Chronology of Anthropogenic Heavy-Metal Fluxes and Pb Isotope Ratios Derived from Radiometrically Dated Lake Sediments in Northern Germany

Anthropogenic inventories and fluxes of Pb, Zn, Cu, and Sninto the sediments of two lakes, a drinking water reservoir(Neumühler See) and an urban lake (Ziegelsee), both in ornear Schwerin, Germany, were investigated. A simplefreeze-coring technique was used for reproducible samplingof undisturbed surface sediments. Sediment chronology wasestablished for Ziegelsee by gamma spectrometry of thenuclides ¹³⁴Cs, ¹³⁷Cs, ²⁴¹Am, ²¹⁴Pb,²¹⁴Bi and ²¹⁰Pb; bioturbation in Neumühler Seeprevents this. Anthropogenic heavy-metal loads weredetermined using Co as tracer for the geogenic portion. Anthropogenic heavy-metal inventories of Ziegelsee exceedthose of Neumühler See by factors of 3.0, 6.0, 5.6, and 6.8for the heavy metals Pb, Cu, Zn, and Sn, respectively. Theanthropogenic Pb flux into Ziegelsee increased from 1870 to1965 and decreased below the 1870 level by 1990. Isotoperatios of anthropogenic Pb change with time and indicatedifferent sources (lignite, gasoline). The anthropogenicCu, Zn, and Sn fluxes into Ziegelsee with respect to timeare comparable to that of Pb, but between 1960 and 1980pronounced local peaks appear and this was not determinedin the Pb flux.