Lead Sources to the Amundsen Sea, West Antarctica

The
global prevalence of industrial lead (Pb) contamination was
exemplified decades ago by the predominance of anthropogenic Pb in
samples of Antarctic surface ice and in Southern Ocean surface waters.
Decreases in environmental Pb contamination corresponding with the
near-global phase-out of leaded automobile gasoline beginning in the
1970s have since been observed. Measurements of Pb concentration in
snow and ice core samples from Antarctica show that recent fluxes
of industrial Pb to Antarctica have similarly declined. Here, we present
measurements of Pb concentrations and isotopic compositions in seawater
and surface sediments from the Amundsen Sea continental shelf including
the Amundsen Sea Polynya. Both sets of measurements show that most
(∼60–95%) of the Pb at our sites, at the time of sampling,
is natural in source: that is, derived from the weathering of Antarctic
continental rocks. These fluxes of natural Pb then become entrained
into polynya waters either from sediment resuspension or from the
transport of sediment-laden glacial melt waters to the polynya.