A primer on sediment-trace element chemistry

Introduction 1 1.0 Importance of sediments to aquatic trace element chemistry 1.1 Monitoring studies 1.2 Suspended versus bed sediments -utility for various types of studies 1.3 Partitioning of trace elements between dissolved and solid phases 1.4 Fluvial transport of trace elements by suspended sediments 1.5 Comparison of trace element concentrations in suspended and bottom sediments versus dissolved levels 1.6 Effect of suspended sediment concentration on fluvial transport of trace elements 1.7 Historical trace element levels 2.0 Physical and chemical factors affecting sediment-trace element chemistry 2.1 Introduction 2.2 Physical factors 2.2.1 Grain-size ranges and the effect of grain size 2.2.2 Chemical analysis of various grain sizes in bottom sediments 2.2.3 Chemical analysis of various grain sizes in suspended sediments 2.2.4 Effect of grain size on trace element concentrations in samples collected from the same and different basins 2.2.5 Comparison of samples having similar bulk chemistries but differing grain-size distributions 2.2.6 Effect of grain size on sediment-associated chemical transport at differing discharge rates 2.2.7 Measuring grain-size distributions 2.2.7.1 Differences in grain size distributions induced by using different techniques 2.2.7.2 Differences in grain size distributions induced by sample pretreatment 28 2.2.8 Effect of sediment surface area 2.2.9 Importance of surface area to sediment-trace element concentrations 2.2.10 Measuring surface area 2.3 Chemical factors 2.3.1 Cation exchange capacity 2.3.2 Composition significant sedimentary trace element collectors 2.3.2.1 Iron and manganese oxides 2.3.2.2 Organic matter 2.3.2.3 Clay minerals 2.3.3 Introduction to and utility of chemical partitioning 2.3.4 Chemical partitioning methods 2.3.4.1 Chemical partitioning -instrumental methods 2.3.4.2 Chemical partitioning ~ partial extraction methods 2.3.4.2.1 Chemical partitioning of suspended sediments by partial extraction 2.3.4.2.2 Chemical partitioning of bottom sediments by partial extraction IV 2.3.4.3 Chemical partitioning by density gradient and mineralogy 2.3.4.4 Chemical partitioning using statistical manipulation of data 2.3.4.5 Chemical partitioning using mathematical modelling 2.4 The interrelation and relative importance of selected physical and chemical factors affecting sediment-trace element chemistry 2.4.1 Relative importance of physical and chemical factors to sediment-trace element chemistry 2.4.1.1 The interrelation of grain size and surface area to each other and to sediment-trace element chemistry 2.4.1.2 The interrelation of grain size and geochemical substrate to each other and to sediment-trace element chemistry 2.4.1.3 The interrelation of surface area and geochemical substrate to each other and to sediment-trace element chemistry 2.4.2 The interrelation of grain size, surface area, and geochemical substrate to each other 2.4.3 Predicting sediment-trace element concentrations using physical and chemical factors 3.0 Sediment-trace element data manipulations 3.1 Introduction 3.2 Limitations of analytical data 3.3 Corrections for grain size differences 3.4 Carbonate corrections 3.5 Normalization to 'conservative' elements 3.6 Effects of applying corrections to sediment-trace element data 4.0 Sampling sediments 4.1 Sampling sediments general considerations 4.2 Bottom sediments 4.2.1 Sampling surficial bed sediment 4.2.2 Sampling bed sediments at depth 4.3 Suspended sediments 4.3.1 Sampling suspended sediment in fluvial environments 4.3.2 Cross-sectional spatial and temporal variations in suspended sediment and associated trace elements and their causes 4.3.2.1 Differences due to sampler type or sampling design 4.3.2.2 Horizontal variations 108 4.3.2.3 Vertical variations 4.3.2.4 Importance of silt/clay-versus sand-sized suspended sediment for trace element transport 4.3.2.5 Suspended sediment and associated trace element temporal variations during constant discharge 4.3.3.6 Suspended sediment and associated trace element temporal variations during changes in discharge 5.0 Summary and general considerations 118 Selected references Index 135