ABSTRACT
This chapter deals with unique aspects of the aquatic organism-xenobiotic interaction, as well as those interactions determining environmental fate and toxicity. Agricultural runoff of pesticides and fertilizers, as well as aerial deposition of mercury, pesticides, polychlorinated biphenyls, and polycyclic aromatic hydrocarbons are often cited examples of toxicant introduction into aquatic systems by nonpoint sources. Groundwater contamination comes from many sources including septic tanks, landfills, hazardous waste sites, pipelines, irrigation, pesticide application, wells, and natural sources such as saltwater intrusion or natural leaching. Collectively, water quality can influence the availability, chemical form, and ultimately the toxicity of chemicals in the aquatic environment. Sediments are primary repositories for abiotic and biotic materials in the aquatic environment. Water hardness is influential in the disposition and toxicity of a variety of aquatic contaminants. Ingestion of pollutant-associated particles may provide another important route of contaminant assimilation in sediment feeding benthic organisms.
