Edward Callender, Peter C. Van Metre
As a result of the Clean Air Act,
lead (Pb) emissions to the atmosphere have been greatly
reduced since the mid-1970s. As part of its National
Water Quality Assessment, the U.S. Geological Survey
has been using paleolimnological techniques to assess
past trends in hydrophobic contaminants. In urban-suburban
environments, reservoir sediment cores show prominent
peaks in Pb distributions that correlate well with the
rise and fall of leaded gasoline. However, Pb concentrations
in sediments are approximately double those of baseline
values prior to the 1950s and 1960s. It is apparent
that significant concentrations of anthropogenic Pb
still exist in soils and aquatic sediments and that
it will take many years to reduce these concentrations
to prepollution values, even if there are no new sources
of Pb pollution.
Environmental Science & Technology.
News. Vol. 31, No. 9, 1997. 424A-428A.
Edward Callender
U.S. Geological Survey
432 National Center
Reston, VA 20192
Peter C. Van Metre
U.S. Geological Survey
8011 Cameron Road
Austin, TX 78754
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