Contributors: J.A. Arnold, S.W. Coffey, D.E. Line, and J. Spooner, Extension Biological & Agricultural Engineering Specialists, and D.W. Moody, U.S. Geological Survey

POLLUTANTS AND STORMWATER RUNOFF


Toxic and Synthetic Chemicals

A number of toxic and synthetic chemicals have been identified in stormwater but all have been at very low concentrations. These chemicals have leached from their original products or from their point of use and range from pesticides and plasticizers (chemicals used in plastics to make them flexible), to wastes from petrochemical industries. Some amounts of wood preservatives and wood coatings to prevent sap stains have also been detected.

Sources. In general, a wide range of toxic and synthetic chemicals can be found in stormwater, mainly from manufactured products that have had chemicals leached from them, from industrial processes and from fossil fuel combustion and lubricating oils. Heavily used highways have shown high concentrations of synthetic chemicals, mainly combustion products. Pesticides used for controlling nuisance vegetation and animal pests may be picked up by stormwater runoff.

Impacts. Many of the synthetic chemicals exhibit toxic effects on various aquatic plants and animals. As with the metals, some synthetic and toxic chemicals bind with sediment and will settle out of the water. Although these chemicals may be tied up in the sediment for long periods, they can be redissolved in the water if the chemical and biological conditions change. Many of the chemicals can accumulate in the food chain, possibly threatening aquatic life, fish and food for humans.

Indicator parameters. Pungent odors, multi-colored slicks, dead fish, barren channels or ponds and masses of sticky substances may indicate the presence of synthetic or toxic substances.

Source reduction. Private citizens can practice good housekeeping, which will remove plastics and other trash from areas where chemicals can leach out and enter stormwater. Industry and commercial business should take measures to prevent release of toxic and organic chemicals and be prepared to contain spills with no release of chemicals. Pesticides should be used according to product label directions and only with caution near water bodies.

Removal. Toxic and synthetic chemicals that attach to sediment can be removed by settling in dry detention basins and wet retention ponds. If the chemicals are dissolved in the water, infiltration techniques will allow the chemicals to be biologically consumed as the stormwater passes through the soil. Very high concentrations of toxic chemicals may require special treatment processes to remove or destroy the chemical.

Return to: Surface Water Pollutants and Stormwater Runoff

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Last Modified: 07/10/96