The transfers of sediments and associated contaminants play an important role in catchment ecosystems as they directly influence water quality, habitat conditions and biogeochemical cycles. Contaminants may include heavy metals, pesticides, nutrients, radionuclides, and various organic, as well as organometallic compounds. The environmental risk posed by sediment-bound contaminants is largely determined by the sources and rate at which sediments are delivered to surface water bodies, the residence time in catchments, lakes and river systems as well as biogeochemical transformation processes. However, the dynamics of sediment and contaminant redistribution is highly variable in space and time due to the complex non-linear processes involved. This session thus focuses on sources, transport pathways, storage and re-mobilization, and travel times of sediments and contaminants across temporal and spatial scales as well as their impact on catchment and freshwater ecosystems.

This session particularly addresses the following issues:

• Delivery rates of sediments and contaminants from various sources (i.e. agriculture, urban areas, mining, industry or natural areas);
• Transport, retention and remobilization of sediments and contaminants in catchments and river reaches;
• Modelling of sediment and contaminant transport on various temporal and spatial scales;
• Biogeochemical controls on contaminant transport and transformation;
• Studies on sedimentary processes and morphodynamics, particularly sediment budgets;
• Linkages between catchment systems and lakes, including reservoirs;
• Analysis of sediment archives to appraise landscape scale variations in sediment and contaminant yield over medium to long time-scales;
• Impacts of sediments and contaminants on floodplain, riparian, hyporheic and other in-stream ecosystems;
• Response of sediment and contaminant dynamics in catchments, lakes and rivers to changing boundary conditions and human actions.