A comparison of heavy metal concentrations in storm water residual sediments withing urban storm water drainage systems located in south central Minnesota

This study is a comparison of heavy metal concentrations in urban stormwater residual sediments found within receiving bodies of water in Blue Earth, Waseca and Faribault Counties in South Central Minnesota. This study assessed the quantity of heavy metal loading occurring in stormwater residual sediments within receiving bodies of water. Residual sediments were collected from ten municipalities in South Central Minnesota. These municipality's urban storm water flows into the Blue Earth, Le Sueur, and the Minnesota Rivers and/or into other bodies of water which eventually flow into these rivers. Residual sediment samples from 90 sampling locations within the ten municipalities were analyzed. This study reaffirms urban stormwater's impact on the concentration of heavy metal loading on residual sediments within the receiving body of water, presents correlations found between metals and other metals, and metal concentrations and grain size analysis. In addition, this study looked at the inter and intra relationships including frequencies and concentrations of metals found within the ten individual communities and between the communities. Compared to heavy metal concentrations found within sediments located upstream from storm sewer outlets, the average heavy metal concentration of residual sediments collected at storm sewer outlets were higher for all eight metals (Cr, Al, Pb, Fe, Cu, Mn, Ni and Zn) investigated as part of this study.