Summary of attenuation-removal mechanisms for primary pollutants found in stormwater runoff. Adapted from Horner, 1994 as reported in the Wisconsin Storm Water Manual Part 2.
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Mechanism Pollutants affected Promoted by
Sedimentation Solids, BOD, pathogens, particulate COD, P, N, metals, synthetic organics Low turbulence
Filtration Solids, BOD, pathogens, particulate COD, P, N, metals, synthetic organics Fine, dense herbaceous plants, constructed filters
Soil incorporation All Medium-fine texture
Precipitation Dissolved P, metals High alkalinity
Sorption - adsorption Dissolved P, metals, synthetic organics High soil Al, Fe, high soil organics (Met), circumneutral pH
Sorption - ion exchange Dissolved metals High soil cation exchange capacity
Oxidation COD, petroleum hydrocarbons, synthetic organics Aerobic conditions
Degradation - photolysis COD, petroleum hydrocarbons, synthetic organics Direct sunlight
Degradation - volatilization Volatile petroleum hydrocarbons, synthetic organics High temperature and air movement
Degradation - biological BOD, COD, petroleum hydrocarbons, synthetic organics High temperature and air movement
Plant metabolism P, N, metals High plant surface area
Pathogen die off Pathogens Plant excretions
Nitrification Ammonia Dissolved oxygen >2 mg/L, low toxicants, temperature >5-7°C, circumneutral pH
Denitrification Nitrate, nitrite Anaerobic, low toxicants, temperature >15°C

This page was last edited on 15 July 2015, at 16:16.

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