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El Paso and Ciudad Juarez are neighboring cities on the U.S.--Mexico border
that historically have experienced particulate matter (PM) pollution of their
shared airshed. Pb and As are important pollutants present in the particulate
matter fraction trapped by air sampling filters. We examined air filters from
as early as 1977 to as recently as 2001 to determine the oxidation state and
speciation of As and Pb present on these filters. We believe that the lead
found on these air filters has three possible major sources: a local copper
smelter, leaded gasoline (in use until approximately 1990 in Mexico), and a
mixed general urban lead input. Information on the chemical speciation of Pb
and As is important in determining bioavailability, fate, and possible sources
of these contaminants.
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