The distribution and transport of lead over two centuries as recorded by lake sediments from northeastern North America

Abstract

We evaluated anthropogenic Pb deposition along a west-east transect from the Adirondack Mountains, New York, USA (ADIR) region, the Vermont-New Hampshire-Maine, USA (VT-NH-ME) region, and Nova Scotia, Canada (NS) region using 47 210Pb-dated lake sediment records. We used focus-corrected Pb inventories to evaluate cumulative deposition and breakpoint analysis to evaluate possible differences in timings among regions. Peak Pb concentrations decreased from west to east (ADIR region: 52–378 mg kg−1, VT-NH-ME region: 54–253 mg kg−1, NS: 38–140 mg kg−1). Cumulative deposition of anthropogenic Pb also decreased from west to east (ADIR region: 791–1344 mg m−2, VT-NH-ME region: 209–1206 mg m−2, NS: 52–421 mg m−2). The initiation of anthropogenic Pb deposition occurred progressively later along the same transect (ADIR region: 1869–1900, VT-NH-ME region: 1874–1905, NS region: 1901–1930). Previous lead isotope studies suggest that eastern Canadian Pb deposition over the past ~150 years has originated from a mix of both Canadian and U.S. sources. The results of this study indicate that anthropogenic Pb from sources west of the ADIR region were deposited in lesser amounts from west to east and/or Pb sources reflect less population density from west to east. The timing of the initiation of anthropogenic Pb deposition in the NS region suggests that Pb from gasoline may be an important source in this region.