Contaminated sediments contain chemicals at concentrations that pose a known or suspected threat to aquatic life, wildlife or human health (USEPA, 1994).

Sediment textures range from sand to clay, pebbles to glacial rubble, syrup to mud. They line river bottoms and lake beds, and bays, estuaries, coasts, and oceans. Sediments can become contaminated from a variety of sources: polluted runoff from farms and streets, air deposition, or point discharges of pollution. For example, 37 million pounds of chemicals are discharged into America’s waters every year, according to the Environmental Protection Agency.  Chemicals discharged from pipes and pollution from other sources can often wind up settling onto sediments.

Contaminants, or toxins, found in sediments include bioaccumulative contaminants that bind to lipids and fats, and thus transfer efficiently through the food chain. Other types of toxins include those such as heavy metals or many Polycyclic Aromatic Hydrocarbons (PAHs) that may pose less biomagnification risks but can affect organisms directly by skin (dermal) contact or ingestion.  

Follow COA's links about the basic facts on toxins, toxins in the food chain, effects to wildlife, and locations of contaminated sediments.