Physicochemical and biological assessment and characterization of contaminated sediments

Physicochemical and biological processes that influence contaminant fate and transport in sediments are diverse, and include physical chemical behaviour, biological processes at microbial and macro scales, as well as pore water and solid phase transport. Spatial and temporal variability in these environmental characteristics and processes are large, and can be difficult to portray and predict. We herein present a series of case studies that evaluate environmental processes and properties that must be assessed with respect to studies of contaminated sediments. These topics are: chemical behaviour of metals in the environment; biological processes and sediment properties influencing contaminant release from sediments; the biogeochemistry and adsorptive capacity of ambient organic compounds in aquatic environments; and new approaches to modeling and scaling the spatial distribution of relevant processes and sediment properties. In a concluding assessment of our state of understanding for these processes and properties, we find that significant knowledge gaps remain in terms of both causal and statistical uncertainty, and these uncertainties should be the focus of new research and development in assessment and characterization of contaminated sediments.