Stable Pb isotope ratios in aerosols, precipitation, and size-fractionated particulate matter in the Gulf of Maine, Scotian Shelf, and Labrador Sea

Abstract

Measurements of Pb isotopes in aerosols, precipitation, and size-fractionated particulate matter from the Gulf of Maine, Scotian Shelf and Labrador Sea are used to investigate the source of Pb. The 206Pb/ 207Pb ratio in aerosols and precipitation collected at New Castle, NH suggests that anthropogenic Pb is a mixture of US and Canadian sources. 206Pb/ 207Pb ratios in >53 μm particulate matter from the Gulf of Maine and Scotian Shelf slope waters are consistent with contaminant Pb inputs predominantly from US and Canadian sources, while in shelf waters 206Pb/ 207Pb ratios in >0.4 μm and >53 μm particles are consistent with a mixture of US and Canadian sources, as well as Pb associated with resuspended surface sediment. 206Pb/ 207Pb ratios in particulate matter (>0.4 μm, 10–53 μm, and >53 μm) from Labrador Sea surface waters range from 1.165 to 1.211 and are a mixture of Pb derived from ore compositions consistent with Broken Hill, Australia and southeast Missouri, US sources.