Pesticide accumulation rates in a managed marsh along Lake Erie

Cores from two marshes along the southern shore of Lake Erie were super(210)Pb age-dated and analyzed for persistent pesticide pollutants using column chromatographic separation and analysis with gas chromatography. Soils in both watersheds have low to very low permeability and are dominated by a very poorly drained silty clay. Land-use practices in the watersheds of either marsh changed little since 1950; however, both watersheds are marked by decreased area dedicated to orchards and concurrent increase in residential and road area. The increase in grain size in recent years may be associated with a period of high water in Lake Erie since the early 1970s. The pesticide accumulation rates were calculated and indicate an airborne source for HCHs and endrin and possibly current illegal usage of DDT. The ratio of metabolite to parent molecule did not appear to change with sediment age. Also, there appeared to be a delay between pesticide application and deposition in the marshes.