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Isotopic tracers of lead contamination in the Great Lakes
Title
Isotopic tracers of lead contamination in the Great Lakes,
Description
, , , Fluxes of lead to the Great Lakes are dominated by atmospheric depositions of industrial lead, which account for ~ 64% of the lead inputs to Lake Ontario and >90% of the inputs to Lake Superior. It has recently been demonstrated that lead aerosols in the Great Lakes region may be identified by the contrasting 206Pb/207Pb ratios of industrial leads from the United States (1.221 ±0.009) and Canada (1.151 ±0.010). Here we show that those ratios may also be used to identify and trace industrial lead inputs to the Great Lakes. These corroborate spatial gradients in lead concentrations in surface waters, which range from 290 pmol kg−1 in Hamilton Harbour to <10 pmol kg−1 in the central waters of Lake Ontario. The latter concentrations and corresponding residence-time estimates, which are both an order of magnitude lower than previously reported, indicate that lead is rapidly scavenged in the epilimnion during periods of high primary productivity. We find that industrial lead from Canada and the United States are the two principal sources of lead contamination in the Great Lakes., ,
Author
Flegal, Nriagu, Niemeyer, Coale
Date
1989-01-01T00:00:00Z
Copper, zinc, cadmium and lead in surface waters of lakes Erie and Ontario
Title
Copper, zinc, cadmium and lead in surface waters of lakes Erie and Ontario,
Description
Concentrations of Cu, Zn, Cd and Pb were determined from 16 stations in Lake Ontario and Lake Erie, using trace metal sampling and analytical technique developed for seawater analysis employing graphite furnace atomic absorption. While Cu concentrations are consistent with previously reported data for the Great Lakes, concentrations of Zn, Cd and Pb are one to two orders of magnitude below those previously reported. These new data, however, were substantiated by complementary measurements of these samples for Pb concentrations and isotopic compositions as determined by isotope dilution mass spectrometry in a concurrent study, and are consistent with measurements of these elements in oceanic surface waters. Using reported trace metal inputs, these current measurements yield estimates for the residence times of Cu, Zn, Cd and Pb in the Lake Ontario epilimnion of 950, 5, 9, and 4 days, respectively. Lake Erie residence times are similar, averaging 660, 23, 20 and 9 days for Cu, Zn, Cd and Pb respectively. These short residence times are qualified by the imprecision of the elemental input estimates., Cited By (since 1996):30, CODEN: STEVA, ,
Author
Coale, Flegal
Date
1989-01-01T00:00:00Z