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CONSTRUCTED WETLANDS FOR TREATMENT OF HEAVY METALS IN URBAN STORMWATER RUNOFF: CHEMICAL SPECIATION OF WETLAND SEDIMENTS
Citation:
MUTHUKRISHNAN, S. CONSTRUCTED WETLANDS FOR TREATMENT OF HEAVY METALS IN URBAN STORMWATER RUNOFF: CHEMICAL SPECIATION OF WETLAND SEDIMENTS. Presented at 10TH INTERNATIONAL CONFERENCE ON WETLAND BIOGEOCHEMISTRY, ANNAPOLIS, MD, April 01 - 04, 2007.
Description:
Heavy metals in urban stormwater runoff are primarily removed by sedimentation in stormwater best management practices (BMPs) such as constructed wetlands. Heavy metals accumulated in wetland sediments may be potentially toxic to benthic invertebrates and aquatic microorganisms, and need to be routinely removed. These maintenance practices are important to minimize heavy metal contamination risk and maximize operational efficiency of these BMPs. Chemical speciation studies help in understanding and controlling the behavior of heavy metals, and are recognized as a necessary requirement in designing an effective BMP maintenance protocol. This research is being conducted at U.S. EPA’s Urban Watershed Research Facility in Edison, NJ, to evaluate the relative efficiencies of wetlands and retention ponds in attenuating heavy metal loads in urban stormwater runoff. BMP removal efficiencies were assessed for both particulate and soluble heavy metals. The geochemical associations of heavy metals in wetland sediments were investigated by chemical speciation techniques in order to understand heavy metals behavior in BMP sediments. Additionally, a stormwater wetland BMP was monitored to investigate the effects of maintenance and clean-up procedures on sediment heavy metal loads and their speciation. Results from four different stormwater sampling and sediment monitoring events will be discussed.