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The natural variation of sediment phosphorus fractions in the littoral zone of Vernon Arm, Okanagan Lake,… Petticrew, Ellen Lesley 1983

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THE NATURAL VARIATION OF SEDIMENT PHOSPHORUS FRACTIONS IN THE LITTORAL ZONE OF VERNON ARM (OKANAGAN LAKE, BRITISH COLUMBIA) by ELLEN LESLEY PETTICREW B . S c , Queen's U n i v e r s i t y , 1978 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n THE FACULTY OF GRADUATE STUDIES Department of Geography We a c c e p t t h i s t h e s i s as c o n f o r m i n g t o t h e r e q u i r e d s t a n d a r d THE UNIVERSITY OF BRITISH COLUMBIA March 1983 E l l e n L e s l e y P e t t i c r e w , 1 9 8 3 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 Library s h a l l make i t f r e e l y a v a i l a b l e for reference and study. I further agree that permission for extensive copying of t h i s thesis for s c h o l a r l y purposes may be granted by the head of my department or by h i s or her representatives. It i s understood that copying or p u b l i c a t i o n 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 Geography  The University of B r i t i s h Columbia 2075 Wesbrook Place Vancouver, Canada V6T 1W5 Date DE-6 (2/79) - ii -ABSTRACT The variability of sediment phosphorus in the littoral zone of Vernon Arm of Okanagan Lake, British Columbia was investigated. Spatial variability was determined by transects and comparisons of two environmentally different zones. Temporal variability, was determined from a seasonal sampling period of 52 days and an early summer 10 day period was evaluated. The natural variation of sediment P concentration was seen to associate spatially with physical sediment characteristics. Temporal variation was observed in each fraction. Replicate sampling of sediment P fractions at one site and at one point in time indicated that the only significant natural variation was in the organic P fraction. In a short time period (10 days) organic P and non-apatite inorganic P concentrations were seen to vary, presumably due to temperature fluctuations. Over a longer period (52 days) apatite P and non-apatite inorganic P were altered in a weedy near shore site but not in a deeper non-weedy zone. The role of weeds in the nutrient transfers between water and sediment were noted to be of significance. Resuspension of bottom sediments due to turbulent water conditions was determined to be the parameter effective in altering sediment P fractions during the summer of 1979. Iron in Vernon Arm sediments was not found to control phosphate levels by chemical precipitation but rather appeared to play a role in adsorption-desorption processes as non-occluded iron complexes. - iii -TABLE OF CONTENTS PAGE ABSTRACT ii LIST OF FIGURES vii LIST OF TABLES ix ACKNOWLEDGMENTS x CHAPTER 1. INTRODUCTION 1 2. LITERATURE REVIEW 2-1 Eutrophication, The Problem 3 2-2 Phosphorus, The Limiting Nutrient 5 2-3 Phosphorus Forms in The Environment 6 2-4 Limnetic Phosphorus Cycling 9 a) External Inputs 10 b) Compartments 12 c) Internal Storages 14 2-5 Approaches to Phosphorus Input Regulations 17 2-6 Sediment Phosphorus 17 a) Sediment Composition 18 b) Forms of Sediment Phosphorus 18 1) Organic Phosphorus 19 2) Inorganic Phosphorus 19 i) Occluded phosphorus 19 ii) Discrete phase precipitates 20 iii) Non-occluded phosphorus 20 2-7 Factors Affecting Phosphate Release 21 a) Physical Processes 21 b) Biological Processes 22 c) Chemical Processes 23 1) Mineralization 24 2) Adsorption and Desorption 24 3) Solubilization and Precipitation 26 2-8 The Iron/Oxygen Controversy 28 - iv -PAGE 3. EXPERIMENTAL PROCEDURES 3-1 Experimental Approach 32 3-2 The Environment 32 a) Vernon Arm 34 b) Surficial Geology 34 c) Vernon Creek Watershed 37 3-3 Sampling Locations 37 a) Site Selection 39 b) Site Description 39 c) Sampling Methodology 40 1) Sediment Collection 40 2) Aqueous Parameters 42 3) Interstitial Water 45 d) Sampling Schedule 48 3-4 Analytical Chemistry of Phosphorus 50 a) Orthophosphate Analysis 50 1) Factors Affecting Colorimetric 52 Orthophosphorus Determinations i) Flow Cells 52 ii) Sample Turbidity 52 iii) Ion Interference 52 b) Extraction Techniques for Sediment Phosphorus 52 1) Sediment Extraction Method 53 3-5 Sampling and Preservation of Phosphate Samples 55 a) Water 55 b) Sediment 56 3-6 Analytical Methodology 57 a) Water 57 1) pH 57 2) Oxygen and Temperature 58 3) Orthophosphorus 58 b) Sediment 58 1) Phosphorus Extraction 58 2) Extractable Iron Analysis 59 3) Organic Matter and Particle Size 59 c) Reagents 59 3-7 Statistical Evaluation 59 4. EXPERIMENTAL RESULTS 4-1 Zone 2 and Zone 3, Summer 1979 63 4-2 Zone 3, 3une 1980 68 - V -PAGE 4-3 Ekman Transects, August 1979 74 4-4 Variation Exhibited by the Component Fractions 78 of Total P 4- 5 Variation Due to Experimental Error 81 5. DISCUSSION a) The Sewage Spill 84 b) Sediment Sample Thawing 87 5- 1 Qualitative Comparison of Zone 3, 1979 and 1980 87 5-2 Zone 2, Summer 1979 88 a) Apatite Phosphorus 88 1) Hydrologic Inputs 88 2) In situ Generation of Apatite 91 3) Apatite Transport 91 4) Temperature Effects 93 b) Non-Apatite Inorganic Phosphorus 94 1) Changes in the Overlying Water Chemistry 94 2) Iron Associated Phosphorus 97 3) Biotic Use of Available Phosphorus 100 c) Causal Factors Affecting Zone 2, 1979 103 5-3 Ekman Transects 103 a) Particle Size 103 b) Apatite Phosphorus 105 c) Organic Matter 106 5- 4 Zone 3, June 1980 107 a) Natural Variability 107 b) Interstitial Phosphorus 108 c) Organic and Non-Apatite Inorganic Changes 108 6. SUMMARY, CONCLUSIONS AND RECOMMENDATIONS 6- 1 Natural Variability 113 6-2 Spatial Variability 115 6-3 Temporal Variability 115 6-4 Recommendations 116 BIBLIOGRAPHY 118 - vi -PAGE APPENDICES 1. Vernon Creek Monitoring Data (M.O.E.) 124 2. Okanagan Lake Monitoring Data (M.O.E.) 126 3. Sediment Phosphate Extraction Method 128 4. Particle Size Analysis - Hydrometer Method 133 5. Statistical Methods 138 6. Statistical Tables Indicating Insignificant Differences 142 7. Regression Analysis Data 147 8. Phosphorus Fraction Values 152 - vii -LIST OF FIGURES Number Title Page 2-1 The Basic Limnetic Phosphorus Compartments and Pathways 13 2- 2 Effect of pH on Various Phosphorus Forms 27 3- 1 The Okanagan Basin in British Columbia-Canada 33 3-2 Vernon Arm, Bathymetry and Bottom Profile 35 3-3 Eastern End of Vernon Arm (Photograph) 36 3-4 Distribution of Markers to Identify Underwater Sampling Sites 41 3-5 Ekman Dredge Sediment Sample (Photograph) 43 3-6 Ekman Transect Sampling Locations 44 3-7 Aqueous Collection and Monitoring (Photograph) 46 3-8 Sediment Squeezer (Photograph) 47 3-9 Sediment Peeper Collection (Photograph) 49 3- 10 Sediment Phosphorus Fractionation Analysis 60 4- 1 Linear Regression Plot for Ekman Transect 1 -Distance to 79 Shore versus Apatite Phosphorus. 4- 2 Range of Variation Exhibited by the Component Fractions of 80 Total Phosphorus 5- 1 Hydrograph and Sediment Loadings - The Mouth of Vernon 86 Creek, Summer 1979 5-2 Phosphate Fractions for Zone 3, 1979 and 1980 89 5-3 Windspeed and Direction for July 1979 - Vernon Arm 92 5-4 Bottom Water Parameters Monitored, 1979 Zone 2 and Zone 3 95 5-5 Linear Regression Plot for Zone 2, 1979 - pH Versus CDB Iron 96 5-6 Interstitial Water Phosphorus, Non-Apatite Inorganic 98 Phosphorus Versus Time for Zone 2, 1979 5-7 Linear Regression Plot for Zone 2, 1979-Interstitial P Versus 99 Non-Apatite Inorganic P - viii -Number Title Page 5-8 Causal Factors Affecting Zone 2, 1979 104 5-9 Interstitial Water Concentration Profile and Phosphate Values 109 for Sediment Cores, Zone 3, 1980 5- 10 Non-Apatite Inorganic, Organic Phosphorus and Temperature 111 Versus Time, Zone 3, 1980 6- 1 Phosphorus Pools and Fluxes in Vernon Arm Littoral Zone 114 A - l Technicon Layout for Orthophosphate Analysis 131 - ix -LIST OF TABLES Number Title Page 4-1 Analysis of Variance Tables for Zone 2, 1979 - Apatite and 64 Non-Apatite Inorganic Phosphorus 4-2 Duncan's Multiple Range Test for Zone 2, 1979 - Apatite and 65 Non-Apatite Inorganic Phosphorus 4-3 Correlation Matrix for Zone 2, 1979 66 4-4 Correlation Matrix for Zone 3, 1979 67 4-5 Analysis of Variance Tables for Zone 3, 1980 - Total, Apatite, 69 Organic and Non-Apatite Inorganic Phosphorus 4-6 Statistical Comparison of Daily Replicate Phosphate Forms for 71 Zone 3,1980 4-7 Duncan's Multiple Range Test for Zone 3, 1980 72 4-8 Correlation Matrix for Zone 3, 1980 73 4-9 Analysis of Variance Table for Ekman Transect 1 75 4-10 Duncan's Multiple Range Test for Ekman Transect 1 76 4-11 Correlation Matrix for Ekman Transect Variables 77 4-12 Statistical Comparison of a Sample Analysis - Within and 82 Between Runs - X -ACKNOWLEDGEMENTS I would like to acknowledge my gratitude to my major professor Dr. H.O. Slaymaker, for his advice and patience throughout this study. Appreciation is extended to Dr. K. Hall for his advice, and to other faculty members who offered constructive critism of my work. I am also thankful for the assistance of Joe Schnittker, Dan Moore, Sue Pate, Greg Inkster, and Bill Milsom for their assistance in the field collection of samples. My thanks are also extended to the B.C Department of Agriculture in Kelowna for the use of their laboratory facilities and to Dr. W. Oldham and S. Jasper for permission to use the environmental engineering laboratory within the Department of Civil Engineering at U.B.C. My special thanks to Susan Liptak who aided me in solving numerous problems in the laboratory and to both Thorn Gallie and Geoff Sunahara who provided moral support and companionship throughout this endeavor. The support of Barbara and Kelly Collins of Sandy Beach Resort in Vernon was also greatly appreciated. I also thank Melanie McDonald for typing the manuscript. -1 -CHAPTER 1 INTRODUCTION Eutrophication, the natural aging of a lake, has been accelerated in North American water bodies in recent years. Agriculture, urbanization and waste treatment have been considered a prominent cause of this acceleration. The recognition of surplus nutrients cycling through these degrading aquatic systems has generated concern regarding the role of phosphorus and nitrogen in eutrophication. In order to determine appropriate management programs to restore lake quality, an understanding of the nutrient inputs, exports, storages and fluxes is required. Various forms of phosphorus are found in lake sediments. Soluble phosphorus is both adsorbed by and released from these sediments. The direction of phosphorus exchange appears to depend on the ambient aquatic conditions, involving chemical, biological and physical parameters. If sediments are to remain as a 'sink' for phosphorus in order to control eutrophication, the conditions regulating the exchange processes require elucidation. Laboratory studies on sediment cores, whole lake experiments and mathematical simulations have been utilized to evaluate the role of sediments in the phosphorus budget of a lake. Many of these studies have tended to overlook the role of oxygenated shallow water sediments of the littoral zone. In order to determine if these sediments are important in phosphorus exchange, a 52 day study and a subsequent 10 day study of Okanagan Lake littoral sediments were undertaken. Two sample plots were selected in Vernon Arm in order to observe the changing levels of sediment phosphate. The various forms of sediment phosphorus and the ambient aquatic conditions were measured in order to determine if any causal relationships were apparent among these parameters. To . - 2 -enable an evaluation of temporal changes the natural phosphorus variability of nearshore sediments was required. In an attempt to quantify this, intensive single site sampling and a large scale spatial study were conducted. Three questions were addressed: 1) Can changes in the sediment phosphate levels be detected in an oxic littoral zone a) within two sites, over a 52 days period? b) within one site over a 10 day period? c) among three spatial transects? 2) If these changes can be detected a) in what direction is the phosphorus moving? b) what factors can be identified as causal? 3) If changes cannot be detected, what are the error sources that confound the problem? For example, does the natural variation of sediment phosphorus fractions exceed those changes which are observed over both time and space? - 3 -CHAPTER 2 LITERATURE REVIEW This chapter presents a survey of the available literature which deals with phosphorus in aquatic systems. An introduction to the processes involved in eutrophication precedes a discussion of limnetic phosphorus cycling. The forms of sediment phosphorus and the factors affecting its exchange are discussed. 2-1 EUTROPHICATION, THE PROBLEM In recent decades the study of biogeochemical cycling of nutrients in freshwater systems has emphasized the need for information regarding the various sinks, sources, reservoirs and fluxes of relevant elements. This increased concern regarding cycling developed through man's attempt to assess the impact of his activities within the environment, which necessitated the understanding of the natural circulation of material throughout the biosphere. The deterioration of the quality of most North American surface waters in the 1960s spurred the investigation of the role of nutrients in aquatic environments. Evidence of changing water quality was expressed in reductions of fish populations and species changes in numerous lakes and rivers. The process associated with this deteriorating water quality is called eutrophication. In the life cycle of lakes, eutrophication is the dynamic process of aging; over many years a pristine oligotrophic lake environment may develop through several trophic stages to become a marshy sediment filled dystrophic bog. The stage preceding dystrophic is termed eutrophic and exhibits such characteristics as increased growth of primary producers such as weeds and algae, increased rates of sedimentation, increased concentration of soluble nutrients and a decrease in the diversity of flora and fauna. - i r -on a short-term basis the maintenance of trophic status, be it oligotrophic, mesotrophic etc., is dependent upon the steady state equilibrium among many factors. This homeostasis is exemplified by the interaction of two factors, photosynthesis and aerobic respiration. Generally, photosynthesis is the utilization of carbon dioxide and water to produce organic compounds and oxygen, two components necessary for cell growth. Alternatively, aerobic respiration is the utilization of oxygen by organisms which facilitate the breakdown of organic matter. When lake photosynthesis exceeds in-lake respiration the growth of algal blooms and macrophytic weeds is increased resulting in a positive oxygen balance. But when respiration surpasses photosynthesis, decay exceeds cell production which may result in a depletion of the oxygen supply, or a negative oxygen balance. Disturbance of the equilibrium between photosynthesis and respiration tends to result in fluctuations in oxygen availability which can dramatically alter the in-lake biological and chemical systems. Another component of this homeostasis which influences the balance between cell production and decay is nutrient availability. Nutrients, a necessary component of all life forms, are utilized by aquatic plants in certain chemical forms and ratios. An increase of soluble nutrients results in increased growth of primary producers such as algae and weeds. Regulation of the amounts of soluble nutrients in the water column is a function of the behavior of both internal and external sources and sinks. Anthropogenic alterations of nutrient supplies to lakes has resulted in imbalances in the short-term equilibrium which is necessary for maintenance of trophic status. Man's dependence upon natural waterways as a disposal system for his agricultural runoff and domestic sewage has increased the nutrient levels of lake inflow waters (Higgins and Burns, 1975). The effect of this human -5-interference has been to accelerate the natural process of eutrophication, resulting in prematurely aged water bodies. 2-2 PHOSPHORUS, THE LIMITING NUTRIENT In an attempt to retard eutrophication and eventually restore the quality of a lake, the growth of primary producers must be kept in balance with the lake's ability to respire. One method of manipulating the rate of primary growth is to first identify and then control the "limiting" or "key" nutrient acting within the system. The concept of a limiting nutrient was developed from Liebig's mid-ninteenth century 'Law of the Minimum'. Liebig's law proposed that the substrate which is in least abundance in an organism's environment relative to that which is required for organism growth, will determine the rate of growth of the organism. In 1973, Lee proposed an alternative concept of a "key" aquatic plant nutrient. This key nutrient would be an essential plant nutrient that man could cost-effectively manipulate, such that it reaches concentrations in the environment which causes it to become the nutrient which limits plant growth. Phosphorus has been considered the nutrient most often limiting primary production in temperate aquatic ecosystems (National Academy of Sciences, 1967, Lee, 1973, Vollenweider and Dillon 1974). This idea is supported by the fact that in many natural systems, phosphorus is present in concentrations that limit algal growth (Lee, 1973) and it differs from the other essential nutrients such as carbon and nitrogen in that it is almost entirely associated with living or non-living particulate matter (Rigler, 1973). As phosphorus has been suggested as the biologically limiting element in a number of systems, Lee (1973) suggests that it also becomes the key element and should be the focus of anthropogenic control. The arguments which substantiate Lee's proposal are 1) phosphorus is often derived primarily from sources relating to man's activities whereas N, C, - 6 -and trace elements are commonly derived from natural sources and therefore are not as amenable to man's control, and 2) significant P input reductions to excessively fertilized lakes can be achieved by removing phosphorus from domestic waste waters. As early as 1968, Vollenweider developed an empirical formula to enable the prediction of the trophic status of lakes, which was based on the relationship between total annual phosphorus loading and the mean lake depth, over flushing time. This emphasis on the movement of phosphorus within the lake system ignores the complexities of the ecosystem and time, but has some predictive ability. In the years following the introduction of Vollenweider's classic model, research directed its focus toward phosphorus in lake systems. The recent emphasis has been towards elucidating the role and economy of phosphorus by studying the more detailed transfers and components which are involved in aquatic phosphorus cycling. 2-3 PHOSPHORUS FORMS IN THE ENVIRONMENT In nature phosphorus is most often found in either the solid or liquid state, as the quinquevalent positive ion P^ +, as it is able to maintain its valency throughout both assimilation and degradation (Higgins and Burns, 1975). In the differentiation of phosphates four general groups are identified: 1) orthophosphates - PO^-2) polyphosphates - a series of chain phosphates 3) metaphosphates - ring structures 4) ultraphosphates - highly branched structures (extremely unstable in aqueous solution). The classification of phosphorus in environmental systems generally recognizes four basic categories: - 7 -1) a) organic b) inorganic 2) a) dissolved (soluble) b) particulate Within the phosphorus cycle, organic phosphorus comprises a large pool for which regeneration is fast. Phosphorus is absolutely necessary to all life forms as it functions in the storage and transfer of a cell's energy, as well as in their genetic systems (Cole, 1975). In organisms it is found in nucleic acids, DNA, RNA and phosphoproteins as well as in vitamins, nucleotide phosphates, ADP, ATP and low molecular weight esters of enzymes (Wetzel, 1975). Organic phosphorus temporarily immobilized in animal, plant or microbial matter must decay and mineralize (be broken down by bacteria to an inorganic form) before it is 'available' for recycling in the environment. Phosphorus in mineral or inorganic form is found in meteorites, rocks and soils. The element is eleventh in abundance in igneous rocks and occurs in 187 different minerals of which only one family, the apatites is quantitatively important (Goiterman, 1973a). The weathering of these P bearing igneous rocks, coupled with the mining of offshore deposits of P rich guano beds for fertilizers provide the main terrestrial sources of inorganic phosphates. Solubilization, of this biologically unavailable phosphate, by microbes or changing environmental conditions such as pH or temperature releases P as available inorganic phosphates. Because phosphorus in the lithosphere occurs only in the quinquevalent state, its solubility is not affected by the redox potential of the environment (McKelvey, 1973). But oxidation and reduction processes do affect the solubilities of some metals with which the orthophosphate ion complexes (such as iron and aluminum) and therefore this process can affect the levels of available phosphates as well. In aquatic ecosystems phosphorus is also categorized by its physical state, being either solid (particulate) or liquid (dissolved). These forms are - 8 -operationally defined by filtering a water sample using a .45u filter. Phosphates which filter through are considered dissolved, whereas materials greater than A5p are defined as particulate P (Rigler, 1973). Dissolved phosphates of marine or freshwater origins may be composed of: 1) orthophosphates - PO^~ 2) polyphosphates - (primarily of synthetic detergent origin) 3) organic colloids, or phosphorus combined with adsorptive colloids Wetzel, (1975) further states that particulate P of water samples may include: 1) P in organisms (in forms mentioned previously) 2) mineral phases of rocks and soils including P adsorbed onto inorganic complexes such as clays, ferric hydroxides and carbonates. 3) P adsorbed onto dead particulate organic matter. A relatively recent classification differentiates those forms of particulate P into inorganic, organic and labile (Logan, 1982). In this scheme labile P is the relatively small but important component which is most mobile. It is loosely adsorbed onto solids, exchangeable, easily dissolved and easily hydrolyzed. Implicit in the classification schemes for phosphorus is the assumption that a specific chemical extractant can selectively remove a particular P form. Given the great complexity of phosphorus chemistry and mineralogy it is not surprising that this assumption is highly tenuous. Therefore researchers have begun to utilize operational definitions which require no judgement as to the selectivity of the extractant but yet provide significant information about the chemistry and/or mineralogy of phosphorus (Logan, 1982). The terms available or bioavailable phosphorus represent the P portion which is immediately available for uptake by the biota. It is this P fraction - 9 -which it is desirable to monitor and control. This biologically mobile phosphorus is largely composed of soluble orthophosphates, but it also includes some soluble organic P and potentially the particulate labile P. As previously mentioned, laboratory techniques have enabled the definition of operational forms of phosphates, which correspond to various chemical determinations, which can only approximate the morphologically and chemically distinct phosphorus compartments. The use of various extraction techniques has led to much confusion and misrepresentation within the phosphorus literature. Several attempts have been made (Olsen, 1967, Golterman, 1967, Rigler, 1975) to clarify, define and reclassify the environmentally salient phosphorus components, but no one scheme has yet been accepted by the research community. In this report the terminology of Logan's (1982) aquatic P classification scheme will be utilized. Like the others it is not inclusive, but it does represent those phosphorus forms which are environmentally significant. 2-ir LIMNETIC PHOSPHORUS CYCLING A lake is generally perceived as an open system, exchanging materials and energy with its surroundings. Yet the extent to which a limnetic phosphorus cycle is considered open is entirely a function of the individual system. As phosphorus is not returned to the atmosphere, the export of P from a lake system by outflow (in water and biota) and groundwater discharge should approximate inflow over a given time period. Since this is often not the case, phosphorus cycling in many lakes is likened to a closed system, if and when the majority of mobile phosphorus is supplied from internal sources. However, when a system exhibiting accelerated eutrophication is to be considered, it is not appropriate to - 10 -overlook the external P sources, as in recent years anthropogenic inputs have played a major role in altering the phosphorus cycle of many lakes, a) External Inputs The three salient sources of external phosphorus input to a lake system are streamflow drainage from the surrounding watersheds, atmospheric loadings and groundwater supply. Inputs from the watersheds supplying the lake transport both dissolved and particulate P, the latter comprising the dominant portion. Fluvial particulate phosphates enter a lake in association with either sediments or organics. Sediment associated P is another operationally defined term as it includes all the phosphorus related to the mineral (inorganic) portion of the fluvial sediments. This would incorporate the labile P adsorbed onto clays of mineral complexes, as well as the phosphorus bound in the mineral complexes of Fe, Ca and Al. Living organic matter, as well as dead and decaying particles would be carried lakeward to comprise the particulate organic fraction. Inputs of both particulate and dissolved phosphorus are highly dependent on the hydrologic regime. Storm events, sediment availability and variations in the contributing area of the watershed can affect both the amounts, and concentrations of suspended sediments and phosphates delivered by the stream. In a natural watershed the stream phosphate levels generally reflect the lithology, climate and vegetative cover of the region. This background concentration can be strongly masked in an agricultural or urban watershed where the streamflow phosphate levels are increased by either point sources of pollution or loading by land runoff. Point sources such as sewage treatment plant outfalls or storm sewer outlets not only influence lake phosphorus levels, but also increase the P concentration in a localized area, which is often evidenced by deterioration of quality immediately downstream (Uhlmann, 1979). Surface and subsurface flow to stream channels may include native soil - 1 1 -phosphate, fertilizer P and/or livestock and rural wastes, as the runoff tends to reflect the activities within the watershed. The P contribution of streams to lakes is highly dependent upon the size of, and the activities within the watershed. A stream's loading of total phosphorus may exhibit wide variations for both a daily time period and on an annual basis. Atmospheric inputs of phosphorus can be attributed to such sources as industrial air pollution, bare agricultural fields, unpaved roads, seeds, leaf litter, pollen and birds (Reckhow, 1978). Understandably the variation in surficial lake loading from these sources exhibits a wide range, and is dependent upon many other controlling factors. Atmospheric inputs are conveniently subdivided into two categories of precipitation and dry fallout. The P content of precipitation is usually low, less than 30 ug/1; the main sources of precipitation P being airborne dusts from agricultural erosion or industrial pollution (Wetzel, 1975). Dry fallout incorporates all of the other mentioned sources, including any material which drops or is blown into the lake system. While the role of atmospheric P inputs is generally of minimal significance in eutrophic systems, it should not be overlooked in budget calculations of more pristine environments. Groundwater supplies of nutrients, which enter the lake at the sediment-water interface, may be heavily laden with forms of P. This is especially true if the above ground supplies of phosphorus (in such forms as fertilizers or manures) are solubilized by precipitation and allowed to percolate to the groundwater table. But in most cases groundwater phosphate levels are quite low, averaging 20 ^jg/1 (Wetzel, 1975), as dissolved P is quickly removed in the soil column by biotic uptake and/or adsorption onto clays or metal complexes. Precipitates of phosphorus could also develop as the oxygen and pH conditions change with depth in the soil profile. - 12 -Both influent and effluent groundwater zones may exist in the shallow regions of a lake. When influent groundwater mixes with sediment interstitial water complications arise in the measurement and assignment of each parameter, b) Compartments Figure 2-1 schematically represents the basic components of a limnetic phosphorus cycle. The physical compartments and processes presented in the sketch, and discussed in the text, are associated with a summer stratified temperate lake (unless otherwise stated). This example is a very useful explanatory tool as it maximizes the potential biological processes and allows for the thermal stratification of lake water. The compartmentalization of this scheme separates both morphologic zones and mixing zones. The littoral zone, defined as the shoreward shallow region which is capable of supporting rooted macrophytes (Cole, 1975) is here differentiated from the profundal, deep zone. This morphologic separation is necessary as the biologic material responsible for the dominant P cycling of each zone can exhibit large differences in both character and abundance. The major mixing zones, which exist when the lake is stratified by density differences, are termed the epilimnion and hypolimnion. Generally as the thermal differences between surface and bottom waters increase, the lake is considered to increase in stability. When a lake exhibits stability, the bottom waters or hypolimnion do not effectively mix with the surface or epilimnion waters. This physical separation can impede chemical as well as biological migration of materials. The biologic and thermal lake separations are only temporary as both are highly dependent on the season. Atmospheric temperature changes, coupled with strong winds will destroy the thermal stratification in both spring and fall. This The Bas ic Limnetic Phosphorus Compartments and Pathways -In-tends to cause full lake mixing which is termed 'overturn1. Seasonal changes are also reflected in a temperate littoral zone, in that the standing crop of macrophytes tends to diminish in autumn, with no winter growth which therefore reduces the large biomass differences between it and the profundal zone that exist through spring and summer, c) Internal Storages The principal storage sites for lake phosphorus are: a) living or dead particulate suspended matter (seston) b) inorganic particulate matter, suspended or settling through the water column c) the variety of colloidal and filterable compounds usually termed dissolved, as they are less than .45u d) organic compounds in rooted plants e) phosphorus in free swimming animals and f) phosphorus present in lake sediments. As phosphorus is cycled within the lake system the size of these pools is constantly changing, reflecting the alteration of physical conditions and the response of the biota (Hooper, 1973). The rates of exchange between the various forms can be very rapid, on the order of minutes (Rigler, 1975), or considerably slower, in terms of hundreds of years. It is apparent that at any point in time the majority of lake phosphorus (greater than 90%, Wetzel, 1975) is tied up in solid organic forms, whereas the essential soluble orthophosphate ion is generally available in only very low concentrations. In a comparison of water samples from several North American lake studies Wetzel (1975) presents a table which indicates that dissolved orthophosphate ranged from 6 - 13% of the total P, representing concentrations of 1.5 to 3.0 jjg/1. Consistently small proportions of PCty-P would seem to indicate that the sources of bioavailable P are either limited or restricted, or that this nutrient form is recycled quite rapidly. The ability to quantify aqueous P movement was - 15 -facilitated by the post World War II use of radio isotopes, specifically 32p a s a phosphate. Tracer studies by Rigler (1964) revealed the very rapid cycling of phosphorus. The 32p added to epilimnetic waters was removed very quickly, and it became apparent that both bacteria and algae were competing for this valuable nutrient. With radioactive P Rigler determined that the low levels of soluble orthophosphate, which had been noted to remain constant for hours, were actually being utilized by plankton and replaced by equal amounts from metabolic losses. In his tracer studies Rigler determined that within four weeks 77% of the radiophosphate was removed from the water column, 3% being found in sediments, 2% leaving via the lake outlet and the remainder largely taken up by littoral organisms (Cole, 1975). The quantities of the different phosphorus fractions and the kinetics of the exchange have been investigated in a series of lakes, ranging in both size and trophic status. In general they appear to agree with the results obtained by Lean (1973). In his exemplary systems, the summer epilimnetic waters contained greater than 95% of their phosphorus as particulate P. The three mechanisms affecting this fraction are: 1) release of soluble orthophosphates by autolysis or excretion 2) removal from the epilimnetic water by settling or 3) conversion to XP, the low molecular weight phosphorus compounds which are excreted by algae during rapid growth and senescence. The inorganic PO^ -P release from particulate P was noted to be the dominant exchange, being 70 times that of organic P release. Colloidal P is a soluble macromolecular phosphorus which has a molecular weight greater than 5,000,000 (Wetzel, 1975). It is produced by the polycondensation of low molecular weight phosphorus (XP). Both XP and this colloidal P may release soluble PCty-P but the hydrolysis of XP to - 16 -PCty-P was insignificant when compared to the colloidal release of orthophosphate (Wetzel, 1975). In a review of the literature Rigler (1975) states that the soluble PO^ -P generally accepted as the source of P for phytoplankton, exhibits turnover times of 1-8 minutes in the summer stratified epilimnetic waters of a variety of lakes. In the simplified P cycling model presented by Lean (1973), phosphates entering the hypolimnion can arrive in particulate form being transported from the epilimnion within organic matter (as animals, plants or detritus) or associated with settling mineral material. The dissolved phosphorus input to the summer hypolinmion can be due to: 1) the senescence of organisms and organic matter either in the bottom sediments or in the water column 2) excretory products of organisms 3) the release of sorbed or bound PO^ -P from the mineral component of the sediments 4) the flux of sediment interstitial P to the overlying water and 5) the possible exchange of epilimnetic dissolved phosphorus across the thermocline, or thermal boundary separating the two lake compartments. In the literature the rapid cycling of phosphorus has been emphasized within epilimnetic waters, not due to the lack of activity within the hypolimnion but rather because they behave as individual compartments and because the majority of primary production occurs in the top waters. The problem of algal growth and benthic primary productivity is generally restricted within deep lake hypolimnions due to the reduction of light required for photosynthesis. The nutrient status of a hypolimnion may become apparent when lake stratification breaks down allowing overturn and the resultant mixing of lake waters. If large soluble P levels have accumulated in the summer hypolimnion they are now mixed throughout the lake, becoming available to those areas where the light and temperature regimes permit primary productivity. - 17 -2-5 APPROACHES TO PHOSPHORUS INPUT REGULATIONS The acknowledgment of phosphorus as a potential 'key' element in many lake systems resulted in the implementation of a variety of government policies. Government agencies, at all levels, developed programs in an attempt to reduce the external phosphorus loading to lakes. Several examples of programs implemented in regions of Canada and/or the United States are: 1) improvements in the treatment of sewage and urban wastes 2) removal of polyphosphates from household detergents 3) legislated limitations of nutrient outputs from point sources, such as industrial outfall pipes and 4) intensive studies concerning the use of fertilizers and cropping methods, in order to reduce these non-point source contributions. The initial emphasis, by governments, on external sources indicated that the anthropogenic inputs were most amenable to control. Although this approach was both costly and inconvenient it provided a pause in the accelerated process of eutrophication. In the years following implementation of government water quality policies, many lakes responded to reduced phosphorus inputs by exhibiting a stabilization in their trophic status. In order to further improve lake quality and/or restore the previous trophic status the management of the other P sources was required. Due to years of increasing anthropogenic inputs, and the inherent imbalance between lake P inputs and outputs, a large buildup of internal phosphorus occurred in most systems. In order to ascertain the feasibility of restoring lake quality, information regarding the behavior and importance of internal P storage forms and fluxes was required. 2-6 SEDIMENT PHOSPHORUS The two major storage compartments within a lake are generally considered to be the living organisms and the sediment. As previously mentioned - 18 -the biomass may recycle P quite rapidly, but this rate is dependent upon the type of organism (fishes, benthic organisms, macrophytes, plankton etc.) and its location within the lake. While the storage and regeneration of sediment P had been documented as early as 1941 by Mortimer, the role of lake sediments in P cycling was less well defined with respect to both mechanisms and time scale. a) Sediment Composition The materials comprising lake sediments are differentiated in terms of their provenance. The in situ breakdown of materials defines autochthonous sediments while the breakdown products of material transported to that region of the lake bottom are termed allochthonous sediment. While these two categories define the source of lake bottom sediments they do not discriminate between the physical or chemical characteristics of bottom materials. The ratio of organic debris (in various stages of decomposition) to mineral material of various grain sizes basically defines sediment composition. This ratio which varies widely from lake to lake, as well as within most lakes, is a function of several factors, the most dominant ones being: 1) the supply of both organic and mineral matter 2) the ambient energy regime which imports and exports material, thereby sorting the sediment 3) the biological activity in the sediment which mixes, decomposes and adds to the bottom sediments 4) the aqueous chemical conditions such as pH, CO2, O2 and temperature which affect the solubilities and therefore the presence of mineral components in the sediment, as well as affecting the living environment for the benthic organisms. b) Forms of Sediment Phosphorus The wide variation of total phosphorus values reported in the literature - 19 -is understandable when one considers the large number of factors influencing P accumulation in lake sediments (Syers, et al., 1973). Williams et al., (1971a) reported total P values ranging from 580 to 7000 ug/g for surficial calcareous and non-calcareous sediments. Total phosphorus levels in sediments are determined by the levels of organic and inorganic P, which are probably controlled by largely independent factors (Williams et al., 1971a) 1. Organic Phosphorus The organic matter in lake sediments is derived from inputs of primary production within the aquatic ecosystem (autochthonous) as well as from terrestrial biota (allochthonous) (Cranwell, 1976). The incorporation and diagenesis of this material within the sediment column is the source of the organic esters of phosphoric acid, which defines the sediment organic P fraction. Golterman (1973b) and Hesse (1973) state that not much is known about the types of organic compounds which remain undecomposed in the sediments, but Golterman suggests they will be incorporated as humic iron phosphate compounds which are biochemically not very active. Rodel et al. (1977) indicates that while more than half the organic P in lake sediments has not been characterized according to specific compounds, inositol phosphates represented 12-63% of the organic P in several Wisconsin lakes, the presence of appreciable amounts of nucleic acid P was also suggested. 2. Inorganic Phosphorus Inorganic phosphates in natural water sediments are differentiated by the three terms occluded, non-occluded and discrete. i) Occluded phosphorus includes those orthophosphate ions within the matrices of P retaining components. Generally this phosphate is not available to the environment unless the materials are degraded. -20 -ii) Discrete phase precipitates of Fe, A l and Ca phosphates are assumed to exist in sediment columns. They include such minerals as hydroxyapatite (Caio (P04)6 (OH)2) variscite (AIPO4), strengite (FePCty) and vivianite (Fe3 (PO^)2 8H20).The actual isolation of a precipitate from natural waters is extremely difficult due to the amorphous and mixed crystalline structure of the rest of the sediment. Therefore the existence of precipitates is based on solubility product criteria. Because the solubility product of a particular chemical species is exceeded, either in the interstitial water or the overlying water, investigators argue that the species should be found in the sediments (Lee, 1970). Variscite, strengite, hydroxyapatite and to a lesser extent vivianite have been suggested as the possible mineral forms which could precipitate in freshwater environments. The solubility criteria are strongly dependent upon pH, temperature and the availability of oxygen. iii) Non-occluded phosphorus is considered by Williams et al., (1971a) to be in more intimate contact with the surrounding aquatic phase than the other forms of inorganic P. It was therefore presumed that this fraction would respond more readily to changes in limnological conditions. Non-occluded phosphorus involves the orthophosphate ions sorbed onto the surfaces of P retaining components such as clay minerals, organics and amorphous mineral materials. The exchange between the solid and solution phases would be controlled by adsorption and desorption reactions. Muljadi, et al., (1966) proposed a three site theory of P adsorption for kaolinites and aluminum oxides. The two active surface sites involved: 1) the exchange adsorption of orthophosphate for hydroxyl groups located on the clay edge face and 2) the electrovalent linkage of H2PCty~ a t edge sites of hydrated aluminum oxides. These sorption mechanisms have also been utilized in explaining the observed association of orthophosphate with amorphous Fe and A l hydrated oxides, and amorphous aluminosilicates. - 21 -2-7 FACTORS AFFECTING PHOSPHATE RELEASE The removal of phosphorus from the sediment column may occur by a variety of methods, each exhibiting one, or a set of, controlling factors which influence the rate, form and the ultimate location of the transferred P. The effective processes regulating P exchange can be classified as physical, biological and chemical, a) Physical Processes Physical processes include the transfer of water above the sediment interface, as well as the mixing of sediments due to both turbulent transfer and agitation by organisms (bioturbation). Obvious concentration differences exist between the sediment and overlying water (typically lake sediments have 1-2 thousand ppm P (Lee, 1970)), but the concentration of P within the interstitial sediment water may be much greater than that of the lake water. Rittenburg et al. (1955) found soluble orthophosphate concentrations in interstitial water to be up to fifty times as great as that in the overlying water. If in contact these systems will attempt to equilibrate, but any movement of water above the sediment surface tends to transport the leached material away. This situation allows for the occurrence of concentration-dependent reactions. Turbulent waters above the sediment act to resuspend solid matter which also enhances exchange. This exchange could be concentration-dependent, oxygen-dependent, or temperature dependent, but Viner (1975), has shown that by exposing larger surface areas of materials to the water, increased exchanges of nutrients occur. Mixing within the surficial zone of the sediment exposes them to conditions which enhance exchange. The variation of energy regimes from lake to lake as well as within one lake, is one factor which will determine the depth of sediment which is exposed to exchange conditions. A proposed depth in the - 22 -order of 15 cm is often considered to be the active portion of the sediment column, which is mixed by both benthic organisms and energy transfers from the overlying water (Lee, 1970). Mixing within this zone is not necessarily homogeneous due to the nature of the processes, but is important to recognize that this volume of sediment can potentially be exposed to those conditions which enhance exchange. In the classic work by Mortimer (1941) it was assumed that only the surface layer of sediment was available for phosphate exchange. While this assumption may be valid for certain chemical reactions, it does not sufficiently represent the total volume of sediments (and therefore the total mass of P stored in the sediment) which is potentially involved in exchange processes over a long-term period. While turbulent effects of water contribute to sediment mixing, Petr (1976) presumes that organisms play a greater role. Benthic burrowing animals, rough fish and gases produced by anerobic bacteria all actively contribute to sediment movement. Sediment characteristics must be considered before applying a value of mixing depth, as fine slurry-like sediments are more likely to mix to a greater depth than coarse mineral sediments, b) Biological Processes Biological factors can affect sediment exchange both directly and indirectly, but it appears that the greatest effects are due to the activities of microbes and primary producers which directly utilize P (Lee, 1970). The breakdown of organic matter, or mineralization, within the sediment is carried out by a wide range of microbes capable of phosphate ester metabolism. Hooper (1973), states that bacteria appear to be the dominant agent in the alteration of organic phosphorus to inorganic phosphorus. Microbes also assist in P exchange by solubilizing inorganic P compounds and creating either acidic or reducing - 23 -environments (Higgins and Burns, 1975). The incorporation of both minerals and organics by some organisms, such as filter feeders, zooplankters and grazers, results in a restructuring of phosphorus compounds, which may be excreted back into the sediment or removed and transported to another portion of the lake. Some less direct, albeit important biological factors affecting P exchange include the utilization of nutrients by phytoplankton. If sediment P exchange is concentration-dependent, increased phytoplankton consumption may result in a significantly decreased water concentration, which could be balanced by a release from the sediments or sediment interstitial water. Photosynthesis and respiration of aquatic organisms also result in alterations of chemical characteristics of the water column (such as pH and the concentration of organic matter). pH (discussed in a later section) plays an important role in nutrient release, while the amount of decomposing organic matter exerts an influence on the quantities of oxygen utilized. It is well documented (Mortimer, 1941, Lee, 1970, Kamp-Nielsen, 1974, Anderson, 1975) that oxygen appears to play a dominant role in sediment phosphorus activity. It is apparent therefore, that biological factors may both directly and indirectly affect nutrient exchange from lake sediments, c) Chemical Processes Chemical processes occurring at the sediment water interface are very complex, as the response relationships are dependent upon so many interacting ambient conditions. The in situ determination of the roles of each chemical process has been hampered by such complications. The three processes which alter the forms of sediment phosphates are mineralization, adsorption/desorption, and solubilization/precipitation. Again each of these processes may be controlled by one or more factors which fluctuate in the surrounding environment. The commonly documented chemical factors affecting -2k-phosphate exchange are: pH, temperature, oxygen concentration and soluble orthophosphate concentration gradients. 1. Mineralization Phosphate mineralization requires the activity of micro-organisms which possess one of the phosphatase enzymes which enable the breakdown of organic phosphorus compounds (Kuznetsov, 1970). The behaviour of these organisms is effectively controlled by temperature, oxygen and pH. Although a large number of micro-organisms are capable of mineralizing organic phosphorus, each group functions within a specific range of both temperature and pH. Dormancy or death may occur when this range is exceeded. The presence or absence of oxygen in the sediment environment also directly affects phosphate mineralization. Shapiro (1967) determined that the metabolism of P by micro-organisms was dependent largely on aeration conditions. Anaerobic conditions (lack of available oxygen) resulted in an immediate liberation of soluble phosphate to the overlying water column. 2. Adsorption and Desorption Adsorption and desorption of phosphates on sediments have been described by isotherm models such as the Langmuir or Freundlich equations (Logan, 1982). Experimentation with radioactively labelled phosphates have allowed equilibration rates and properties to be elucidated. It is apparent that the adsorption process is inorganic and reversible. While equilibrium models have limited uses as predictive models they have allowed the characterization and comparison of various types of sediments. In the uptake and adsorption of chemical species by solids the distribution of the chemical species obeys a simple distribution law, under certain conditions C S = KC -25-where C and Cs are the concentrations in solution and on the solid and K is a factor relating the two (Lerman, 1979). Generally, K is a function of temperature solution composition and the nature of the solid substrate. P adsorption increases with decreasing particle size due to the specific surface effects (Hesse, 1973), therefore the finer materials have a greater affinity for sorption. Since the fine particles are resuspended most easily by turbulence at the sediment-water interface, they are exposed to a greater volume of water as they resettle through the water column. Changes in temperature, oxygen, pH and phosphorus concentration will determine whether these materials will adsorb or desorb during their suspension, but it is apparent that resuspension will increase the possibility of P exchange occurring. Isotherms developed by Muljadi et al. (1966), indicate varying adsorption capabilities of clay minerals at different temperatures. Generally phosphorus adsorption is increased as temperature increases, although these investigators attempted to identify and differentiate three separate binding sites. The active surface sites of major importance in the short-term sorption process are increased with higher temperatures (40°c), presumably due to the breaking of bonds which creates new sites for adsorption. Cooling to 20°c allowed the maintenance of the newly formed sites, whereas cooling to 2°c caused some desorption indicating possible bond reformation. Logan (1982), states that the reaction rates for adsorption/desorption are affected by the soil solution ratio. The concentration of available phosphate in the aqueous solution will affect the direction and the rate of sorption to some extent. Hayes (1964), determined that maximum adsorption of phosphorus by muds occurred at pH values between 5 and 7, when the H2PCty~ ion was dominant (Hesse, 1973). - 26 -3. Solubilization and Precipitation Solubilization or precipitation of phosphate compounds in natural waters has been theoretically determined by solubility product criteria. Working strictly with the theoretical information it is apparent that pH, temperature, oxygen and phosphorus concentration will alter the equilibrium of solids and liquids. In (Figure 2-2) (modified from Stumm and Morgan, 1970) the curve representing the equilibrium solubility of AlPOt>(s) is at a minimum at pH 6. At this pH AlPO^( s) maintains an equilibruim with a soluble PO^ concentration of 10 ug/1, raising the concentration above this results in increased precipitation to compensate for the oversaturation. Decreased levels of PO4. at pH 6 will result in no precipitation, as the water solution is considered undersaturated. Theoretically at pH 6 and a PCty concentration of 100 ijg/1 the Fe and Ca compounds will be in solution whereas AIPO4. will have begun precipitation in an attempt to maintain soluble PCty concentration of 10 ug/1. An increase in the pH, while maintaining a constant level of 100 ug/1 PO4 in the system should cause precipitation of Ca5(OH)(POt>)3(s) (pH 6.2) and a dissolution of AlPO*i( s) (pH 7). Decreasing the pH at this concentration could cause a slight precipitation of FePO*/(s) at pH 5 (as it just intersects with the solubility equilibrium curve here) and a dissolution of both the Fe and A l compounds at pH's below. It is of interest to note here that the dissolved inorganic P concentration in lake waters rarely exceeds 300 ug/1 (Stumm, 1964) and most often appreciably lower values are reported in the literature. Calculations for water containing 40 mg/1 Ca indicate that at pH 7 the precipitation of Ca^(OH)(POi^2 w * l l limit the soluble phosphate level to approximately 10 ug/1. Yet a Ca concentration of 100 mg/1 at the same pH will lower the P equilibrium concentration to 0.1 ^ug/1. From (Figure 2-2) it is -27-Figure 2-2 E f f e c t of pH on Var ious Phosphorus Forms 0 2 4 6 8 10 12 PH (modified from Stumm and Morgan 1970) - 28 -apparent that an elevation in the pH of natural Ca containing waters will lead to the formation of apatites which concurrently reduce the levels of soluble inorganic P in the water column. While these set values are determined for pure crystals of mineral species, it is extremely difficult to extrapolate these conditions to the lake environment, where the complexity of the sediment composition undoubtedly modifies these predictions which are based on experimental thermodynamics (Syers et al., 1973).. 2-8 THE IRON/OXYGEN CONTROVERSY Lake systems are generally considered to be well buffered due to the amounts of clay minerals, CaC03 and particulate organic matter contained within them (Lee, 1970). Therefore they often do not exhibit large or abrupt changes in pH. Following periods of overturn, pH values are relatively constant with depth but following the development of stratification, activities within the epilimnion tend to increase its pH while hypolimnion pH's are decreased. At the sediment surface this change in pH could be very effective in altering the solubility of Al-P, Ca-P or Fe-P compounds. Small changes in pH may alter not only the equilibrium of a reaction but also the kinetics, thus a unit change in the concentration of hydroxyl ion could increase the rate of a reaction one hundred times (Morgan and Stumm, 1965). As mentioned previously the exchange of P sorbed on clay particles can also be affected by pH changes. Therefore the complexity of determining distinct relationships between solubilization/precipit-ation reactions and pH is increased when dealing with natural sediments. Experimentation in controlled laboratory conditions have resulted in a wide variation of values, likely due to the composition of the sediments and the ambient conditions utilized. Anderson (1975), studied the effects of pH ranging -29 -between 7.7 and 11.2 on P release from calcium compounds in oxic conditions. No exchange of iron or aluminum was noticed. Maximum release to overlying water was noted at pH 9.2. The liberation of P below pH 9.2 was determined to be an exchange of HPCty- for hydroxyl ions (desorption) as opposed to solubilization. Kamp-Nielsen (1974) experimented with release of P from Ca and Fe compounds through a pH range of 5 to 10, utilizing both oxic and anoxic conditions. His oxic experiment indicated that P exchange is determined by the solubility of iron phosphate at pH values below 5 and above 9.5. This is in accordance with the pH range which Stumm and Morgan (1970) predicted for the dissolution of iron phosphate. Kamp-Nielsen found that in the pH interval 5.0-8.0 the oxic phosphate exchange was not connected to the formation of iron or calcium phosphates. Hydroxyapatite formation was apparently involved between pH's 8.0-9.0. Anoxic conditions stimulated a release of P and Fe within the pH range 5.7 -7.0, whereas anoxic pH's of 7.5 to 9.0 produced hydroxyapatite which acted to control the exchange. In early studies the role of clay minerals and organics in releasing or adsorbing P was underplayed, while the role of precipitates, specifically Fe, was emphasized. The role of iron phosphates was initially considered only to involve precipitation/solubilization processes, yet more recently the ability of amorphous iron oxide gels to sorb orthophosphate was recognized (Williams, et al., 1971a). The analytical techniques utilized did not attempt to differentiate discrete Fe complexes from the amorphous gels. Syers et al. (1973) noted that it is essential to distinguish between the sorption of inorganic P by hydrous ferric oxide gel, and the precipitation of inorganic P as a discrete phase ferric phosphate. - 30 -It has been apparent since Mortimer's (1941) paper that oxygen concentration is a causal factor in the release of P from these compounds. Mortimer concluded that in the presence of oxic conditions, ferric compounds were insoluble and the free ferrous iron noted in the oxygenated waters was precipitating in ferric form. With the onset of anoxic conditions the oxidized insoluble ferric phosphate was reduced, liberating soluble ferrous iron and phosphate (Mortimer, 1941). Mortimer found that for these conditions to occur the oxygen concentration and redox potential above the sediment had to be as low as 0.5 mg/1 and E7 = 0.25v respectively. Many subsequent studies have viewed the effect of oxygen conditions on P release, with most concentrating on the role of iron as a control mechanism. In 1941, Mortimer felt that the oxidized layer formed an efficient trap for iron and phosphorus by complexation and adsorption, but in a subsequent paper (1971) he stated that oxic conditions could exert a measurable, but quantitatively unimportant influence on lake chemistry. Results from Lake Mendota sediments (Lee et al., 1976) indicated that this model holds over very short time periods only. Initially the model conditions were observed, as phosphorus and iron were released from sediments during anoxic conditions. As well, with the introduction of oxygen, ferric iron was precipitated and a decrease in soluble orthophosphate was noted. However, when the laboratory experiment was monitored over a longer time period (up to 1800 hours) an appreciable release of orthophosphate was noted. In this case iron could not have been dominating the release of orthophosphate to the system. Schindler et al., (1976) noted that Experimental Lake 227 did not exhibit the classic release of P due to anoxic conditions, as proposed by Mortimer and widely believed by many. The sediment of Lake 227 did not contain appreciable amounts of ferric compounds, which possibly supported the 'iron-dependency' - 31 -model - but in an attempt to determine the role of iron, it was artifically supplied to the lake. Schindler (public lecture, 1978) stated that inputs of iron which subsequently experienced both anoxic and oxic conditions did not alter the sediment P budget of the lake. Releases of PCty were noted during both oxic and anoxic conditions. It appears then that the role of iron is not as dominant as was believed in the past. It is an active mechanism affecting P release, but does not appear to consistently control nutrient supplies to lakes. In the past proposals to maintain oxic conditions at the sediment interface were suggested as a method of controlling PO4 release to lake water. Utilizing Lee's results, it would appear that aeration of the hypolimnion would not totally limit this process. As well, it would appear that the shallow, consistently aerated portions of a lake may be contributing large amounts of phosphorus annually. - 32 -CHAPTER 3 EXPERIMENTAL PROCEDURES 3-1 EXPERIMENTAL APPROACH Field studies of sediment phosphorus contributions to lake water have generally followed either a mass balance approach to whole lake environments (Schindler et al., 1976, Ryding and Forsberg, 1976) or have consisted of in situ sampling of sediment and/or water from containers at the sediment-water interface (DiGiano and Snow 1976, Sonzogni et al., 1977). At this time there appear to be few examples of field research which integrate the results of controlled laboratory studies with in-lake measurements of sediment phosphorus fractions, for undisturbed and unenclosed lake sediments. In the summer of 1979 and 1980 a study of undisturbed littoral sediments was undertaken in Vernon Arm of Okanagan Lake in British Columbia. During a 52 day period in the summer months of 1979 lake bottom sediments were collected in order to determine if any phosphorus fractions were significantly changing and if so, which fractions. The following summer a 10 day sampling period was evaluated. Physico-chemical parameters of the water lying above the sampled sediments were concurrently monitored. Sampling for the determination of the natural variability of unenclosed and undisturbed littoral sediments was undertaken. 3-2 THE ENVIRONMENT Vernon Arm is situated in the Okanagan Valley, in the southern interior region of British Columbia (Figure 3-1). This valley lies in the interior dry belt, a rain shadow between the Coast Mountains on the west and the second wet belt of the Columbia Mountains on the east (Chapman, 1952). In the Koppen system T H E O K A N A G A N B A S I N in British Co lumbia C a n a d a - 34 -of classification this region exhibits a mid latitude steppe (BSK) climate. In this warm, dry lake region agriculture and tourism are the major economic activities. Natural water resources in this area have gradually deteriorated, due to the consumptive use of water by municipal and agricultural sectors (Okanagan Basin Agreement, 1974). The problems of excessive weed growth around the shorelines and summer algae blooms are still evident. a) Vernon Arm Vernon Arm is a long narrow (approximately 5 km by 1.5 km) east, southeast facing bay of Okanagan Lake. A bottom profile and a generalized bathymetric sketch of Vernon Arm is presented in Figure 3-2. Figure 3-3 displays the end of the bay where Vernon Creek debouches into the larger water body. Note the mixed land use and rolling topography. The water of this bay is well oxygenated year round (Stockner and Northcote, 1974) and well mixed throughout the summer period. The lack of a well defined thermocline in the littoral zone is presumably due to mixing caused by regular strong evening winds, which generate surface waves. The pH of the water in Vernon Arm is restricted to a small range due to the natural buffering capacity of the lake water by bicarbonate ions. Samples taken from the Arm during the Okanagan Basin Study (1974) indicate that the bottom sediments consist approximately of 30% sand, 55% silt and 15% clay. Sediment inputs to Vernon Arm include shoreline erosion, aeolian deposition as well as the material carried by Vernon Creek and the few ephemeral streams on the steep sided north and south shorelines. b) Surficial Geology. The surficial materials surrounding the Arm are comprised of lacustrine deposits of silt with minor clay and sand, fan deposits of poorly sorted gravel sands and clays, pre-Fraser glaciation unconsolidated sediments, terrace deposits Vernon Arm Bathymetry and Bottom Profile VERNON CREEK - 3 6 -Figure 3-3 Eastern End of Vernon Arm - 37 -of gravel and sand and as well modern lacustrine deposits which are predominantly silt (Fulton, 1975). c) Vernon Creek Watershed The mouth of Vernon Creek, which drains a 297 km.2 watershed, is situated at the eastern most end of Vernon Arm. Vernon Creek has its headwaters in the Grizzly Hills of the Thompson Plateau. Three lakes, Ellison, Wood and Kalamalka act as storage areas for the water and sediment moving through the system. That portion of the watershed between Kalamalka and Okanagan Lakes is influenced by a variety of land uses. Urban components include light industry, residential and municipal buildings as well as a secondary sewage treatment plant. The agricultural components consist of grazing, feedlots, row crops and orchards. The sediment inputs to the bay from Vernon Creek have been monitored since 1977 and indicate that maximum inputs occur in late May/early 3une while mid summer and mid winter show the lowest loading values. Particle size analysis of Vernon Creek spring samples indicate that approximately 75% of the suspended material is clay and silt with the remaining 25% being sand sized material (Gonzales, pers. comm., 1978). 3-3 SAMPLING LOCATIONS The Vernon Arm location was selected for this field program due to evidence of past eutrophic conditions. Large macrophyte (weed) beds composed predominantly of Myriophyllum spicatum (commonly known as Eurasian milfoil) were known to infest the near shore area of Vernon Arm. Nutrient inputs to the system from Vernon Creek had been measured by the Ministry of Environment (M.O.E.) approximately four times per year since 1971. Mean total phosphorus values at the creek mouth prior to mid 1977 were 0.523 mg/1 while - 38 -orthophosphate concentrations were 0.438 mg/1. Monitoring following 1977 indicates that mean total phosphorus values have dropped to 0.055 mg/1 while orthophosphorus values are 0.037 mg/1 (M.O.E. test results for site 05-00091 -see Appendix 1). During 1977 an experimental treatment program was implemented at the Vernon Municipal Sewage Treatment Plant. Until the spring of 1977 the plant had been discharging up to three million gallons of treated sewage into Vernon Creek daily. The experimental system consisted of transporting a majority of the treated effluent to surrounding agricultural fields for use in spray irrigation. The solid sludge was dried and sold as garden fertilizer (Vernon Daily News, 1979). The historical water quality of the nearshore zone included two sites along the public beach north of the creek mouth. In this case M.O.E. has sampled only for total phophorus (TP), semi-annually since 1975. The two sites both exhibit a decline in total P following the 1977 sewage treatment plant implementation. The TP values for both sites are noted in Appendix 2. The pre 1977 mean TP values for the two sites are 0.016 mg/1 and 0.024 mg/1. The Kin Beach TP levels decreased to mean values of 0.008 and 0.009 mg/1 following 1977. The Vernon Arm littoral area is not necessarily representative of the Okanagan Mainstem Lakes nearshore region, but rather was chosen as the site for this study due to: 1) the accessibility of historical data for both sediment and water 2) the past history of eutrophic conditions that would have resulted in relatively high sediment P values 3) the existence of an experimental sewage treatment plant, and a seasonal weed monitoring program which resulted in a number of continuing eutrophication-related studies in Vernon Arm. - 39 -a) Site Selection Two underwater sampling sites were selected at distances of approximately 175 and 375 meters from the stream mouth. They were both located within the active mixing zone of river and lake water, exhibited during spring freshet. In an attempt to ascertain the dimensions of the river plume at that time of year thermal transects coupled with air reconnaissance was performed during the period of 1979 peak flows. Sample locations were selected in approximately three and six meters of water depth and marked with surface buoys. Their position within the more turbid mixing zone was then rechecked aerially. As mentioned previously this choice of site positions was expected to insure nutrient rich waters and detectable phosphorus levels in each sediment fraction. Initially three sites were selected for comparison. The third site was located in the nearshore zone in approximately one meter of water at a distance of approximately 50 m from the river mouth. This active, well mixed zone was predominantly composed of sandy materials with no macrophytic growth. The positioning of transect lines and floats was undertaken but disturbances of both anthropogenic and limnologic origin caused this site to be disregarded. The problems involved in maintaining a relatively undisturbed plot in a highly popular boating zone rendered this location undesirable. b) Site Description In May of 1979 the two sites were positioned and transect lines to demarcate the underwater plots were installed by SCUBA. Three rope lengths of 9 to 10 meters were set out to form a triangle which enclosed approximately O^m^  of undisturbed bottom sediments. Subsurface floats, (one meter below the water surface) at each vertex of the triangle delimited the area of the sample site. Fluorescent floats were tied to the subaqueous transect lines in order to -40 -aid in the rope's flotation, and as well to facilitate locating the ropes during periods of poor visibility. A fourth buoy located a few meters from the sample plots marked the site at the waters surface, so as to enable quick and efficient locating of the plots by boat. This buoy was also used as a descent line by the diver in order to ensure minimal disturbance of the sample plot. One sediment collecting pan was positioned within the roped boundary, at each site, to allow an estimate of net sedimentation (natural fallout plus disturbed resuspended material). Figure 3-4 illustrates the distribution of markers for the underwater sediment plots, c) Sampling Methodology Sampling at the two sites took place between 0800 hr. and 1200 hr. on the collection dates. In the afternoon, water and core samples were transported on ice to a laboratory in Kelowna for PO4-P analysis. Dissolved oxygen concentration, temperature and pH of the bottom water overlying the sample plots were recorded in the boat on site, while sediment grabs and cores were collected by the diver. Water samples for aqueous phosphorus were collected, filtered immediately and stored in a cooler on the boat. Sediment cores and grab samples were kept cold and then subdivided and frozen upon reaching shore. One intact sediment core was kept upright and transported in a cooler to the Kelowna laboratory for squeezing, to obtain interstitial water samples. 1. Sediment Collection For the collection of bottom samples the diver carried two hand held corers and six small airtight vials for surface grab samples. By descending along the surface buoy line located approximately two meters away from the plot, sediment disturbance was minimized. All underwater movement by the diver was achieved by walking rather than swimming (again to minimize disturbance). -41-F igu re 3-4 D i s t r i b u t i o n of M a r k e r s to Identify Unde rwa te r Sampl ing S i t e s T surface marker bouy subsurface marker f l o a t s — i ^ l a n d diving line A ^ 4-*-transect ropes f \ C1/2 m off bottom) f loatat ion and _ / l j \ transect marke r ! " * / undisturbed \ . unenclosed sediment^ / \ ^/ (jfh-sediment pan ^ - 42 -The outside perimeter of the triangle was used as the path to the sample collection locations, the inside region of the triangular plot was not to be entered by the diver. Sediment samples were collected from inside the plot by kneeling at a position on the outside of the boundary rope and leaning over to sample from within the undisturbed region. Over the period of the 1979 summer the shallower site developed a thick weed bed which grew the full height of the water column. In order to allow passage of a diver along the collection paths, the weeds were continually plucked in the meter surrounding the triangle. This allowed unimpeded and safe access to the sample area. In the survey undertaken to investigate spatial variation, bulk surface sediment samples were collected. An Ekman dredge was used to obtain an undisturbed block of sediment. Core tubing was used to subsample this material further as it allowed easier separation of material by depth. (Figure 3-5). This material was either frozen for future P fractionation or bagged and stored for future particle size analysis. A sketch map of the Ekman transects (Figure 3-6) indicates the relative positions of the sample sites. The first transect (ET1) began in the area adjacent to the zone 3 sample plot. This transect was oriented perpendicular to the shore and consisted of 7 samples along a 275 m distance. The second transect, perpendicular to ET1 at the 22 site, consisted of 5 samples over a distance of 250 m. The depth of this transect was nearly constant at approximately 3 m. ET3 was also perpendicular to the intitial transect but intersected at the area of Z3, which is an area of approximately 6 m depth. Along ET3 6 samples were collected over a distance of 200 m. 2. Aqueous Parameters While the diver was below collecting sediments, parameters - 0 3 -F igure 3-5 Ekman Dredge and Sed iment Sample and co r i ng a p p a r a t u s for s u b s a m p l i n g -- 4 4 -Ekman T r a n s e c t Sampl ing F igure 3-L o c a t i o n s 6 J J . 3A- . - t ! l !kw . . E T 3 A E T 3 O , ET3D ET3F I I JET 1 B I I i I E T I C I .ET 1 D I . ' EJ LE E T 2 A ET2B E T 2 C l E J 1 F ET2D E T 2 E i 1ET1G - 45 -characterizing the bottom waters were determined by the boat tender. A 6 m length of nalgene tubing was lowered from the side of the boat to a point approximately 6 cm above the sediment surface. A water sample was pumped into the boat where it was subsampled for immediate: 1) analysis of pH and 2) filtration through .45 u nucleopore filters. A combined oxygen and temperature probe was also lowered to this bottom position to collect readings of these parameters. A measurement of bottom water velocity was attempted at the outset of the project but the impellor system utilized was not sufficiently sensitive. From dye experiments which followed, it was determined that bottom water flow was slow and unidirectional during periods of calm surface water conditions. The use of the filtered bottom water samples in orthophosphate analysis, coupled with PCty-P analysis on sediment core water was used to obtain an estimate of the aqueous P concentration gradient. Figure 3-7 shows the pH meter and oxygen/temperature probe being utilized on site from within the boat. 3. Interstitial Water Two methods were used to evaluate phosphate levels in the sediment interstitial waters. Initially a sediment squeezer similar to Reeburgh's model (1967) was utilized. This instrument pictured in Figure 3-8 uses air pressure against a diaphram to squeeze 7 to 10 cm subsections of a core. The interstitial water extracted is a mixture of fluid from various depths which makes it impossible to assign discreet values of PO^ -P a depth profile. A lumped value which presumably incorporates the oxygenated and unoxygenated layers of the sediment results. This instrument is designed for use in an oxygen free environment in order that the bottom layers of sediment, which are usually anaerobic may maintain that status. This would limit the loss of soluble P to - 46 -F igure 3-7 A q u e o u s C o l l e c t i o n and Mon i to r ing -47-F igure 3-8 Sed iment s q u e e z e r -a f t e r R e e b u r g ' s d e s i g n -- 48 -precipitation. Maintenance of an oxygen free environment during transport to the laboratory was not feasible in this study and therefore the squeezer results represent interstitial P values from oxygenated subsamples. A second technique was used during the second summer of the project and resulted in two quite detailed depth profiles of interstitial water. The peeper system shown in Figure 3-9 was planted for a period of 10 days in the deeper sample plot. This teflon sampler was made of three pieces, a backing with a series of indented pockets which held approximately 5 mis. of fluid, a dialysis membrane which allowed transferral of soluble but not particulate materials and a front piece with windows corresponding to the pockets, which clamped the membrane tight to the backing and allowed exchange into the pockets. The peepers were filled with distilled water, clamped together to form a unit and left overnight to soak in an oxygen free environment (nitrogen gas was bubbled through a high cylindrical container which was full of distilled water which covered the peepers). The peepers were transported to the sample plots in the oxygen free environment and buried in the sediment by a scuba diver. They were left to equilibrate for a period of 10 days. Of the 55 windows, 8 to 10 were left above the sediment surface to allow an indication of the bottom water P-PO^  values. From this a reliable estimate of orthophosphorus gradient was obtained. When the peepers were retrieved the soluble material in each pocket was sampled with a syringe through the membrane and preserved for PO^ -P analysis. d) Sampling Schedule In May of 1979 the sample plot locations were selected and the transect lines and marker floats positioned. The first collection of samples took place on 3une 28, 1979. Seven sampling dates over a period of 52 days followed during - 49 -F i gu r e 3-9 Sed iment Peepe r C o l l e c t i o n -50-that summer. The sampling dates were as follows: June 28, July 17, July 20, July 23, August 13, August 16, August 19. Pre-summer, pre-weed conditions were monitored on June 28. During both July and August a set of 3 sampling days, with collections on every third day was undertaken. These closely spaced collections were to identify any shorter-term temporal changes. Each sampling date involved a collection of values for: pH, O2, T, sediment P, aqueous PO^ -P and squeezed interstitial PCty-P. Three transects of bulk surface sediment collection, for identification of spatial variability was undertaken on August 15, 1979. In June of 1980, a 10 day study involving only the deeper zone was initiated on June 3. The parameters collected in this second field season included pH, O2, T, sediment P, and peeper PO^ -P gradients. The sampling dates for this season were as follows: June 3, June 5, June 9, June 10, June 11, June 12, June 13. 3-4 ANALYTICAL CHEMISTRY OF PHOSPHORUS a) Orthophosphate Analysis A variety of analytical techniques can be used for the analysis of phosphate compounds. In a review paper on phosphorus determinations Olsen (1967) mentions gravimetric, titrimetric, photometric, solvent extraction and ion exchange as possible choices. In the analysis of natural waters the photometric method has been most widely used. The basic method of phosphorus analysis consists of a conversion of all phosphates to orthophosphorus followed by the formation of a 12 -molybdophosphoric acid which is then reduced to form a blue heteropoly compound (Burton, 1973) (one molecule of phosphate, complexes with 12 - 51 -molecules of molybdate in an acid medium to form molybdophosphoric acid). A variety of reducing agents will form a heteropoly blue color from which the intensity, which is directly proportional to the P concentration, is measured photometrically. Of the seven common reductants used in water research, the two most popular are stannous chloride and ascorbic acid. Murphy and Riley (1962), state a few disadvantages of the stannous chloride method. They found that the reduction rate was sensitive to temperature changes, and that the salt of marine sample solutions interfered to create considerable error. Recent water chemistry studies have adopted the ascorbic acid method for both fresh and salt water analysis. Ascorbic acid used as a reductant, when combined with antimony (as potassium antimonyl tartrate) rapidly produces a purple-blue color whose intensity remains stable for 30 minutes. Murphy and Riley (1962), found the absorption maximum of this complex to be 882 um. The absorbance of the solutions prepared through the Murphy and Riley (1962), technique obey Beer's Law over the concentration range of 0-2 ppm PO^-P. Good precision in this method can be achieved routinely except at low orthophosphate concentrations. Murphy and Riley (1962), state a coefficient of variation of less than one per cent when the PO4-P concentration is above 20 ug/1. Solvent extraction allows detection below this level to a limit of 0.2 ug/1 (Stevens, 1963). Various organic solvents (iso-butanol, benzene, n-butanol, n-hexanol) are used to extract the phosphomolybdic acid before the reduction of phosphomolybdate to the heteropoly blue compound (Olsen, 1967). The distinct advantage of this extraction method is increased sensitivity, yet logistical laboratory problems often restrict this technique. -52-1. Factors Affecting Colorimetric Orthophosphorus Determinations Determinations using a colorimetric technique can be affected by a number of variables. i) Flow cell lengths which are used in a spectrophotometer will determine the volume of fluid that the photocell is able to analyse for absorption. Increasing this distance (length of the cell) increases sensitivity. ii) Sample turbidity is a second problem which is encountered in colorimetric techniques. Precipitates which form and/or particulates incorporated in the sample must be removed before a spectrophotometric reading is taken. These particles block the light path, biasing the absorption readings which subsequently create error in concentration determinations. iii) Ion interference is caused by the presence of other ions in the sample which also react with molybdate to form a blue color thereby interfering by creating a more intense blue solution. The resultant increase in absorbance readings is called positive interference. Both arsenate and silicate have been noted to interfere with color development for phosphorus determinations. b) Extraction Techniques for Sediment Phosphorus a. When considering that portion of phosphorus which is particulate, or associated with the solid phase a different set of procedures for analysis is required. Initially the fractionation methods for lake sediments were modelled from soil phosphorus studies (Mehta et al. 1954, and Chang and Jackson, 1957). Many modifications of the Chang and Jackson (1957), method have been suggested for various types of soils as well as for wet sediment analysis. J.D.H. Williams wrote a series of papers with others (Williams et al. 1970, 1971 (a, b, c), 1976, Shukla et al. 1971, Li et al. 1972, Sommers et al. 1972) which focussed on analytical methods for fresh water sediments of both calcareous and non-calcareous natures. - 53 -Over a period of years they attempted to characterize labile, aluminum-associated, iron-associated and calcium-associated phosphorus. As mentioned previously chemical extractions cannot identify naturally occurring P compartments but may only identify different forms chemically. Again, the approach to measuring phosphorus is to alter all forms to orthophosphorus which is subsequently developed using the ascorbic acid method for colorimetric determination. The difficulty arises when sediment fractions must be selectively altered to orthophosphorus without disturbing or incorporating the remaining P fractions. The forms of sediment phosphorus which are identified by Williams's technique are: total phosphorus (TP), inorganic phosphorus (IP), and apatite phosphorus (AP). Non-apatite inorganic phosphorus (NAIP) and organic phosphorus (OP) can be determined by subtraction of the three analytically determined fractions NAIP = IP - AP, OP = TP - IP. 1. Sediment Extraction Method Drawing from the various extraction techniques proposed by Williams over a period of years, a modified, streamlined methodology was developed at the National Water Research Institute (NWRI) in Vancouver B.C. An outline of the laboratory procedure is presented in Appendix 3. Basically a sediment sample is subsampled into three low weight (0.25 g) portions. Wentz and Lee (1969), indicate that phosphorus extracted as ugP/g sediment, varies with sample weight. The curve for this relationship peaks when very small samples, 0.03 to 0.08 g are analysed. The curve drops and begins to level out at 0.25 g. To reduce error and allow interstudy comparison, sample sizes are chosen from values along this plateau. One of the 0.25 g samples is used for total P analysis. It is roasted in a muffle oven at 550°c for two hours in order to oxidize all organic matter. - 54 -The ash is dissolved in 1 N. HC1 for two periods of 16 hours. This HC1 displaces sorbed P ions from colloids as well as solubilizes available carbonates which release sediment inorganic P (Sommers et al., 1972). The acid bath hydrolizes the ashed phosphates and converts all forms to orthophosphorus. Inorganic P is determined by washing a subsample twice in 1 N. HC1 for 16 hour periods. The organics are not available for hydrolysis but rather polyphosphates, precipitates and sorbed P are altered to the orthophosphate form. Inorganic phosphate which is in the apatite form is determined through the use of a separate method. To do this a third subsample is extracted with citrate dithionite bicarbonate (C.D.B.). This reagent displaces iron, bound in sediments and allows an estimation of proportion of iron associated phosphates. The supernatant of the C.D.B. wash in analysed by atomic absorption for iron concentration. The iron free sediment is then washed a second time in 1 N. NaOH to remove the organic bound P. This supernatant is discarded and the sediment washed a final time in 1 N. HC1. Previous washes have thus removed organics, precipitate associated P and sorbed P. The final wash solubilizes the remaining P complexes which are considered to be apatite forms. Organic P is not determined directly, but rather is estimated by subtraction (Total P - Inorganic P). Mehta et al. (1954) and Sommers et al. (1972) have developed methods for organic determinations but there are quite laborious. In order to reduce the technical workload and complexity of the analysis this modified extraction method leaves the organic fraction to be determined by subtraction. The difference between direct organic determination and determination by difference was found to be insignificant in a number of experimental comparisons (Kirkland, pers. comm., 1979). -55-3-5 SAMPLING AND PRESERVATION OF PHOSPHATE SAMPLES a) Water Field collection of samples for phosphorus analysis involves a number of logistical and technical problems. As mentioned previously P can cycle rapidly and in order to determine quantitatively the various P compartments in a water sample, separation must occur immediately. Filtration of a water sample through a 0.45 u filter theoretically separates colloidal and particulate matter from the aqueous sample. The differentiation of particulate and soluble at 0.45 u is an arbitrary, but standard method for water chemistry. Initially problems with filtration included leaching of P from filter papers, adsorption of P onto papers, uneven pore sizes and clogging. Recently filtration papers of acetate or polycarbonate, which are non P adsorbing, and of well distributed pore sizes have allowed better, more reliable phase differentiation. Storage vials for collection of materials creates another logistical problem, and to some degree still remains a controversy. Some types of plastics will adsorb P onto the bottle surfaces or exchange P complexes for ions already attached to available sites on the plastic. Populations of micro-organisms which survive on some types of plastics also greatly alter the P concentration during storage. Glass, when properly cleaned exhibits negligible adsorption and is therefore considered the most appropriate storage container. Packing, shipping and general field use often restricts the use of glass. Laboratory glassware must be acid washed, initially with concentrated sulfuric acid overnight followed by IN HC1 rinses before use. Contamination of glassware by exposure to the atmosphere or from previous use must be guarded against, especially when dealing with samples containing low levels of phosphorus. Recently the development of new materials such as polypropylene, polystyrene and - 56 -polytetraflorethylene have reduced the storage problems in that adsorption and microbial growth is more controlled on these materials. When transportation to the laboratory facilities is not immediate the water samples should be stored (after filtration) at 4°c, or below the ambient water temperature from which the sample was taken. In order to preserve water samples some researchers have used chloroform, mercury, toluene or dichloroethane (Burton, 1973). A number of people feel this alters the P components and is a cause of anomalous results (Viner, 1975). Unfiltered water may be preserved with acid for the analysis of total phosphorus, but should not be subsampled for the soluble P components following this as biological materials may leach or uptake P forms to change the relative composition. Ideally water samples should be analysed within an hour of sampling. Cooling at 4°c is required during transport, while freezing of samples should be considered if the delay period is lengthy. Freezing of water samples does not appear to alter the water chemistry if it is accomplished rapidly following filtration. Thawing and refreezing tends to increase the variance in analysis (Burton, 1973). Each sampling situation permits the use of different techniques and materials. Tradeoffs of precision and accuracy for cost, timing and field logistics must be considered before entering the field. Research projects vary greatly in field methodology which aids in explaining some variance between experimental results. Since information and instructions regarding field methods are not standardized, we can use them only as basic guidelines. Reproduction of a given method throughout a project will help reduce the observed variance, b) Sediment Sample preparation for sediments has become more straightforward in - 57 -the past few years. Before freeze-drying was an accessible method, samples were air dried and crushed, or frozen and analysed immediately upon thawing. Differing attitudes are expressed in the earlier literature as to the effect of these techniques on P readings. If a freeze-drying apparatus is available sediment samples should be frozen immediately upon sampling (or kept below ambient sample temperature until frozen). Thawing of samples should not be permitted as organics and orthophosphate fractions may alter very rapidly with warming. Freeze-drying involves placing a frozen sample in a vacuum at low pressures and low temperatures for approximately three days (the length of time is a function of the water volume). Ice is drawn out of the sample by sublimation, removing water without disturbing the P fractions in the sediment. A frozen mud and water sample is reduced to a powdery, flaky consistency. This in turn should be ground with a mortar and pestle to a homogeneous consistency in order to analyse the sediment in a representative fashion. Most nutrient and chemical analyses can be performed on samples treated in this way, but particle size determinations are likely not representative due to the change in texture. If this information is required a subsample should be removed before freeze-drying. 3-6 ANALYTICAL METHODOLOGY a) Water 1. pH A portable Orion Ion-analyser, specific ion meter, coupled with a gel filled combination electrode was used for direct readings of pH. The electrode was standardized each day before use with pH buffer solutions of 10 and 4 . pH was read to ± 0.05 units. - 58 -2. Oxygen and Temperature A portable Yellow Spring Instrument Co. combination oxygen and temperature probe (model No. 51) was used for field measurements. To standardize the instrument a volume of water, which had been left for 16 hours to saturate at ambient temperature was used to set the dissolved oxygen (D.O) content. Temperature was read to ± O.PC. 3. Orthophosphorus Orthophosphate analysis of filtered lake water and squeezed sediment interstitial water was performed in the Kelowna laboratory with the use of two instruments. A Bausch and Lomb Spectrophotometer 70, with a 5 cm flow through cell was used for samples, with more than 100 ug/1 PO^ -P. When sample volumes were limited and when orthophosphorus values were less than 100 jjg/1 a Klett Summerson photoelectric colorimeter was utilized. This automated system could handle smaller sample volumes and exhibited greater sensitivity. The two systems were calibrated against each other on a series of samples to standardize the soluble PO^ -P results. In the U.B.C. Civil Engineering Environmental Laboratory phosphorus analysis of sediment extracts was performed using a Technicon Autoanalyser II. This automated sampling, mixing and reading system was set for a range of 0-4 mg/1 PO^ -P. (see Appendix 3 for Technicon procedure) In each of these PO^ -P analyses, Murphy and Rileys (1962) molybdenum blue method mentioned previously was utilized for colorometric determination, b) Sediment 1. Phosphorus Extraction The fractionation of sediment phosphorus was performed using a modified Williams technique. This method, which has been discussed previously, was modified by the National Water Research Institute in Vancouver B.C. - 59 -The various steps in this procedure are illustrated in Figure 3-10, whereas the detailed description of laboratory technique is included as Appendix 3. 2. Extractable Iron Analysis The iron extracted during the citrate-dithionite-bicarbonate (C.D.B.) washing was measured for all sediment samples with a Jarrel-Ash Model 810 atomic absorption spectrophotometer. Atomization of the sample took place in an air/acetylene flame; determinations were made at a wavelength of 2483 A°. 3. Organic Matter and Particle Size The determination of particle size and organic matter content followed Lavkulich's (1978) method. Hydrogen peroxide removal of organics allowed a loss of weight determination. An ASTM 152-H model hydrometer was used to evaluate particle size on a mixture of sediment, dispersing agent and distilled water. The reagents, equipment and procedures are noted in Appendix 4. c) Reagents All chemicals used in this study were reagent grade unless otherwise specified. 3-7 STATISTICAL EVALUATION A number of statistical techniques were used to evaluate the changes in sediment phosphorus fractions. A two way analysis of variance (ANOVA), employing a completely randomized block design (Little and Hills, 1978) was undertaken in order to distinguish significant daily differences for each sediment fraction. When significant differences were apparent at a 95% confidence interval, mean separation using Duncan's multiple range test was performed to identify which individual or groups of means were different from the others. Sediment Phosphorus F rac t ionat ion Ana l y s i s S a m p l e 1 ( 0 . 2 5 0 0 g) R o a s t at 5 5 0 C 2 H o u r s R e s i d u e 8 u p e r n a t e n t S h a k s w i th 25 mla 1 N H C L - 16 h o u r s R e s i d u a S u p e r n a t a n t S h a k e w i th 25 mis 1 N H C L - 1 6 h o u r s R e s i d u e D i s c a r d e d T o t e l f E x t r a c t ( T P ) S a m p l e 2 ( 0 . 2 5 0 0 g) S u p e r n a t e n t S h a k e wi th 25 mis 1 N HC I-16 h o u r s R e s i d u e S u p e r n a t e n t S h a k e wi th 25 mis 1 N HC I-16 h o u r s R e s i d u e D i s c a r d e d T o t a l I n o r g a n i c P E x t r a c t (T IP ) T o t a l O r g a n i c P ( T O P ) = TP-T IP N o n A p a t i t e I n o r g a n i c P (N AIP) - T I P-AP S a m p l e 3 C 0 . 2 5 0 0 g ) S u p e r n a t e n t 85 C . 25 ml C O B e x t r a c t ( 3 0 min . ) R e s i d u e Fe a n a l y s i s by a t o m i c a b s o r p t i o n S u p e r n a t e n t D i s c a r d R e s i d u e S h a k e w i th 25 ml 1 N N a O H - 1 6 h o u r s S u p e r n a t e n t S h a k e w i th 25 ml 1 N H C I - 1 6 h o u r s R e s i d u e S u p e r n a t e n t S h a k e w i t h 25 ml 1 N H C I - 1 6 h o u r e R e s i d u e D i s c a r d e d A p a t i t e P E x t r a c t ( A P ) -61 -For each site correlation coefficient matrices were calculated. The components regressed included all measured field parameters as well as the values for each sediment fraction. This technique was attempted in order to determine the degree of association between all combinations of two variables in the matrix. The coefficient of correlation (r value) is a measure of the degree of association, and may attain a maximum value of ±1. The V values are presented in the matrices. Individual linear regression plots were developed when the correlation matrix indicated significant 'r' values. Means, standard deviations and coefficients of variation were determined for all samples, grouped by sediment fraction (i.e. 68 values for each of TP, OP, NAIP, AP). This was undertaken in order to evaluate the relationships among phosphate fractions as well as to view the variation in their contribution to total P values. Presentation of ANOVA results are in the form of tables showing the treatment and block values for degrees of freedom, sum of squares, mean square, calculated F, and the required F at a 95% confidence level. When significant differences occur the least significant difference (L.S.D.) value at 95% confidence is presented. These L.5.D. values were used to perform Duncan's multiple range test whose results are presented as follows: L.S.D.(.05) = 48 Treatment Means 643 630 622 614 587 538 Mean Groups This presentation allows a visual recognition of those means which belong to the same population (as shown by the solid lines). Overlapping of populations is also - 62 -apparent with this technique and therefore it allows an understanding of which means are significantly different from others. The statistical methods utilized in the techniques mentioned above are presented in Appendix 5. - 63 -CHAPTER * EXPERIMENTAL RESULTS 4-1 ZONE 2 AND ZONE 3, SUMMER, 1979 The results of the two sites sampled for phosphate sediment fractions in the summer of 1979, were tested in a 2x2 ANOVA, and a mean separation where necessary. The shallower (3 m) weedy site referred to as zone 2 (Z2) indicates that over the 52 day sampling period statistically significant changes in both apatite and non-apatite inorganic P (NAIP) occurred (See Table 4-1). Table 4-2 indicates the mean grouping for both of these fractions in Z2. It is apparent that the initial period of the summer exhibited the lowest apatite values, yet these are not all significantly different from the values at the end of the summer. The highest mean value occurs on July 23, the midpoint of the sampling period, and also just three days following the lowest mean value. NAIP groups quite succintly into two populations, with the highest mean values occurring on the three earliest sampling dates. The latter part of the summer exhibits much lower NAIP values. Note here the position and value of July 23, and compare this to the preceding sampling date of July 20. A very large difference is exhibited within this fraction. Zone 3 sediment fractions, and the other P fractions for Z2 did not exhibit any significant differences during this time period. The statistically insignificant ANOVA tables are presented in Appendix 6. Correlation matrices for Z2 and Z3 are presented in Table 4-3 and 4-4. The relationships between phosphate fractions for the sample zones and the monitored in-lake parameters are viewed in this statistical technique. The calculated 'r* values are presented in the matrix, while the significant V values at 95% and 99% probability are indicated to the right of the matrix. - 6 4 -Table 4-1 Analysis of Variance Tables for Zone 2, 1979 TITLE: APATITE-P TREATMENTS: Sampling Days BLOCKS: Re p l i c a t i o n of Sample Source of Degrees of Sum of Va r i a t i o n Freedom Squares n = 6 k = 2 Mean F Required LSD^Q 5 Square F at 95% Tot a l (nk-l)= 11 16389 Treatment (n-1) = 5 14323 2865 8.30 5.05 47.75 Block (k-1) = 1 341 341 0.99 6.61 Error (BxT) (n-l)(k-l)=5 1725 345 TITLE: NAIP TREATMENTS: Sampling Days n=6 BLOCKS: Re p l i c a t i o n of Sample k=2 Source of Degrees of Sum of Mean F Required L S D . 0 5 V a r i a t i o n Freedom Squares Square F at 95% Total (nk-1) = 11 129264 Treatment (n-1) - 5 120082 24016 21.81 5.05 85.33 Block (k-1) = 1 3675 3675 3.34 6.61 Error(BxT) (n-l)(k-l)=5 5507 1101 - 6 5 -Table 4-2 Duncan's Multiple Range Test for Zone 2,1979 APATITE-P Least s i g n i f i c a n t difference = 47.75 units = mg/kg Treatment Means 643 630 622 614 588 538 Mean Groups Sample Date J u l y 23 Aug 16 Aug 19 J u l y 20 June 28 June28 NAIP Least S i g n i f i c a n t Difference = 85.33 Units = mg/kg Treatment Means 270 268 205 65 53 40 Mean Groups Sample Date July 17 June28 Ju l y 20 Aug 16 Ju l y 23 Aug 19 _ 66-Table 4-3 Corre l a t i o n Matrix f o r Zone 2, 1979 TP NAIP AP OP CDB pH TEMP P0 4 GRAD NAIP .576 AP -.357 -.828 OP -.381 -.933 .634 CDB -.442 -.738 .800 .577 PH -.307 -.701 .687 .662 .776 TEMP -.895 -.811 .515 .701 .661 .494 PO4 .824 .419 -.103 -.318 -.067 -.304 -.637 GRAD -.705 -.797 .751 .608 .606 .271 .794 .360 TIME -.189 -.822 .495 .967 .490 .569 .571 -.303 .464 PO^ = bottom water concentration GRAD = orthophosphorus gradient df = 4 r(.05) r(.01) = .811 - .917 _ 67. Table 4-4 Cor r e l a t i o n Matrix for Zone 3, 1979 TP NAIP AP OP CDB pH TEMP PO^ GRAD NAIP .474 AP .315 -.668 OP .354 -.436 .625 CDB -.693 -.113 -.473 -.275 pH .262 -.017 .078 .695 -.174 TEMP .124 -.679 .753 .850 .053 .285 P0 A .622 .424 -.059 .527 -.110 .426 .348 GRAD .493 .115 .628 .114 -.410 -.419 .247 -.0003 TIME .683 .046 .459 .644 -.247 .507 .422 .515 .496 PO^ » bottom water concentration GRAD - orthophosphorus gradient df - 5 r(.05) - .755 r(.01) - .875 - 68 -In zone 2 the total P fraction is negatively correlated with temperature, while positively related to bottom water P concentrations. The negative association with temperature is also noted in the NAIP fraction. NAIP associates in a strong negative fashion with the other phosphorus fractions (AP and OP) and time. This further substantiates the observations of decreasing summer levels of NAIP associated with increases in other fractions. While the organic P fraction is significantly related to time the noted increase of OP values over the length of study was not found to be statistically important. The matrix available for Z3 is presented here but recall that in the summer of 1979 no significant P fraction changes were recognized. Temperature appeared to be the only parameter which associated with changing sediment fractions. Organic P exhibited a strong positive relationship to temperature. This is similar to Z2 (though insignificant in that case) while both relationships between NAIP and temperature are negative. 4-2 ZONE 3, JUNE 1980 In the following summer the deeper non-weedy Zone 3 was sampled over a 10 day period. The results of the ANOVA performed on data from these seven sample days with five replicates, are represented in Table 4-5. Two questions were addressed in this portion of the study, the first being, what natural variability was noted in littoral sediments collected from the same site at the same time? The second question was to determine if significant differences in sediment P were exhibited over a short time period. The natural variation of sediment P fractions was evaluated by sampling one area of 400 cm^  with five replicates for each sampling date. Seven sampling dates (therefore 7x5 samples) were used to indicate this variance. Variability associated with the sampling technique is incorporated into this estimate of natural sediment - 69 -Table 4-5 Analysis of Variance Tables f or Zone 3, 1980 TITLE: TOTAL-P TREATMENTS: Sampling Days n = 7 BLOCKS: Source of V a r i a t i o n R e p l i c a t i o n of Degrees of Freedom Sample Sum of Squares Mean Square k = F = 5 Required F at 95% LSD .05 Total (nk-1) = 34 90329 Treatment (n-1) = 6 56377 9396 14.06 2.51 33.75 Block (k-1) = 4 17908 4477 6.70 2.78 Error (BxT) ( n - l ) ( k - l ) = 24 16044 669 TITLE: APATITE-P TREATMENTS: Sampling Days n = 7 BLOCKS: Replication of Sample k = 5 Source of V a r i a t i o n Degrees of Freedom Sum of Squares Mean Square F Required LSD F at 95% - 0 5 Total (nk-1) = 34 12747 Treatment (n-1) = 6 4163 694 2.24 2.51 Block (k-1) = 4 1161 290 0.94 2.78 Error (BxT) (n-1)(k-1) = 24 7423 309 TITLE: ORGANIC-P TREATMENTS: Sampling Days n = 7 BLOCKS: Source of V a r i a t i o n Replication Degrees of Freedom of Sample Sum of Squares Mean Square k F = 5 Required F at 95% LSD • 05 Total (nk-1) = 34 111509 Treatment (n-1) = 6 55393 9232 8.52 2.51 51. 15 Block (k-1) = 4 19264 4816 4.44 2.78 Error (BxT) (n-1)(k-1) = 24 36852 1536 1.41 1.85 Sampling (nk-1) = 34 36852 1083.8 Error TITLE: NAIP TREATMENTS: Sampling Days n = 7 BLOCKS: Source of V a r i a t i o n Replication Degrees of Freedom of Sample Sum of Squares Mean Square k = 5 Required F F at 95% LSD .05 Total (nk-1) = 34 118730 Treatment (n-1) = 6 98361 16394 20.18 2.51 37.21 Block (k-1) = 4 869 217 0.27 2.78 Error (BxT) (n-1)(k-1) = 24 19500 813 - 70 -variability. Table 4-5 indicates that total P and organic P vary significantly (as noted by the F values for the blocks which represent replications). The fact that the total P value registers as significantly different may reflect the effect of organic P forms changing. Both NAIP and AP are well below the F values required for significant difference. The daily replicate means, standard deviation and coefficient of variation for each P form are compared for the total sample (7x5) population statistics in Table 4-6. To evaluate short-term sediment P changes the same samples and statistical techniques of ANOVA are used. Significant differences are observed in three forms of sediment phosphorus - total, NAIP and organic. Apatite is not significantly altered in this time period. Duncan's multiple range test results are presented in Table 4-7. It is apparent that the samples from the two earliest dates, June 3 and 5 separate out in the same grouping consistently and as well June 13 groups in either the lowest or highest mean values. The correlation matrix for the data is presented in Table 4-8. As the values of PO4-P and P gradient were not collected on a daily basis (the peepers were used to summarize this period's conditions) they are not included in the matrix. The positive association between apatite P and total P is not of importance as apatite does not change significantly over this study period. Strong negative relationships between AP and both pH and temperature are also noted. NAIP exhibits strong negative associations with both OP and CDB-Fe. Over the sampling period NAIP increases while OP decreases. This is also noted in the positive V value for NAIP and time. The CDB-Fe fraction decreases significantly over time. This is reflected in a negative association with NAIP and a positive association with OP. -71 -Table 4-6 S t a t i s t i c a l Comparison of Daily Replicate Phosphorus Forms, f or Zone 3, 1980 June 3 June 5 June 9 June10 June11 June12 June 13 n=5 n=5 n=5 n=5 n=5 n=5 n=5 TOTAL P Y 6 CV NAIP Y 6 CV APATITE P Y e CV ORGANIC P Y e cv 940 980 1027 1055 1016 1047 964 23.6 32.7 35.5 29.5 52.7 42.6 12.4 2.5 3.3 3.5 2.8 5.2 4.1 1.3 105 89 213 218 191 207 229 40.5 26.2 24.5 28.1 25.0 23.0 15.5 38.6 29.5 11.5 12.9 13.1 11.1 6.8 628 641 655 652 658 643 631 30.7 12.8 10.9 12.7 17.7 6.1 19.9 4.9 2.0 1.7 2.0 2.7 0.9 3.2 210 251 160 185 164 197 104 42.7 44.9 35.0 17.1 68.4 40.2 19.5 20.3 17.9 21.9 9.2 41.7 20.4 18.8 n = number of observations Y = mean of n observations €• = standard deviation CV = c o e f f i c i e n t of v a r i a t i o n P F r a c t i o n units = mg/kg - 72 -Table 4-7 Duncan's Multiple Range Test f o r Zone 3, 1980 A. TOTAL-P Least s i g n i f i c a n t difference tQ5 = 33.75 units = mg/kg Treatment Means 1055 1047 1027 1016 980 964 940 Mean Groups Sample Date (June) 10 12 9 11 5 13 3 B. ORGANIC-P Least s i g n i f i c a n t difference #Q5 = 5 1 . 1 5 units = mg/kg Treatment Means 251 210 197 185 164 160 104 Mean Groups Sample Date (June) 5 3 12 10 11 9 13 C. NAIP Least s i g n i f i c a n t difference.Q5 = 37.21 units = mg/kg Treatment Means 229 218 213 207 191 105 89 Mean Groups Sample Date (June) 13 10 9 12 11 3 5 C o r r e l a t i o n Matrix f o r Zone 3,1980 TP NAIP AP OP CDB pH TEMP NAIP .602 AP .778 .403 OP -.021 -.799 -.044 CDB -.507 -.966 -.396 .845 pH -.705 -.244 -.817 -.145 .223 TEMP -.733 -.282 -.894 -.097 .260 .629 TIME .542 .907 -.449 -.730 -.889 -.131 -.140 df = 5 r(.05) - .755 r(.01) = .875 -74 -k-3 EKMAN TRANSECTS, AUGUST 1979 The phosphate fractionation values for the three transects completed in August 1979 were statistically analysed with the same methods as previous data, although the parameters used in the correlation matrix were somewhat different. A sketch map of the Ekman samples sites was included in Chapter 3 (Figure 3-6) Table k-9 indicates that the P values vary significantly over the distance sampled in transect 1(ET1). Neither of the two transects perpendicular to ET1 exhibited significant differences among P fractions. The seven samples were analysed in a 2x2 ANOVA using P fractions as the blocks and locations as the treatments. This technique was applied in order to identify significant differences between sampling locations. The variation among P fractions is known to be significant (i.e. comparing AP, OP, NAIP) yet the table also indicates that sample locations are statistically different. The mean separation test shown in Table 4-10 indicates that the means group into two. The six deepest sites are within one population while the shallowest site stands alone. The ranking of means very nearly follows the order of sampling with the deepest exhibiting the highest value and the shallowest, the lowest (the sample in the weedy 3-4 m depth is the only one out of position). The relationships between the phosphate values of ET1 and the other lake parameters which may be affecting them are presented in a correlation matrix table. Table 4-11 presents the 'r' values for the combination of 11 variables. Total P is significantly related to all variables except for 'distance to shore'. Significantly negative correlations exist among all P fractions and the sand size component of the sediment samples. For a better analysis of the relationships it is good to view the separate P fractions and their associations. Non-apatite inorganic P associates at the 99% level with the clay sized fraction of the sediment. CDB extractable iron, percent silt and organic matter - 75 -Table 4-9 Analysis of Variance Table f o r Ekman Transect 1 TITLE: EKMAN TRANSECT #1 TREATMENTS: Sampling Locations BLOCKS: P Fractions (0, A, NAIP) Source of V a r i a t i o n Total Treatment Block Error (BxT) Degrees of Freedom Sum of Squares (nk-1) = 20 (n-1) = 6 (k-1) = 2 (n-1)(k-1) = 12 1080578 33437 1033492 13649 Mean Square n = 7 k = 3 Required F at 95% 5573 5573 4.90 516746 454.34 1137 3.00 3.89 LSD ,05 60.00 - 76 -Table 4-10 Duncan's Multiple Range Test f o r Ekman Transect 1 ET1 Least s i g n i f i c a n t difference #Q5 = 60.00 units = mg/kg Treatment Means 399 336 327 323 313 302 214 Mean Groups Location fi 5 5 5 ^ 3 ^ (by water depth) Table 4-11 Corre l a t i o n Matrix for Ekman Transect Variables TP NAIP AP OP CBD %SAND %SILT %CLAY %ORG DEPTH TP NAIP NAIP .848 AP .836 .539 OP .968 .767 CDB .958 .943 %SAND -.993 -.853 -.804 -.969 -.965 %SILT .986 .803 .842 .961 .932 -.992 %CLAY .950 .876 .777 .922 .965 -.985 .972 %0RG .955 .856 .849 .876 .919 -.961 .951 .976 DEPTH .807 .462 .831 .813 .622 -.800 .846 .735 .776 DIST .672 .321 .831 .639 .449 -.633 .702 .543 .620 .923 %ORG = per cent organic matter DIST = d i s t a n c e to shore df - 5 r(.05) = .755 r(.01) = .875 - 78 -are also significantly associated with NAIP. Apatite P associates significantly with all particle size fractions as well as the per cent organic matter. There is no simple explanation for these relationships except that they may be reflecting their shared association with water depth and distance. The regression plot for AP versus distance to shore is shown in Figure 4-1 and is discussed later. Organic P levels related strongly with a number of parameters. At the 95% confidence limit all parameters except distance from shore are associated with OP content. As expected the organic matter reflects the amounts of organic P present in the samples, therefore these variables are not independent of each other. The association of water depth with organic P does not reflect the expected negative relationship that would be controlled by light availability for plants which produce detritus. The sand size fraction relates strongly and negatively to most parameters, while as mentioned previously per cent clay and per cent silt associate with most fractions and parameters excepting distance to shore (for silt) and water depth (both for clay). 4-4 VARIATION EXHIBITED BY THE COMPONENT FRACTIONS OF  TOTAL P Figure 4-2 presents three histograms which portray each of component fractions of total P, (apatite, organic, non-apatite inorganic) and their per cent contribution to the total P value for each sample (i.e. A p / T P X 100, NAIP/jp x 100). 68 values were calculated and plotted in order to determine the relative proportion of each form with respect to the total value, and the variation exhibited by each form. - 7 9 -F igure 4-1 L inea r R e g r e s s i o n Plot for Ekman T r a n s e c t 1 - D i s t a n c e to Shore v e r s u s A p a t i t e P h o s p h o r u s -Distance (m) -80-Figure 4-2 Range of Variation Exhibited by the Component Phosphorus Fractions of Total Phosphorus 30 40 SO 60 70 80 90 100 P a r c a n t of T o l i l P 10 2 0 30 4 0 SO 6 0 70 8 0 9 0 100 P a r c a n t o l T o t a l P E • A p a t i t e P 6 0 50 4 0 30 o Z 201 1 0 LEGEND —TIS TC 515 4 0 6 0 6 0 7 0 "o'C" " B0 TOO P a r c a n t o l T o l i l P H^} Summer 1980 X \ v Z2 1979 =BMi Ekman Transect MM Z3 1979 - 81 -The bottom axis represents the percentage contribution of that P form to the total P value (these are plotted in 10 compartments of 10 per cent). It is apparent that apatite P continually comprises the dominant portion of the total P (50-90%) while NAIP and OP tend to fall in the same region of 0-40%. The variation exhibited in apatite phosphorus is lower (a coefficient of variation of 8.5%) as evidenced by the number of values which fall into the one decile of 60-70%. Both OP and AP have a majority of their samples in two deciles, yet exhibit coefficients of variation of 38.1% and 35.8% respectively. The various origins of the samples are indicated in this histogram in order to identify whether the source of variation is due to sampling location or time. It appears from this number of samples that a relatively homogeneous variance is exhibited among the various origins of these apatite, organic and non-apatite inorganic phosphate values (i.e. samples from one time or place do not tend to group in one decile but rather spread out among the total range). 4-5 VARIATION DUE TO EXPERIMENTAL ERROR In Table 4-12 the error associated with the experimental analysis is presented. To evaluate the reproducibility of a phosphate value one sediment sample was analysed 30 times in two different runs. (14 samples per run were compared statistically). Note that the coefficients of variation are higher when the two groups are analysed as one. This indicates that analysis from run to run increases the experimental error to some degree. This is to be expected as each run involves slightly different conditions due to preparation of new standards, varying extraction conditions and slight alterations in laboratory facilities (temperature, lighting etc.). Several tests were undertaken to evaluate the sources of potential error in the laboratory technique and it appears that: 1) varying shaking times 2) - 82 -Table 4-12 S t a t i s t i c a l Comparison of a Sample Analysis Within and Between Runs BETWEEN RUNS n = 30 (2 runs included) Phosphate Fr a c t i o n Mean Standard Deviation C o e f f i c i e n t of V a r i a t i o n Total-P 1020 17.94 1.74 Apatite-P 641 14.17 2.21 Organic-P 196 20.22 10.32 NAIP 184 17.11 9.32 WITHIN RUNS n = 14 (run 1) Phosphate Fraction Mean Standard Deviation C o e f f i c i e n t of V a r i a t i o n Total-P Apatite-P Organic-P NAIP 1008 633 190 194 13.87 9.42 16.61 14.56 1.38 1.49 8.74 7.51 n = 14 (run 2) Phosphate Fract i o n Mean Standard Deviation C o e f f i c i e n t of V a r i a t i o n Total-P 1034 10.08 0.97 Apatite-P 650 13.59 1.31 Organic-P 200 23.09 11.54 NAIP 175 13.95 7.97 - 83 -sample storage and 3) use of parafin as a test tube sealant did not contribute significantly to the experimental error. Wrist action shakers were utilized to mix the sediment and extracting solution for a period of 16 hours. On occasion these machines would falter or shut down through the shaking period. The effect of shortened and/or extended shaking was unknown. A test to determine the variations in sediment P concentrations due to changing shaking time was undertaken. Six samples which spanned a time period of 8 to 24 hours were tested for variance among P forms. Within this time range no statistical significance was noted. The loss or alteration of P fractions during storage was another possible source of error. Some samples which were analysed in more than one run, and involved a storage period of at least one year, were viewed in order to perceive a direction and/or the form of phosphate gains or losses. It became apparent that while changes occurred in the P values they were not unidirectional and not consistantly from one form to another (See Appendix 6 for statistically insignificant tables). Losses of sediment P, or alterations in P fractions within the freeze-dried sediment did not appear to be a problem. The caps of the shaking test tubes are supposed to be teflon in order to reduce contamination. Parafin sealing paper was used over the tubes as teflon caps were not available. Tests for absorption, leaching and/or contamination indicated that this was not a significant source of error. -84 -CHAPTER 5 DISCUSSION Several tendencies are observed in the data through the use of statistical methods. These are: 1) Over a 52 day period changes are taking place in the inorganic phosphorus fractions of a weedy shallow site. Apatite phosphorus increases while non-apatite inorganic phosphorus decreases. 2) A spatial survey indicates that phosphorus components are strongly associated with the physical sediment characteristics. 3) The following summer in a deeper non-weedy site short-term changes occur in all fractions but apatite. 4) Natural variability of the three sediment phosphorus fractions appears to be significantly important (as before at a 95% confidence level) in the organic phosphorus fraction only. 5) No significant relationship was noted between CDB iron and pH. Yet in the temporal studies, the two areas which exhibited significant change (Z2, 1979 and Z3, 1980) exhibit high negative 'r' values for CDB-Fe and NAIP. Before continuing to discuss the results presented in Chapter 4, it is necessary to address two events which occurred during the experimental period. These two events, one a sewage spill and the other a thawing of preserved samples caused some concern as to the validity of the data. These situations and their presumed effects on the data set are presented as follows, a) The Sewage Spill A sewage treatment plant spill which occurred on 3uly 25, 1979 accidentally disposed of 25,000 gallons of treated sewage sludge in Vernon Creek. The material had been treated once in an anaerobic tank and had - 85 -experienced two settling treatments. The digested sludge which reached the creek was approximately 5% solids and contained urban sewage and industrial effluents. As the creek was experiencing low flows at this time of year, the city flushed the materials into Vernon Arm by opening the creek inlet at Kalamalka Lake. A reflection of this event is noted as a small peak on the hydrograph (Figure 5-1). The resultant influx of sewage into Vernon Arm resulted in increased coliform counts which rendered the beaches unsafe for swimming. It is unknown at what rate the material would have mixed with the water of the bay and become diluted as the hydraulics of the Arm were not studied. In order to compare the effects of this spill on the area it is appropriate to consider that previous to the implementation of the new sewage treatment plant facilities, three million gallons of treated materials (as above) were discharged into the creek on a daily basis. The effect of the change in treatment plant operations on total phosphorus and orthophosphorus concentrations for the creek and the Arm have been noted earlier (Chapter 3-3). It would seem that while this spill represents a large flux of phosphorus into the system, the volume of water and the sinks for phosphorus would readily incorporate this phosphorus without major changes to any one compartment. To view this, the orthophosphorus and sediment organic P values for the 52 day period should be considered (see Appendix 7). In both zone 2 and zone 3 no trend of increased soluble PCty-P is noted in the period following the spill. Infact water sampled for orthophosphorus at the creek mouth on several dates preceeding the spill indicated PO4-P values greater than the mean value (of 0.53 mg/1) for the creek before the implemented sewage treatment plant changes. Organic phosphorus fractions are noted to increase over the period of the summer in zone 2 during 1979, but not in zone 3. The changes in organic P in Z2 - 8 6 -Figure 5 - 87 -cannot be specifically associated with the July 25th incident, and as well the total change over the period is not found to be significantly different. While the sewage spill of July 25th should be kept in mind when interpreting the results of the 1979 data it does not seem that this influx of phosphorus resulted in forcing of the natural conditions of nutrient cycling in Vernon Arm. b) Sediment Sample Thawing In September 1980, sediment samples which had been collected and frozen during the month of June were being stored in a freezer at the University of British Columbia. A unfortunate mistake resulted in the unplugging of the freezer, such that all the samples were completely thawed when the situation was discovered. Preservation techniques up to this point involved all samples being immediately frozen and subsequently freeze-dried. The possibility of this thawing affecting the sediment phosphorus levels was investigated. Four samples, two duplicates of two days had been removed from the freezer prior to the melt for freeze-drying. This allowed some comparison of the fraction changes which took place. The ANOVA tables are included in Appendix 6. From this comparison it did not appear that the thawing changed any forms of P significantly. A recent paper by Williams et al. (1980) states that: Samples were stored frozen. Before use they were thawed and centrifuged to remove excess water: this process did not result in any increase in phosphorus leaching. It is therefore safe to assume that intercomparison of 1980 zone 3 data is appropriate as the majority of samples underwent the same thawing process. 5-1 QUALITATIVE COMPARISON OF ZONE 3, 1979 AND 1980 Sediment sampling in zone 3 incorporated a portion of both 1979 and - 88 -1980. Figure 5-2 presents the values of the phosphate fractions for this time period. A comparison of the two sampling periods allows us to view the range exhibited by each fraction over a period of approximately twelve months. Both NAIP and OP fractions exhibit a wider range during the 1980 sampling period. While the full range for the 1979 season is unknown due to non-continuous sampling it is apparent that the activity noted for 10 days in June 1980 surpasses that of the two six day sample periods in 1979. The net seasonal change noted for 1979 can be estimated by comparing the June 28 and the August 19 values. In each fraction this difference is again much smaller than the range exhibited in June 1980. This information could be interpreted in two ways: 1) the early summer period is a more active time for changes in NAIP and OP and/or 2) intensive daily sampling allows a better estimation of the natural ranges while spot sampling throughout a season can identify only general seasonal fluxes. 5-2 ZONE 2, SUMMER, 1979 The changing concentrations of the NAIP fraction in zone 2 is accompanied by a change in the opposite direction of apatite phosphorus. These changes do not necessarily indicate a chemical transformation of the phosphorus forms as the inputs and outputs of sediment were not controlled in this field situation. a) Apatite Phosphorus Inputs of apatite P, the mineral form of phosophorus could be derived from: 1) hydrologic inputs of riverine sediments 2) in situ generation of the P mineral 3) transport of apatite P from other bottom regions. 1. Hydrologic Inputs The hydrograph and the daily sediment loading of Vernon Creek where it - 8 9 -AP E 700 -650 -600 -K 2 50 " 1 5 0 -N AIP j? 50 E 250 OP O) E PH 1 50 9.0 6.0 7.0 30 20 Temp ° C 10 I I I I June 28 Figure 5-2 Phosphate Fractions for Zone 3, 1979 & 1980 I I I E.I i I j u | y 17 20 23 1979 A u g . — i — i — ' — r — • TT1— 13 16 19 j u n e 3 5 0|11|13 10 12 1980 -90 -enters Vernon Arm are shown in Figure 5-1. The high spring sediment inputs persist until mid June. The abrupt drop in flow from Vernon Creek was anthropogenically caused. On June 13, 1979 the creek where it leaves Kalamalka Lake was damned in order to impede the mixing of Kalamalka Lake water with Okanagan Lake. This was done in an attempt to contain the inputs of 2-4-D which was used to control weed growth in Kalamalka Lake. The creek was subsequently opened on July 14. Resultant flow and sediment load peaks are noted at this time. Reid (1979) in a study of Kamloops Lake of B.C. , which has a watershed covering of glacial till similar to the Vernon area, indicates that the concentration of apatite phosphorus was found to be most abundant in the 62-45 um fraction and was evident at a quarter of this concentration in the 17-10 um fraction. Her findings that 70% of the total phosphorus which enters Kamloops Lake is in the form of apatite is consistent with the analysis, by BC-NWRI, on a single sample of bulk suspended sediment from the spring flow of Vernon Creek. (Gray, pers. comm., 1980). That apatite exists in such small grain sizes could account for the delayed deposition of material at a site 175 m from the creek mouth. Smith et al. (1978), state that natural apatite crystals are sufficiently small to remain in suspension for a considerable time before sedimenting to the bottom of a lake. The maximum summer value of AP in Z2 was noted on July 23, 9 days following the creek reopening. The existence of a mature weed bed at this site could also delay the deposition of any fluvial inputs, this might be termed 'mineral interception'. Daily mean values of AP following the July 23 sampling are grouped statistically with this maximum, indicating no significant inputs following this point. - 91 -2. In situ Generation of Apatite An elevation in pH of calcium laden waters would theoretically lead to the formation of apatites, with a resultant decrease in the levels of soluble inorganic P in the water column. Ministry of the Environment data indicate that the Vernon Arm nearshore zone historically has abundant levels of soluble Ca (30-35 mg/1). An increase in pH from 7.5 to 7.9, accompanied with a drop in soluble PCty-P from 18 ug/1 to 5 ug/1 is noted between July 20 and July 23. Yet from the theoretical solubility curves presented in Figure 2-2 it appears that with Ca concentrations of 35 mg/1, an increase to pH 7.9 would limit the levels of soluble P to below 0.01 ug/1. If the formation of apatite P occurred at this time, a soluble P supply from other sources would have to be generating the excess PO4-P which is noted in the water column. 3. Apatite Transport The possibility of apatite transferral from one region of the lake to the zone 2 site is another explanation for the noted increased of apatite P. The results of the sediment pan collection were seasonal values only and while a higher sedimentation value (.08 g/cm2) was noted in Z2 (Z3 =.02 g/cm2) it was not possible to distinguish separate input events. Bottom water velocity during sampling events was noted to be unidirectional and not detectable with the available equipment. Yet transport of material between sample dates is not ruled out and as mentioned previously strong evening winds did generate large surface waves on occasion. In order to determine if an event of significance did occur between the sample dates of July 20 and July 23 meteorological data were plotted. July values of wind direction and speed, at a weather station located on a knoll in Vernon, (approximately two miles upstream of the mouth of Vernon Creek) are presented in Figure 5-3. Wlndspeed and Direct ion for July 1979 Vernon A r m -» SE W SE SE S SW W E SE NE NW N N N N S NE N SE S NE E SE SW SE W W N SE SE N E SE S SE H tit SW S S W SW W S W W SW SW SW W W SW S NW N NU S E N N SE 30 TJ Zx>\ a "10 * J u l y 2 4 5 6 B ^ 10 11 12 13 14 15 I t W N E NW SW SE SE SE N SE S N N N SE NE N SE SE SE N W W SW SW W SW SW w S W W N W N W N N S N N N S E E W S W S S E S N N S E S E NE 10 5 ift • July t, H » 5B Ti fi * s fi 3 n « » » 3i O C i w - 9 3 -In order to create surface disturbances on Vernon Arm the wind direction would have to be west or southwest in order to maximize fetch. Several evening events are noted from these directions (see July 2, 11, 20, 21, 22, 28, 29, 31). The period preceding the July 17 and July 20 sampling dates are relatively calm, yet the evening of the 20th through the early morning of July 23 exhibits consistently strong evening winds (up to 33 km/hr - 20 mph.) The disturbance of the bottom by wind generated waves caused resuspension of material. This was evidenced as reduced visibility by the diver sampling for sediment in the lake. This phenomenon was noted at both sites 2 and 3 and therefore would appear effective even in the deeper 6 m site. It is difficult to ascertain if this resuspension of bottom materials caused the change in apatite values for zone 2 as one might expect the same effect in zone 3. Yet from the Ekman transect which compared P fractions over these distances it seems that AP values do not differ significantly. A resuspension and subsequent settling of apatite particles might not change the surface concentration. If macrophyte interception of apatite inputs from fluvial sources was indeed occurring following the reopening of the creek, this physical disturbance of the weed bed could explain the increased apatite composition of the sediment following July 20. 4. Temperature Effects In the data sets from the first summer insignificant, but positive correlations exist between apatite values and temperature yet in Z3 1980 a significant negative V value is observed. This negative relationship coincides with the findings of Smith et al. (1978). It was noted that micro-organisms were able to utilize sufficient orthophosphorus from apatite samples, and that test algae were found growing on the surfaces of apatite crystals. Increases in temperature generally stimulate the growth of these micro-organisms, which -94 -may explain the relationship noted in Z3 between increasing temperature and decreasing apatite. b) Non-Apatite Inorganic Phosphorus The daily mean values of the zone 2 NAIP fraction are also noted to change significantly on the July 23rd sampling date. In this case the three earliest sample dates exhibit the highest values while post July 22nd values are up to 200 ug/g less. As discussed earlier several factors are known to affect the levels of NAIP as this form contains the most labile compartments of sediment P. Some factors which may be reflected in increasing NAIP values in this shallow, weedy site are: 1) changes in the overlying water chemistry 2) iron associated phosphate which undergoes chemical changes 3) biotic usage of available PCty-P. 1. Changes in the Overlying Water Chemistry Figure 5-4 presents bottom water data collected in zone 2 and zone 3 for the sampling period of 1979. In regression analyses NAIP correlated significantly with only temperature in Zone 2. The values of pH, which control solubility products, were maintained within the alkaline range of 7.4 and 8.3. According to Kamp-Nielsen's (1974) experiments aerobic phosphate exchange was not associated with iron or aluminum precipitates in this pH range. pH and CDB-Fe exhibit a high positive V value in this data set but it is apparent from Figure 5-5 that Fe values do not exhibit a significantly wide range. Therefore this relationship is not considered to be causal. (The roles of occluded versus non-occluded iron compounds will be discussed further). The phosphorus gradient, as calculated from squeezed sediment interstitial water and bottom water concentrations, did not correlate significantly with the NAIP fraction. Yet a plot comparing the temporal changes -95-F i g u r e 5-4 B o t t o m W a t e r P a r a m e t e r * M o n i t o r e d Zone 2 and Zone 3 1979 o to CM o o » «0 CM • o> c c O o NI NI 1° ,\ t* V r. •A i t: .-5*-<0 O E • * "5—3> (0) 'flujii r> ** - . |u*|ptJD r 0 d o —i - 9 6 -F igure 5-5 L i n e a r R e g r e s s i o n P lot for Z o n e 2, 1979 -pH v e r s u s C D B Iron r= .776 1—\ c © 90-E •o <D w E 80-CO c o cn — © o 70-E o k_ i M r — » — 7.0 — i — 7.5 — i — 8.0 PH - 9 7 -of interstitial PCty-P and NAIP indicates an interesting relationship. This information is presented for Z2 in Figure 5-6. Note the strong inverse relationship and the date on which values significantly change - July 23. The linear regression plot for these two parameters is presented as Figure 5-7. The r value of -.796 is not significant at the .05 level (r = .811) but it does indicate the general negative relationship. Changes in the labile sediment P (represented here as the NAIP fraction) have been considered to be affected by phosphorus concentration gradients (Lee, 1970). The technique used in this study to determine the P gradients during the summer of 1979, may not have been sensitive enough to detect this relationship. Yet a distinct inverse relationship can be noted by viewing the sediment NAIP and interstitial PCty-P data. The theory regarding P gradient effects on sediment P was presented by Li et al. (1972). Inorganic P associated with sediment particles regulates the IP status of the associated interstitial water, through interrelated adsorption-desorption and exchange processes. IP in the interstitial water in turn influences the dissolved IP levels in the overlying water, the magnitude and direction of the influence being dependent on the relative concentrations of dissolved IP in the interstitial and lake water. Interchange between these two components is probably regulated in part by diffusion but mainly by mixing. Figure 5-6 cannot be explained simply with the concentration gradient theories, as the presence of a large weed bed in zone 2 undoubtedly exerts some influence on the interstitial P concentrations, this will be discussed further in a following section. 2. Iron Associated Phosphorus pH changes have been considered to be ineffective in altering the Fe - 9 8 -F igu re 5 In te rs t i t i a l Wa te r P h o s p h o r u s N o n - A p a t i t e Inorganic P h o s p h o r u s v e r s u s T ime Zone 2 1979 3 0 0! 2 5 0-2 0 0^ 1 5 0 -1 0 0-5 0 i N AI P* • CD 2 . 5 E \ 2 . 0 H . 5 o co IN T - P - 1 . 0 CO © 0 . 5 i June 2'8 July 1 '7 j 2"3 Aug. 1'3| 1'9 2*0 1 6 •99-Figure 5-7 L i nea r R e g r e s s i o n Plot for Z o n e 2 1979 - In t e r s t i t i a l P v e r s u s N o n - A p a t i t e Inorgan ic P r - .7 9 6 3 0 O | O) >2 0CH E < 2 1001 0 1.00 2 . 0 0 Int. P (mg/l) 3 . 0 0 - 100 -associated PO^ -P for this data set. Yet the role of the amorphous iron gel complex, estimated by the sediment extraction method, may be important (Syers et al. 1973). Li, et al. (1972), indicated that the levels of sediment NAIP and the ability of these sediments to sorb additional IP were related by the presence of an amorphous gel complex which was dominated by Fe. The CDB technique of determining iron in sediments represents both the occluded and. non-occluded iron oxides. Therefore inactive iron phosphate complexes which require pH change stimulation, as well as sorbing iron gel complexes will both be represented in the CDB-Fe value. Since it is not known what proportion each of these iron forms represent in the CDB values it is inappropriate to regress CDB-Fe and NAIP as they are not mutually independent. What can be deduced from this data set is that iron associated phosphates of the occluded form are not controlling the P regime of this nearshore zone. If that were the case changes in CDB-Fe should be associated strongly with soluble PCty-P values over both time and space. The sediment CDB-Fe values exhibit a small range compared to the other fractions of sediment P (c.v. of CDB-Fe = 9%, c.v. of NAIP = 36%). This stability of CDB-Fe content indicates that the role of the amorphous gel complex in absorption-desorption is probably important here, but the complex itself is not changing form but rather acting as a site for exchange. 3. Biotic Use of Available Phosphorus The investigation of the role of rooted aquatic plants in nutrient cycling has recently been given more attention in the literature. Macrophytes are known to absorb nutrients far in excess of their normal metabolic requirements (Kistritz, 1978), but for some time it was suspected that the leaves, as opposed to the roots were the main site for nutrient uptake. - 101 -The lack of a well defined root system in submersed, as compared to emergent macrophytes, has led some investigators to believe they were of secondary importance (Barko and Smart, 1980). Through the use of radioactive labelling Carignan and Kalff (1980), concluded that nine common species of aquatic macrophytes can take up to 100% of their phosphorus from sediments when grown in situ in both a mesotrophic and mildly eutrophic bay. Myriophyllum spicatum was one of the species included in this study. The uptake of PCty-P by the aquatic macrophytes was found to correspond almost perfectly with the mobile fraction of sediment P, which is considered to be the interstitial P of lake sediments which is in dynamic equilibrium with a variable amount of P loosely held by the particulate phase (Carignan and Kalff, 1980). While the sediment fractionation technique does not distinguish this mobile fraction specifically, it does represent a portion of the NAIP fraction. Interstitial P then, can be utilized by the roots of macrophytes. The fibrous root system of M. spicatum are adventitious, beginning above the sediment and penetrating downward up to a depth of three meters. This aquatic macrophyte has the capability of utilizing either its root system or its foliage for uptake of soluble P. It is a scavenger and can draw nutrients from the most accessible source switching from roots to leaves within hours (Painter, pers. comm., 1982). Interstitial phosphorus values increase greatly on July 23 then slowly begin a downward trend. This abrupt change could indicate that the plants suddenly reduce root uptake of PCty-P from interstitial stores and switch to a supply in the water column. This reduction of interstitial P use would presumably be associated with an increase in sediment NAIP as the equilibrium with the available P is restored. The data for the surface sediments do not - 102 -indicate this, but rather the NAIP values decrease and remain low for the rest of the summer. Since M. spicatum can utilize both sediment and water as a nutrient source (Bristow and Whitcombe, 1971, Kanasneimi, 1980) it would be expected that they would draw from the accessible pool. The odd behavior of the interstitial P and NAIP fractions in zone 2 could be explained by the following scenario, but strict evidence for this scheme is not available. With three days of strong winds generating surface waves in Vernon Arm bottom materials would be resuspended. Adsorption and desorption of the mobile NAIP fraction would occur while the fines remained suspended in the turbulent water. The desorbed soluble P could either be diluted within the water volume of the bay, resorbed to material or taken up by aquatic organisms. Since the bay was mixing well over this period of time one would assume that soluble PO^-P levels would dilute to some extent. But the fines would also be mixing within the water column, such that they would have a chance to resorb some of the lost PO^-P. Since NAIP levels are noted to drop severely on July 23 and remain low for the rest of the summer, it would appear that the P has associated with another component. If the macrophytes alternated their source of P uptake and exhibited luxury consumption (uptaking nutrients beyond their immediate need) at this time, the soluble P which was once associated with the mineral material would now be incorporated as plant material. The demands on interstitial P as a source of PCty-P would be reduced, therefore allowing increased values between July 20 and 23. As the summer progressed and soluble P levels dropped to normal levels the plants would switch back and draw PCty-P from the sediment. The decreased values of surficial sediment NAIP would remain low for the rest of the summer period as the supply of soluble inorganic phosphorus in the water column has been utilized elsewhere. - 103 -The competition between plant uptake and sediment adsorption can be seen to favor the plants in that they exhibit an uptake process which can contain their collected nutrients, whereas sediment which is passively moved throughout the water column will adsorb and desorb depending on the ambient conditions. The influx of soluble P associated with the sewage spill on July 25 would allow the plants to continue to draw nutrients from the water column, c) Causal Factors Affecting Zone 2, 1979 In order to view the relative timing of the salient changes which occurred in zone 2 during 1979, the hydrologic and wind regimes are presented along with the significant sediment phosphorus changes (Figure 5-8). When this data is juxtaposed it is apparent that mineralogical inputs from Vernon Creek on the July 14 opening could have been mixed by strong southwesterly winds which occurred on July 21 and 22. The resuspension of bottom materials combined with wind disturbance of the material stored within the weed bed could account for the abrupt changes in both the NAIP and apatite fractions. Note again that the sedimentation pans were used only for seasonal collections and therefore specific events could not be identified. 5-3 EKMAN TRANSECTS a) Particle Size The results of the spatial transects indicate that the physical composition of the sediment strongly relates to sediment phosphorus fractions. Each sample in the ET1 transect associates significantly with the per cent silt and clay while they each associate negatively with per cent sand. In 1969, Frink recognized that changes in the P fractions at different depths in a lake were actually a function of changing sediment composition as opposed to varying conditions at the different depths. Finer materials were sorted and transported -104-Figure 6-8 C a u s a l F a c t o r s A f f e c t i n g Z o n e 2 1 9 7 9 Hydrologic and Wind Regimes In Relation to Apatite and NAIP Changes SW E SE SW SW W 2 3<H a. • •o i i o i days ot strong SW winds r— —i—i—i— July i 17 20 23 300-1 200-1 650i 600H p. < 100 i a. < 550 NAIP AP»v * / % » < I \ June 28 July 17 20 23 - 105 -to the deeper areas while heavier grain sizes remained in the shallower high energy zone. Williams et al. (1976) attempted to determine size and P fraction relationships from 48 surficial samples from Lake Erie. They found that NAIP and OP were concentrated in the fine grained sediment while organic phosphorus values were generally lower in the nearshore zone. Clay particles and other small grained materials which have broken edge faces have the capacity to sorb ions. High adsorption values are noted for fine grained materials due to their increased surface area per volume. As materials become larger and more spherical fewer adsorption sites are available and smaller surface area to volume ratios are presented for potential adsorption sites. Of the seven samples collected along Ekman transect 1, only the shallowest sample exhibited any difference in particle size composition. This final sample was predominantly sand sized materials. The other six samples in the transect were strikingly similar in particle size composition, with clay sized material comprising 14-15% and silt 33-38% (See Appendix 7) these small grain sizes would include the amorphous Fe gel complexes, Al, Ca phosphate precipitates and clay particles, all which exhibit the potential to adsorb PO^ -P. b) Apatite Phosphorus The association of apatite P with distance to the shore was noted to be significant in Chapter 4 (Figure 4-1). This relationship is likely a function of the grain size of the apatite fraction as it is noted to increase as the water depth and distance to shore increases. If the apatite fraction is predominantly less than 63 microns it will be removed from the nearshore zone due to sorting by wave energy. Even though inputs of apatite are delivered to the lake from the creek mouth, this size range would be too small to settle out in the first few - 106 -hundred meters of the river plume. An evaluation of deeper sites in front of and away from the creek plume coupled with estimations of fluvially delivered apatite grain sizes would allow a better understanding of the distribution of AP delivered to Vernon Arm by Vernon Creek, c) Organic Matter The per cent of organic matter was also determined for these samples. While the shallowest sample has the lowest value, the six remaining sites have approximately equal values ranging from 8.0-9.0%. The four samples following this shallow sandy site were located within the weed bed, but the final two samples were in the deeper non-weedy area. The two final values exhibit similar organic matter values to the preceeding four samples. The weed bed had not begun to die back on this date, although some detritus from the plant material, of the previous years weed beds would be expected. The inputs of the sewage spill three weeks earlier could have masked any difference along this transect, but the volume of the spill, the distance required for uniform dispersion and the time of sampling make it difficult to accept this explanation. Possibly the inputs of phytoplankton and benthic organisms, coupled with transport of bottom materials within the shallow littoral zone account for the consistency of organic matter content. Alternatively the mineralization of organic matter may be occurring at different rates in different regions. Williams et al. (1976) found that the spatial variation of phosphate fractions in the Lake Erie basin did not exhibit any trend. The 48 surface sample P values could not be linked to any areas of major P inputs to Lake Erie. In this case the researchers felt that distribution of sediment P was determined by other parameters which affect sedimentation, such as water movement. - 107 -In this data set, only one sample falls significantly outside of the main group. This dominantly sandy sample is located closest to the zone of P inputs yet does not exhibit high P values. The other ET1 samples do not allow the proximity of a pollution source to be identified, as their P fractions are not significantly different. Spatial variation seemed to be more strongly controlled by grain size than availability of soluble P. 5-4 ZONE 3, JUNE 1980 a) Natural Variability Over a 10 day sampling period (in June 1980) NAIP and OP fractions were noted to change significantly in value. Only apatite phosphorus did not exhibit any changes. The variability in replicates of these samples, exhibited statistically significant error in the organic fraction. The results of the 2x2 ANOVA table (Table 4-5) indicate that the natural variability exhibited by the organic fraction does not exceed the variability exhibited over the 10 day period (i.e. block (replication) F value is less than treatment (sample day) F , which are both less than the F value representing the interaction between blocks and treatments). Therefore we can assume we are looking at real changes in the organic P in this time frame. Changes in the organic P sampled from a 400 cm^ plot, as five replicates per day, varied in sediment concentration while the other portions (NAIP, OP) did not. This would indicate that the sampling method is not at fault (as both NAIP and AP are within the statistically significant range) and that the method of obtaining OP by subtraction is not a problem (as NAIP is also an additive term). Therefore the significant variation exhibited in replicate samples of organic phosphorus should be natural. - 108 -b) Interstitial Phosphorus The profile of interstitial PO^-P was evaluated for this time period with the use of two peepers planted in the sediment. Figure 5-9 indicates the average values obtained, to a depth of 28 cm. Accompanying these data are the sediment core values (TP, NAIP) for two sample days. The NAIP values indicate that the minimum values generally coincide with that depth of sediment which appears to experience the redox plane (2-6 cm). This zone fluctuates to some extent and causes precipitation and solubilization of Fe precipitates due to changing oxygen conditions. To a depth of approximately 6 cm the POzpP is generally associated with the sediments, with less available as interstitial P (this is also a function of the availability of Fe for precipitation). Further down in the profile a larger portion of PO^-P is soluble as interstitial P as the redox conditions do not permit phosphate precipitation. Migration of soluble PCty-P within the lower zone, due to concentration gradients has been noted (Carignan and Flett, 1981) and can aid in explaining the variation in NAIP with depth. (Fluctuating concentrations of soluble POii-P due to migration causes concentration-dependent adsorption and desorption at depth). While the precipitate components of NAIP at depth are lessened due to the absense of oxygen, the mobile loosely adsorbed components still react with the surrounding environment. c) Organic and Non-Apatite Inorganic Changes The factors affecting the levels of sediment organic P are: 1) inputs of detritus 2) micro-organic population 3) ambient water conditions controlling micro-organisms such as temperature, oxygen, and pH. The existence of oxygen in the top few centimeters of sediment was maintained over the sample period, as evidenced by the presence of abundant oxygen in the water above the sediment. The changing temperature over the 10 day period may have had some effect on the changing levels of organic -109-Figure 5-9 I n t e r s t i t i a l W a t e r C o n c e n t r a t i o n P r o f i l e a n d P h o s p h a t e V a l u e s f o r S e d i m e n t C o r e s Z o n e 3 1 9 6 0 Interstital Water Profile Sediment Core P (mg/kg) NAIP Total P -2-0 2-4 6 8 10 12 1*1 16 18 20 22 24 26 June 3 5 3 5 0 100 260 ci 160 260 800 9001000 860 900 1000 K> ! / '•' /! /! •/ f t I ' ' 1 1 I I I ' ' ' /.• I t .' / \ » » \ / \ t \ \ N t I I • I* -" '! \l il t II I I \ \ . I • I t • \ • \ 1. V « "1 500 ' 2000 3000 i o b o P O 4 - P U i g / 0 - 110 -phosphorus. Figure 5-10 indicates how temperature fluctuates with respect to the changing values of NAIP and OP. The mineralization of organic matter is the breakdown of detrital material. Golterman (1973b) found it to be strongly temperature dependent and scarcely detectable at 3 ° C . The liberation of phosphates into the water as soluble P O 4 - P was 50% complete a few hours following the onset of cell autolysis (Golterman, 1973b). Hooper, (1973) explained that while autolysis is an important factor in P liberation the role of bacteria had not been properly evaluated. He stated that while up to 40% of the cell phosphorus is liberated shortly after cell death, 80-90% is liberated within 24 hours (due to bacterial breakdown). Short-term changes in NAIP and OP can generally be seen to be moving in opposite directions. A general decrease in OP over time is associated with an increase over time in NAIP. The most dramatic changes occur between June 5-9 and 12-13. Note the temperature patterns at the time. (Figure 5-10). If temperature increases stimulated organic P breakdown the release of soluble P O 4 - P would be towards the interstitial water. The migration of this P O 4 - P towards the water column and to the binding sites on the fine materials adsorptive sites is expected. Therefore increasing temperature could decrease organic P while increasing NAIP levels. Temperature does not correlate significantly with either NAIP or OP in this case. This could be explained by the existence of activation temperatures, or threshold values. While the general trend is one of organic P loss throughout the sampling period the temperature actually drops in the first few days. This temperature change may not affect certain groups of bacteria or limit autolysis, but rather -111-F igure 5-10 Non-Apa t i t e Inorganic, O rgan i c Phosphorus and Tempera tu re ve rsus Time Zone 3 1980 2 0 o 18 © 3 16" to I— e 14" a E • 12-l -1 o-/ 240-| 220 2 0 0-18 0--160-] i 4 0-a 1 20-100 80 I A .NAIP / s s \ s V . ^ v. ' \ / •OP 1 1 1 — r 3 5 9 10 1 1 1 2 13 Time (days) - 112 -just alter the rate of the process. The sharp increase over two days of 6 ° C could potentially have activated more bacteria and/or increased the rate of autolysis, which resulted in the large decrease of OP between June 12-13. Other factors which could affect OP changes, such as removal of organic matter by mechanical activity or the migration of the population of micro-organisms do not seem acceptable when the other data are considered. The concomitant change in NAIP points towards the process of mineralization. The 10 day period included relatively calm and cloudy weather, such that bottom turbulence by wind storms was not a relevant factor. Temperature alone cannot explain the variations but rather appears to play an indirect role in influencing biological activity. - 113 -C H A P T E R 6 SUMMARY, CONCLUSIONS AND RECOMMENDATIONS The present investigation studied the variability of sediment phosphorus in the littoral zone of Vernon Arm of Okanagan Lake, British Columbia. The experimental approach used to address the questions presented in this thesis indicate that: 1) changes in sediment P are detectable in an oxic littoral zone. Natural, temporal and spatial variations are noted. 2) the phosphorus is moving both into and out of the sediment. The direction is not uniform for all P fractions and is dependent upon the ambient limnological conditions. Figure 6-1 portrays the important phosphorus pools and fluxes noted in the Vernon Arm littoral zone. Natural variation of the phosphate fractions was determined through the analysis of replicates from single small plots. Spatial variability as determined from transects and comparisons of two environmentally different zones was undertaken. Temporal variability, as determined from a seasonal sampling period of 52 days and an early summer 10 day period was evaluated with respect to certain parameters of the overlying water column. 6-1 NATURAL VARIABILITY The natural variation of sediment phosphorus was evaluated with a series of replicates sampled from 400 cm^ plots. With seven sampling events consisting of five replicates each it appeared that organic phosphorus was the only fraction that exhibited significant variation within sample replication. The use of a two way analysis of variance allowed for the separation of replicate variance and temporal variance. While the variance exhibited within the replicates of organic P h o s p h o r u s P o o l s a n d F l u x e s In V e r n o n A r m L i t t o r a l Z o n e S o l u b l e P w a t e r s e d i m e n t d e c a y - 115 -P was significant it did not exceed the variance associated with the temporal changes. This indicates that the changes in organic P with time are real and not just an artifact of natural sediment variation. 6-2 SPATIAL VARIABILITY Spatial variability of sediment phosphorus was observed within the nearshore zone but tended to relate to the physical sediment characteristics rather than the relative position of the sample site with respect to inputs of phosphorus. This is more a function of the sorting of sediments by the energy of both creek inflow and waves such that heavy particles, which have lower P content, are deposited closer to shore while finer materials travel lakeward. The sediment P of the two environmental zones sampled exhibited different behavior over the 52 day period. The deeper non-weedy zone did not exhibit any significant (95% confidence level) changes while the shallower weedy site underwent changes in the non-apatite inorganic and apatite fractions. 6-3 TEMPORAL VARIABILITY Changes in phosphorus fractions over time were noted in both the 52 day study and the 10 day sampling period. Wider ranges of the NAIP and OP fractions were noted for the intensive 10 day sample period as compared to the net seasonal change, and spot sampling changes observed in 1979. In the seasonal study (52 days) only the shallow weedy site exhibited significant changes. Apatite P and non-apatite P were noted to increase and decrease respectively. The changes in these chemical forms of phosphorus were noted to be associated with turbulent water transfer and weed nutrient usage. The effect of wind generated waves in the P budget of Vernon Arm appears to have caused significant changes. Potentially it may have: - 116 -1) disturbed the weed bed and caused a deposition of apatite P held on plant foliage 2) resuspended bottom sediments which underwent desorption therefore reducing the non-apatite inorganic fraction 3) caused increased levels of soluble P in the water column such that macrophytes were enabled to switch their source of nutrient supplies from sediments to the water column. It is difficult to ascertain if the apatite P is being generated in situ, although with an increase of soluble P in the water column following the turbulent conditions, sufficient levels of soluble orthophosphorus would have been available for chemical generation. The increase in apatite P therefore could be a combination of in situ generation and additional fluvial inputs. The short-term 10 day study indicated that organic phosphorus was significantly decreasing while non-apatite P increased. The limnological characteristic controlling these exchanges appears to be temperature related. The increase in bottom water temperature over this time period seems to have stimulated mineralization of the organic fraction resulting in increased non-apatite P. In both temporal studies the role of iron in controlling soluble phosphorus levels was not seen to be a function of occluded iron complexes but rather appeared to play a role in the adsorption-desorption process as non-occluded iron complexes. 6-4 RECOMMENDATIONS To manage lakes in terms of eutrophication we see that the shallow littoral zone which has long been considered inactive in the sediment P budget, must be viewed more closely. As a number of this study's results are - 117 -speculative, it is apparent that future investigations of undisturbed, unenclosed littoral sediments should include: 1) monitoring of plant nutrient levels to evaluate their role as a nutrient 'pump' 2) quantification of live microbial biomass and/or microbial activity in both natural sediments and cores incubated at different temperatures in order to elucidate the microbes role in the noted temperature effects 3) collection of event oriented sediment pan data throughout the height of the water column. This would allow an estimation of the amount of resuspension as well as enable P fraction analysis on materials suspended at different heights in the water column. Turbulent transfers of the mobile phase of inorganic phosphorus has been seen to be effective in altering the seasonal pattern of littoral sediments. The magnitude of this exchange needs to be evaluated with respect to a full lake phosphorus budget in order to determine its relative importance, as it does not appear to be significant in a non-weedy area where there is less competition for soluble orthophosphorus. An estimation of sediment P fluxes over a season can be determined by periodic sampling but the magnitude and frequency of event oriented fluxes will be overlooked. The periods of major activity, such as early summer when mineralization of organic P appears important, as well as the occurrence of sediment P altering events (such as resuspension) should be evaluated with respect to estimations of annual P budgets. In order to properly evaluate the importance of these P fluxes the timing of these changes in sediment P forms with respect to the needs of the biotic community should be undertaken. 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The application of the phosphorus loading concept to eutrophication research, National Research Council of Canada Publication No. NRCC 13690 of the Environmental Secretariat, pp. 44. cr F E N v I R U N M E N T EST RESULTS' FOR S I T E 0500091 A L L V E R N O N C H . " U / S ' . M T H . O K A N . 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METH 117 PREP PHENOL METH 118 PREP PHOS ORT METH I 19 PREP PHCS T C T M E T H MG/L L 10 . 0150 MG/L 0101 2 . 0 6 0001 0 . 3 8 0101 0 . 6 3 0001 0 . 7 0101 0 .94 0001 0102 4 .35 PPP l 1.4 0101 1.67 0001 2 .93 0001 4 . 4 4 000 1 1.58 0001 L 10. 0101 0.82 0001 3 .07 0001 1.429 0001 L 10. 0101 L 10. 0101 1. 0102 1 . 6 000 1 01 1 0 . 8 9 0101 1.61 0001 0 1 1 2 . 0102 4.00.2 000 1. 01 1 2. 0102 3.46 0001 0 1 I 9«_4^__0 1 01 0 .84 0001 0.54 0 101 L 10. 0101 2 9 . 0 1 0 2 0 1 1 0 1 1 2. 0102 0 . 9 3 6 0001 3 . 5 6 0001 MG/L 0.291 1701 0 . 1 5 2 1703 0 . 3 3 6 1703 0 . 9 4 1703 0.61 1703 0*333 1703 0 . 2 1 9 1703 0 . 7 4 5 1703 0 . 1 9 6 1703 0 . 8 4 1703 0.11 1703 0 . 1 8 9 1703 0 . 7 4 6 1703 MG/L 1.03 9191 0 . 4 0 6 0101 0.272 <HQt. 0 . 15 0101 0 .191 0103 0 .81 0103 0 . 3 7 7 0103 1.03 0103 0 . 9 4 5 0103 0 . 5 1 6 0103 0 . 4 3 8 0103 0 . 2 6 3 0103 0 . 8 4 0103 0 . 3 S 9 0103 0 . 3 6 0103 0 . 3 6 9 0103 0 . 9 S 0103 0 . 7 7 6 0103 0 . 1 4 2 0103 0 . 2 2 7 0103 S I T E OE00091 C O N T I N U E D TrSf "ReSuLTS F O R S I T E 0 5 0 0 0 9 1 S U B M I T T I N G A G E N C Y : A L L D E P T H : A L L S A M P L I N G L O C A T I O N : A L L M I N 1 S I H Y • F~~ V E R N O N C R . U / S . M T H . O K A N . L K ~ E N ~ ~ V — r " R 0 ~ N ~ H ~ E N T I t NLVhMMLH—T9HT PTTOE P P SHEET 6 OF 1 2 PAGE 2 FOR 0I JANUARY I 9 6 S T O 16 NOVEMBER 1581 * * S T A R T * * * F I N I S H * D E P T H S B S A M P L E C 1 1 3 P R E P 1 1 4 P R E P 1 1 5 P R E P 1 1 7 P R E P I 1 B P R E P 1 1 9 P R E P V H P H M V M 0 H M M E T R E S A G T P L O C T N I T K J E L M E T H N I T T O T L M E T H B . O . D . M E T H P H E N O L M E T H P H O S O R T M E T H P H O S T O T M E T H 7 7 0 S 0 2 1 4 3 0 7 7 1 1 1 9 1 5 3 0 TPBTra"oT~T3TO~ 7 8 0 5 1 0 1 6 3 0 7 8 0 9 0 5 1 3 1 0 7 9 0 6 1 9 1 4 1 5 7 9 1 2 0 4 0 0 0 0 8 0 0 3 1 3 1 1 3 0 9 0 0 5 2 7 - 1 ^ 1 3 5 8 0 0 7 0 2 1 6 0 0 8 0 1 0 1 5 1 3 3 0 8 1 0 6 1 0 1 2 0 5 0 0 5 0 1 M G / L 0 . 9 0 1 0 1 M G / L M G / L M G / L M G / L 0 . 0 9 5 1 7 0 3 0 0 5 0 1 0 O S 0 1 1 0 0 5 0 1 0 . 4 6 0 1 0 1 0 . 4 0 1 0 1 0 . 4 5 0 1 0 1 1 . 0 7 0 0 0 1 0 . 9 9 0 0 0 1 0 . 5 5 0 0 0 1 0 0 5 0 1 0 0 5 O 1 0 0 5 0 1 0 0 5 0 1 0 0 5 0 1 0 0 5 0 1 0 0 5 0 1 0 0 5 0 1 0 . 5 2 0 1 0 1 0 . 4 9 0 1 0 1 0 . 5 3 0 1 0 1 0 . 9 1 8 0 0 0 1 0 . 8 5 0 0 0 1 1 . 2 3 0 0 0 1 L 0 . 0 0 2 0 4 0 1 0.013 1703 0 . 4 4 0 1 0 1 0 . 4 2 0 1 0 1 1 . 3 0 1 0 2 2 . 0 0 0 1 IB. 0 1 0 1 L 0 . 0 0 3 1 7 0 3 0 . 2 9 0 1 0 1 0 . 4 9 0 1 0 1 0 . 5 8 0 0 0 1 MG/L 0 . 2 7 0 1 0 3 0 . 0 7 0 1 0 3 0 . 0 4 2 1 7 0 3 0 . 0 3 8 0 1 0 3 0 . 0 2 3 1 7 0 3 0 . 0 7 6 0 1 0 3 0 . 0 1 4 1 7 0 3 0 . 0 6 2 0 1 0 3 0 . 0 3 6 1 7 0 3 0 . 0 2 2 1 7 0 3 0 . 0 7 1 0 1 0 3 0 . 0 5 2 0 1 0 3 0 . 0 3 4 1 7 0 3 0 . 0 7 5 ~ 0 1 0 T 0 . 0 4 1 1 7 0 3 0 . 0 6 0 1 0 3 0 . 0 0 ? 1 7 0 3 0 . 0 3 7 0 1 0 3 0 . 0 2 4 1 7 0 3 0 . 0 8 5 0 1 0 3 0 . 0 2 4 1 7 0 3 S I T E 0 5 0 0 0 9 1 C O N T I N U E D - 126 -APPENDIX 2 T E S T R E S U L T S F O R S I T E 0 5 0 0 4 5 7 S U B M I T T I N G A G E N C Y : A L L D E P T H : A L L S A M P L I N G L T T C A T I O W T A L L M I N I S T R Y D F H N V T R O N M O K A N A G A N L . K I N B E A C H E A S T r t I E N C V E M B f c H TO P T C E 7"^  S H E E T 4 O F 6 P A G E ( F O R 0 1 J A N U A R Y 1 9 6 5 T O 1 6 N O V E M B E R 1 9 8 1 ~ < * * S T A R T * * Y M D H M * F I N I S H * D E F T H Y M D H M M E T R E S 7 5 0 4 3 3 1 2 3 0 7 5 0 4 3 0 1 2 4 5 4 . 2 7 7 5 0 8 1 B 0 9 4 0 7 5 0 8 1 8 0 9 5 0 2 7 6 0 5 0 5 1 0 2 5 7 6 0 5 0 5 1 0 3 0 2 f 6 0 B 0 5 1 0 0 0 76TTBT)5 T 0 T 5 2 S B S A M P L E C A G T P L O C T O E 0 1 2 0 5 0 1 2 V I 1 9 P R F P P H C S T O T M E T H M G / L 0 . 0 1 7 0 1 0 3 0 . 0 1 1 7 0 3 1 2 0 P H F P 1 2 1 P R E P 1 2 4 P R E P 1 3 1 P R E P 1 4 3 P R E P S I L I C A M E T H S U L P H A T E M E T H C A R 8 N 1 0 M E T H A C I D : 8 . 3 M E T H C H L O W O . A M E T h 7 7 0 4 0 6 1 2 1 0 7 7 0 4 0 6 1 2 1 5 7 7 0 8 1 6 1 1 3 0 7 7 0 8 1 6 1 1 4 0 7 8 0 4 0 5 1 1 4 0 7 8 0 4 0 5 1 1 5 0 7 8 0 8 0 3 1 5 0 5 7 8 0 8 0 3 1 5 1 0 7 9 0 4 0 5 1 2 5 0 7 9 0 4 0 5 1 3 1 0 7 9 0 7 3 0 1 3 5 0 7 9 0 7 3 0 1 4 0 3 R 0 0 3 2 5 1 5 4 0 8 0 0 3 2 5 1 5 4 5 R C 0 8 1 <3 1 4 5 0 R 0 5 B 1 9 T 5 < J C 0 5 0 1 2 V O S 0 1 2 V 2 0 5 0 1 2 V 2 0 5 0 1 2 V 2 0 5 0 1 2 V 2 0 5 0 1 2 V 2 O S O J 2 V 2 0 5 0 1 2 V 2 0 5 0 1 ? V 2 C 5 0 1 2 V 0 . 0 1 6 0 1 0 3 0 . 0 0 6 1 7 0 3 0 . 0 1 6 0 1 0 3 0 . 0 0 4 1 7 0 3 0 . 0 1 5 0 1 0 3 0 . 0 0 6 1 7 0 3 0 . 0 1 6 0 1 0 3 0 . 0 0 8 1 7 0 3 0 . 0 0 7 0 1 0 3 0 ^ 0 0 8 1 7 0 3 0 . 0 0 7 0 1 0 3 0 . 0 C 3 1 7 0 3 0 . 0 0 9 0 1 0 3 0 . 0 0 5 1 7 0 3 0 . 0 1 1 0 1 0 3 O . O O T 1 7 0 T 0 . 0 0 6 0 1 0 3 0 . 3 0 4 1 7 0 3 0 . 0 0 9 0 1 0 3 0 . 0 0 3 1 7 0 3 0 ^ 0 0 7 0 1 0 3 0 . 0 0 4 1 7 0 3 M G / L 4 . 1 1 7 0 2 3 . 4 1 7 0 2 3 . 9 1 7 0 2 4 . 1 7 0 2 4 . 5 1 7 0 2 4 . 1 1 7 0 2 4 . 4 1 7 0 2 4 . 1 1 7 0 2 4 . 5 1 7 0 2 4 . 2 1 7 0 2 4 . 4 1 7 0 2 4 . 2 1 7 0 2 M G / L 3 0 . 1 1 7 0 1 2 8 . 7 1 7 0 1 2 9 . 2 1 7 0 1 ~ 2 S . " 1 T 0 1 2 8 . 8 1 7 0 1 2 7 . 7 1 7 0 1 3 0 . 4 1 7 0 1 2 8 . 5 1 7 0 1 2 8 . 5 1 7 0 1 2 9 . 2 1 7 0 1 M G / L 2 4 . 0 10 1 2 5 . 0 10 1 2 8 . 0101 2 5 . 0101 2 6 . 0101 2 5 . 0101 2 9 . 0101 2 8 . 0101 2 8 . 0101 2 9 . 0101 M G / L M G / L 0 . 0 0 4 * 3 1 0 1 0 .00 33*3101 0 .0022*3101 E 3101 M 0 .0029*3101 L 0 . 5 0101 0 .00 33*310 I 0 . 0013*3101 0 .00 38*3101 L 0 . 5 0 1 0 1 0 .0008*3101 0.00 23*3101 0 .001*3101 5 I T F . 0 5 0 O 4 S 7 C G N T I N U E C r M I M I 5 T n Y T F S T P F 5 U L T ? . F O R S I T F 1 R , 0 1 4 5 8 O K A N A G A N L . K I N i l ^ A C H VkFS S U B M I T T I N G A G F N C V t A L L D E P T H : A L l *5AMPI_ TNr> i n r A T i r N T AI L * * S T A R T * * * F I N I S H * D E F T H S B S A M P L F C 1 1 9 P R F P V M D H M Y M D H M M F T R F S A G T P L O C T P H C S T O T M F T H M G / L 7 5 0 4 3 0 1 2 0 0 7 5 0 4 3 0 1 2 1 5 4 . 2 7 0 5 0 1 2 0 . 0 1 4 0 1 0 3 0 . 0 0 5 T 7 C 3 7 5 0 8 1 9 1 0 1 0 7 5 0 8 1 8 1 0 2 0 2 0 5 0 1 2 V 0 . 0 3 3 0 1 0 3 0 . 0 1 2 1 7 0 3 7 6 0 5 0 5 1 0 4 5 7 6 0 5 0 5 1 0 5 0 2 0 5 O 1 2 V 0 . 0 1 9 0 1 0 3 0 . 0 0 4 1 7 0 3 7 f c 9 B 0 5 1 0 3 0 7 6 0 8 0 5 1 1 $ 5 2 0 5 "ITI 2 V D . 0ZTT 0 1 0 T " 0 . 0 1 4 1 7 0 3 7 7 0 4 0 6 1 2 2 5 7 7 0 4 0 6 1 2 3 0 2 0 5 0 1 2 V 0 . 0 3 5 0 1 0 3 0 . 0 2 2 1 7 0 3 7 7 0 8 1 6 1 1 5 0 7 7 0 8 1 6 1 2 0 0 2 0 5 O 1 2 V 0 . 0 1 2 0 1 0 3 0 . 0 0 5 1 7 0 3 7 8 0 4 0 5 1 2 0 5 7 8 0 4 0 5 1 2 1 5 2 0 5 0 1 2 V 0 . 0 0 7 0 1 0 3 0 . 0 0 5 1 7 0 3 ~ T B " 0 W T ~ I S 2 5 7 H 0 H 0 3 1 5 3 5 2 0 5 0 1 2 V 0 . 0 0 9 0 1 0 3 0 . 0 0 5 1 7 C 3 7 9 0 4 0 5 1 2 3 5 7 9 0 4 0 5 1 2 5 0 2 0 5 O J 2 V 0 . 0 1 3 0 1 0 3 7 O 0 7 3 0 1 4 3 0 7 9 0 7 3 0 1 4 4 0 2 0 5 0 1 2 V 0 . 0 0 6 0 1 0 3 0 . 0 0 4 1 7 0 3 8 0 0 3 2 5 1 5 2 5 8 0 0 3 2 5 1 5 3 5 2 0 5 P 1 2 V 0 . 0 1 1 0 1 0 3 0 . 0 0 3 1 7 0 3 8 T J 0 8 1 9 1 5 1 0 2 0 5 " 0 1 ~7. V 0 .~0T O T O T 0 . 0 0 4 1 7 0 3 8 1 0 4 0 1 1 1 5 5 8 1 0 4 0 1 1 2 0 0 2 0 5 0 1 2 V 0 . 0 1 1 0 1 0 3 0 . 0 0 7 1 7 0 3 8 1 0 8 1 9 O O O O 2 0 5 0 1 2 V 0 . 0 1 1 0 1 0 3 0 . 0 0 5 1 7 0 3 8 1 0 6 1 9 1 1 0 0 8 1 0 8 1 9 1 1 3 0 2 0 5 0 1 2 V - 127 -M V I c r M F N T if ncv^nnEir T T P I S t - t E T 4 C F 6 P A G E F CP 0 1 J A N U A R Y 1 9 o 5 T C 1 * N O V F M R E B 1 9 8 1 20 p » r p S I L I C A M E T H M G / L 4 . 1 7 0 2 3 . 7 1 7 0 2 4 . 1 7 0 2 * . I 1 7 0 ? 4 . 6 1 7 0 2 4 . 1 1 7 0 2 4 . 4 1 7 0 2 4 . 1 1 7 0 2 4 . 5 1 7 0 2 1 2 1 P R E P 1 2 4 P R E P 1 3 1 P R F P 1 4 3 P R E P S U L P H A T F M E T H C A R f l N 1 0 M E T H A C I D : 8 . 3 M E T H C H L O R O . A M E T H M G / L 2 9 . 2 1 7 0 1 2 9 . 7 1 7 0 1 2 9 . 2 1 7 0 1 3 0 ^ 5 1 7 D 1 2 9 . 7 1 7 0 1 2 6 . 8 1 7 0 1 3 0 . 9 1 7 0 1 2 8 . 5 1 7 0 1 2 8 . 5 1 7 0 1 4 . 2 1 7 0 2 4 . 4 1 7 0 2 4 . ? 1 7 0 2 4 . 5 1 7 0 2 5 . 1 7 0 2 2 9 . 2 1 7 0 1 M G / L 2 4 . 0 1 0 1 2 5 . 0 1 0 1 2 7 . 0 1 0 1 2 5 . 0 1 0 1 2 7 . 0 1 0 1 2 5 . 0 1 0 1 2 9 . 0 1 0 1 2 7 . 0 1 0 1 2 7 . 0 1 0 1 2 9 . 0 10 1 M G / L M G / L 0 . 0 0 4 3 * 3 1 0 1 0 . 0 0 4 2 * 3 1 0 1 0 . 0 0 2 6 * 3 1 0 1 E 3 1 0 1 M 0 . 0 0 3 3 * 3 1 0 1 L 0 . 5 0 1 0 1 0 . 0 0 3 4 * 3 1 0 1 0 . 0 0 1 1 * 3 1 0 1 0 . 0 0 3 8 * 3 1 0 1 L 0 . 5 0 1 0 1 0 . 0 0 0 7 * 3 1 0 1 0 . 0 0 2 4 * 3 1 0 1 M 0.0008*3101 M 0 . 0 0 2 2 * 3 1 0 1 M 0 . 0 0 0 9 * 3 1 0 1 S I T E 0 5 0 0 4 5 6 C O N T I N U E D - 128 -APPENDIX 3 Sediment Phosphate Extraction Method (modified from: Kirkland and Chamberlain, 1981) Object: To measure the principal phosphorus fraction in lake sediments. The method outlined is a technicon modification of the J.D.H. Williams (1976) method with M.T. Downes (1978) arsenic interference removal reagent from N.W.R.I., Vancouver, B.C. This yields the four desired fractions (see Figure 3-10) 1. Total P 2. Apatite P 3. Non-apatite inorganic P = Inorganic P - Apatite P k. Organic P = Total P - Inorganic P It also produces an extract for the measurement of C.D.B. Iron by atomic absorption spectrometry. Clean the following glassware: 100 ml volumetrics (for apatite and C.D.B. Fe) 200 ml volumetrics (for Total P and Inorganic P) screw top centrifuge tubes and caps crucibles and lids stirring rods graduated cylinders assorted large 500 ml and 100 ml volumetrics DAY 1 1) -Reagents to make: Several litres of 1 N. HC1 1 1. of 1 N. NaOH C.B. reagents 67 g. sodium citrate 9.3 g. sodium bicarbonate to 1 litre 2) -label glassware, numbers for the different samples and letter codes for the different series: "A" apatite "F" C.D.B. Fe "T" Total P no letter for Inorganic P 3) -measure about .2500 g of sediment into marked centrifuge tubes, for the apatite and inorganic P series. Record the actual weight in the logbook. - 129 -4) -weigh .2500 g of sediment into crucibles for the total P series. Roast these samples with lids on, in a muffle furnace at 550°C for 2 hrs. Remove from oven and allow to cool. DAY 2 1) -complete any roasting not done on Day 1 2) -to the apatite series "A" -turn on water bath, set to 85-90°C -add 25 mis of citrate (CB) reagent to each centrifuge tube, using a tipper -place the rack of tubes in the bath and allow them to reach 80 °C -add about .6 g of sodium dithionite to each tube and stir the sediment for 15-20 minutes -remove from the bath, place the teflon lined caps on loosely and centrifuge the tubes for 20 minutes at 2400 rpm -after centrifuging decant the supernatant into the "F" series volumetrics for the Iron measurement, make sure no sediment is transferred. 3) -to the "F" series volumetrics -make up to volume on each sample flask, -prepare Fe stds (fresh daily) to 10, 20, 50, 70 and 100 ppm with 25mls C.B. reagent and one scoop dithionite per std to match matrices. (N.B. citrate depresses Fe signal on air-acetylene flame.) -start AA, warm lamp 30 minutes before starting analyses. Lamp current 5mA, slit-width 0.2 nm, wave length 248.3 nm, oxidizing air-acetylene flame, (P.M. voltage 374-400) -chart recorder: lOmV full-scale, 0.25 in./min. -establish baseline, run full set of standards, start samples. Introduce air to the dilution line to rinse mixing coil, etc. between samples. Rerun stds every 5-6 samples, run full set of stds at end of samples 4) -to the "A" series residue, add 25 mis of 1 N. NaOH, with a tipper and secure the caps. 5) -to the inorganic series, add 25 mis of 1 N. HC1, with a tipper and secure the caps. 6) -to the "T" series, transfer the sediment from the crucibles to the centrifuge tubes using aliquotes of 1 N. HC1, (25 mis total) to assist transfer, secure the caps. 7) -place series "A", "T" and inorganic P centrifuge tubes on the shakers, for overnight agitation. - 130 -D A Y 3 1) -turn off the shaker and centrifuge the samples, 20 minutes at 2400 rpm 2) -for the "A" series decant these and discard the supernatant. 3) -for the "T" series and Inorganic P series decant into the appropriate volumetric flask. 4) -using a tipper, add 25 mis of 1 N. HC1 to each centrifuge tube, secure the caps and place on the shaker 5) prepare standards and reagents for the technicon -stock P-100 ppm, .4394 g K H 2 P O 4 made up to 1 litre for combined reagent A 13.1 mis cone. H 2 S O 4 , made to 200 mis B 3.32 g ammonium molybdate to 100 mis C 1.12 g potassium antimony tartrate to 100 mis D 6.92 g ascorbic acid to 100 mis (leave dry until needed) for Arsenic interference removal agent 7.1 mis cone. H 2 S O 4 15.15 g sodium metabisulphite 2.97 g sodium thiosulphate made up to 1 litre DAY 4 1) -remove samples from the shaker, centrifuge for 20 minutes at 2400 rpm 2) -for series "A", decant into their volumetrics; to the residue add 25 mis 1 N. HC1 and return to the shaker 3) -for the "T" series and inorganic series, decant each into the retained volumetrics and make to volume 4) -to run the Technicon: (see Figure Al) -turn water bath on, also recorder amplifier, etc. -prepare super-reagent, i.e. make previously weighed dry chemicals to volume using distilled water add 50 mis A add 15 mis B add 5 mis C add 30 mis D (in that order) to a 125 ml erlenmeyer flask, swirling well after each addition. Then add approximately 1.2 mis 1% ultra wet solution to flask, -put reagents in place, and with the sample tube in the sampler wash flask, start pumping reagent through the technicon. - 131 -Figure A-1 T e c h n i c o n Layout for O r thophospha t e Ana l ys i s 50x2 mm. Flow Ce l I LMC= long mixing coil SMC = small mixing coil - 132 --prepare working standards from the 100 ppm stock working std. Volume Stock Solution 1 PPM (100 ml) — 1 ml stock 2 PPM (200 ml) - 4 ml stock 4 PPM (100 ml) — 4 ml stock -working standards are made up to the same normality as the samples to be measured that day eg. "T" series and inorganic series are .25N HC1 "A" series is .50 N HC1 -follow standard technicon procedures to measure the samples DAY 5 1) -turn of shaker, centrifuge and decant the "A" series as previously done. 2) -analyse by technicon as on Day 4 3) -write up results, read sample concentration off the technicon output, concentration (mg/1) X lit. X 103 4 gm sed. used = ug. P/gm sediment 4) -wash up all glassware used, and place in drying ovens for next analyses - 133 -APPENDIX * Particle Size Analysis - Hydrometer Method (from: Lavkulich, 1978) Reagents 1) Hydrogen Peroxide (30%). 2) Amyl Alcohol. 3) 0.4 N NaqP707 '10H20 (w.r.t. Na +) Dissolve 50 gm of Naj^O/'lO^O per liter of distilled water. Special Equipment 1) Electric Mixer (Milkshake type). 2) Glass sedimentation cylinders market at the 100 ml level and with a diameter such that the 100 ml mark is 36 ± 2 cm from the bottom on the inside. 3) Plunger for stirring the suspension in the cylinders. 4) Constant temperature room or bath (if necessary a large water bath, unregulated, can be used). 5) Hydrometers (ASTM type 152 H with graduations in gm/1). These should be numbered and calibrated so that each sample will have a known, standardized hydrometer. To calibrate, make up 50 ml of 0.4N Na^O/.lO^O to 1 litre in a sedimentation cylinder. Mix thoroughly with the plunger and allow the temperature to stabilize. Record the temperature. Lower the hydrometer carefully into the solution and determine the scale reading at the upper edge of the meniscus surrounding the stem. Procedure A. Set "1": for Soil - P.M. Determination 1) Record the weight of a clean, dried 600 ml beaker. Add 40.00 gm of soil. - 134 -2) Make up to the 300 ml mark with distilled water and stir. 3) Carefully, to avoid excessive foaming, add H2O2 in 10-20 ml increments until the reaction slows, indicating completion. If too much foaming does develop, add a few drops of amyl alcohol. Leave at room temperature for 2 days. A Watch Glass should be placed over beakers to prevent clay from splattering out. Wash Watch Glasses into beakers. 4) Heat on a hot plate to about 80°C until excess H2O2 is removed (at least 4-5 hours). Check by the addition of a small amount of H2O2 that all the O.M. has been destroyed. 5) Remove from heat. 6) Oven-dry at 105°C for 24 hours. Cool and record the final weight of the beaker plus sample. B. Set "2": for Hydrometer Readings These are duplicate samples of Set "1". Steps 2-5 of the Procedure for Set "1" must be carried out simultaneously for set "2" and each set of duplicate samples must be treated identically. 1) Weigh out 40.00 gm of soil into a 600 ml beaker. 2-5) As in Part A for Set "1". 6) Cool to room temperature. 7) Wet sieve the sample through a 300 mesh (50 micron) screen, collecting the sand fraction. This fraction is dried at 105°C for 24 hours, and then weighed. Optional Following drying, crush the sand fraction gently by hand and run it through a nest of sieves of the following sizes: 1000 microns (16 mesh) 500 microns (32 mesh) 250 microns (60 mesh) 100 microns (150 mesh) Weigh each portion to determine the fractions of sand. 8) Transfer the material which passed through the 300 mesh sieve (from Step 7) back to its original beaker. Add 50 ml of 0.4N Na^O/'lO^O and let sit for 10 minutes. 9) Transfer to an electric mixer and mix for 10 minutes. 10) Transfer the suspension into a 1 litre sedimentation cylinder, making sure to remove all soil from the mixer. Make up to 1 litre with distilled water and place in the water bath. - 135-11) Stir the suspension with the plunger. Use strong, upward strokes near the bottom to lift into suspension any particles which may have lodged there but move cautiously near the top of the cylinder to avoid spilling the contents. Stir each sample for about 45 seconds so that readings can be taken for a number of cylinders at 1 minute intervals. 12) Record the time the stirring finishes. 13) Lower the hydrometer into the suspension. 14) Readings are taken at: 30 minutes 1 hour 2 hours 3 hours 6 hours 24 hours The temperature is recorded with each reading. Before taking readings it is advisable to check the hydrometers for air bubbles or particles adhering to the bulb. These result in incorrect readings, possibly giving a summation value of more than 100%. Clean the bulb with spray from a wash bottle (not into the cylinder). 15) The suspension is stirred again. Readings are taken at: 20 seconds 1 minute 2 minutes 3 minutes 5 minutes 10 minutes It is advisable to carry out these readings after the 24 hours reading rather than at the beginning of the run since the samples have then reached a more stable temperature. Calculations A To standardize the hydrometer readings to 20°C: a. For every °C above 20°C add on 0.36 to the hydrometer reading. b. For every °C below 20°C subtract 0.36 from the hydrometer reading. - 136 -Example Hydrometer Reading: 8.0 Temperature: 28°C Corrected Hydrometer Readings: 8.0 + (8.0 x 0.36) = 10.88 c. Hx = Hydrometer reading at time X (following correction) HD = Hydrometer reading for water and dispersant solution B. Sample Weight (O.M. destroyed): Wt. (O.M. Destroyed) = Wt. Sample + Beaker (gm) _ wt. After Treatment Beaker (Ws) C. % Sand: %Sand= Wt. Sand (gm) x 100 Wt. Sample (O.M. Destroyed) (gm) % Very Fine Sand (50 u - 100 u) % Fine Sand (100 u - 200 u) % Medium Sand (250 u - 500 u) % Coarse Sand (500 u - 1000 u) % Very Coarse Sand (1000 u - 2000 p) D. Per cent material in Suspension at Time X (Tx) 100 (Hx - HD) Ws E. Particle diameter size in Suspension at Time X (Tx) Ca (n/nBO)1/2 Txl/2 Where: Ca is a sedimentation parameter based on a temperature of 30°C, Shown in the following table: - 137 -Hx-HD Ca Hx-HD Ca Hx-HD Ca -5 50.4 -4 50.1 -3 49.9 -2 49.6 -1 49.4 0 49.2 1 48.9 2 48.7 3 48.4 4 48.2 5 47.9 6 47.7 7 47.4 8 47.2 9 47.0 10 46.7 11 46.4 12 46.2 13 45.9 14 45.6 15 45.3 16 45.0 17 44.8 18 44.5 19 44.2 20 43.9 21 43.7 22 43.4 23 43.1 24 42.8 25 42.5 26 42.2 27 41.9 28 41.6 29 41.3 30 41.0 31 40.7 32 40.4 33 40.1 34 39.8 35 39.5 36 39.2 37 38.9 38 38.6 39 38.3 40 38.0 and where (n/n30)!/2 is a correction factor for viscosity variation with temperature, as in the following table. Temperature, °C Viscosity, poise Correction factor 20 0.01009 1.1221 21 0.00984 1.1086 22 0.00961 1.0950 23 0.00938 1.0821 24 0.00916 1.0696 25 0.00895 1.0507 26 0.00875 1.0450 27 0.00855 1.0334 28 0.00836 1.0218 29 0.00818 1.0100 30 0.00800 1.0000 -138-APPENDIX 5 S t a t i s t i c a l Methods Sample Calc u l a t i o n for Two Way Analysis of Variance Using phosphorus f r a c t i o n values as the blocks, and samples c o l l e c t e d along a t r a n s e c t as t r e a t m e n t s we w i s h t o d e t e r m i n e i f the t r e a t m e n t s a r e s i g n i f i c a n t l y d i f f e r e n t . (It i s expected that blocks w i l l e x h i b i t s i g n i f i c a n t d i f f e r e n c e s as they represent d i f f e r e n t P f r a c t i o n s — i n cases where r e p l i c a t e s a m p l e s a r e used as b l o c k s we can d e t e r m i n e i f t h e y a r e s i g n i f i c a n t l y d i f f e r e n t using t h i s same t e s t ) . Treatments T o t a l Inorganic Organic Apatite N.A.I.P. Treatment Means SI 1017.08 822.34 194.74 655.17 167.17 571.2 S2 1006.97 810.00 196.97 674.99 135.01 564.8 S3 970.51 755.17 215.34 615.38 139.79 539.2 S4 938.99 781.87 157.12 619.31 162.56 532.0 S5 979.73 783.75 195.98 607.16 176.59 548.8 S6 906.64 780.32 126.32 619.14 161.18 518.6 S7 643.17 630.97 12.20 '560.40 70.57 383.4 Block Means Y.j 923.4 6 - 64.01 766.3 VARIANCE TABLE Source of V a r i a t i o n df Block (B) (n-1) Treatment (TR) (k-1) B x TR ( n - D ( k - l ) Sampling Er r o r (nk-1) Total (nk-1) 156.9 621.4 144.9 e-355.73 Y.. - 522.57 4 6 24 34 34 F Required F .05 .01-628.30 2.65 3.93 SS MS 3543227.32 885806.83 122918.40 20486.40 14.53 2.38 3.39 47934.85 1997.29 1.42 1.85 2.39 47934.85 1409.85 (1.29Z) 3714080.57 109237.66 139-Where: df* degrees of freedom SS= sum of squares MS» mean squares standard deviation To c a l c u l a t e Y i . , treatment mean £Yi/n where Y i - sum of values i n a given row n • number of blocks Y j . , block mean t Yj/k where SLYj - sum of values i n a given column k • number of treatments Y.. , grand mean S-Yij/nk where i Y i j • sum of a l l values i n table nk • number of blocks x number of treatments Determine and note the standard deviation of.the treatment and block means To complete Variance t a b l e : SS^ sum of squares of t o t a l sample £(Yij - Y..) \ 2 nk variance x number of samples MSg mean square of block x nk x k 2 ( Y j . - Y j ) z k-1 (standard deviation) x number of treatments SS T sum of squares of block MSg x df B mean square block x degrees of freedom of block MS^ mean square treatment |Z(Yi. " Y i ) 2 n - 1 (standard d e v i a t i o n ) ^ x number of blocks x n -140-S S T B sum of squares of treatment MS T R x df TR mean square of treatment x degrees of freedom of treatments SS E Bum of squares of erro r (also equal to sum of square of block x treatment) ( s s E « s s B x T ) s s E • s s T - ss f l - s s T R » sumof squareof t o t a l - SS b l o c k - SS treatment MS T mean square t o t a l 1 SS T / (nk - 1) sum of squares of t o t a l / t o t a l degrees of freedom MS£ mean square er r o r SS E / (nk - 1) sum of squares of error / t o t a l degrees of freedom MSg t r mean square of combined block and treatment SS E / (n - l ) ( k - 1) sum of squares of error (or S S g x ^ ) Tj calculated F value f o r t o t a l MS T /MSg F^ R calculated F value f o r treatment MS T R / MSg F„ calculated F value for block MSB / MSg X sampling error MSg / MS T x 100 Compare Fg to F values f o r appropriate df at .05 and .01 confidence l i m i t s obtained from s t a t i s t i c a l tables. As the c a l c u l a t e d F v a l u e s i n the proc e e d i n g v a r i a n c e t a b l e exceed the r e q u i r e d F v a l u e s at 95 and 99Z c o n f i d e n c e l i m i t s we can say th a t both treatments and blocks e x h i b i t s i g n i f i c a n t d ifferences. Blocks which represent phosphorus f r a c t i o n s were expected to be d i f f e r e n t but we can now state that some di f f e r e n c e e x i s t s among the means of the i n d i v i d u a l samples. -141-In order to determine those means which are s i g n i f i c a n t l y d i f f e r e n t from others we use a Duncan's M u l t i p l e Range Test which groups s i m i l a r means, as indicated by the underscored l i n e s . Arrange means i n order of decreasing magnitude 571.1 564.8 548.8 539.2 532.0 518.6 383.4 Calculate L.S.D.,the l e a s t s i g n i f i c a n t difference L.S.D. - t I 2s 2/n where; s 2 - M.S.E. (1997.29) n • number of values to c a l c u l a t e Y (5) t - t value f o r df (at .05) (2.064) Using the L.S.D. v a l u e c a l c u l a t e D the s h o r t e s t s i g n i f i c a n t d i f f e r e n c e a l l o w a b l e beween two means at a c e r t a i n distance,known as p ( i . e . 571.2 i s 4 positions from 539.2) D = R(L.S.D.) Where R i s a value taken from s t a t i s t i c a l tables f o r m u l t i p l e range tests Develop a table to evaluate the s i g n i f i c a n t difference with respect to p o s i t i o n P o s i t i o n (p) 2 3 4 5 6 7 R at .05 D 1.00 1.05 1.08 1.10 1.12 1.13 58.34 61.26 63.01 64.18 65.34 65.92 Compare a l l means to the o t h e r s , e v a l u a t i n g t h e i r d i f f e r e n c e i n v a l u e to the s i g n i f i c a n t l y d i f f e r e n t value f o r those positions. If i t exceeds the D value, the two means are s i g n i f i c a n t l y d i f f e r e n t with 95% confidence i n t e r v a l s . Group l i k e means. - 142 -APPENDIX 6 S t a t i s t i c a l Tables Indicating I n s i g n i f i c a n t Differences Zone 3, 1979 Anova Tables TITLE: TOTAL-P TREATMENTS: Sampling Days n = 7 BLOCKS: Repli c a t i o n of Sample k = 2 Source of Degrees of Sum of Mean Required V a r i a t i o n Freedom Squares Square F F at 95% Total (nk-1) = 13 15598 Treatment (n-1) = 6 7382 1230 0.90 4.28 Block (k-1) = 1 16 16 0.01 5.99 Error (BxT) (n-1)(k-1) - 6 8200 1367 TITLE: APATITE-P TREATMENTS: Sampling Days n = 7 BLOCKS: Replic a t i o n of Sample k = 2 Source of Degrees of Sum of Mean Required V a r i a t i o n Freedom Squares Square F F at 95% Total (nk-1) = 13 9953.42 Treatment (n-1) - 6 6964.42 1160.74 3.99 4.28 Block (k-1) = 1 1244.95 1244.95 4.28 5.99 Error (BxT) (n-1)(k-1) = 6 1744.05 290.68 TITLE: ORGANIC-P TREATMENTS: Sampling Days n = 7 BLOCKS: Replication of Sample k = 2 Source of Degrees of Sum of Mean Required V a r i a t i o n Freedom Squares Square F F at 95% Total (nk-1) = 13 11964 Treatment (n-1) = 6 747 125 0.01 4.28 Block (k-1) = 1 201 201 0.02 5.99 Error (BxT) (n-1)(k-1) = 6 11015 TITLE: NAIP TREATMENTS: Sampling Days n = 7 BLOCKS: Replic a t i o n of Sample k = 2 Source of Degrees of Sum of Mean Required V a r i a t i o n Freedom Squares Square F F at 95% Tot a l (nk-1) = 13 46688 Treatment (n-1) = 6 11915 1986 0.37 4.28 Block (k-1) = 1 2803 2803 0.52 5.99 Error (BxT) (n-1)(k-1) = 6 31970 5328 - 143 -Zone 2, 1979 Anova Tables TITLE: TOTAL-P TREATMENTS: Sampling Days BLOCKS: Replication of Sample Source of Va r i a t i o n Total Treatment Block Error (BxT) Degrees of Freedom Sum of Squares n k Mean Square 6 2 (nk-1) = 11 17053 (n-1) = 5 5325 1065 (k-1) = 1 6029 6029 ( n - D ( k - l ) = 5 5698 1140 0.93 5.29 Required F at 95% 5.05 6.61 TITLE: ORGANIC-P TREATMENTS: Sampling Days n = 6 BLOCKS: Repli c a t i o n of Sample k = 2 Source of Degrees of Sum of Mean Required V a r i a t i o n Freedom Squares Square F F at 95% Tot a l (nk-1) = 11 61377 Treatment (n-1) = 5 48051 9610 3.99 5.05 Block (k-1) - 1 1282 1282 0.53 6.61 Error (BxT) ( n - l ) ( k - l ) = 5 12044 2409 - 144 -Ekman Transect Anova Tables TITLE: EKMAN TRANSECT 2 (ET2) TREATMENTS: Transect Samples BLOCKS: P Fractions Source of Va r i a t i o n Degrees of Freedom Treatment Block BxT Sampling Erro r T o t a l (k-1) = 4 (n-1) = 4 (n-1)(k-1) = 16 (nk-1) = 24 (nk-1) = 24 Sum of Squares 7558.27 2821206.72 16733.25 16733.25 2845498.24 k = 5 n = 5 Mean Square 1889.57 705301.68 1045.83 697.22 118562.43 Required F at .05 .01 2.71 1011.59 1.50 (0.59%) 2.78 4.22 2.78 4.22 2.09 2.85 TITLE: EKMAN TRANSECT 3 (ET3) TREATMENTS: Transect BLOCKS: P Fractions Samples k = 6 n = 5 Source of Degrees of Va r i a t i o n Freedom Sum of Squares Mean Square F Required F at .05 .01 Treatment (k-1) = 5 Block (n-1) = 4 BxT (n-1)(k-1) = 20 Sampling ( n k _ i ) = 29 Error T o t a l (nk-1) = 29 10211.10 3206692.34 26036.86 26036.86 3242940.30 2042.22 801673.09 1301.84 897.82 111825.53 2.27 892.91 1.45 (0.80%) 2.55 3.73 2.70 4.04 1.94 2.57 - 145 -2-Way Anova Table TITLE: SHAKING TIME COMPARISONS FOR 1 SEDIMENT SAMPLE TREATMENTS: Shaking Times n = 6 BLOCKS: P Fractions k = 5 Source of Degrees of Sum of Mean Required V a r i a t i o n Freedom Squares Square F F at 95% Total (nk-1) = 29 3490741 120370 Treatment (n-1) = 5 1985 397 1.54 2.62 Block (k-1) = 4 3482584 870646 3387.73 2.78 Error (BxT) ( n - l ) ( k - l ) = 24 6172 257 Comparison of 3 samples analysed a f t e r various storage times. Storage Sample Total-P A-P I-P 0-P NAIP Time ET1A -26 +18 -2 -28 +16 .5 months ET1C -12 -1 +15 +3 +14 13 months Z3, June 3A +44 +36 -67 -23 -31 2 months - values i n table represent the change and d i r e c t i o n of change i n the given P f r a c t i o n of a sample analysed at 2 separate times - As they are not consistently changing i n one d i r e c t i o n or i n one f r a c t i o n i t appears that sample storage does not influence P con-centrations i n freeze-dried sediment - 146 -Anova Testing to Determine the E f f e c t of Sample Thawing TITLE: TOTAL-P TREATMENTS: Sampling Days n = 2 BLOCKS: Replication of Sample k = 3 Source of Degrees of Sum of Mean Required V a r i a t i o n Freedom Squares Square F F at 95% Total (nk-1) = 5 1588 Treatment (n-1) = 1 150 150 0.42 18.51 Block (k-1) = 2 727 364 1.02 19.00 Error (BxT) (n-1)(k-1) = 2 711 356 TITLE: APATITE-P TREATMENTS: Sampling Days n = 2 BLOCKS: Replic a t i o n of Sample k = 3 Source of Degrees of Sum of Mean Required V a r i a t i o n Freedom Squares Square F F at 95% Total (nk-1) = 5 4806 Treatment (n-1) = 1 401 401 0.24 18.51 Block (k-1) = 2 1036 518 0.31 19.00 Error (BxT) (n-1)(k-1) = 2 3369 1685 TITLE: NAIP TREATMENTS: Sampling Days n = 2 BLOCKS: Replication of Sample k = 3 Source of Degrees of Sum of Mean Required V a r i a t i o n Freedom Squares Square F F at 95% Total (nk-1) = 5 ' 14745 Treatment (n-1) = 1 1067 1067 0.24 18.51 Block (k-1) = 2 4733 2367 0.53 19.00 Error (BxT) (n-1)(k-1) = 2 8945 4473 TITLE: TOTAL--P - one sample r e p l i c a t e of June 11 was changed f o r thi s Anova TREATMENTS: Sampling Days n - 2 BLOCKS: Replic a t i o n of Sample k = 3 Source of Degrees of Sum of Mean Required V a r i a t i o n Freedom Squares Square F F at 95% To t a l (nk-1) = 5 1643 Treatment (n-1) = 1 991 991 28.31 18.51 Block (k-1) = 2 617 309 17.63 19.00 Error (BxT) (n-1)(k-1) = 2 35 -147-APPENDIX 7 Regression Analysis Data Legend and Units for Regression Data Parameters TP T o t a l Phosphorus AP A p a t i t e Phosphorus OP Organic Phosphorus CDB-FE CDB Iron micrograms PO^-P / gram sediment micrograms PO^-P/ gram sediment micrograms PO^-P / gram sediment micromoles Fe / gram sediment pH pH TEMP Temperature degrees centigrade PO^-P Soluble Orthophosphate Concentration micrograms / l i t P GRAD Phosphorus Gradient (INT-P to PO^-P) TIME Number of Days into Experiment days DEPTH Water Depth from Surface meters DIST Distance to Creek Mouth meters ZSAND Per cent Sand (of inorganic portion) %SILT Per cent S i l t (of inorganic portion) %CLAY Per cent Clay (of inorganic portion) %0RG Per cent Organic Matter (of t o t a l sample) -148-REGRESSION DATA Zone 2, Summer 1979 Mean Sediment Phosphorus Values and Bottom Water C h a r a c t e r i s t i c s DATE 280679 170779 200779 230779 160879 190879 —————— ————— ————— 11 1 TP 909 898 925 856 901 892 NAIP 268 270 205 53 65 40 AP 588 538 614 643 630 622 OP 54 92 106 160 207 231 CDB-FE 65 62 70 81 84 68 pH 7.8 7.4 7.5 7.9 8.3 7.9 TEMP 19.0 20.7 19.3 23.5 21.8 21.7 POA-P 9 10 18 5 12 6 P GRAD 1.16 1.34 1.78 2.49 1.66 1.99 TIME 1 20 23 26 50 53 -149-Regression Data Zone 3, Summer 1979 DATE Mean Sediment Phosphorus Values and Bottom Water C h a r a c t e r i s t i c s 280679 170779 200779 230779 130879 160879 190879 TP 954 1005 1000 966 990 1028 1004 NAIP 202 190 203 142 146 216 217 AP 582 633 628 638 659 625 608 OP 171 182 170 187 187 189 180 CDB-FE 81 66 73 76 75 73 74 pH 7.9 8.2 7.4 7.9 8.2 8.2 8,2 TEMP 17.3 19.0 18.2 22.6 22.5 22.0 17.5 P0 4-P 4 5 3 7 3 25 9 P GRAD 0.83 1.26 1.77 1.42 1.44 1.36 1.42 TIME 1 20 23 26 47 50 53 -150-REGRESSION DATA Zone 3, June 1980 Mean Sediment Phosphor us Values and Bottom Water C h a r a c t e r i s t i c s DATE 030680 050680 090680 100680 110680 120680 130680 —————— ————— TP 940 980 1027 1055 1016 1047 964 NAIP 105 89 213 218 191 207 229 AP 628 641 655 652 659 643 631 OP 210 251 160 185 164 197 104 CDB-FE 78 82 67 70 68 68 66 pH 8.1 8.0 7.9 8.0 8.0 8.0 8.1 TEMP 15.0 15.0 12.5 11.0 11.0 14.0 17.0 TIME 1 3 7 8 9 10 11 -151-REGRESSION DATA Ekman Transect 1, August 15 1979 Sample Location C h a r a c t e r i s t i c s , Physical Sediment Values and Phosphorus Values SAMPLE ET1A ET1B ET1C TP 1017 1007 971 NAIP 167 135 140 AP 655 675 615 OP 195 197 215 CDB-FE 68 65 67 %SAND 47 48 48 %SILT 38 37 37 %CLAY 15 15 15 %ORG 9 9 8 DEPTH 6.1 5.5 5.2 DIST 400 325 250 ET1D ET1E ET1F ET1G 939 980 907 643 163 177 161 71 619 607 619 560 157 196 126 12 64 74 65 21 51 50 54 76 34 34 33 20 15 14 14 4 9 8 8 4 4.5 3.4 2.7 1.8 200 175 150 125 -152-APPENDIX 8 Phosphorus F r a c t i o n Values (Micrograms PO^-P / Gram Sediment) DATE LOCATION TP NAIP AP OP — — 150879 ET1A 1017 167 655 195 150879 ET1B 1007 135 675 197 150879 ET1C 971 140 615 215 150879 ET1D 939 163 619 157 150879 ET1E 980 177 607 196 150879 ET1F 907 161 619 126 150879 ET1G 643 71 560 12 150879 ET2A 1002 217 615 170 150879 ET2B 1028 212 668 148 150879 ET2C 966 190 676 100 150879 ET2D 958 181 587 189 150879 ET2E 956 162 660 134 150879 ET3A 978 146 647 186 150879 ET3B 949 146 656 147 150879 ET3C 911 123 656 132 150879 ET3D 907 161 619 126 150879 ET3E 1017 167 655 195 150879 ET3F 964 268 556 139 280679 Z2A 903 263 580 59 280679 Z2B 915 272 595 48 170779 Z2A 860 260 545 56 170779 Z2B 935 279 531 128 200779 Z2A 941 194 604 143 200779 Z2B 908 216 623 68 230779 Z2A 815 64 653 98 230779 Z2B 896 42 632 221 160879 Z2A 879 12 656 211 160879 Z2B 923 117 603 203 190879 Z2A 847 1 627 219 190879 Z2B 937 78 617 242 280679 Z3A 972 184 603 185 280679 Z3B 937 220 561 156 170779 Z3A 1003 202 627 174 170779 Z3B 1006 178 639 189 200779 Z3A 1005 216 622 166 200779 Z3B 994 189 632 173 230779 Z3A 952 113 643 197 230779 Z3B 980 171 632 177 130879 Z3A 979 171 667 142 130879 Z3B 1001 120 650 231 160879 Z3A 984 94 648 246 160879 Z3B 1071 338 602 132 190879 Z3A 1043 236 627 180 190879 Z3B 964 198 589 179 -153-DATE LOCATION TP 030680 Z3A 934 030680 Z3B 922 030680 Z3C 945 030680 Z3D 922 030680 Z3E 979 050680 Z3A 923 050680 Z3B 990 050680 Z3C 989 050680 Z3D 1005 050680 Z3E 995 090680 Z3A 978 090680 Z3B 1024 090680 Z3C 1031 090680 Z3D 1078 090680 Z3E 1022 100680 Z3A 1026 100680 Z3B 1040 100680 Z3C 1104 100680 Z3D 1050 100680 Z3E 1054 110680 Z3A 963 110680 Z3B 954 110680 Z3C 1063 110680 Z3D 1054 110680 Z3E 1044 120680 Z3A 977 120680 Z3B 1071 120680 Z3C 1077 120680 Z3D 1074 120680 Z3E 1035 130680 Z3A 955 130680 Z3B 952 130680 Z3C 979 130680 Z3D 975 130680 Z3E 957 NAIP AP OP 144 642 158 153 573 196 73 636 237 83 645 193 70 642 268 83 652 188 132 639 220 67 635 288 94 623 288 70 654 271 210 641 127 176 671 177 243 658 130 224 652 211 214 652 155 209 643 174 182 662 195 260 634 210 221 660 169 216 661 177 213 638 95 191 654 109 179 660 223 155 651 248 215 686 144 200 641 137 176 652 243 240 646 191 210 641 223 209 636 190 245 602 108 244 632 76 210 652 116 228 622 126 218 646 94 


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