAIN MINERALS  Ryder RI  Verm., C h i . , 1 1 1 . , Amph., Q., F.  R2, R3  C h i . , Verm., 111., Q., F .  R4-, R5, Marble  R6  C h i . , Verm,, Q., F .  Hill  Ml  Verm., C h i . , 111., Q., F .  M2  Mt., C h i . , 111., Q., F .  M3. M4-, M5  Verm., C h i . , 111., Q., F .  Abbotsford Al,  A2, A3* A4-, A5. A6  Verm., C h i . , I l l , , Q., F .  Summer S2 S3.  Verm., C h i . , Amph., Q., F . (plagioclase) S4-, S 5 , S 6 , S7  Verm., C h i . , 111., Amph., Q., F . ( p l a g i o c l a s e ) #  Notes  Verm. ( V e r m i c u l i t e ) s C h i .(Chlorite)s Mt. ( M o n t m o r i l l o n i t e ) 5 111, ( I l l i t e ) s Amph. ( A m p h i b o l e s ) : Q. ( Q u a r t z ) s F . ( F e l d s p a r ) .  39. I n the Marble H i l l s o i l , m o n t m o r i l l o n i t e . ;  (smectite) i n the B f  1  i s not p r e s e n t as an independent  m i n e r a l but seems t o o c c u r i n t e r s t r a t i f i e d w i t h and m i c a ( i l l i t e ) .  chlorite  Montmorillonite i s i d e n t i f i e d  by  g l y c e r o l s o l v a t i o n w i t h which i t e x h i b i t s : an e x p a n s i o n o  of i t s b a s a l s p a c i n g (15  A a t room r e l a t i v e  t o about 18 X:  40 - 50$ R.H.)  humidity  upon h e a t i n g t o 550°C,  the m i n e r a l c o l l a p s e s e n h a n c i n g the 10 A peak.  An i n t e g -  r a l s e r i e s o f peaks a s s o c i a t e d w i t h the l a r g e s t b a s a l 0  s p a c i n g of 14 A which does not expand by g l y c e r o l s o r p t i o n and does not s h i f t upon h e a t i n g a t 550°C, a s s u r e s the p r e s e n c e o f c h l o r i t e . Smectite One  can o r i g i n a t e i n a number of ways.  i s by i n h e r i t a n c e , f o r example the A l b e r t a P o d z o l  d e s c r i b e d by Pawluk ( i 9 6 0 ) .  A second i s by s y n t h e s i s  from the amorphous a l u m i n o s i l i c a t e s and/or the s o l u b l e c o n s t i t u e n t elements ( J a c k s o n , 1 9 6 5 ) .  The  third possible  o r i g i n o f s m e c t i t e i s as d i r e c t a l t e r a t i o n p r o d u c t (Jackson,  1965); P o t a s s i u m may  be p a r t i a l l y removed from each  l a y e r g i v i n g mica-smectit;e a-b  of mica  d i r e c t i o n s or i t may  i n t e r s t r a t i f i c a t i o n i n the  be s e l e c t i v e l y removed i n t e r n a l l y  from c e r t a i n l a y e r s (the " p r e f e r e n t i a l w e a t h e r i n g of J a c k s o n e t a l . , 1952) the c - a x i s d i r e c t i o n .  plane"  giving interstratification in S e v e r a l examples o f these types  of  i n t e r s t r a t i f i c a t i o n have been c o n s i d e r e d by Sudo e t a l ( i 9 6 0 ) .  40.  I n t e r s t r a t i f i c a t i o n s of v e r m i c u l i t e - i l l i t e c h l o r i t e (present i n d i f f e r e n t proportions) are claimed for  t h e o t h e r h o r i z o n s o f t h e Marble H i l l s o i l and f o r  a l l h o r i z o n s o f Ryder, Summer, and A b b o t s f o r d The  soils.  d e t e r m i n a t i o n o f t h i s type o f i n t e r s t r a t i -  f i c a t i o n was based on a c o m b i n a t i o n  of the c h a r a c t e r i s t i c s  of each component-layer. a  0  10 A c l a y mica ( l l l i t e ) has a 10 A b a s a l spacing  and i t s i n t e g r a l s e r i e s o f h i g h e r o r d e r r e f l e c t i o n s  do n o t s h i f t upon e i t h e r s o l v a t i o n w i t h g l y c e r o l or h e a t i n g a t 550°C.  V e r m i c u l i t e m a i n t a i n s i t s 14 A peak  upon s o l v a t i o n w i t h g l y c e r o l and under h i g h r e l a t i v e h u m i d i t y , which d i s t i n g u i s h e s i t from s m e c t i t e ,  which,  as seen above, expands i t s b a s a l s p a c i n g t o about 18 A, At 550°G, v e r m i c u l i t e s h i f t s t o 10 A peak and t h a t d i s t i n g u i s h e s i t from c h l o r i t e which does n o t s h i f t upon h e a t i n g a t 55° ° C C h l o r i t e p r e s e n c e i s a s s e s s e d , as mentioned p r e v i o u s l y , by an i n t e g r a l s e r i e s o f peaks (7.01 A, 4.7 A, 3.5A) a s s o c i a t e d w i t h t h e b a s a l s p a c i n g o f 14 A which does n o t expand by g l y c e r o l s o r p t i o n and does n o t s h i f t upon h e a t i n g a t 550°C.  Because t h e same peaks a r e  a s s i g n e d t o k a o l i n i t e which has t h e same b e h a v i o u r upon s a t u r a t i o n w i t h Mg and K and h e a t i n g t o 300°C and 55°°C, an e x a m i n a t i o n by an i n f r a r e d a b s o r p t i o n t e c h n i q u e was needed t o d e f i n i t e l y a s s e s s t h e presence o f c h l o r i t e .  41.  F o r Ryder and Summer s o i l s t h e c h l o r i t e appears t o he an F e - r i c h t y p e o f c h l o r i t e as i n d i c a t e d by t h e f a c t t h a t t h e f i r s t and t h e t h i r d b a s a l r e f l e c t i o n s a r e weak and t h e second and f o u r t h o r d e r b a s a l r e f l e c t i o n s a r e strong ( C a r r o l l ,  1970),  I n t e r s t r a t i f i e d mixtures  o f t h e t h r e e components,  m i c a - v e r m i c u l i t e - c h l o r i t e were t h e predominant and t h e most s i g n i f i c a n t m a t e r i a l s  present.  SUCCESSIVE EXTRACTIONS AND INFRARED SPECTROSCOPY FOR THE CHARACTERIZATION OF THE INORGANIC AMORPHOUS SYSTEM IN SOIL CLAYS, S e l e c t i v e d i s s o l u t i o n a n a l y s i s i n v o l v i n g treatment w i t h a l k a l i s has been used t o o b t a i n some e s t i m a t e s amorphous c o n s t i t u e n t s i n s o i l c l a y s . for  These p r o c e d u r e s  amorphous m a t e r i a l s e x p l o i t t h e f a c t t h a t t h e r e a c t i o n  rate v a r i e s widely according t o s p e c i f i c surface e x t e n t o f s t r u c t u r a l o r d e r , and c h e m i c a l and  of the  area,  bond s t r e n g t h ,  i s a c c o r d i n g l y h i g h e r o r much h i g h e r f o r amorphous  t h a n f o r most c r y s t a l l i n e m a t e r i a l s . (i960)  Hashimoto and J a c k s o n  p r e s c r i b e d a t r e a t m e n t o f c l a y w i t h NaOH and t h e y  c o n c l u d e d t h a t s u b s t a n t i a l amounts o f a l l o p h a n e ,  free  silica  and a l u m i n a were b r o u g h t i n t o s o l u t i o n by a t r e a t m e n t w i t h an excess o f 0,5 N NaOH a t t h e b o i l i n g p o i n t f o r a r e s t r i c t e d time ( 2 , 5 m i n u t e s ) .  Only s m a l l amounts o f c r y s t a l l i n e  c l a y m i n e r a l s were d i s s o l v e d d u r i n g t h e same d i g e s t i o n period.  4-2.  Follet et a l .  (1965)  s t u d i e d a p r o c e d u r e which  i n v o l v e s p r o t r a c t e d c o n t a c t w i t h Doth c o l d and h o t weak a l k a l i n e s o l u t i o n ( 5 % NagCO^), i n o r d e r t o d e t e c t t h e a l k a l i - s o l u b l e m a t e r i a l i n a p o d z o l and a n o n - c a l c a r e o u s humic g l e y s o i l i n which c r y s t a l l i n e l a y e r s i l i c a t e s predominate. minerals  They found t h a t , as f a r as t h e c r y s t a l l i n e  a r e concerned, s u c c e s s i v e  treatments with c o l d  and h o t d i l u t e NagCO^ s o l u t i o n d i d n o t r e s u l t i n a p p r e c i a b l e d i s s o l u t i o n . They used r e p e a t e d e x t r a c t i o n s t o reduce the s i l i c a and a l u m i n a removed t o a s m a l l and v i r t u a l l y constant  l e v e l o f about 0.2 - 0 . 5 % o f t h e sample w e i g h t . The  a s s o c i a t i o n o f amorphous s i l i c a t e s  with  " f r e e " i r o n o x i d e s has a l s o been i n f e r r e d from d i s s o l u t i o n of s i l i c o n and aluminum i n a d d i t i o n t o i r o n d u r i n g removal of e x t r a c t a b l e i r o n o x i d e s from s o i l c l a y s (Me.hra and Jackson,  I960?  Follet et a l . ,  1965).  Assuming t h a t t h e i n o r g a n i c amorphous m a t e r i a l i n t h e c l a y f r a c t i o n o f t h e s o i l s s t u d i e d i s a complex p o l y p h a s e system, i t was f e l t t h a t an a p p r o p r i a t e  approach  t o remove i t s e l e c t i v e l y from t h e system i n o r d e r t o c h a r a c t e r i z e and o b t a i n a b e t t e r u n d e r s t a n d i n g o f t h e c o m p o s i t i o n and t h e s t r u c t u r e o f t h e system i t s e l f was n e c e s s a r y . <•  I n t h i s s t u d y , an attempt was made t o combine  chemical s e l e c t i v e d i s s o l u t i o n procedures with p h y s i c a l t e c h n i q u e s on two o f t h e s o i l s e r i e s used b e f o r e 1 and Summer, as shown s c h e m a t i c a l l y i n F i g u r e 5.  Ryder  FIGURE 5 A schematic r e p r e s e n t a t i o n o f successive extractions of i n o r g a n i c amorphous system and c o r r e s p o n d i n g  < 2)i clay sample  successive treatment  Fraction remaining  no treatment  5% N a C 0 2  (a) + Na-pyrophosphate (b)  c  (a+b)+ Ac. NH -oxalate (c) 4  Analysis applied  X-ray; IR;  (a)  3  analyses.  II  H  C  n  Surface area  M  II  II  4  (a + b + c) + citrate-dithionite (d)  II  II  II  44. The  most u s e f u l t e c h n i q u e i n t h i s p a r t i c u l a r  experiment was f e l t t o be i n f r a r e d s p e c t r o s c o p y because, u n l i k e X-ray d i f f r a c t i o n , t h e c o n t r i b u t i o n s o f t h e s o l u b l e and  i n s o l u b l e components t o any a b s o r p t i o n band a r e a d d i -  t i v e , and t h e double-beam s p e c t r o p h o t o m e t e r e n a b l e s t h e d i f f e r e n c e s between t h e two samples t o be r e c o r d e d The  s p e c t r a alone provide  simply.  much i n f o r m a t i o n r e g a r d i n g t h e  m i n e r a l o g y and c o m p o s i t i o n o f a r a t h e r wide range o f m a t e r i a l s , from amorphous t o w e l l c r y s t a l l i z e d aluminum and i r o n o x i d e s and The  silicates,  hydroxides.  c l a y s o f t h e two s o i l s e r i e s used i n t h i s  experiment were o b t a i n e d  by s u p e r - c e n t r i f u g i n g t h e 1 0 0 -  mesh s i e v e d s o i l s p r e v i o u s l y t r e a t e d w i t h NaOCl ( a t pH 9 . 5 ) t o remove t h e o r g a n i c m a t t e r .  The < 2 ^ c l a y s were t h e n  freeze-dried. The 1.  adopted p r o c e d u r e i n d e t a i l i s as f o l l o w s s Weigh f o u r f r a c t i o n s ( a , b, c, d) (200 mg each) of each sample i n t o a 50 ml c e n t r i f u g e  plastic  t u b e , whose t a r e has been t a k e n on an a i r - d r y basis, 2,  Add 16 ml o f %  NagCO^ s o l u t i o n h e a t i n g at 90°0  f o r f i f t e e n minutes i n a w a t e r b a t h .  ( A single  treatment was f e l t t o be s u f f i c i e n t  and adopted  f o r t h i s s t u d y o and o n l y f o r f i f t e e n minutes becauseo  checking the rate o f d i s s o l u t i o n , i t  (continued) was found t h a t i t decreased v e r y r a p i d l y and t h e infrared spectra - d i f f e r e n t i a l spectra i n t h i s case - showed no s i g n i f i c a n t changes e x c e p t i n t o t a l p e r c e n t t r a n s m i s s i o n between t h o s e t r e a t e d f o r f i v e minutes i n t h e s i n g l e and f o r t h i r t y minutes i n t h e double t r e a t m e n t s ) . M i x t h e samples i n t e r m i t t e n t l y \during t h e h e a t i n g p e r i o d . C e n t r i f u g e a t 2500 rpm f o r t e n m i n u t e s .  The  s u p e r n a t a n t s o l u t i o n s h o u l d be p e r f e c t l y  clear.  Determine S i and A l (no Fe i s brought  into  s o l u t i o n ) on t h e e x t r a c t s b y a t o m i c a b s o r p t i o n spectrophotometry. All  t h e t r e a t e d samples a f t e r t h e d i s s o l u t i o n  e x t r a c t i o n were washed t h r e e t i m e s w i t h 10 ml o f IM NaCH^COO/NaCl ( l / l )  m i x t u r e a d j u s t e d t o pH 5 . 0  with a c e t i c a c i d (the acetate alone r e s u l t e d i n d i s p e r s i o n o f t h e sample).  T h i s washing was  r e p e a t e d a f t e r each s e l e c t i v e d i s s o l u t i o n t r e a t ment t h a t f o l l o w e d i n o r d e r t o a v o i d  secondary  e f f e c t s o f t h e t r e a t m e n t i t s e l f on t h e measurements due t o changes i n t h e s t a t u s o f exchangeable cations„ The e x c e s s o f t h e washing m i x t u r e was t h e n removed by s u c c e s s i v e washing w i t h 10 ml o f water/raethanol (l/l),  10 ml o f methanol/acetone  of acetone.  ( l / l ) , and 10 ml  6.  From one (a) o f t h e f o u r r e p l i c a t e s , t a k e a s u i t a b l e p o r t i o n o f u n d r i e d sample f o r X-ray diffraction.  The remainder o f t h i s r e p l i c a (a)  i s saved f o r i n f r a r e d and s u r f a c e a r e a d e t e r m i n ation. 7.  The r e m a i n d e r o f r e p l i c a ( a ) and the t h r e e r e p l i cates l e f t  ( b , c, d) a r e f r e e z e - d r i e d , p u t i n t h e  p l a s t i c tubes and weighed  ( i n o r d e r t o know the  weight l o s s due t o t h e t r e a t m e n t and t h e amount of sample used f o r t h e next t r e a t m e n t ) . 8.  T r e a t t h e ( b , c, d) r e p l i c a t e s w i t h 20 ml 0.1 M Na-pyrophosphate  (Na^PgO^) a d j u s t e d t o pH 10,0  w i t h H C l and shake f o r about s i x t e e n hours a t 25°C i n a c o n t r o l l e d - t e m p e r a t u r e chamber. 9.  C e n t r i f u g e a t 8200 rpm f o r t e n minutes and t h e n wash as p e r number 5.  10.  From the (b) r e p l i c a t e , t a k e , as i n number 6, a s u i t a b l e p o r t i o n o f sample f o r X-ray and f r e e z e dry  the remainder o f (b) and t h e two l e f t ( c , d)  r e p l i c a t e s - p u t t h e l a t t e r i n t h e p l a s t i c tubes and we i g h . 11.  On t h e e x t r a c t s determine S i , Fe and A l , a f t e r p r o p e r d i l u t i o n , by atomic a b s o r p t i o n s p e c t r o s c o p y .  12.  The two r e m a i n i n g r e p l i c a t e s ( c , d) a r e now t r e a t e d w i t h 10 ml o f a c i d NH^- o x a l a t e ( a t pH 3*0) and shaken i n darkness f o r f o u r h o u r s .  47 • 13•  C e n t r i f u g e at 2500 rpm f o r t e n minutes,  taking  care t h a t the supernatant s o l u t i o n i s p e r f e c t l y clear. 14.  Determine S i , Fe, and A l on the e x t r a c t s by absorption  15.  atomic  spectrophotometry.  Wash as per number 5 and r e p e a t the  procedure  d e s c r i b e d i n number 6 . 16.  The remaining f r e e z e - d r i e d r e p l i c a t e  (d) i s put  i n t o a p l a s t i c tube, weighed and then t r e a t e d w i t h 16 ml of 0 , 3  M N a - c i t r a t e , 2 ml of 1 M NaHCO^ and  about 400 mg of d i t h i o n i t e 17.  (Na2S20^) powder.  C a r r y out the e x t r a c t i o n i n a waterbath f o r f i f t e e n minutes  at 80°C  s t i r r i n g c o n t i n u o u s l y f o r the  f i r s t minute and then i n t e r m i t t e n t l y f o r the r e s t of the p e r i o d . times. 18.  C e n t r i f u g e a t 1600 -  2200 rpm„  Wash a g a i n as per number 5 and repeat the procedure of number 6$  19.  Repeat the same treatment two more  f r e e z e - d r y the sample.  On the e x t r a c t s , determine S i , Fe and A l , a f t e r proper d i l u t i o n , by atomic a b s o r p t i o n spectrophotometry.  Weigh:the sample f o r l o s s d e t e r m i n a t i o n .  These experiments were designed t o determine  the nature of  the m a t e r i a l d i s s o l v e d by the treatments a p p l i e d , and i t  was t h e r e f o r e e s s e n t i a l t h a t no d i s p e r s e d c l a y be l o s t d u r i n g t h e t r a n s f e r r i n g , washing and d e c a n t i n g  procedures.  Care was t a k e n t o ensure t h a t the c l a y remained f l o c c u l a t e d throughout the t r e a t m e n t s  and washings•  The r e s u l t s o f these s u c c e s s i v e e x t r a c t i o n s a r e r e p o r t e d i n Tables  9 and 10 i n % o f each element.  F o r the  Summer s e r i e s , i n Table 10, t h e d a t a o f t h e Na-pyrophosphate e x t r a c t i o n a r e n o t r e p o r t e d because no a p p r e c i a b l e amounts o f t h e t h r e e elements c o u l d be d e t e c t e d i n t h e solution.  RESULTS AND DISCUSSION ON SUCCESSIVE EXTRACTION EXPERIMENT A few g e n e r a l o b s e r v a t i o n s about T a b l e s 7 and 8,on  t h e p e r c e n t e l e m e n t a l d a t a e x t r a c t e d a f t e r each  treatment  i n both c l a y s f o l l o w s .  elements and a f t e r a l l t r e a t m e n t s f o r Summer i n comparison t o Ryder.  A h i g h e r amount f o r a l l i s g e n e r a l l y observed On b o t h c l a y s no  d e t e c t a b l e Fe was e x t r a c t e d by 5% N a C 0 y 2  F o r a l l t h r e e elements, t h e h i g h e s t amount e x t r a c t e d i s observed a f t e r a c i d NH^-oxalate t r e a t m e n t . ing d i t h i o n i t e treatment,  Follow-  t h e e x t r a c t i o n o f A l and S i  i s much lower t h a n a f t e r o x a l a t e , w h i l e t h e e x t r a c t i o n o f Fe.; i s s t i l l q u i t e h i g h . ,  I t i s i n t e r e s t i n g t o compare t h e F e , A l and S i  data a f t e r oxalate "successive" e x t r a c t i o n s reported i n Tables  7 and 8 w i t h those r e p o r t e d i n Tables 4.1, 4.2, and  49. TABLE 7 RYDER  SUCCESSIVE EXTRACTIONS ON < 2yu CLAY 5% Na CO^ (a) 2  Sample  Horizon  Rl R2  Ap  R3  Bf  R4  Bf^  R5 R6  BIIC C  B  l  f  2  Rl R2  B  R3  Bf  R4  Bf^  R5  BIIC C  R6  Ap l  f  2  Rl R2  Ap  R3  Bf  R4  Bf-j  R5  BIIC C  R6  B  f  l 2  NaPyroph. (D)  oxal. (c)  Aluminum (fo by wt) 0.30 0.165 2.75 0.184 4,62 0,37 0.14? 0.36 4.10 0.164 0.32 3.75 0.164 5.01 0,39 4.34 0.193 0.33 S i l i c o n (f> by wt) 0.009 0.055 0.55 0.013 1.50 0.055 0.047 0,013 1.76 0.011 0.046 1.51 0.011 0.047 2.38 0.054 0.009 2,14 I r o n ([fo by wt) O.09 5.25 0.04 5.19 0.04 5.14 0.03 4.53 0.03 3.05 0,02 2.08  Total Amorph. (a+b+c)  3.215 5.174 4.637 4.234 5.564 4.863  0.614 1.568 1.820 1.567 2.438 2,203  5.34 5.23 5.18 4.56 3.06 2,10  Dithionit<  0,39 0.63 0.81 0.69 0.80 0.42  0,30 0.30 0.33 0,29 0,34 0.34  2.99 4.36 5.27 4.15 3.88 1.61  50 TABLE 8 SUMMER SUCCESSIVE EXTRACTIONS  %  NH^-  Na C0^  oxalate  (a)  (b)  2  Sample  Horizon  ON < 2yu CLAY Total  Dith-  Amorph,  ionit<  (a + b)  (d)  0.80  1.49  0.09  9,87  0.52  Aluminum (fo by wt) S2  Ae  0.69  S3 S4  Bf ;  3,48  Bfcg  3.24  9.24  13.35 12.48  S5 S6  BC  3,06  7.89  10.95  0.78  eg  0.46  1.12  1.58  0.17  S7  HCg  0.31  1.04  1.17  0.13  v  ,  0.52  S i l i c o n (fo by wt) S2  Ae  S3  Bfh  S4  Bfcg  S5  BC  s6  Cg  S7  HCg  -  0.46  0.46  0.14  • -  5,80  5.80  0.37  4.80  4,80  0.32  4.76  4.76  0.86  0,86  0.60 0.30  0.86  0.86  0.29  0,61  0,61  0.69  2.72  2.72  1.76  6.29 7.41  6.29 7.41  3.09 5.58  1.53  1.53  0.80  2.32  2,32  0,85  -  -  -  I r o n (f, by wt) S2  Ae  S3  Bfh  S4  Bfcg  S5 S6  Be  S7  . Cg HCg  -  -  -  51 > 4.3  a f t e r oxalate "separate" e x t r a c t i o n s .  The  differences  are q u i t e s t r i k i n g , and the f a c t t h a t the amounts e x t r a c t e d by o x a l a t e a f t e r the samples were p r e v i o u s l y t r e a t e d w i t h 5% NagCOy are so much h i g h e r t h a n those a f t e r a oxalate treatment, alkali  simple  can be e x p l a i n e d by assuming t h a t the  t r e a t m e n t p r o v i d e s an i n c r e a s e i n the d i s p e r s i o n  of c l a y .  I n p a r t i c u l a r , i t appears t h a t most o f the " f r e e "  i r o n o x i d e s i n the two  c l a y s i s i n a c c e s s i b l e to oxalate  u n t i l the a l k a l i - s o l u b l e a l u m i n o s i l i c a t e s have been removed.  The  f a c t t h a t no Fe i s b r o u g h t i n t o s o l u t i o n by  NagCO^ does not n e c e s s a r i l y imply t h a t the s i l i c a  and  a l u m i n a are f r e e and uncombined w i t h i r o n o x i d e s i n the original clay. alkali  The  s i l i c a and a l u m i n a not removed by  t r e a t m e n t w i l l be d i s s o l v e d , a l o n g w i t h  by a c i d N H ^ - o x a l a t e ;  consequently,  iron,  i t i s considered  that  t h i s l a t t e r f r a c t i o n i s much more c l o s e l y a s s o c i a t e d w i t h the i r o n  oxides.  ,  A few o b s e r v a t i o n s  10 seem w o r t h w h i l e  t o make.  and F e 0 ^ i n r e s p e c t t o S i 0 2  on the d a t a o f T a b l e s 9 The  2  and  molar r a t i o s o f AlgO^  b o t h decrease w i t h d e p t h i n  the Ryder, w h i l e the molar r a t i o o f F e 0 ^ i n the Summer 2  i n c r e a s e s w i t h depth from S3 The  t o t a l percent  ( B f h ) down. amorphous m a t e r i a l c a l c u l a t e d  a f t e r Na C0-j and o x a l a t e e x t r a c t i o n on 12 2  F e  2^3  +  percent  S  ^2^  c l a y (AlgO^ +  f°ll° q u i t e c l o s e l y , i n b o t h c l a y s , the w  l o s s e s c a l c u l a t e d a f t e r the same e x t r a c t i o n s ,  TABLE 9 RYDER  Amorphous m a t e r i a l e x t r a c t e d from ^2yu c l a y s by s u c c e s s i v e Na-pyrophosphate + A c i d N H ^ - o x a l a t e . content;  extractions?  I n the t a b l e are a l s o i n c l u d e d :  m o l a r r a t i o o f amorphous o x i d e s ;  fo sum o f amorphous  oxides;  %  NagCO^ +  % loss; surface  % clay area j  fo amorphous o x i d e s i n t h e s o i l o Rl  R2  R3  R4  3  60O8  9.78  8,76  8.00  fo FegO^  7.64  7.48  7.40  6.52  4.40  3.00  % SiO^  1.31  3o36  3.90  3.35  5.22  4.71  15.03  20.62  20.06  17.87  20,14  1 /2.9  1 /2.2  1 /2.4  Sample  %  AI O 2  % (AlgO^ + FegO^ + S i 0 ) 2  Si0  2  / AlgO^ / F e 0 2  3  1  A . 6  - molar r a t i o  /5.8  %<2/«clay  11.53  f> Amorph, i n s o i l  S u r f a c e a r e a (m /g)  Note:  The p e r c e n t o f A l g O y (a+b+c)  A . 9  /1.9  9.19  10.52  2  1/  /0.8  16.90 1  A.9  /0.6  8.63  9.00  8.83  7.30  5.12  1.78  1.81  1,58  1.47  0.86  12.72  23.07  22.40  18,97  23.17  17.25  123.02  170.87  176.97  124.71  109.22  87.04  1.73  fo l o s s  /2.Z  R6  R5  FegO^,  g i v e n i n T a b l e 7.  and S i 0  2  a r e c a l c u l a t e d from t h e " t o t a l amorphous"  TABLE 10 SUMMER Amorphous m a t e r i a l e x t r a c t e d from <2j\ c l a y by s u c c e s s i v e e x t r a c t i o n s ! 5% Na C0^ + A c i d NH^-oxalate + d i t h i o n i t e . The t a b l e a l s o includes» molar r a t i o o f amorphous o x i d e s ? i sum o f amorphous o x i d e s ? % < 2 ^ c l a y ? % amorphous o x i d e s i n s o i l ? % l o s s ; s u r f a c e a r e a . 2  S4  Sample  S2  % AlgO-j  2.82  25.23  23.59  fo F e 0 ^  0.87  3.89  %  Si0  0.98  %  (A1 0^  4.67  2  2  2  + Fe 0^ 2  + Si0 ) 2  S i 0 / A 1 0 ^ / Fe 0-^ - molar r a t i o 2  2  2  1  S6  S7  20.69  2.99  2,21  8.99  10.60  2.19  3.32  12.41  10.27  10.18  1,84  1.84  41.53  42.85  41,47  7.02  7.37  S3  1  /2.9  /2.00  /0.3  /0.9  1  /2.3 /0.9  % < 2^A c l a y  2.80  6.50  io amorph. i n s o i l  0.13  2.69  5.05  % loss  5.02  42.14  64.96  172.45  S u r f a c e a r e a (m /g)  Note:  The % AlgO^, F e g O ^ and S i 0 i n T a b l e 8,  2  11.80  S5  1  /2.0  A.o 2.4  1  A.6 A .  2  1  A . 2 A . 8  8,1  7.9  1.00  0,57  0,58  43.20  42.07  8,00  8.08  206.35  158.37  99.12  103,89  a r e c a l c u l a t e d from " t o t a l amorphous" ( a + b ) g i v e n  and w h i l e i t seems q u i t e u n i f o r m l y d i s t r i b u t e d down t h e p r o f i l e i n Ryder, i t i s low ( 4 , 6 7 % ) i n t h e e l u v i a t e d h o r i z o n ( A e ) , q u i t e h i g h and u n i f o r m i n B f h , B f c g and B.C., and low a g a i n i n Cg and IIGg h o r i z o n s o f t h e Summer c l a y .  I n t h i s c l a y , t h e t o t a l amorphous c o n t e n t  i n t h e i l l u v i a t e d h o r i z o n s i s much h i g h e r than i n t h e correspondent  i l l u v i a t i o n h o r i z o n s o f Ryder c l a y ( a t  l e a s t two t i m e s ) . L o o k i n g a t F i g u r e 8.1 and 8 . 2 i n which t h e t o t a l amorphous c o n t e n t f o r t h e two c l a y s i s r e p r e s e n t e d , a l o n g w i t h p e r c e n t o f * 2^ c l a y d i s t r i b u t i o n down t h e p r o files,  i t can be observed,  t h a t t h e t o t a l amorphous  m a t e r i a l d i s t r i b u t i o n s f o l l o w c l o s e l y the percent of <2^ c l a y d i s t r i b u t i o n s except f o r t h e B.C. sample o f the Summer c l a y , i n which, even though t h e p e r c e n t o f <2yu c l a y  i s v e r y low ( 2 . 4 % ) , t h e amorphous a c c u m u l a t i o n  i s very high (41,47%),  when one observes a g a i n i n T a b l e s  9 and 10, t h e d i s t r i b u t i o n o f p e r c e n t amorphous as c a l c u l a t e d f o r t h e s o i l as a whole, i t can be t h a t i t f i r s t i n c r e a s e s t o a maximum i n B f 3 f o r Ryder and i n B f c g f o r Summer, t h e n i t decreases u n i f o r m l y towards t h e l o w e r horizons. .  F i g u r e 6 and 7 r e p r e s e n t t h e d i s t r i b u t i o n s o f  % AlgO^, F e 0 ^ and S i 0 , as e x t r a c t e d by s u c c e s s i v e 2  2  t r e a t m e n t s o f 5% Na C0^ and a c i d NH^-oxalate, 2  ^2jl*  from  c l a y s , and t h e d i s t r i b u t i o n o f t h e < 2yu c l a y  itself.  55  '2 EXTRACTED  BY SUCCESSIVE TREATMENTS  (% AS PRESENTED IN TABLE  9);  AND< 2/1 CLAY CONTENT.  %  Al 0 2  3  ~ Fe 0 2  FIGURE 7, SUMMER EXTRACTED AND <  -  3  Si02  DISTRIBUTION  '  ALONG THE PROFILE OF  %  <2g  CLAY  Al 2O3 - F * ^ - Si0  BY SUCCESSIVE TREATMENTS (% AS PRESENTED IN TABLE  2fJL  CLAY.  2  10);  56.  Total A m o r p h o u s - % (SiC>2 + A l 0 2  FIGURE 8.1.  RYDER  3  +  Fe 0 ) 2  3  i  %  <2/j.  - DISTRIBUTION ALONG THE PROFILE OF TOTAL  (% Si0 + I A l 0 + I F e ^ ) 2  2  3  F I G U R E 8.2.'  Amorphous -  % (Si02 + AI2O3 + Fe 03) 2  '  %  2  EXTRACTED  2  3  2  9)  CLAY,  < 2 ^ CLAY  SUMMER - DISTRIBUTION ALONG THE PROFILE OF TOTAL  (% Si0 + A) 0 + % Si0 )  AMORPHOUS  (AS PRESENTED IN TABLE  EXTRACTED,. BY.. SUCCESSIVE. TREATMENTS;. AND .%.< 2  Total  CLAY  (AS PRESENTED IN TABLE  BY SUCCESSIVE TREATMENTS; AND I < 2 LL  AMORPHOUS  10) CLAY.  $7.  I t c a n be observed t h a t s (i)  The d i s t r i b u t i o n s closely  o f t h e amorphous  components  f o l l o w t h a t o f t h e c l a y , except as  p o i n t e d out p r e v i o u s l y f o r t o t a l  amorphous  m a t e r i a l i n t h e B.C. Summer h o r i z o n . (ii)  The A1 0^ c o n t e n t  i s g e n e r a l l y higher i n both  2  clays i n respect t o S i 0  2  and F e 0 ^ 2  contents.  Low i n Ap and Ae h o r i z o n s , i n c r e a s e s d r a s t i c a l l y i n t h e i l l u v i a l h o r i z o n s i n which i t maintains  i t s e l f reasonably  c o n s t a n t , and  then i t l e v e l s o f f a t lower (iii)  depths,  The F e 0 ^ d i s t r i b u t i o n f o l l o w s t h e same p a t t e r n 2  as t h e < 2^ c l a y d i s t r i b u t i o n and t h e c o n t e n t i s u n i f o r m l y h i g h through  a l l the horizons  from Ap t o Bf3 d e c r e a s i n g d r a s t i c a l l y i n B I I C and C h o r i z o n s i n t h e Ryder c l a y .  In  the Summer c l a y , t h e F e 0 ^ c o n t e n t f o l l o w s 2  the same p a t t e r n d e s c r i b e d f o r A 1 0 ^ c o n t e n t . 2  (iv)  The S i 0  2  content  i n Ryder i s q u i t e low i n Ap  h o r i z o n , i t goes up r e a c h i n g a maximum i n the B f , decreases 2  i n Bf3 and i n c r e a s e s a g a i n  i n t h e two l o w e r h o r i z o n s ,  I n t h e Summer i t i s  a l s o v e r y low i n Ae, i n c r e a s e s t o a maximum i n B f h h o r i z o n and decreases  constantly with  The d i s t r i b u t i o n o f t h e above t h r e e  depth.  amorphous  components seems t o be c o n s i s t e n t , p a r t i c u l a r l y i n t h e Summer c l a y , w i t h a model o f w e a t h e r i n g  i n a podzol  soil  p r o f i l e of a m a t e r i a l h a v i n g the composition of the G horizon clay. The high content of amorphous components i n Bfh, B f c g , and BC h o r i z o n s of Summer c l a y seems t o he due not only t o the process of i l l u v i a t i o n  from the upper  h o r i z o n s , but a l s o to accumulation due t o the impeded drainage i n the  subsoil.  59 INFRARED SPECTROSCOPY STUDIES G r e a t care has t o be t a k e n i n p r e p a r i n g for  samples  i n f r a r e d s p e c t r o s c o p i c a n a l y s i s , e s p e c i a l l y when com-  p a r i s o n s a r e made f o r d i f f e r e n c e s o r s i m i l a r i t i e s between two  samples.  I n t h i s s t u d y , n o t o n l y a q u a l i t a t i v e compari-  son b u t a l s o a q u a n t i t a t i v e comparison was a t t e m p t e d . As mentioned p r e v i o u s l y , i n t h e d e t a i l p r o c e d u r e o f these s u c c e s s i v e e x t r a c t i o n s , t h e samples were f r e e z e d r i e d a f t e r each s u c c e s s i v e e x t r a c t i o n , and l e f t f o r seventy-two hours i n a d e s s i c a t o r w i t h MgtNO^Jg-^HgO (about 5 5 % R.H.) f o r e q u i l i b r a t i o n ,  K B r p e l l e t s were p r e -  p a r e d w e i g h i n g , t o t h e f o u r t h d e c i m a l p l a c e , a 1 mg subsample d i r e c t l y i n t o a s m a l l m o r t a r t o w h i c h 99 rag o f K B r ( c o n c e n t r a t i o n o f sample/KBr = 1/100) was added so as t o a v o i d l o o s i n g t h e sample i n t r a n s f e r r i n g i t from a w e i g h i n g boat t o a s m a l l m o r t a r i n which t h e sample i s v e r y  gently  ground (no h a r d g r i n d i n g was n e c e s s a r y because t h e vacuum f r e e z e d r y e r gave s o f t minutely-powdered s a m p l e s ) .  Careful  m i x i n g and g r i n d i n g e n a b l e d t h e p r e p a r a t i o n o f t r a n s p a r e n t p e l l e t s , w i t h f a i r l y even d i s t r i b u t i o n o f t h e sample w i t h i n the K B r when i t underwent a t e n t o n - p r e s s u r e procedure.  i n vacuum  The p e l l e t s were r u n f o r i n f r a r e d s p e c t r a  immediately a f t e r preparation.  The KBr p e l l e t s were p r e p a r e d  under t h e same c o n d i t i o n s by t h e same o p e r a t o r a t a l l t i m e s so t h a t t h e s p e c t r a o b t a i n e d comparable.  are considered  t o be  reasonably  The  assurance t h a t t h e K B r p e l l e t s a r e i n t h e same  c o n d i t i o n i s q u i t e important i n f r a r e d spectroscopy",,  i n t h e so c a l l e d  "differential  The d i f f e r e n t . s p e c t r a were, i n f a c t ,  o b t a i n e d by p l a c i n g t h e K B r p e l l e t s p r e p a r e d b e f o r e and a f t e r t h e t r e a t m e n t  from t h e c l a y s  i n t h e "sample beam" and i n  the " r e f e r e n c e beam" o f t h e s p e c t r o p h o t o m e t e r , r e s p e c t i v e l y ? w h i l e t h e o r d i n a r y s p e c t r a were o b t a i n e d by u s i n g a pure KBr p e l l e t as r e f e r e n c e .  Any imbalance among t h e K B r p e l l e t s  due t o causes o t h e r t h a n s e l e c t i v e d i s s o l u t i o n g i v e s r i s e t o a b s o r p t i o n e f f e c t s i n t h e d i f f e r e n c e spectra,, I n t h e p r e s e n t s t u d y , t h e observed v a r i a t i o n s between r e p l i c a t e s o f p e l l e t s i n t h e major S i - 0 s t r e t c h i n g , OH s t r e t c h i n g , and 0H(H 0) b e n d i n g a b s o r p t i o n bands d i d n o t 2  exceed 2 - 3% o f t h e absorbance. I t i s b e l i e v e d that the s p e c t r a presented  below  (which r e f e r s t o R3 sample o f Ryder c l a y ) a r e s i g n i f i c a n t as f a r as t h e d i f f e r e n t d i s s o l u t i o n a b i l i t y o f t h e d i f f e r e n t reagents  used i s concerned.  They a r e a l s o q u i t e comparable  as t o t h e t r e n d t h a t c a n be seen i n t h e d a t a o f s u c c e s s i v e e x t r a c t i o n s presented The  i n Table 7,  S i - 0 bands a r e t h e s t r o n g e s t bands i n t h e  s i l i c a t e s t r u c t u r e and can be r e a d i l y r e c o g n i z e d  i n the  i n f r a r e d s p e c t r a o f such m i n e r a l s by a v e r y s t r o n g band i n the r e g i o n 9 0 0 - 1100 cm  ( s t r e t c h i n g ) as w e l l as l e s s  i n t e n s e bands i n t h e 400 - 800 cm"  1  region  (bending).  The  OH group r e t a i n s s u f f i c i e n t  individuality  i n the i n f r a r e d s p e c t r a o f complex l a y e r s i l i c a t e s t r u c t u r e s t o he c o n s i s t e n t l y r e c o g n i z e d . bands i n the  3000  -  3800  cm  The  absorption  r e g i o n are due  s t r e t c h i n g v i b r a t i o n s of protons  t o the  a g a i n s t oxygen.  The  p r e s e n c e of t r i v a l e n t i o n s i n o c t a h e d r a l s i t e s produces b e n d i n g modes o f the type H-0-A1 o r H - 0 - F e ^ -1 t o 920 cm  +  i n the  800  region. The  O H - s t r e t c h i n g and OH-bending f r e q u e n c i e s  are markedly a f f e c t e d by the i o n t o which they c o o r d i n a t e d and t h e i r environment. d i s t i n c t OH-stretching  The  are  absence o f  f r e q u e n c i e s i n the  3600 -  any cm"  3700  r e g i o n and the p r e s e n c e o f the b r o a d O H - s t r e t c h i n g  and  OH  b e n d i n g bands are i n t e r p r e t e d t o mean t h a t the samples c o n t a i n amorphous m a t e r i a l s .  These r e g i o n s are  important  i n a s s e s s i n g the impact o f the p r e s e n c e o f amorphous materials.  I n f a c t , the amount o f water absorbed on  the  s u r f a c e s o f s o i l m i n e r a l phases p r e s e n t i n the samples i s r e l a t e d t o the s u r f a c e a r e a and t h i s r e l a t i o n can  be  r e a d i l y seen by comparison of the s p e c t r a i n F i g u r e  14  w i t h the s u r f a c e a r e a d a t a i n T a b l e 11 f o r the B f 3 Ryder horizon. (Table 11 - page  62.)  .62. TABLE 1 1 S u r f a c e a r e a (m /g) surface  of B f 3 Ryder h o r i z o n  a r e a o f the same a f t e r :  (b) A c i d NH^-oxalate  (a) 5% NaCO^  (c) D i t h i o n i t e .  Sample R3  c l a y and the  S u r f a c e A r e a (m / g r ) 177.0  - Untreated clay  R3 - a  141.9  R3 - b  51.6  R3 - c  4-5.2  In Figure c l a y (Ryder B f 3 )  9a, 10a, and 11a, the s p e c t r a o f u n t r e a t e d  and those o f the same c l a y a f t e r the  three  d i s s o l u t i o n t r e a t m e n t s are drawn f o r comparison. The  s p e c t r a show t h a t the samples were a f f e c t e d  d i f f e r e n t l y by the d i f f e r e n t t r e a t m e n t s , i f one observes t h e absorption  bands i n the 3000 - 3700 cm" and 1635 cm" 1  ( s t r u c t u r a l HgO) some h i g h s u r f a c e  r e g i o n s i t h i s suggested the p r e s e n c e o f a r e a amorphous i n o r g a n i c m a t e r i a l s .  band around 1000 cm much.  1  (Si-0  The  s t r e t c h i n g ) i s not a f f e c t e d as  An o v e r a l l p i c t u r e o f how the s i n g l e  extraction  t r e a t m e n t a f f e c t e d the c l a y sample i s p r e s e n t e d i n T a b l e 1 4 . In Figure  9b, 10b, and l i b are p r e s e n t e d the  differ-  ent s p e c t r a between the u n t r e a t e d c l a y and the c l a y a f t e r ( a + b ) , ( a + b + c ) and a f t e r (a + b + e + d) respectively.  extraction  The s p e c t r a have been o b t a i n e d b y p l a c i n g  the  u n t r e a t e d c l a y i n the sample-beam and the t r e a t e d ones i n  Figure 9 a .  4000  3000  2000  1600  WAVENUMBER  1200  800  CM"  1  Figure 9o.  Comparison between infrared spectra of untreated Clay-R3 and Clay-R3 after (a + b) extraction [•}.  Figure 9b.  Differential infrared spectra between untreated Clay-R3 (in sample-beam) and Clay-R3 after (a + b) extraction (in ref erence-beam).  400  Figure 10a  4000  3000  2000  1600  WAVENUMBER  1200  800  400  CM"  1  extraction (e).  Figure  10a.  Comparison between infrared spectra of untreated Clay-R3 and Clay-R3 after ( a t b + c )  Figure  10b.  Differential infrared spectra between untreated Clay-R3 (in sample-beam) and Clay-R3 after (a + b + c) extraction (in reference-beam).  Figure  lla.  Figure  !ia.  Figure  lib.  Comparison  Differential extraction  between  infrared  infrared s p e c t r a  of the untreated  Clay-R3  and C l a y - R o after ( a + b + c + d)  extraction  spectra of the untreated Clay-R3 (in sample-beam) and Clay-R3 after (a + b + c + d )  (in refe rence - beam ).  4000  3000  2000  1600  WAVENUMBER  1200  CM  800  400  -1  Figure  12.  Differential infrared spectra of. C l a y - R 3 after (a + b) extraction (in sample-beam) and C l a y - R 3 after ( a + b + c ) extraction (in reference-beam).  Figure  13.  Differential infrared spectra of Clay-R3 after (a+b + c) extraction (in sample-beam) and Clay-R3 after ( a + b + c + d) extraction (in reference-beam).  ON ON  3000  2000  1600 WAVENUMBER  1200  800  400  CM~'  Comparison beteen infrared spectra of untreated C l a y r R 3 and C l a y - R 3 successive extractions: (a) 5 % Na CC>3 and Na - Pyrophosphate, (b) Ac. N H - o x a l a t e , (c) Dithionite. 2  4  675. the reference-beam, so t h a t F i g u r e 9b r e p r e s e n t s t h e spectrum o f t h e a l u m i n o s i l i c a t e amorphous phase e x t r a c t e d by 5% Na C0^; i n F i g u r e 10a i s t h e combined spectrum o f t h e 2  a l u m i n o s i l i c a t e amorphous c a r b o n a t e - s o l u b l e phase p l u s t h e iron-aluminum p o l y h y d r o x y  amorphous phase brought i n t o  s o l u t i o n by a c i d NH/j,-oxalate, which completes t h e c l e a n i n g action of the c r y s t a l l i n e minerals. l a t t e r phase a l o n e i s r e p r e s e n t e d  The spectrum o f t h e  i n Figure 12,  by p l a c i n g t h e sample a f t e r carbonate  obtained  treatment  i n the  sample-beam and t h e sample a f t e r o x a l a t e t r e a t m e n t  i n the  reference-beam. F i n a l l y , i n F i g u r e 13» i s p r e s e n t e d  t h e spectrum  of t h a t p o r t i o n o f t h e c r y s t a l l i n e m a t e r i a l w h i c h has been a t t a c k e d and b r o u g h t i n t o s o l u t i o n by c i t r a t e - d i t h i o n i t e treatment.  I t i s assumed, t h a t a l l t h e amorphous m a t e r i a l s  have a l r e a d y been removed a f t e r a c i d NH^-oxalate s u c c e s s i v e extraction.  F o l l o w i n g t h i s treatment,  the c h a r a c t e r i s t i c  broad band o f t h e O H - s t r e t c h i n g mode due t o amorphous m a t e r i a l i s s u b s t i t u t e d by t h e c h a r a c t e r i s t i c bands o f , t h e c r y s t a l l i n e m i n e r a l s p r e s e n t i n t h e sample.  CONCLUSION I t appears t h a t s u c c e s s i v e s e l e c t i v e a n a l y s i s , combined w i t h t h e i n f r a r e d  dissolution  spectrophotometry  t e c h n i q u e , has-proved t o be a s u i t a b l e p r o c e d u r e f o r u n l o c k ^ i n g t h e door t o q u a l i t a t i v e as w e l l as q u a n t i t a t i v e d e t e r m i n a t i o n o f t h e i n o r g a n i c amorphous system o f s o i l .  68.  The primary in  purpose of the f i r s t procedure adopted  t h i s study was to evaluate the e x t r a c t i o n a b i l i t y of  d i f f e r e n t e x t r a c t a n t s as to t h e i r u s e f u l n e s s i n c h a r a c t e r i z i n g the Bf h o r i z o n s o f Podzol  soils.  From the r e s u l t s found  the a b i l i t y of the o x a l a t e  procedure to remove more aluminum than the c i t r a t e - d i t h i o n i t e procedure i s r e a d i l y e v i d e n t . On the o t h e r hand, the c i t r a t e d i t h i o n i t e procedure e x t r a c t s higher q u a n t i t i e s o f i r o n  than  the o x a l a t e method. T h i s w r i t e r agrees with McKeague t h a t the c i t r a t e d i t h i o n i t e procedure i s l e s s s p e c i f i c than the o x a l a t e dure because the former removes c r y s t a l l i n e i r o n from the s o i l ,  proce-  compounds  e s p e c i a l l y from s o i l s high i n c l a y . The o x a l a t e  i r o n values showed no a p p r e c i a b l e i n c r e a s e o f i r o n with i n c r e a s i n g c l a y content. T h i s i n d i c a t e s that the o x a l a t e method d i f f e r e n t i a t e s more s p e c i f i c a l l y between amorphous and c r y s t a l l i n e forms of i r o n . Thus the o x a l a t e e x t r a c t a b l e i r o n ( and aluminum ) v a l u e s can separate  soils ln classification  systems b e t t e r than the c i t r a t e - d i t h i o n i t e e x t r a c t a b l e i r o n ( and aluminum ) v a l u e s . The  s u c c e s s i v e d i s s o l u t i o n a n a l y s i s a l l o w s the  s e p a r a t i o n of a t l e a s t two c l e a r l y d i f f e r e n t phases of the amorphous m a t e r i a l present  i n the c l a y : the f i r s t  which i s d i s s o l v e d by 5% sodium carbonate,  phase,  i s represented by  an amorphous a l u m i n o s i l i c a t e and p o s s i b l y f r e e amorphous alumina and s i l i c a ;  the m a t e r i a l separated out by the succe-  s s i v e o x a l a t e treatment  r e p r e s e n t s a phase much more  specific  68a than that one  obtained w i t h no p r e v i u o s a l k a l i treatment.  t h i s second phase s i l i c a a n i alumina  In  are most l i k e l y to be  c l o s e l y a s s o c i a t e d with each o t h e r and w i t h the amorphous iron oxides. The  I n f r a r e d spectroscopy and the s u r f a c e area  d e t e r m i n a t i o n a f t e r each s u c c e s s i v e treatment  allowed  cha-  r a c t e r i z a t i o n of each phase from a p h y s i c a l p o i n t of view. On the b a s i s of t h i s study i t seems premature to suggest  that the s u c c e s s i v e e x t r a c t i o n procedure  can be used  w i t h any u s e f u l n e s s i n d e v i s i n g c r i t e r i a f o r c l a s s i f i c a t i o n purposes.  Much more confidence c o u l d be put on the  results  o b t a i n e d by s u c c e s s i v e d i s s o l u t i o n a n a l y s i s i f there would be l e s s u n c e r t a i n t y i n regard to the s p e c i f i c i t y of d i s s o l u t i o n procedures,  chemical  and the s i g n i f i c a n c e , i n terms of  s t r u c t u r a l order o r d i s o r d e r , of the f r a c t i o n s which they dissolve.  69/.  LITERATURE CITED  1,  A l l i s o n , LoE, 1965. Organic carbon. I n A,C. 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S c i 9% 599 - 607,  15,  F i e l d e s , M, and R . J . F u n k e r t . 1966. The n a t u r e o f a l l o p h a n e i n s o i l s . P a r t 2. D i f f e r e n c e s i n composit i o n . N,Z. J l . S o i l S c i , 9» 608 - 622.  16,  F o l l e t t , A.C., W.J. McHardy, B.D, M i t c h e l l , and B.F.L, Smith 1964, Chemical d i s s o l u t i o n t e c h n i q u e s i n t h e s t u d y o f s o i l c l a y s . P a r t 1-2, C l a y M i n e r a l s 6s 23 - 43.  17,  F r a n z m e i e r , D.P., B.F, H a j e k , and C.H. Simonson, 1963. Use o f amorphous m a t e r i a l t o i d e n t i f y s p o d i c h o r i z o n s . S o i l S c i , S o c . Amer. P r o c . 29s 737 - 743.  18,  Gastuche» M.C,, F» T o u s s a i n t J , J , F r i p i a t , R, T o u i l l a u x o and M, Van Meerssche, 1963. C l a y M i n e r a l s 5§ 227 ~ 233.  19,  Gorbunov N . I . , G.S, D z y a e v i c h , and B.M. T u n i k , 1961. Methods o f d e t e r m i n i n g n o n - s i l i c a t e amorphous and c r y s t a l l i n e s e s q u i o x i d e s i n s o i l s and c l a y s . S o v i e t S o i l S c i . l i s 1252 - 1259.  20,  G r e e n l a n d , D.J., and J.M, Oades, 1969. I r o n h y d r p x i d e s and c l a y s u r f a c e s . 9 t h I n t e r . Cong. S o i l S c i . 2s 657 - 667.  21,  Hashimoto, I . , and M.L. J a c k s o n , I960. R a p i d d i s s o l u t i o n o f a l l o p h a n e and k a o l i n i t e - h a l l o y s i t e a f t e r . d e h y d r a t i o n . C l a y and C l a y m i n e r a l s . P r o c . 7 t h Conf. 102 - 113.  22,  J a c k s o n , M.L, 1958. S o i l c h e m i c a l a n a l y s i s . H a l l I n c . Englewood C l i f f s , N.J. 468 p.  23,  L a i , S,, and L.D. S w i n d a l e , 1969. C h e m i c a l p r o p e r t i e s o f a l l o p h a n e from H a w a i i a n and Japanese s o i l s . Soil S c i . Soc. Amer. P r o c . 33: 804 - 808.  24,  L a v k u l i c h , L,M., and J.H. Wiens. 1970. Comparison o f o r g a n i c m a t t e r d e s t r u c t i o n by hydrogen p e r o x i d e and sodium h y p o c h l o r i t e and i t s e f f e c t s on s e l e c t e d m i n e r a l c o n s t i t u e n t s . S o i l S c i . S o c . Amer. P r o c . 34s 755 - 758.  9  9  Prentice  71. 25,  McKeague,, J,A,, and J.H, Day* 1966, D i t h i o n i t e and o x a l a t e e x t r a c t a b l e Fe and A l as a i d s i n d i f f e r e n t i a t i n g ' v a r i o u s c l a s s e s o f s o i l s , Can.J, S o i l S c i ,  46 s 13-22. 26,  McKeague J.A, 1967. An e v a l u a t i o n o f 0 1 M p y r o phosphate and p h r o p h o s p h a t e - d i t h i o n i t e i n comparison w i t h o x a l a t e as e x t r a c t a n t s o f t h e a c c u m u l a t i o n p r o d u c t s i n p o d z o l s and some o t h e r s o i l s . Can. J , S o i l S c i , 47s 95 - 99.  27,  McKeague, J.A., J , E , Brydon, and N,M„ M i l e s , 1971. D i f f e r e n t i a t i o n of. forms o f e x t r a c t a b l e i r o n and aluminum i n s o i l s . S o i l S c i . Soc, Amer. P r o c ,  0  35*  33-37.  28,  Mehra, O.P., and M.L, J a c k s o n , I960, I r o n o x i d e removal from s o i l s and c l a y s by a c i t r a t e - d i t h i o n i t e system b u f f e r e d w i t h sodium b i c a r b o n a t e . 7th N a t l , Confo on C l a y s and C l a y M i n e r a l s , pp, 31.7 - 327,  29,  M i t c h e l l , B.D., V.C, Farmer, and W.J, McHardy. I960, Amorphous i n o r g a n i c m a t e r i a l s i n s o i l s . Adv. Agron.  16s  327 - 383.  30,  M u i r , A, 1961, The p o d z o l and p o d z o l i c s o i l s , Adv, i n Agron. 13? 1 - 56,  31,  P a r f i t t , R.L, 1972. Amorphous m a t e r i a l i n some Papua New G u i n e a s o i l s . S o i l S c i . Soc, Amer, P r o c .  36s  683 - 691.  32,  Pawluk, S, 1967. S o i l a n a l y s i s by atomic a b s o r p t i o n spectrophotometry. Atomic A b s o r p t i o n N e w s l e t t e r . V o l , 6, No, 3. PP. 53 - 56.  33,  P e e c h , M. 1965. Hydrogen-ion a c t i v i t y . I n A.C. B l a c k e t a l . (ed.) Methods o f s o i l a n a l y s i s , P a r t 2  9T4~  926.  34,  Raman, K.V,, and M.M. M o r t l a n d , 1969/1970. Amorphous m a t e r i a l i n a s p o d o s o l : some m i n e r a l o g i c a l and c h e m i c a l p r o p e r t i e s . Geoderma, 3s 37 - 44,  35*  S o i l S u r v e y S t a f f , S o i l C o n s e r v a t i o n S e r v i c e and U.S. Department o f A g r i c u l t u r e . 1967. Soil Classification. A comprehensive System. 7th A p p r o x i m a t i o n U.S. Government P r i n t i n g O f f i c e , Washington, D.C,  36.  Sumner, E.M. 1963. E f f e c t o f i r o n o x i d e s on p o s i t i v e and n e g a t i v e charges i n c l a y s and s o i l s . Clay M i n e r a l s . 5: 218 - 238.  72. 37.  Tamm, O.C., 1932. Uber d i e Oxalatmethode i n d e r Chemischen Bodeanalyse, Meddel, S t a t . S k o g s f o r s o k a n s t . Sweden. H 2?: 1 - 20.  38.  Van Reeuwijk, L.P., and J.M. De V i l l i e r s . 1968. P o t a s s i u m f i x a t i o n o f amorphous a l u m i n o s i l i c a g e l s . S o i l S c i . Soc. Amer. P r o c . 32: 238 - 240.  39.  Wada, K,, and D i J . 1 9 7 0 . S e l e c t i v e d i s s o l u t i o n and d i f f e r e n t i a l i n f r a r e d spectroscopy f o r c h a r a c t e r i z a t i o n o f amorphous c o n s t i t u e n t s i n s o i l c l a y s . C l a y M i n e r a l s 8: 241 253.  40.  Yuan, T.L. 1968. C o m p o s i t i o n o f the amorphous m a t e r i a l i n the c l a y f r a c t i o n o f some e n t i s o l s , i n c e p t i s o l s , and s p o d o s o l s , J , S e r i e s Paper No. 2981, F l o r i d a A g r i c u l t u r a l Experimental Stations, G a i n e s v i l l e , F l o r i d a , 32601.  s  73. STRUCTURE AND  PROPERTIES OF  AMORPHOUS IRON-ALUMINOSILICATE SYSTEMS  INTRODUCTION I n s o i l g e n e s i s , the r o l e o f amorphous aluminos i l i c a t e s have been r e p e a t e d l y r e f e r r e d t o as b e i n g i m p o r t a n t i n d i f f e r e n t i a t i o n o f d i f f e r e n t c l a s s e s of soils.  Few  studies," however, have been conducted  on the  s t r u c t u r e and p r o p e r t i e s o f amorphous i r o n - a l u m i n o s i l i c a t e systems..  Because o f the problems o f c o n t a m i n a t i o n o f  amorphous systems w i t h c r y s t a l l i n e m a t e r i a l and v a r i o u s k i n d s o f o r g a n i c matter," many i n v e s t i g a t o r s have t u r n e d t h e i r attention to synthetic a l u m i n o s i l i c a g e l T h i s approach  i s based on t h e assumption  systems.  that properly  p r e p a r e d a r t i f i c i a l g e l s can be compared w i t h i n o r g a n i c amorphous systems i n the n a t u r a l w e a t h e r i n g environment f o r c h e m i c a l and p h y s i c a l c h a r a c t e r i s t i c s and for s t r u c t u r a l composition.  consequently,  The approach used i n t h i s  study  was t o p r e p a r e s y n t h e t i c i r o n - a l u m i n o s i l i c a t e g e l systems and t o s t u d y t h e i r c h e m i c a l and p h y s i c a l p r o p e r t i e s and attempt t o d e f i n e the s t r u c t u r a l arrangement o f these g e l systems.  To d a t e , no s t u d i e s have been r e p o r t e d i n the  l i t e r a t u r e on complex c o p r e c i p i t a t e s o f the i r o n - a l u m i n o s i l i c a t e g e l system which are b e l i e v e d t o be s i m i l a r to t h e i r r e a l counterparts i n nature.  reasonably  74. M i l l i k e n et a l , (1950) suggested t h a t amorphous a l u m i n o s i l i c a t e s are composed of s i l i c a and  alumina p a r t i c l e s ,  interbonded by the condensation of hydroxyl  groups at  interfaces.  The  s i l i c a tetrahedral structure w i l l  the l o c a l formation  of f o u r f o l d coordinated  r i s e to-an a l u m i n a t e - l i k e alumina content (15  -  structure.  30%)  The  aluminum g i v i n g  they found t h a t the amount of percentage of  excess of alumina i n the s i l i c o - a l u m i n a mix-  ture c r y s t a l l i z e s i n t o bohemite and fold  induce  Above a c r i t i c a l  aluminate decreases s t e a d i l y w i t h d e c r e a s i n g silica.  their  h y d r a r g i l l i t e with s i x -  coordination. Synthetic  a l u m i n o s i l i c a t e s c h a r a c t e r i z e d by  s p e c i f i c s u r f a c e area and  high surface  used as c r a c k i n g c a t a l y s t s .  a c i d i t y , are  large  commonly  In the numerous c o n t r i b u t i o n s  d e a l i n g with the s t r u c t u r e of amorphous a l u m i n o s i l i c a t e s , emphasis i s l a i d on the type of aluminum bonding; order to e x p l a i n the a c i d i t y and such compounds, i t has  and  catalytic activity  in  of  been suggested t h a t the c a t a l y s t i s  not merely a mixture of s i l i c o n and  aluminum, but a r e a l  chemical combination of both elements.  T h i s assumes t h a t  a p o s i t i v e hydrogen i o n i s a s s o c i a t e d with a t e t r a h e d r a l aluminum, and  that the c a t a l y t i c a c t i v i t y  a c i d i c hydrogen. and  w r i t t e n as  The  (HA1  i s due  a c t i v e c o n s t i t u e n t has  SiO^)^  to t h i s  been proposed  (Henin et a l , 1 9 6 3 ) .  75. Tamele (1950) had p r e v i o u s l y c o n s i d e r e d the e x p l a n a t i o n f o r the f o r m a t i o n o f a c i d s i t e s i n aluminos i l i c a t e s as t h e c o n d e n s a t i o n o f t h e s u r f a c e h y d r o x y l groups o f the i n c o m p l e t e l y p o l y m e r i z e d s i l i c a  hydrogel  w i t h h y d r o x y l groups o f t h e h y d r o l i z e d aluminum i o n s . D a n f o r t h (I960) i n o p p o s i t i o n t o M i l l i k e n e t a l . (1950), suggested  t h a t aluminum i s p r e s e n t i n a l u m i n o s i l i -  c a t e s i n t h r e e formss to  (a) f r e e alumina  (b) aluminum bound  s i l i c a ^ and ( c ) aluminum h y d r o x i d e n e u t r a l i z i n g a c i d  exchange s i t e s .  He c o n s i d e r e d t h a t an aluminum t e t r a h e d r o n  s h a r i n g c o r n e r s w i t h s i l i c a t e t r a h e d r a a c t s as B r o n s t e d acid.  A l u m i n a l i n k e d by two o r t h r e e bonds t o s i l i c a ,  would form a L e w i s a c i d on d e h y d r a t i o n . De Kimpe e t a l , (1961) s t u d i e d t h e i n f l u e n c e o f simultaneous  a d d i t i o n s o f aluminum and s i l i c o n i n t h e  common pH range o f aluminum h y d r o x i d e p r e c i p i t a t i o n w i t h the hope t h a t t h e r e c r y s t a l l i z a t i o n o f t h e h y d r o x i d e might be r e t a r d e d and t h e f o r m a t i o n o f a l a y e r s i l i c a t e s t r u c t u r e might be f a c i l i t a t e d .  X - r a y s t u d i e s o f such g e l s gave no  i n d i c a t i o n o f c r y s t a l l i z e d aluminum h y d r o x i d e .  The l a c k o f  X - r a y r e f l e c t i o n s has been e x p l a i n e d by p o s t u l a t i n g t h a t s i l i c a c o n t r o l s t h e development o f t h e system,  imposing  m a i n l y i t s t h r e e - d i m e n s i o n a l framework. Though t h e y i e l d o f c r y s t a l l i n e phase was v e r y poor i n t h e experiments the presence did  c a r r i e d out by these a u t h o r s i n  o f aluminum " a d e t a i l e d s t u d y o f t h e g e l phase 0  show a tendency towards o r g a n i z a t i o n .  76,  K a o l i n i t e appeared a t l o w pH, where t h e s i x f o l d s t r u c t u r e o f aluminum was s t a b i l i z e d .  coordinated  A t h i g h pH v a l u e s ,  a m i c a - l i k e c l a y m i n e r a l appeared„ as t h e f o u r f o l d  coordinated  aluminum i n c r e a s e d i n t h e g e l s t r u c t u r e . De Kimpe e t a l (I96I) concluded reasonable  t h a t i t seems  t o a t t r i b u t e the low y i e l d of the c r y s t a l l i n e  phase t o ; ( i ) t h e i n s o l u b i l i t y o f s i l i c a a t t h e pH v a l u e s under s t u d y which induced  t h e p o l y m e r i z a t i o n o f an alumina-  s i l i c a g e l , and ( i i ) t h e aluminum i o n e a s i l y by isomorphous s u b s t i t u t i o n w i t h s i l i c o n .  interchanges  The hexaco-  o r d i n a t e d form b e i n g s t a b l e o n l y a t l o w pH. Leonard e t - a l .  (1964),  according to t h e i r studies  on amorphous a l u m i n o s i l i c a t e s by X - r a y f l u o r e s c e n t s p e c t r o scopy and i n f r a r e d s p e c t r o s c o p y ,  r e p o r t e d t h a t , as f a r as  aluminum atoms a r e concerned, t h r e e d i f f e r e n t oxygen e n v i r o n ments c a n be d i s t i n g u i s h e d , c o r r e s p o n d i n g ( i ) alumina octahedra,  respectively to*  ( i i ) alumina t e t r a h e d r a s h a r i n g  c o r n e r s , o r ( i i i ) a l u m i n a t e t r a h e d r a s h a r i n g edges.  The  d i s t r i b u t i o n o f t h e s e t h r e e d i f f e r e n t t y p e s depends upon t h e aluminum c o n t e n t and t h e p r e t r e a t m e n t The  spectroscopy  temperature„  of X-ray fluorescence  lines  provides the p o s s i b i l i t y of a d i r e c t c h a r a c t e r i z a t i o n , o f the c o o r d i n a t i o n numbers o f aluminum and s i l i c o n i n v a r i o u s amorphous a l u m i n o s i l i c a t e s a t d i f f e r e n t h y d r a t i o n l e v e l s .  77.  W i t h X-ray f l u o r e s c e n c e , i n e f f e c t , one measures the e m i s s i o n wavelength o f A l Ko( ( o r S i Ko( ), u s i n g a r e f l e c t i o n from an EDTA c r y s t a l i n t h e r e g i o n o f 2 9 = 142.5°; Small hut s i g n i f i c a n t s h i f t s i n the angular p o s i t i o n of the A l K<*  ( o r S i K°( ) l i n e a r e o b t a i n e d f o r d i f f e r e n t  tion states; Al—  coordina-  The r e s u l t s a r e c a l i b r a t e d by r e f e r e n c e t o  PO^ and A l ^ -  Si  2  0^ (OH)^ ( K a o l i n i t e ) .  A calibra-  t i o n l i n e i s drawn between t h e 2 © - v a l u e s o b t a i n e d w i t h A I * 1  PO^ and k a o l i n i t e  9  from which an e s t i m a t e  i s obtained, o f the  p r o p o r t i o n s o f A l i o n s i n t h e two c o o r d i n a t i o n s t a t e s i n a mixture.  Although  these e s t i m a t e s  high accuracy  of A l ~  cannot be c l a i m e d f o r  and A l ~ , n e v e r t h e l e s s , when t h e  r e s u l t s f o r t h e g e l s a r e examined g r a p h i c a l l y , a c l e a r t r e n d i s seen towards s i x f o l d c o o r d i n a t i o n as t h e AlgO^/AlgO^ Si0  2  +  r a t i o i n c r e a s e s beyond,: a c e r t a i n l i m i t , , o r as pH  c o n d i t i o n s become more a c i d i c . D i s c u s s i n g t h e i r r e s u l t s , Leonard e t a l , , (1964) observed t h a t t h e samples p o o r i n aluminum and d r i e d a t 100°C c o n t a i n A l e s s e n t i a l l y i n t e t r a h e d r a l form, a t t h e o p p o s i t e extreme, t h e pure a l u m i n a sample composed o f a mixture  o f bohemite and b a y e r i t e , c o n t a i n e d  c o o r d i n a t e d atoms o n l y .  I n the intermediate range, the  samples a r e composed o f m i x t u r e s JjT Al  sixfold  o f t h e two f o r m s , t h e  contents decreasing l i n e a r l y with i n c r e a s i n g A l  contents.  A c c o r d i n g t o these a u t h o r s , t h e s t a b i l i t y o f t h e  t e t r a h e d r a l form i s secured by f o u r s i l i c a surrounding  an aluminum t e t r a h e d r o n  tetrahedra  ( F i g u r e I A ) , when t h e  .78.  0 1  - 0 -  Si 1  1  - 0 -  0  0  1  Si -  i  0  1 0 1  0 — Si — 0 11 0  i  0 1  -0  i o  H*  i  Si — 0 I  -  -  0 Increasing amounts of AI and hydration. i  I  0  i  0  1  O-Si - 0 — H 1  i  Si '  0 0 H  Si I  v X'/ \ • X ' /  0 -  H  \ / •0. / ' \ 0 / i0 X 0 ' \0 / Al  . ; Al  I  0 -Si I  0  0  Al .  Al  I  H  Si i  0  I Si l  i  0  Stable  H  0 -  0 i  c  i  0 - 0 - Si |  0  01  O-Si  0  1  Dehydration  Al  / ' / 0 1  -O-Si  |  0 i  F I G U R E 1.  SCHEMATIC STRUCTURAL (FROM LEONARD et at.  x  Al  |  1  0  -  0 - Si - 0 • l  0  • \ Al  •V/  0  1  Al  " \ /  0 0 1 1 0 0 - O - S i 1 - 0 - Si - 0 1  0  1  0  RELATIONSHIPS IN SILICOALUMINAS  1  79.  aluminum c o n t e n t i s h i g h enough t o p r e c l u d e such an  arrange-  ment, s i x f o l d c o o r d i n a t i o n numbers become dominants the content of c o n s t i t u t i o n a l water increases a c c o r d i n g l y (Figure I B ) . In  t h i s c h a p t e r , an attempt w i l l be g i v e n t o g i v e  evidence f o r the phase c o n s t i t u t i o n and s t r u c t u r e composit i o n o f s e l e c t e d i r o n a l u m i n o s i l i c a t e g e l systems.  In a  subsequent c h a p t e r , a comparison w i l l be drawn between these a r t i f i c i a l systems and n a t u r a l amorphous c o n c e n t r a t e s o b t a i n e d by an a c i d d i s p e r s i o n procedure  from a s o i l .  80. MATERIALS AND  (a)  METHODS  Samples p r e p a r a t i o n Three samples with d i f f e r e n t molar SiOg/AlgOy'  F e 0 ^ r a t i o s were prepared 2  i n p l a s t i c beakers by  adding  dropwise and with v i g o r o u s continuous s t i r r i n g a mixed s o l u t i o n of 0.6 M f e r r i c c h l o r i d e (Fe Cl^'oHgO) and aluminum c h l o r i d e ( A l C l ^ "6H 0) t o a s o l u t i o n of 0.6 2  sodium m e t a s i l i c a t e ( N a t a t i o n was  2  SiO^ 9 H 0 ) :  c a r r i e d out at pH  2  the c o l d  M  coprecipi-  7,0.  The S i / A l / F e r a t i o and c o n c e n t r a t i o n were a d j u s t e d so t h a t at l e a s t 5 g of g e l was The compositions  obtained from each  beaker.  r e a l i z e d are g i v e n i n Table 1,  . '  The slow a d d i t i o n of S i , A l and Fe ions at the pH s t u d i e d was  b e l i e v e d to be f a v o r a b l e f o r the f i x a t i o n of  SiO^ t e t r a h e d r a at the time of the f o r m a t i o n of the and aluminum hydroxide  iron  framework.  The samples were allowed t o stand o v e r n i g h t , the pH was  r e a d j u s t e d the next morning, the samples were cenrtrir-  fuge-washed r e p e a t e d l y and f r e e z e d r i e d . p h y s i c a l and chemical determinations were  On these samples, conducted,  (b) I n v e s t i g a t i o n Methods Among the p h y s i c a l d e t e r m i n a t i o n s conducted X-ray d i f f r a c t i o n (Cu KX r a d i a t i o n ) , i n f r a r e d  were  spectroscopy  {1% c o n c e n t r a t i o n i n KBr p e l l e t s and Beckman Ir-20 s p e c t r o photometer),  s p e c i f i c s u r f a c e area d e t e r m i n a t i o n by ethylene  g l y c o l monoethyl e t h e r s o r p t i o n procedure.  81.  The samples were a l s o c h e m i c a l l y analyzed by a c i d d i g e s t i o n and the elements determined by atomic spectrophotometry Successive  absorption  ( S i determined by d i f f e r e n c e ) . e x t r a c t i o n s by 5 % NagCO^, a c i d NH^-  oxalate and c i t a t e - b i c a r b o n a t e  d i t h i o n i t e were  attempted.  Potassium f i x a t i o n was determined a c c o r d i n g to the o u t l i n e d below and the c a t i o n exchange c a p a c i t y  procedure  (C.E.C.)  was determined by s a t u r a t i n g the sample w i t h Na-acetate solution,  washing with e t h a n o l , r e p l a c i n g sodium w i t h  ammonium and d e t e r m i n i n g the d i s p l a c e d sodium w i t h atomic absorption  spectrophotometry.  K-Fixation  Procedure  I s o l a t i o n of amorphous i r o n - a l u m i n o s i l i c a t e s from s o i l s appears to be i m p o s s i b l e because instability  of t h e i r  general  i n reagents such as a l k a l i s and a c i d s commonly  employed d u r i n g e x t r a c t i o n  of the c o l l o i d a l system.  i t was considered opportune to p l a c e r e l i a n c e  Thus,  on a  synthetic  system to p r o v i d e at l e a s t a model f o r the n a t u r a l  inorganic  amorphous system. The samples used f o r t h i s experiment were the same as outlined p r e v i o u s l y (AS-1, AS-2, A S - 3 ) ;  and the method  t h a t f o l l o w s i s m o d i f i e d from Van Reeuwijk and De V i l l i e r s (1968).  Subsamples of 1 0 0 g of f r e e z e - d r i e d g e l s were  equili-  b r a t e d with 50 ml of IN K C l s o l u t i o n at pH 7.0 (adjusted w i t h s m a l l amounts of H C l or KCH with no a p p r e c i a b l e  effects  82.  on t h e n o r m a l i t y o f K C l ) , a f t e r the  The  s u s p e n s i o n were l e f t  s a m p l e s were c e n t r i f u g e d and of  IN s o l u t i o n s  tively,  o f NH^  a l l a t pH  potassium.  The  7,0  crucibles,  dried  were t a k e n up priately  C l , Ca C l  e l e c t r o l y t e was ( I t l ) and  rophotometry  and  2  The  w i t h 15  MgCl ,  ml  respec-  2  removed b y  once w i t h  a t 105°C o v e r n i g h t and  The  resulting  were a n a l y z e d by  watersacetone  f o r potassium,  w h i c h had  to tared  weighted. and  the  solutions,  atomic  washing  T h e y were residues appro-  absorption spect-  been d r y - f i x e d  by  hydrogels.  RESULTS AND  DISCUSSION  For structure characterization, been.useful elements:  S i , A l , Fe,  on t h e a r t i f i c i a l  fluorescence spectroscopy.  to  s o , s t r u c t u r e i n f e r e n c e s w i l l be  do  s t u d i e s p r e v i o u s l y proposed  (1961)?  Leonard  Leonard  by  drawn f r o m  other authors  and  4,  results  Fripiat  are  three  coprecipitates  However, n o t b e i n g  e t a l , (1964)?  experimental  have  of the  by  able  similar  (De Kimpe e t e t a l . (1965);  e t a l . (1966)? , C l o o s e t a l , (1968 and The  1, 2 , 3  i t would  t o measure t h e c o o r d i n a t i o n s t a t e  X-ray  al.  times  s a m p l e s were t r a n s f e r r e d  i n IN HC1.  diluted,  repeated  standing overnight.  i n HF/HC10^ (20/1) on a s a n d b a t h  digested  the  The  was  i n o r d e r t o remove e x t r a c t a b l e  excess  mixtures.  o f pH  washed s e v e n  C l , Na  once w i t h w a t e r i e t h a n o l (1:1)  adjustment  1969).  summarized  i n Tables  -  83 o  Samples A S - l , AS-2, AS-3 a r e c h a r a c t e r i z e d , r e s p e c t i v e l y by a low, medium-high, and h i g h aluminum c o n t e n t , w h i l e the i r o n c o n t e n t i s c o n s t a n t l y a medium v a l u e , as can be seen from t h e atomic r a t i o s and % e l e m e n t a l The  ratios.  s p e c i f i c s u r f a c e a r e a p r o g r e s s i v e l y decreased  w i t h t h e i n c r e a s i n g A l / A l + S i atomic r a t i o and t h e same b e h a v i o u r c a n be noted f o r C.E.c, expected  These t r e n d s were  i f one c o n s i d e r s t h e f a c t t h a t g o i n g from an  A l / A l + S i atomic r a t i o o f 0,30 t o 0,79 p r o g r e s s i v e l y mpre o r d e r e d s t r u c t u r e s a r e b u i l d i n g up i n t h e p o l y m e r i c phases present.  A t h i g h e r A l / A l 4 S i v a l u e s , (0,85) Gloos e t a l .  (1969) has shown t h e presence  o f a c r y s t a l l i n e phase com-  posed o f a m i x t u r e o f pseudobohemite and b a y e r i t e . The p r o g r e s s i v e o r d e r i n g o f t h e polyphase i s c o n s i d e r e d r e s p o n s i b l e f o r t h e a b r u p t decrease s u r f a c e a r e a (m  system  o f both  /g) and C.E.C, as one goes from t h e l o w  v a l u e t o h i g h v a l u e s o f t h e A l / A l + S i atomic  ratio,  (see F i g u r e 2 ) . The C.E.C. o f t h e i n t e r n a l core o f t h e s e a l u m i n o s i l i c a polyphase  irpn-  systems, which a r e c o n s i d e r e d t o be  p l a y i n g t h e r o l e o f a n i o n s , might be b a l a n c e d , a t l e a s t t o some e x t e n t , by hydroxy-iron-aluminum  ions or polynuclear  c a t i o n s o f i n c r e a s i n g c o m p l e x i t y , t h u s d e c r e a s i n g the. n e t charge p e r Al o r Fe atom as t h e atomic r a t i o s  decrease.  84,  The G.E.C. - composition r e l a t i o n s h i p f o r s y n t h e t i c aluminos i l i c a hydrogels has been found at  the p o i n t o f  22%  AlgO^ / AlgO^ +  (molar r a t i o S i 0 / A l 0 ^ o f 6.0). 2  De V i l l i e r s , Al  (De V i l l i e r s ,  2  corresponds  Si0  2  1970)  t o peak  composition  This point, according to  with o n e - i n - f o u r s u b s t i t u t i o n o f  f o r S i i n a t e t r a h e d r a l framework, which t h e r e f o r e  appears  t p be the maximum. At molar r a t i o s below 6 . 0 ,  a decrease  i n C.E.G.  w i t h i n c r e a s i n g AlgO^ content suggests t h a t alumina i n excess o f 22% was not accommodated i n the s i l i c a t e s t r u c t u r e and was p r e s e n t p r o b a b l y i n a s i x f o l d c o o r d i n a t e d s t a t e as a second phase,  (see F i g u r e  2).  MOLAR  Si0  2  / AI2O3 .ratio  6 4.8  0.5  0.3  o  400  cr  E  n  300 >-  / /  O <  a. < o  N  \  r-300  \  \  N  200 J  200  \  LU O  \  2 <  o  X LU  100  H  100  O I<  0  .1  20  40  COMPOSITION  FIGURE 2,  (%  60  80  AI 0 ./AI 03 2  3  2  +  100 s i 0  2)  CATION EXCHANGE CAPACITY AND SURFACE AREA OF SYNTHETIC  IRON-ALUMINOSILICATE  HYDROGELS AS DETERMINED AT PH 7 , 0 FUNCTION OF 1 A^OTJ/A^O^+SI O2. POINTS AT 221 AND 0% FOR C . E . C ,  IN THE  ARE  BORROWED FROM J . M . DE V l L L I E R S / 1 9 7 0 , A .  C. E, C,  B,  SURFACE AREA  86.  TABLE  1.  Chemical compos i t i o n , elemental and oxide r a t i o : s p e c i f i c surface area, C.E.C.> X-•Ray D i f f r a c t i o n Data.  AS-1  AS-2  AS-3  Ignition loss %  28.64  35.05  33.81  S i 0 <fo  35,05  16.97  13.83  12.53  33.32  43.24  23.78  14.16  9.12  100.00  100.00  .100.00  A l / A l + S i atomic r a t i o  0.30  0.70  0.79  Fe/Fe + S i atomic r a t i o  0.33  0.39  0.32  1:1,96:0.86  1:3.12:0.66  Sample  2  A1 0 ?  %  3  Total  S i 0 : A1 0^: Fe 0^ molar ratio 2  ?  2  % AlgO^/AlpO^  + SiO  ?  % Fe 0-j/Fe 0^ + S i O  ?  1:0.36:0.68 26.33  66.40 '  75.77  40.42  46.35  39.74  So (m /gr.)  392.36  294.34  219.5^  C.E.C. (meq./lOO gr. )  287.17  52.89.  20.14  amorphous  amorphous  amorphous  2  ?  2  X-Ray D i f f r a c t i o n  87. As mentioned p r e v i o u s l y by van Reeuwijk  and  De V i l l i e r s , the a b i l i t y t o r e p l a c e K by the c o u n t e r NH^,  Na, Ca and Mg,  (charge/radius 3.0  f o r Mg)  = 0.70  ions  i s a f u n c t i o n of t h e i r i o n i c p o t e n t i a l f o r NH^,  1.0  f o r Na, 2.0  f o r Ca,  and  and of t h e i r s o l v a t e d s i z e .  From Table 2, i t appears t h a t the d r y f i x a t i o n of K by the g e l s d e c r e a s e s w i t h i n c r e a s i n g % r a t i o s of A l g O ^ / A1 0^ 2  + Si0  2  and  i t can be^ seen a l s o t h a t K - f i x a t i o n i s  c o v a r i a n t w i t h C.E.C, w h i c h d e c r e a s e s i n a s i m i l a r f a s h i o n . T h i s seems t o be i n accordance w i t h the d i l u t i o n of the polymeric  core and b l o c k i n g of i t s n e g a t i v e charge by  i n c r e a s i n g amounts of the c o a t i n g Fe and A l  the  hydroxide  phases. SUCCESSIVE EXTRACTIONS For d e t a i l s of the s u c c e s s i v e e x t r a c t i o n s , see C h a p t e r 3 i n w h i c h a comparison i s made between the c i a l standards two  artifi-  and the n a t u r a l amorphous c o n c e n t r a t e s  from  soils. The  a r t i f i c i a l sample t r e a t e d here was  the t r e a t m e n t s  which i t was  (a) 5% NagCO-j  (h) a c i d NH^-oxalate and  bicarbonate-dithionite. (on o v e n - d r i e d  The  submitted  AS-2,  and  t o were i n s u c c e s s i o n : (c) c i t r a t e -  % S i 0 , % kl^Oy 2  %  F e ^  - 105°C - b a s i s ) and % l o s s a f t e r the  ments have been c a l c u l a t e d and p r e s e n t e d  i n Table 3  w i t h s p e c i f i c s u r f a c e a r e a (So) v a l u e s , v a r i o u s and oxide r a t i o s and X - r a y d i f f r a c t i o n d a t a .  treattogether  elemental  TABLE 2  DRY FIXATION OF K BY IRON-ALUMINOSILICA GELS  Sample  pH o f KOI saturation  GEL COMPOSITION ^~Al^o^7Xr o 2  3  + sio  2  K FIXED AGAINST EXCHANGE BYs NH  4  Na  Ca  Mg  C.E.C.  meq./lOO g r . AS-1  26.33  7.0  42  63  110  155  287.17  AS-2  66.4-0  7.0  6  21  28  39  52.89  AS-3  75.77  7.0  0  8  14-  22  20,14  89.  A few p o i n t s t o note i n T a b l e 3 ares  (a) 97.16$ o f t h e t o t a l  sample has been removed by d i t h i o n i t e t r e a t m e n t , o n l y 2.84 % o f u n d i s s o l v e d m a t e r i a l ,  leaving  (b). t h e h i g h agreement  between t h e t o t a l % from s u c c e s s i v e e x t r a c t i o n s  and t h e %  l o s s a f t e r t h e t r e a t m e n t s , and, ( c ) t h e ' d r a m a t i c drop o f the s u r f a c e a r e a a f t e r ( a + b) t r e a t m e n t s ,  A comparison o f  these d a t a (Table.3) w i t h d a t a o b t a i n e d f o r sample AS-2 from t h e a c i d d i g e s t i o n  procedure  (but the data i s c a l c u l a t e d  t o t a k e i n t o account t h e l o s s on i g n i t i o n o f adsorbed and s t r u c t u r a l water) i s p r e s e n t e d i n T a b l e 4, As c a n be:seen from T a b l e 4, t h e % A l g O ^ , F e 0 ^ , 2  Si0  2  and t h e v a r i o u s r a t i o s c a l c u l a t e d  5% Na C0^ + a c i d NR^,-oxalate 2  closely related calculated  a f t e r the successive  + d i t h i o n i t e extractions, are  t o the corresponding percentages  after acid  digestion.  and r a t i o s  90. TABLE 3 AS-2 SUCCESSIVE TREATMENTS DATA AND RATIOS. Sample and Treatments  *AS-2(a)  *AS-2 (a+b)  *AS-2(a+b+c)  9.43  40.30  53.74  18.38  22.32  15.94  19.91  T o t a l % S i 0 , A1 0^, Fe 0^ Extraction  75.50  97.16  Loss a f t e r e x t r a c t i o n s  74.60  96.00  1/2.5/1.1  1/2.6/1.1  A l / A l + S i atomic r a t i o  0.74  0.76  Fe/Fe + S i atomic r a t i o  0.46  0.44  f  **AS-2  AlgO^  % Fe 0^ 2  f> S i 0  0.70  2  2  2  2  Si0 /Al 0 /Fe 0 molar r a t i o 2  2  3  2  3  % AI O /AI O^ + S i 0  2  71.75  72.96  % Fe 0^/Fe 0^ + S i 0  2  53.55  52/85  2  3  2  2  2  S u r f a c e a r e a - So -  294.34  31. 82  44.06  (m /gr) 2  X-Ray  amorphous  diffraction  **  not t r e a t e d sample  *  (a)  = Sfo Sodium Carbonate  (a+b)  = Sfo Sodium Carbonate + Ac. ,NH^ O x a l a t e .Extraction  (a+b+c)  = % Sodium Carbonate + A c i d NH^ O x a l a t e + Dithionite Extraction  Extraction  91.  TABLE 4 Comparison between data obtained a f t e r s u c c e s s i v e extraction  (a+b+c)  and data a f t e r a c i d d i g e s t i o n procedure on AS-2  sample.  Sample and Treatments  AS-2 (a+b+c)  AS-2 (Acid D i g . )  I g n i t i o n l o s s fo  35.05  35.05  % AlgO^  36.40  33.32  % Fe 0^  16.19  14.16  fo S i 0  18.15  16.97  1/2.01/0.88  1/1.96/0.86  2  2  S i 0 / A l 0 ^ / F e 0 ^ molar r a t i o 2  2  2  A l / A l + S i atomic r a t i o  0.70  0.70  Fe / Fe + S i atomic r a t i o  0.40  0.39  % A1 0  3  / A1 0  + Si0  2  65.52  66.40  % Fe 0  3  / FegO^ + S i 0  2  47.15  46.35  2  2  2  3  92o  INFRARED SPECTROSCOPY STUDIES The most i n t e r e s t i n g f e a t u r e s t o be considered s p e c t r a concern the bands i n the 1300  on the I.R.  wavelength domain, and band.  As  - 500  cm"  1  in; p a r t i c u l a r , the S i - 0 s t r e t c h i n g  i t can be seen from the s p e c t r a presented i n  F i g u r e 4,  t h i s band i s w e l l developed  samples and comes out at 1025 AlgO^ + S^°2  =  cm"  f o r a l l the three  i n AS-1  (AlgO^  /  26.33$) and i s much more d i s t i n c t and pro-  nounced than i n samples AS-2  and AS-3  where i t comes out  _1 at 95°  cm T h i s behaviour can be e x p l a i n e d t a k i n g i n proper  account the schematic Looking,  s t r u c t u r e s proposed  i n f a c t , at F i g u r e IB, we  i n Figure  1.  can see t h a t Fe or, A l :  octahedra are i n c l u d e d i n a s i l i c o n t e t r a h e d r a network} t h i s i n c l u s i o n may  be assumed t o decrease  the S i - 0 s t r e t c h -  i n g frequency because the o r g a n i z a t i o n of the  silicon  network i s p e r t u r b a t e d with consequent weakening of the cohesion between t e t r a h e d r a ; and t h a t appears happened f o r AS-2  and AS-3  t o have,  which are most l i k e l y t o be i n  the s i t u a t i o n presented i n F i g u r e IB 1 i n o p p o s i t i o n to  AS-1,  which i s most l i k e l y to be i n the s i t u a t i o n presented i n F i g u r e IA. Upon d e h y d r a t i o n ( o r d e h y d r o x i l a t i o n ) going sample AS-1, i n alumina  low i n alumina content, t o AS-2  from  and AS-3» h i g h  content, no r e a l change can be noted  (Figure 5) the frequency of S i - 0 band i s s t i l l  in  AS-1;  a t 1025  -1 cm  ,  AS-1  Figure  5.  Comparison of infrared spectra of iron-aluminosilicate artificial standards A S - I , A S - 2 , and AS-3 after  dehydration  (at 300°C).  95.  but an i n c r e a s e i n the frequency AS-3  o f Si-0 band f o r AS-2 and  from 950 cm" a t 100°C, t o 1025 cm"  observed.  1  1  a t 300°C can be  The e x p l a n a t i o n f o r t h i s k i n d o f b e h a v i o u r can  be found r e f e r r i n g once a g a i n t o t h e schematic proposed i n F i g u r e 1,  I t i s obvious  structures  that tetrahedra pf  the type shown i n F i g u r e IA do n o t change upon dehydration,, but t h e o c t a h e d r a  o f F i g u r e IB w i l l p r o g r e s s i v e l y t r a n s f o r m  i n t o t e t r a h e d r a s i m i l a r t o F i g u r e 1C.  I n AS-1 (low A l  c o n t e n t ) , t h e type A i s t h e o n l y one p r e s e n t and c o n s e q u e n t l y the t e t r a h e d r a network i s almost n o t a f f e c t e d by d e h y d r a t i o n , t h a t i s why no changes i n Si-0 band f r e q u e n c y  occur. .But  f o r AS-2 and AS-3 samples ( h i g h i n A l c o n t e n t ) the dehydrat i o n b r i n g s about a C type o f s t r u c t u r e which can be unders t o o d i n terms o f i n c r e a s i n g t h e s i l i c o n t e t r a h e d r a o r g a n i z a t i o n w i t h t h e consequent i n c r e a s i n g i n t h e Si-0 frequency  stretching  observed f o r these two samples. A behaviour  s i m i l a r t o t h a t one j u s t d e s c r i b e d  can be observed on the s p e c t r a o f AS-2 t a k e n a f t e r s u c c e s s i v e e x t r a c t i o n s ( F i g u r e 6), i n t h e frequency  One c a n note a p r o g r e s s i v e  increase  o f Si-0 s t r e t c h i n g band from 1025 cm  1060 and f i n a l l y t o 1110 cm"  to  as we go from t h e sample  t r e a t e d w i t h 5% Na C0^ t o those t r e a t e d w i t h a c i d NH^-oxalate 2  and d i t h i o n i t e .  With these s u c c e s s i v e t r e a t m e n t s , t h e r e i s  i n f a c t , p r o g r e s s i v e removal (as e x p l a i n e d l a t e r i n t h i s chapter) of polyhydroxy  Fe and A l phases which a r e a c t u a l l y  p e r t u b a t i n g t h e s i l i c o n t e t r a h e d r a network,  consequently  i m p r o v i n g the s i l i c o n t e t r a h e d r a o r g a n i z a t i o n which b r i n g s  untreated  2000  3000  4000  1600  WAVENUMBER Figure 3.1  Infrared  spectra  of A S - 2 untreated and after succe  (b) Ac. N H - o x a l a t e , 4  (c) Dithionite.  CM*'  ssive extractions:  (a) 5 % N a C 0 . 2  3  97.  about a b e t t e r r e s o l u t i o n o f t h e band and an increase, i n the S i - 0 s t r e t c h i n g f r e q u e n c y as shown i n t h e s p e c t r a o f As-2 a f t e r 5% NagCO^ + a c i d NH^-oxalate e x t r a c t i o n , o r , even b e t t e r , a f t e r %  NagCO^ + a c i d NH^-oxalate + d i t h i o n i t e  extraction. On t h e s e s p e c t r a , note i  o t h e r bands a r e i n t e r e s t i n g t o  the band a t 1280 cm"*" a p p e a r i n g i n AS-2 ( a ) and AS-2 3  ( a + b) s p e c t r a and n o t p r e s e n t i n AS-2 ( a + b + c ) spectrum. The h i g h e s t f r e q u e n c y can be a s s i g n e d t o A1-0-H b e n d i n g and the two l o w e r f r e q u e n c i e s t o A l - 0 s t r e t c h i n g mode and t h a t would e x p l a i n why t h e y do n o t show up i n AS-2 and  why t h e y d i s a p p e a r even from t h e AS-2  (a+b+c)  ( a ) and AS-2  (a + b) s p e c t r a upon d e h y d r a t i o n . STRUCTURAL MODEL (a)  F o r m a t i o n o f an i r o n - a l u m i n o s i l i c a t e The c o n d i t i o n s  phase.  under which the experiment was  conducted have s i m u l t a n e o u s l y f a v o u r e d t h e d e p o l y m e r i z a t i o n o f s i l i c a , whose c o n c e n t r a t i o n was q u i t e c l o s e t o i t s s o l u b i l i t y p r o d u c t and t h e d e p o l y m e r i z a t i o n o f t h e aluminum and  i r o n hydroxides. Each c a t i o n (as F e ^ and A l ^ " ) i n s o l u t i o n i s +  4  c o o r d i n a t e d w i t h s i x m o l e c u l e s o f w a t e r and h a l f a p o s i t i v e charge t o each?  contributes  the p r e c i p i t a t i o n of the  c a t i o n would c o r r e s p o n d t o t h e s u b s t i t u t i o n o f an OH f o r a H 0. o  98.  The  s t r u c t u r e of the hydroxide obtained w i l l  then depend upon the ease with v/hich the HgO can be e l i m i n a t e d a f t e r the OH  remaining  fixation.  The removal of t h i s hydrated water seems t o occur r a t h e r e a s i l y i n the case of d i v a l e n t i o n s whose diameter i s l a r g e and the charge t o volume r a t i o low,  consequently,  the a t t r a c t i o n f o r the water molecules of d i v a l e n t i o n s i s l e s s s t r o n g than f o r t r i v a l e n t  ions such as Fe and A l .  On t h i s b a s i s , the e x i s t e n c e of b a s i c ions, l i k e R ( H 0 ) ^ (OH) 2  (where R i n d i c a t e s A l ^ or F e ^ ) +  2  +  with chemic.o-physical c o n d i t i o n s (pH 7.0 can be p o s t u l a t e d .  i n agreement  and weak d i l u t i o n )  To the extent t h a t these ions e x i s t ,  they w i l l l e n d themselves t o the f o r m a t i o n of a phase having the f o l l o w i n g p o s s i b l e formula i n the presence of s i l i c a : 2 S i (OH)^ + R ( H 0 ) ^ 2  HO —  >  H  H  H  0  0  0  1  I H R —  I  Si I  In  (0H)J  —  0  —  I  0  —  Si  —  OH  I  0  0  0  H  H  H  t h i s phase, A l and Fe appear t o be  fourfold  coordinated i n p a r t i a l l y s u b s t i t u t i n g f o r tetrahedral silicon.  99.  F r i p i a t and coworkers (1965)» u s i n g a system p r e pared from aluminum i s o p r o p o x i d e and e t h y l s i l i c a t e have a r r i v e d a t the same b a s i c model and t h e y found t h a t i n the 0 - 0.40 p e r c e n t A l / A l + S i atomic r a t i o r a n g e , o n l y h a l f o f the A l p r e s e n t i s f o u r f o l d c o o r d i n a t e d : the remainder o f the A l i s s i x f o l d c o o r d i n a t e d and t h e r e f o r e not p a r t o f the a l u m i n o s i l i c a t e phase. 1.0 A l / A l + S i ,  I n the c o m p o s i t i o n range 0.40  -  t h e y observed an i n c r e a s e o f the number o f  s u b s t i t u t i o n s o f A l f o r S i i n the a l u m i n o s i l i c a t e  phase,  as w e l l as an i n c r e a s e of s i x f o l d c o o r d i n a t e d aluminum i n the phase c o a t i n g the a l u m i n o s i l i c a t e  core.  Above  0.80  A l / A l + S i atomic r a t i o , t h e y have observed a d e m i x i n g o f c r y s t a l l i n e a l u m i n a but have r e c o r d e d the p r e s e n c e of, pseudobohemite  i n addition to bayerite.  The  aluminosilicate  phase i s t h u s composed o f e l e m e n t a r y p a r t i c l e s c a r r y i n g n e g a t i v e charges which a r i s e from f o u r f o l d c o o r d i n a t e d aluminum i n the t e t r a h e d r a l (°)  silica  framework.  F o r m a t i o n o f A l and Fe H y d r o x i d e s complexes. 3+  As mentioned e a r l i e r , each A l s o l u t i o n i s c o o r d i n a t e d w i t h s i x HgO b u t e s h a l f a p o s i t i v e charge t o each. 3+  i s a t t a c h e d t o an A l  v  3+  or Fe^  ion i n  m o l e c u l e s which c o n t r i When a h y d r o x y l i o n  3+  o r Fe-'  i o n , h a l f of i t s negative  charge w i l l be used t o n e u t r a l i z e h a l f a p o s i t i v e charge c o n t r i b u t e d by the A l ^ o r Fe-^ i o n , l e a v i n g a n o t h e r h a l f +  +  n e g a t i v e charge on the 0H~ u n s a t i s f i e d and a v a i l a b l e t o b a l 3+  ance h a l f a p o s i t i v e charge from a n o t h e r A l ^  3+  o r Fe-' i o n .  n  21  R (OH) +05  2.5  H 0 2  • m H 0 e  -  2  40  amorphous  amorphous  Al / A l + Si  0. 4 0  0.80  1 _  FIGURE  3,  SCHEMATIC  REPRESENTATION  IRON-ALUMINOSILICATE AND I  -  AND STRUCTURAL  F O R M U L A S OF  C O R E - P H A S E A N D P O L Y H Y D R O X Y - 1 RON  A L U M I N U M PHASES WITH V A R Y I N G A l / A l + S i  AMORPHOUS I R O N - A L U M I N O S I L I C A T E  ATOMIC  RATIOS.  ( A l A N D Fe T E T R A H E D R A L L Y  CORE  CO-ORDINATED). II  -  AMORPHOUS P O L Y H Y D R O X Y - I R O N (Al  R = A l * **  3  AND Fe OCTAHEDRALLY +  OR  Fe  AND ALUMINUM COATING  CO-pRDINATED).  3 +  T H E M O D E L S C O R R E S P O N D TO T H E S P E C I F I E D MODIFIED  PHASE  AND S I M P L I F I E D  FROM CLOOS  FIGURES a  i.  IN ABSCISSA.  (1969).  '  101,  The  OH  i s thus shared  e q u a l l y "by the two A l ^  and  f u n c t i o n s as a b r i d g e between them.  or ¥&  ions  T h i s i s considered t o be the fundamental p r i n c i p l e u n d e r l y i n g p o l y m e r i z a t i o n o f hydroxy-aluminum or i r o n ions in solution.  Secondly,,  i t i s b e l i e v e d t h a t the hydroxy-  aluminum or i r o n ions tend t o polymerize r i n g u n i t or m u l t i p l e s o f such u n i t s .  i n a six-membered  This  structural  arrangement u n i t was e a r l i e r proposed f o r A l with a composit i o n A l ^ (OH) R (H 0)^(0H) 2  a l s o a phase, as mentioned b e f o r e , +  2  can be l o g i c a l l y proposed f o r the hydroxy-Al  or Fe i o n s s t r u c t u r e i n s o l u t i o n . The  charges i n the core phase ( i . e . , the i r o n -  a l u m i n o s i l i c a t e anions)  are balanced,  a t l e a s t p a r t l y , by  mono and p o l y n u c l e a r hydroxy-aluminum or i r o n c a t i o n s of i n c r e a s i n g complexity  and d e c r e a s i n g net charge p e r R atom  as the R/R + S i atomic r a t i o i n c r e a s e s (R = A l ^  +  or F e ^ ) . +  CONCLUSION The  s t r u c t u r a l model d i s c u s s e d , although not considered  to be p e r f e c t , presents a u s e f u l p i c t u r e o f iron-aluminos i l i c a t e s t r u c t u r e s as i t o f f e r s an e x p l a n a t i o n f o r some of the experimental  o b s e r v a t i o n s recorded.  example, t o Table 3« "the f a c t t h a t %  Referring, f o r  NagCO^  treatment  removed 9 . 4 3 $ AlgO^ and only a s m a l l f r a c t i o n o f S i 0 can be e x p l a i n e d assuming t h a t the s i x f o l d  2  (0.70$)  coordinated  aluminum on the core surface i s removed f i r s t by the treatment,  102.  l e a v i n g almost i n t a c t the i n t e r n a l s t r u c t u r e . A l s o , the f a c t that v i r t u a l l y no Fe i s removed by the  5% NagCO^ treatment can be p o s s i b l y e x p l a i n e d  by assum-  i n g t h a t most of the i r o n (as most of the aluminum) i s t e t r a h e d r a l l y s u b s t i t u t e d i n the core s t r u c t u r e of the main amorphous phase or i t may be present octahedral attached  as polyhydroxy i r o n i n  c o o r d i n a t i o n c o a t i n g the core but much more s t r o n g l y  than the aluminum.  the r e l a t i v e l y mild 5% N a ^ C O o  Thus, i r o n cannot be removed by treatment.  103  o  LITERATURE CITED 1.  C l o o s , P., A. H e r b i l l o n , J . E c h e v e r r i a . 1 9 6 8 . A l l o p h a n e - l i k e s y n t h e t i c s i l i c o a l u m i n a s . Trans, 9 t h I n t e r , Congr. S o i l S c i . I I 7 3 3 - 7 4 3 .  2.  C l o o s , P., A.J. Leonard, J.P. Moreau, A, H e r b i l l o n , J.J. F r i p i a t . 1969. Structural organization i n amorphous s i l i c o a l u m i n a s . Clay and C l a y M i n e r a l s , 17:  279 - 289.  3.  Danforth, J.D. i 9 6 0 . S t r u c t u r e s and chemical c h a r a c t e r i s t i c s of c r a c k i n g c a t a l i s t s . Actes I I Congr, I n t . C a t a l y s e , P a r i s 1: 1 2 7 1 - 1 2 7 7 .  4.  De Kimpe, C , M.C. Gastuche, and G.W. B r i n d l e y . 1961. Ionic coordination i n a l u m i n o s i l i c i c gels i n r e l a t i o n t o c l a y mineral formation, Amer, M i n e r a l , 46:  1370 - 1381,  5.  De V i l l i e r s , of allophane  6.  F r i p i a t , J . J . , A. Leonard, J.B, Uytterhoeven. 1 9 6 5 . S t r u c t u r e and p r o p e r t i e s o f amorphous s i l i c o a l u m i n a s , I I Lewis and Brb'nsted a c i d s i t e s . J , Phys, Chem. 69s  3274 -  J.M, 1 9 7 0 , Q u a n t i t a t i v e d e t e r m i n a t i o n in soil. Soil Sci, 112: 2 - 12.  3279.  7.  Henin, S,, and S. C a i l l e r e . 1 9 6 3 . Sinthese des mineraux a basse temperature: E s s a i de mise au point. R. c o l l o q u e Int, C.N.R.S. P a r i s , No 1 0 5 : 1 0 7 - 1 1 5 .  8.  Leonard, A., S. Suzuky, J . J . F r i p i a t , and C, De Kimpe. 1 9 6 4 , S t r u c t u r e and p r o p e r t i e s o f amorphous silicoaluminas, I , S t r u c t u r e and p r o p e r t i e s from X-ray f l u o r e s c e n c e spectroscopy and i n f r a r e d s p e c t r o s copy. J . Phys. Chem, 6 8 : 2 6 0 8 - 2 6 1 7 .  9.  Leonard, A,, F. Van Cauwelaert, J . J , F r i p i a t . 1 9 6 7 . S t r u c t u r e and p r o p e r t i e s o f amorphous s i l i c o a l u m i n a s . I I I . Hydrated aluminas and t r a n s i t i o n aluminas. J . Phys. Chem. 7 1 s 6 9 5 - 7 0 8 .  10.  M i l l i k e n , T.,.G.A. M i l l i s , and A.G. Oblat. 1 9 5 0 . The chemical c h a r a c t e r i s t i c s and s t r u c t u r e of c r a c k i n g catalists. D i s c u s s i o n Faraday Soc. 8s 280 - 2 8 9 ,  104. 11.  Tamele, M.W., 1950. Chemistry of the s u r f a c e and the a c t i v i t y o f the a l u m i n o s i l i c a c r a c k i n g c a t a l i s t s . D i s c u s s i o n Faraday Soc. 8s 270 - 279.  12.  Van Reeuwiijk, L.P., and J.M. De V i l l i e r s . 1968. Potassium f i x a t i o n by amorphous a l u m i n o s i l i c a g e l s . S o i l S c i . Soc. Amer. Proc. 32s 238 - 240.  I05o 'THE INORGANIC AMORPHOUS SYSTEM OF SOIL COMPARED TO AN ARTIFICIAL AMORPHOUS IRON-ALUMINOSILICATE SYSTEM INTRODUCTION In the f i r s t chapter, the amorphous i n o r g a n i c m a t e r i a l o f s o i l has been d e s c r i b e d as a polyphase  complex  system l a c k i n g homogeneity and u n i t y o f r e a c t i o n s .  Any  attempt  a t s u b d i v i d i n g s i n g l e phases o f t h i s sytem i s  f r u s t r a t e d by i t s complexity;  the i m p o s s i b i l i t y o f s e l e c t i v e l y  s e p a r a t i n g a phase without a l t e r i n g the chemical and p h y s i c a l nature and i d e n t i t y i n i t s own complex c o n t e x t .  So the r i s k  of c r e a t i n g chemical a r t i f a c t s i s q u i t e h i g h and t h e r e f o r e the r e s u l t s obtained i n the e f f o r t o f s e p a r a t i n g these phases appear t o be m i s l e a d i n g .  D e s p i t e t h i s , the chemical and  p h y s i c a l s t u d i e s o f s o i l has allowed us t o g a i n a deep i n s i g h t i n t o the chemical nature and the p h y s i c a l behaviour o f amorphous inorganic materials. I t i s c l e a r t h a t the more we l e a r n about the s t r u c t u r e and composition o f these polyphase  systems,  the more we w i l l  be able t o e x p l o r e t h e i r o r i g i n , t h e i r n a t u r e , and t h e i r importance  i nsoil  systems.  Faced with e v i d e n t d i f f i c u l t i e s of  i n o r g a n i c amorphous system  an a l t e r n a t i v e approach,  i n direct studies  i n s o i l , and c a s t i n g around f o r  many r e s e a r c h e r s have proposed t o  i n v e s t i g a t e the complexity o f t h i s system  through much more  106.  simple a r t i f i c i a l models, the composition of which can c o n t r o l l e d and stood.  be  the s t r u c t u r a l o r g a n i z a t i o n more e a s i l y under-  To these,  the n a t u r a l system i t s e l f  can be r e l a t e d  by s i m i l a r responses to the same chemical and  physical  analyses. In t h i s study, the a r t i f i c i a l model d i s c u s s e d chapter two,  f o r which a phase c o n s t i t u t i o n and  o r g a n i z a t i o n have been proposed, w i l l n a t u r a l amorphous concentrate a < 2/* c l a y .  a structural  compared with a  d e r i v e d by a c i d d i s p e r s i o n from  In t h i s manner, s t u d i e s on c o r r e l a t i o n s between  a r t i f i c i a l and conclusions  be  in  n a t u r a l systems could a l l o w us to i n f e r some  regarding  the nature and  the s t r u c t u r e of, the  i n o r g a n i c amorphous system i n the s o i l t h a t the model proposed has  studied.  to be prepared: ad hoc  s p e c i f i c amorphous system with which we  This  implies  f o r the  are d e a l i n g , because  of the uniqueness of these systems i n each d i f f e r e n t s o i l . In other words, we  are aware t h a t so f a r no u n i v e r s a l model  can be proposed on the b a s i s of the c o r r e l a t i o n s observed i n our s p e c i f i c MATERIALS AND  case. METHODS  Choice o f c l a y m a t e r i a l  (^2^)  on the c r i t e r i o n of a h i g h p r o p o r t i o n m a t e r i a l and previous  a low  inherent  organic  f o r study was  of amorphous i n o r g a n i c  matter content.  study, the c l a y f r a c t i o n of the B f 3  Ryder s o i l appeared to s u i t the  based  objectives.  From  h o r i z o n of  the  107. I t was f e l t d e s i r e a b l e  t o c o n c e n t r a t e t h e amorphous  i n o r g a n i c m a t e r i a l i n such a manner as t o e x c l u d e t h e h u l k o f the c r y s t a l l i n e l a y e r s i l i c a t e s . '  Thus, a more r e l i a b l e  c h a r a c t e r i z a t i o n o f t h e amorphous system would be p o s s i b l e . The  method s e l e c t e d f o r c o n c e n t r a t i o n  procedure.  However  8  was an a c i d  dispersion  o n l y a s m a l l amount (about 15$) o f t h e  t o t a l c l a y f r a c t i o n was s u s c e p t i b l e  t o such d i s p e r s i o n ,  w h i l e t h e main body o f t h e c l a y f r a c t i o n remained i n t h e flocculated  state.  The  amorphous m a t e r i a l f r a c t i o n a t e d by t h i s means  assumed a p o s i t i v e charge i n t h e H - s a t u r a t e d The  condition.  amount o f c r y s t a l l i n e c l a y d e t e c t e d i n t h e d i s p e r s e d  m a t e r i a l may be i n t e r l a y e r e d w i t h t h e amorphous i r o n a l u m i n o s i l i c a t e p o l y m e r i c phases o r may be p h y s i c a l l y bonded to t h i s positively-charged  f r a c t i o n w h i c h has been i s o l a t e d  by t h e p r o c e d u r e o u t l i n e d below. ACID DISPERSION PROCEDURE The Bf3 horizon  d i s p e r s i o n was performed on the < 2j* c l a y o f  o f t h e Ryder s o i l s  supercentrifugation  once i t was s e p a r a t e d by  from t h e s o i l which was p r e v i o u s l y  i n water o v e r n i g h t t o f a c i l i t a t e s o a k i n g and easy i n l a t e r p r o c e d u r e s , and t h e n p r e t r e a t e d  left  dispersion  w i t h NaOCl a t pH 9 . 5  ( f o u r t r e a t m e n t s i n b o i l i n g w a t e r b a t h f o r 15 m i n u t e s ) t o d e s t r o y t h e o r g a n i c m a t t e r ( L a v k u l i c h and Wiens, 1 9 7 0 ) .  108. To t h e c l a y , soaked i n water and b r i e f l y ( t e n m i n u t e s ) t r e a t e d i n an u l t r a s o n i c d i s p e r s i o n u n i t ( B r o n w i l l Biosonik III5  at i n t e n s i t y 90),  was added, 0 . 1 N HC1 i n  s u f f i c i e n t amount t o b r i n g t h e pH down t o 3 , 0 .  The  finest  c l a y f r a c t i o n became d i s p e r s e d ( w h i l e t h e main body remained f l o c c u l a t e d ) , and was s e p a r a t e d by c e n t r i f u g a t i o n a t 2500 rpm f o r t e n minutes.  To c o m p l e t e l y remove t h e excess H C l ,  r e p e a t e d washings w i t h d i s t i l l e d w a t e r were n e c e s s a r y u n t i l d i s p e r s i o n was a c c o m p l i s h e d ( a l m o s t no f i n e p a r t i c u l e s s h o u l d remain a f t e r c e n t r i f u g a t i o n i n the supernatant l i q u i d ) .  Each  o f the seven washings n e c e s s a r y , were p e r f o r m e d as f o l l o w s s t o 250 ml b o t t l e s , w i t h two t o t h r e e grams o f c l a y , w a t e r was added t o f i l l  distilled  about t h r e e - q u a r t e r s o f t h e b o t t l e ,  t h i s was shaken f o r t e n minutes and t h e n c e n t r i f u g e d .at 2500 rpm f o r t e n m i n u t e s .  To b r i n g down t h i s amorphous  c o n c e n t r a t e d c l a y from the s e p a r a t e d f r a c t i o n , c e n t r i f u g a t i o n , i n a Lourdes s u p e r c e n t r i f u g e a t 12,000 rpm f o r twenty minutes was n e c e s s a r y .  A s m a l l amount o f water was added t o the c e n t r i -  fuged amorphous c o n c e n t r a t e (enough t o make a s l u r r y ) and i t was b r i e f l y  ( f i v e minutes) t r e a t e d again i n the u l t r a s o n i c  unit prior to freeze-drying,  A s o f t , minutely-powdered  m a t e r i a l was o b t a i n e d . The a c i d d i s p e r s i o n t e c h n i q u e has been used by a number o f a u t h o r s t o o b t a i n d i s p e r s i o n o f v o l c a n i c ( D a v i s , 1933f  B i r r e l and F i e l d e s , 1952)  used f o r o t h e r s o i l s .  soils  b u t has r a r e l y been  109  o  De Mumbrum and C h e s t e r s (1964) have o b t a i n e d a c o n c e n t r a t e of amorphous m a t e r i a l by t h i s d i s p e r s i o n t e c h n i q u e from s e v e r a l s o i l s , b u t no q u a n t i t a t i v e i n f o r m a t i o n on t h e amount o f c l a y o b t a i n e d was g i v e n .  Raman and M o r t l a n d (1969), w i t h t h e p u r -  pose o f o b t a i n i n g i n f o r m a t i o n on t h e amounts o f amorphous i n o r g a n i c c o l l o i d s i n s p o d o s o l s , employed two d i f f e r e n t persion techniques:  dis-  t h e normal a l k a l i d i s p e r s i o n (Ua^CQj  s o l u t i o n a t pH 9.5) and a pH 3.7 a c i d d i s p e r s i o n p r o c e d u r e . When c l a y from b o t h t h e a c i d and a l k a l i d i s p e r s i o n p r o c e d u r e s was  s u b j e c t e d t o a 0.5 N NaOH d i s s o l u t i o n (Hashimoto and  J a c k s o n , i960), t h e y found t h a t t h e one o b t a i n e d a f t e r  alkali  d i s p e r s i o n contained higher r e s i d u a l c r y s t a l l i n e m a t e r i a l than the a c i d - d i s p e r s e d c l a y .  They t h e r e f o r e used t h i s  procedure  t o s t u d y i n d e t a i l t h e p r o p e r t i e s o f t h e amorphous s e p a r a t e s which were found t o c o n t a i n between 54 t o 64$  amorphous  material. The  comparison  and a l l c o r r e l a t i o n s i n t h i s  ment a r e drawn between t h e B f ^ amorphous c o n c e n t r a t e  experi(which  w i l l be c a l l e d AC-R3 i n a l l r e f e r r a l s ) and t h e ad h o c p r e p a r e d a r t i f i c i a l i r o n - a l u m i n o s i l i c a t e s t a n d a r d , denominated A S - 2 . , t h e p r e p a r a t i o n and t h e c h a r a c t e r i s t i c s o f which have been a l r e a d y d e s c r i b e d i n c h a p t e r two. I n s e e k i n g f o r c o r r e l a t i o n s between t h e n a t u r a l amorphous system and t h e a r t i f i c i a l one, t h e f o l l o w i n g c h e m i c a l and p h y s i c a l a n a l y s e s were  performed:  110.  (i)  successive selective d i s s o l u t i o n analysis  i n order  t o determine the t o t a l % o f amorphous AlgO^, FegO^, Si0  p r e s e n t i n the samples and t h e n c a l c u l a t i o n o f  2  atomic and molar r a t i o s o f these o x i d e s t o see r e l a t i v e d i s t r i b u t i o n i n the sample„  The  their  detailed  method f o l l o w e d f o r the s u c c e s s i v e s e l e c t i v e e x t r a c t i o n s has a l r e a d y been o u t l i n e d  i n c h a p t e r one,  w h i c h the r e a d e r has t o r e f e r .  The  t i o n s were performed i n t h i s o r d e r : (b) a c i d NH^  o x a l a t e and  P e r c e n t l o s s and  successive extrac(a) 5% Na C0^ 2  (c) c i t r a t e - d i t h i o n i t e .  s p e c i f i c s u r f a c e a r e a were  a f t e r the second (a+b)  to  and  calculated  the t h i r d (a+b+c) t r e a t -  ment , (ii)  t o t a l elemental analysis  by a c i d d i g e s t i o n was  carried  out t o have a comparison w i t h the r e s u l t s o f s u c c e s s i v e  (iii)  selective dissolution  analyses.  X-ray d i f f r a c t i o n and  i n f r a r e d spectroscopy  u n t r e a t e d samples and a f t e r each s i n g l e  on  the  successive  e x t r a c t i o n were conducted, RESULTS AND The analysis  DISCUSSION r e s u l t s of successive s e l e c t i v e  dissolution  on the amorphous c o n c e n t r a t e AC-R3 and  s t a n d a r d AS-2, dissolutions  artificial  a l o n g w i t h the r e s u l t s o f the same s u c c e s s i v e on C l a y - R 3 which i s the < 2^ c l a y o f R3 s o i l sample  not s u b j e c t e d t p a c i d d i s p e r s i o n ,  are r e p o r t e d i n T a b l e  1,  111. A few i n t e r e s t i n g o b s e r v a t i o n s can be d e r i v e d from these  data: The % o f S i 0 , AlgO^ and FegO^ a f t e r 5% NagCO^ + 2  a c i d NH^-oxalate e x t r a c t i o n ( i n d i c a t e d as 'a+b' i n the Table) are markedly higher i n AC-R3 than i n Clay-R3» which i n d i c a t e s a h i g h e r presence  o f amorphous m a t e r i a l i n the  concentrate i n r e s p e c t t o the n o n - a c i d - d i s p e r s e d same t r e n d i s observed  clay.  The  f o r the percent obtained a f t e r 5%  NagCO-j '+ a c i d NH^-oxalate + d i t h i o n i t e e x t r a c t i o n ( i n d i c a t e d as  'a+b+c* i n the T a b l e ) .  Comparison o f the d a t a o f AC-R3  with those o f AS-2 a f t e r (a+b) e x t r a c t i o n , shows a s l i g h t l y higher percent o f SiOg and AlgO^ and s l i g h t l y lower  percent  FegO-j f o r AS-2 w i t h r e s p e c t t o AC-R3» and the same can be s a i d f o r the data a f t e r (a+b+c) e x t r a c t i o n .  These c l o s e  r e l a t i o n s h i p s among the amorphous s p e c i e s present i n the n a t u r a l and a r t i f i c i a l expressed  as the S i 0  2  system can be seen more e a s i l y when / AlgO^ / FegO^ molar r a t i o s ; i n  p a r t i c u l a r , one can observe  a high c o r r e l a t i o n between  AC-R3 (a+b) (molar r a t i o 1/2.85/1.?6) (molar r a t i o  1/2.54/L15).  and AS-2 (a+b)  112. TABLE 1 Percent amorphous A 1 0 2  3 *  F e  2  (  -  Si0  2  in  Clay-R3, AC-R3 and i n AS-2 as e x t r a c t e d by successive  s e l e c t i v e d i s s o l u t i o n and d i t h i o n i t e only and S i 0 / A l 0 / F e 0 j molar r a t i o 2  2  3  2  fo  fo  Si0 /  fo  2  Sample  Si0  Clay-R3 (a+b)  3.89  8.77  Clay-R3 (a+b+c)  4.60  10.30  14.94  1/2.24/3.22  2  A1 0 2  3  F e  2°3  Al 0^/Fe 0^  7.41  1/2.25/1.90  2  2  AC-R3 (a+b)  11.17  31.88  19.62  1/2.85/1.76  AC-R3 (a+b+c)  12.61  33.12  29.37  1/2.62/2.32  1.93  10.21  15.73  1/5.29/8.15  AS-2 (a+b)  15.94  40.30  18.38  1/2.54/1.15  AS-2 (a+b+c)  21.91  49.74  22.32  1/2,27/1,02  20,98  13.94  1/8.16/5.42  AC-R3 ( D i t h .  AS-2 ( D i t h .  only)  only)  2.57""  Clay-R3  u n t r e a t e d c l a y R3  AC-R3  amorphous concentrate R3  AS-2  artificial No, 2 -  (a+b)  sodium carbonate + a c i d NH^-oxalate extraction  (a+b+c)  sodium carbonate + a c i d NHu-oxalate + dithionite extract  (Dith.  only)  iron-aluminosilicate  separate e x t r a c t i o n alone  with d i t h i o n i t e  113. I n c i d e n t a l l y , the AC-R3 (a+b) molar r a t i o v e r y c l o s e t o t h a t o f Clay~R3 (a+b)  i s also  (molar r a t i o 1 / 2 , 2 5 / 1 . 9 0 ) .  A marginal o b s e r v a t i o n should not be missed  on Table  1 r e g a r d i n g the $ Si0 » AlgO^, FegO^ a f t e r a d i t h i o n i t e 2  separ-  ate e x t r a c t i o n ( i n d i c a t e d as * D i t h . o n l y ' i n the Table) f o r AC-R3 ( D i t h . only) and AS-2 ( D i t h . only) as compared t o the same $ a f t e r (a+b+c) e x t r a c t i o n f o r the same two samples.  I t appears  q u i t e c l e a r t h a t the amount o f m a t e r i a l removed by a d i t h i o n i t e treatment  alone i s much l e s s than the amount removed by the  three s u c c e s s i v e s e l e c t i v e e x t r a c t i o n s . In Table 2, there a r e a g a i n some i n d i c a t i o n s o f good c o r r e l a t i o n s between AC-R3 and AS-2 f o r t o t a l percent o f (AlgO^ + FegO^ + S i 0 ) and the s u r f a c e area a f t e r 2  (a+b) and (a+b+c)  extractions. Comparing the t o t a l percent (AlgO^ + Fe^O^ + SiOg) of Clay-R3 (a+b), AC-R3 (a+b), AS-2 (a+b) which are 20.10%, 6 2 . 6 7 $ and 7 4 , 6 0 $ ,  r e s p e c t i v e l y , one can note how much h i g h e r  the p r o p o r t i o n of amorphous m a t e r i a l i s p r e s e n t i n AC-R3 compared t o Clay-R3l the same t r e n d can be noted f o r the same samples a f t e r (a+b+c) e x t r a c t i o n . Both the e x t r a c t i o n s (a+b) and (a+b+c) i n AS-2 are higher, i n amounts than i n AC-R3 but t h i s i s c l e a r l y  understood  when one c o n s i d e r s the f a c t t h a t AS-2 i s t o t a l l y amorphous, while i n AC-R3» there i s s t i l l minerals.  a f r a c t i o n of c r y s t a l l i n e  114  0  TABLE 2 T o t a l % o f the amorphous m a t e r i a l (AlgO^ + F e ° 3 2  Clay-R3»  AC-R3t  +  s  ^°2^ ^  n  and AS-2 as e x t r a c t e d by s u c c e s s i v e s e l e c t i v e  d i s s o l u t i o n and d i t h i o n i t e o n l y (see T a b l e l ) s  % losses after  treatments; s u r f a c e area o f the u n t r e a t e d samples and a f t e r treatments.  ( A 1 0 ^+  Total %  2  %  Surface  Area  / g)  Fe 0^ + S i 0 )  losses  -_  -  176.97  Clay-R3 (a+b)  20.10  23.99  51.57  Clay-R3 (a+b+c)  29.80  35.56  45.23  -  -  280.53  62.67  65.70  46.50  73.03  81.38  33.57  27.90  33.30  -  -  -  294,34  Sample  2  2  * Clay-R3  * AC-R3 • AC-R3 (a+b) AC-R3 (a+b+c) AC-R3 ( D i t h .  only)  * AS-2  (m  2  AS-2  (a+b)  74.60  75.50  .44.06  AS-2  (a+b+c)  93.97  97.16  31.82  AS-2  (Dith.  37.50  37.95  -  * indicates: F o r Clay-R3,  only)  u n t r e a t e d sample AC-R3, A S - 2 ,  (a+b), (a+b+c) - see T a b l e  1.  '  115.  The percent weight l o s s e s are i n good agreement with the t o t a l percent extracted? r e l a t i o n s h i p i n AS-2  one  can note, a c l o s e r  than i n AC-R3 or i n Clay-R3 and  this  i s probably due to the f a c t t h a t other elements p r e s e n t i n the l a s t two  samples were not  determined.  The best c o r r e l a t i o n found f o r these amorphous n a t u r a l and a r t i f i c i a l systems appears to be i n the s u r f a c e area.  As one  looks at the f i g u r e s g i v e n f o r u n t r e a t e d  samples of Clay-R3, AC-R3. and AS-2,  as compared to those  of  the same sample a f t e r (a+b), f o r example, the amorphous mate r i a l present i n these samples i s the r e s p o n s i b l e element f o r the l a r g e s u r f a c e area v a l u e s . (see s u r f a c e a r e a a f t e r drops d r a m a t i c a l l y .  'a+b'  In f a c t , as t h i s i s removed  e x t r a c t i o n ) the s u r f a c e area  I t has a l s o to be p o i n t e d out, t h a t  the l a r g e r the p r o p o r t i o n of amorphous m a t e r i a l i n the sample, the l a r g e r i s the s u r f a c e a r e a v a l u e .  I n c i d e n t a l l y , one  can  note t h a t between the v a l u e s of the s u r f a c e a r e a a f t e r  (a+b)  and  as  (a+b+c) e x t r a c t i o n s , the d i f f e r e n c e i s v e r y s m a l l ;  s m a l l as the d i f f e r e n c e s i n the t o t a l p e r c e n t of amorphous m a t e r i a l e x t r a c t e d by the two mentioned e x t r a c t i o n s . The v a l u e of t o t a l percent of amorphous m a t e r i a l g i v e n f o r AC-R3 a f t e r (a+b+c) e x t r a c t i o n : ( 7 3 . 0 3 $ ) c a n b e r e l i a b l y assumed to r e p r e s e n t much more c l o s e l y the t o t a l amorphous percent than t h a t one extraction.  given a f t e r  exact (a+b)  116.  To help e x p l a i n t h i s , X-ray d i f f r a c t i o n s p e c t r a were examined: (i)  the AS-2 sample g i v e s no d i f f r a c t i o n peaks f o l l o w i n g any  of the e x t r a c t i o n s  ( i i ) the AC-R3* the amorphous c o n c e n t r a t e ,  which, as can be noted i n Table 2, has s t i l l a f r a c t i o n o f c r y s t a l l i n e m a t e r i a l p r e s e n t gave X-ray d i f f r a c t i o n s p e c t r a characteristic with d i t h i o n i t e  of the amorphous m a t e r i a l u n t i l i t was t r e a t e d i n addition to %  NagCD^ and a c i d NH^-oxalate.  T h e r e f o r e , t h i s f a c t suggests t h a t not a l l the amorphous m a t e r i a l was removed a f t e r f o l l o w i n g the d i t h i o n i t e  o x a l a t e e x t r a c t i o n and t h a t only byi  e x t r a c t i o n can i t be concluded  X-ray, t h a t a l l the amorphous m a t e r i a l has been removed; and t h a t i s why i t i s b e l i e v e d t h a t the t o t a l p e r c e n t value after  (a+b+c) e x t r a c t i o n can b e t t e r r e p r e s e n t the t o t a l  amorphous p r e s e n t i n the'AC-R3 sample. appears  This conclusion  t o be a l s o s u s t a i n e d by the f i n d i n g s on  spectroscopy which w i l l be commented  infrared  on l a t e r i n t h i s  chapter. Table 3 g i v e s the t o t a l elemental a n a l y s i s d a t a f o r AC-R3, AS-1, AS-2, AS-3. Si0  2  The p e r c e n t of AlgO-jt FegO^, and  are r e c a l c u l a t e d and expressed  r e p o r t e d i n Table 4.  on an a i r - d r y b a s i s , as  T h i s was done t o :  between the p e r c e n t of these oxides a f t e r a n a l y s i s and a f t e r  total  elemental  (a+b+c) s u c c e s s i v e e x t r a c t i o n f o r the two  samples AC-R3 and AS-2. Table 4 t h a t :  make a comparison  I n t h i s r e g a r d , one can note,  ( i ) the p e r c e n t A l O 9  q  and S i O  ?  are much  from  11?, l o w e r i n AC-R3 a f t e r (a+b+c) e x t r a c t i o n t h a n a f t e r elemental a n a l y s i s . to  total  While the same (a+b+c) e x t r a c t i o n  (29.37%  remove a l l the i r o n  t o t a l elemental a n a l y s i s ) ,  appears  a g a i n s t 29.42% as r e s u l t s from  ( i i ) f o r AS-2,  which i s c o m p l e t e l y  amorphous, the f i g u r e s f o r the two a n a l y s e s a r e almost the same except f o r % S i 0  2  which i s l o w e r a f t e r (a+b+c) e x t r a c t i o n  t h a n a f t e r t o t a l e l e m e n t a l a n a l y s i s and t h a t p a r t i a l l y for  accounts  the u n d i s s o l v e d r e s i d u e r e m a i n i n g a f t e r (a+b+c) e x t r a c t i o n ,  as i t i s r e p o r t e d i n T a b l e  2  (100 -  93.97 = 6,03%  Make a comparison between AS-2 and those o f AS-1  and  AS-3»  residue).  percent oxides values  which can g i v e an i d e a o f the  r e l a t i v e p r o p o r t i o n o f the t h r e e o x i d e s i n the  artificial  standards prepared. T a b l e 5 has two s e c t i o n s :  the u p p e r s e c t i o n r e p o r t s  the atomic r a t i o s A l / A l + S i , the molar r a t i o s SiOg/AlgO^/FegO^, the % AlgO^/AlgO^ + S i 0 , and % ?e Qj/Fe 0j 2  2  2  + Si0  a f t e r t o t a l e l e m e n t a l a n a l y s i s f o r AC-R3» AS-1,  2  as c a l c u l a t e d  AS-2 and AS-35  w h i l e the l o w e r s e c t i o n r e p o r t s the same r a t i o s and p e r c e n t f o r the same samples i n a d d i t i o n t o the Glay-R3 sample as c a l c u l a t e d a f t e r b o t h (a+b) and  (a+b+c) e x t r a c t i o n s .  Some o f the most i n t e r e s t i n g r e l a t i o n s h i p s  include:  r a t i o s and t h e p e r c e n t a g e v a l u e s p r e s e n t e d i n T a b l e 5 f o r AC-R3 a f t e r (a+b) and a f t e r (a+b+c) e x t r a c t i o n a r e i n v e r y c l o s e agreement w i t h the c o r r e s p o n d e n t d a t a o f  AS-2.  These f i n d i n g s are c o n s i d e r e d i m p o r t a n t t o d e r i v e some c o n c l u s i o n s on the c o m p o s i t i o n and s t r u c t u r a l of  organization  t h i s n a t u r a l amorphous system. T h i s w i l l be attempted  i n c o r p o r a t i n g the f i n d i n g s on the i n f r a r e d  studies.  by  118. TABLE 3 T o t a l Elemental  Analysis of  AC-R3, andAS-1, AS-2, AS-3  % Oxides F E  2°3  ft T  1\ J-  n \: ^  0  Mn  AC-R3  AS-1  AS-2  AS-3  21.05  23,78  14.66  9.12  35.29  12.53  0-.30  -  2  -  Na 0 2  4.31  4.16  H0  21.67 15.38  2  -  -  0.80  sio  43.24  -  K 0  ?  oo  -  1.20 2  oo  JJ«.J •-  1.27  1.15  24.48  33.78-  32.66  35.05  16.97  13.83  TABLE 4 T o t a l % o f AlgO^, ? from T a b l e  E 2  °3  a  n  d  Si0  2  recalculated  3 on an a i r - d r y b a s i s i n o r d e r t o  compare w i t h t h e d a t a r e p o r t e d i n T a b l e  fo Oxides  obtained  a f t e r successive s e l e c t i v e  analysis  (a+b+c). (a+b+c)  64.27  33.12  49.74  22.34  13.54  29.37  22.32  26.08  21.04  12.61  21.91  AS-2  AS-3  2°3  45.05  16.58  50.31  Fe 0^  29.42  31.^9  sio  18.92  47.77  2  dissolution  (a+b+c) AS-2  AS-1  ?  1 and  AC-R3  AC-R3  A l  '  119. TABLE 5 Atomic r a t i o : Fe 0 : 2  3  Alg/Al+Si:  % Al p /Al 0 2  3  AS-3 c a l c u l a t e d analysis; clay-R3 AS-2  2  from  3  molar r a t i o : SiOg/AlgO^ +  + Si0  2  the d a t a o f t o t a l  and the same from  AS-1, AS-2,  o f AC-R3»  elemental  c l a y samples R3 (a+b);  (a+b+c), AC-R3 (a+b), AC-R3  (a+b+c),  (a+b), A S - 2 (a+b+c), f o l l o w i n g s u c c e s s i v e  extractions. .  Al/Al Samples  Si0 /  +Si  (atomic  ratio)  Al 0^/Fe 0^ 2  2  Fe 0 /  AlgO^/  2  A1 0^ 9  + Si0  2  2  3  Fe 0^ + S i 0 2  AC-R3  0.73  1/2.29/1.38  68.29  57.77  AS-1  0.30  1/0.36/0.68  26.33  40.4-2  AS-2  0.70  1/1.96/0.86  66.40  46.35  AS-3  0.79  1/3.12/0.66  75.77  39.74  •Clay-R3 (a+b)  0.?4  1/2.25/1.90  69.28  65.57  Clay-R3 (a+b+c)  0.71  1/2.24/3.22  69.26  76.45  AC-R3 . (a+b)  0.77  1/2.85/1.76  74.06  63.72  AC-R3 (a+b+c)  0.74-  1/2.62/2.32  72,42  69.96  AS-2 (a+b)  0.79  1/2.54/1.15  71.66  53.55  AS-2 (a+b+c)  0.72  1/2.27/1.02  69.42  50.46  f  2  120, INFRARED SPECTROSCOPY STUDIES L o o k i n g a t F i g u r e 1, one can note a h i g h comparab i l i t y between the s p e c t r a o f the n a t u r a l and the amorphous system.  artificial  T h i s c l o s e r e l a t i o n s h i p was p o i n t e d  d u r i n g the d i s c u s s i o n of c h e m i c a l a n a l y s e s and s u r f a c e determinations. for  The  out area  same c o m p a r a b i l i t y can a l s o be observed  the s p e c t r a o f the two systems r e c o r d e d a f t e r s u c c e s s i v e  e x t r a c t i o n s and p r e s e n t e d  i n F i g u r e s 2,1  and 3.1»  although  a much more marked r e d u c t i o n of the Si-0 s t r e t c h i n g band around 1000  cm  i s n o t i c e d f o r the AS-2  sample, which i s  t o t a l l y amorphous, w i t h r e s p e c t t o AC-R3D which c o n t a i n s 30 - k0%  of c r y s t a l l i n e m a t e r i a l .  I t i s i n t e r e s t i n g t o note  on both s e r i e s of s p e c t r a , i n F i g u r e s 2,1 i n c r e a s i n g of the f r e q u e n c y  and 3°1»  a progressive  o f the S i - 0 s t r e t c h i n g bands  a g a i n , t h i s i n c r e a s e i s more marked f o r the AS-2  once  sample, as  one s h o u l d e x p e c t , t h a n f o r the AC-R3 sample, A f u r t h e r i n c r e a s i n g of the S i - 0 s t r e t c h i n g ,band i s evidenced  by the i n f r a r e d s p e c t r a of the two samples a f t e r  d e h y d r a t i o n a t 30°°C» as F i g u r e s 2.2 This behaviour  and 3,2  c l e a r l y show.  i s i n t e r p r e t e d as an i n d i c a t i o n of the  e f f e c t of the removing of the d i f f e r e n t amorphous phases from the systems  the l e s s d i s o r d e r e d s t a t u s of the  remaining  s i l i c a framework g i v e s a Si-0 s t r e t c h i n g band a t h i g h e r frequency  t h a n t h a t of the same s i l i c a framework d i f f e r e n t l y  i n t e r r e l a t e d w i t h d i s o r d e r e d phases.  AS-2  _  r  4000  ,  ,  ,  :  .  ,  3000  1  2000  ,  1600 WAVENUMBER  Figure I.  Comparison  between i n f r a r e d  spectra  of  AS-2  and  AC-R3.  •  CM  1  1200 -1  1  1  800  •  1  400  untreated  Figure 2.2.  Infrared spectra of A C - R 3 untreated (dehydrated at 300°C) and after successive extractions and heating  at 300°C:  (a) 5 % NagCC^. (b)Ac. N H ^ - o x a l a t e ,  (c) Dithionite.  untreated  Figure 3.1  Infrared spectra of A S - 2 untreated and after successive extractions: (b)Ac. NH4-oxalate,  (c) Dithionite.  (a) 5 % NagCC^.  untreated  Infrared spectra of A S - 2 untreated (dehydrated at 300°C) and after successive extractions and heating at 300°C : (a) 5 % N a C 0 , (b) Ac. N H - o x a l a t e , (c) Dithionite. 2  3  4  126.  CONCLUSION  There i s l i t t l e  doubt about the h i g h degree of  s i m i l a r i t y e x i s t i n g between the n a t u r a l amorphous system separated from a Bf3 h o r i z o n and  c l a y of the Ryder s o i l  series  the a r t i f i c i a l l y prepared amorphous i r o n - a l u m i n o s i l i c a t e .  T h i s s i m i l a r i t y has been demonstrated c o n s i s t e n t l y by and  p h y s i c a l analyses.  Some doubt may  be  chemical  expressed i n the  c l o s e s i m i l a r i t y between the n a t u r a l amorphous m a t e r i a l s the  and  a r t i f i c i a l l y prepared sample as to s t r u c t u r a l arrangement  of the  constituent  phous m a t e r i a l  elements.  Undoubtedly, the n a t u r a l amor-  i s more complex than the simple  model composition and  artificial  arrangement, yet s t r i k i n g s i m i l a r i t i e s  exist. On the b a s i s postulated studied  t h a t the  of evidence presented, i t can  inorganic  amorphous system i n the  i s a polyphase system with e i t h e r an  or i r o n - a l u m i n o s i l i c a t e  core.  be soils  aluminosilicate  T h i s core phase i s composed  of elementary d i s c r e t e p a r t i c l e s a p p a r e n t l y c a r r y i n g  a  negative charge, which o r i g i n a t e s from f o u r f o l d c o o r d i n a t e d Fe  or A l i n the  tetrahedral  s i l i c a framework.  Surrounding  t h i s core, complex i n t e r a c t i n g polyhydroxy Fe and A l phases i n t e r a c t mainly by v i r t u e of t h e i r p o s i t i v e charge.  127 o I t appears t h a t the combination  of successive  s e l e c t i v e e x t r a c t i o n s with i n f r a r e d spectroscopy i s a v e r y u s e f u l approach  t o g a i n a b e t t e r u n d e r s t a n d i n g of the  nature of these phases.  The approach  of r e c o n s t r u c t i n g  a n a t u r a l system through the s i m p l i f i c a t i o n of a r t i f i c i a l models appears  t o be u s e f u l as a method t o d i s c l o s e the  s t r u c t u r e of amorphous i n o r g a n i c m a t e r i a l s  in soils.  128, LITERATURE CITED  1,  B i r r e l l , K.S, and M. F i e l d e s . 1 9 5 2 , Allophane i n v o l c a n i c ash s o i l s . J , S o i l S c i , 3 s 156 - 166,  2,  - D a v i s , E.B., 1 9 3 3 . S t u d i e s i n the d i s p e r s i o n and d e f l o c c u l a t i o n of c e r t a i n s o i l s . New Zealand J , S c i . Technol, 14: 228 - 2 3 2 .  3,  De Mumbrum, L,E,, and G. C h e s t e r s , 1964. Isolation and c h a r a c t e r i z a t i o n of some s o i l a l l o p h a n e s . Soil S c i . Soc. Am. Proc. 2 8 : 355 - 3 9 9 .  4,  Hashimoto I, and M.L. Jackson, i 9 6 0 . Rapid d i s s o l u t i o n o f allophane and k a o l i n i t e - h a l l o y s i t e a f t e r dehydration. C l a y s C l a y M i n e r a l s , Proc. 7 t h N a t l . Conf. C l a y s C l a y M i n e r a l s . 1 9 5 8 : 102 - 1 1 3 ,  5,  Raman, K.V., and M.M. Mortland. 1 9 6 9 . Amorphous material i n a spodosol: some m i n e r a l o g i c a l and chemical p r o p e r t i e s . Geoderma. 3 : 37 - 44,  

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