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(IP37) Trace Metal Levels in Storm Water Retention Ponds in Suburban Maryland.
Shaw, Amanda*,1, Massal, Laura1, Snodgrass, Joel1, Casey, Ryan1, 1 Towson University, Towson, MD, USA
ABSTRACT- The use of storm water retention ponds as a substitute or aid to sewer drainage systems is becoming a common practice among new housing developments. Over time these ponds naturally become habitat for many species. Few studies have been conducted evaluating sources or levels of trace metal contamination associated with storm water runoff. It is still unknown whether trace metals pose a threat to wildlife that inhabit the ponds, whether there is a relationship between trace metal levels and surrounding land use, and whether there is a correlation between trace metal levels and the age of the ponds. We determined lead (Pb), copper (Cu), cadmium (Cd), and nickel (Ni) levels in six retention ponds in the Owings Mills area of Red Run Branch of the Gwynns Falls watershed in Maryland. Bioavailable trace metals in sediments were determined by leaching each sample with 1M HNO3 following combustion of organic matter at 500°C. Water and sediment samples were analyzed by ICPMS. Results show the presence of Cr, Ni, Cu, Cd and Pb in the water column and sediment in this watershed. Of the six ponds tested, the percentage of ponds with water column metal concentrations below the limit of quantitation (LOQ = 1 g/L) were as follows: Cr, 67%; Ni, 17%; Cu, 33%; Cd, 83%; Pb, 83%. All trace metal levels in water samples were below EPA drinking water criteria. Over all ponds, average leached values for metals in sediments were 17 ± 9.4 g/g for Cr, 32 ±21.8 g/g for Ni, 26 ± 14.0 g/g for Cu, 1.6 ± 3.9 g/g for Cd, and 13 ± 8.1 g/g for Pb. Further investigation is needed to determine trace metal levels in biota and potential toxicity to those organisms.
Key words: retention ponds, trace metals, amphibians, storm
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