ABSTRACT
Suspended matter plays an important role in surface water quality. The amount of suspended matter determines the turbidity of the water, and so the underwater light climate. Moreover, suspended fine sediments are an important vector for contaminant transport in surface waters, since many chemicals adsorb to the negatively charged surfaces of clay minerals and organic matter (see Chapter 4). The sediment may already be contaminated as a result of accidental spill s, atmospheric deposition , or the application of fertiliser or pesticides on soils susceptible to erosion . Soil erosion and deposition (sedimentation ) may accordingly result in an ongoing transfer of contaminants from terrestrial ecosystems to surface water, bed sediments , and floodplains . Moreover, during transport the sediment may be contaminated by discharges into surface water and the subsequent exchange between the soluble and particulate phase. To be able to predict the fate of sediment-associated chemicals, it is therefore not only necessary to understand the adsorption reactions between sediment particles and the soluble phase, but also to understand the fate of the sediment itself.
