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A group of Dartmouth researchers studying the concentrations of toxic metals
at the former Coakley Landfill in North Hampton, N.H. has found that while the
level of iron and some other contaminants decreased, the level of arsenic
slightly increased. The researchers detailed their calculations regarding the
geochemical processes at this site over the last years in a paper published
online on November 23 by Environmental Science
and Technology, a journal of the American Chemical
Society.
Benjamin Bostick and his research team have identified a connection between
increaased levels of arsenic in a New Hampshire landfill and the degredation of
other organic wastes. (photo by Joseph Mehling '69)
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Their research could shed light on how arsenic pollutes groundwater near
landfills, especially in areas where the landfill's organic material mixes with
naturally occurring iron oxides. This process also may explain the high level
of arsenic in drinking water in Bangladesh and other areas of Southeast
Asia.
"Unfortunately, arsenic appears to come from the interaction of
microbes with iron oxides carrying arsenic in the underlying rocks," says
Benjamin
Bostick, a coauthor on the paper and assistant professor of earth sciences. "In the
Coakley Landfill, it appears that these microbes increase arsenic
concentrations by consuming organic wastes and creating a 'reducing condition'
where the oxygen concentration is very low, which is conducive to arsenic
release. We think that arsenic contamination caused by the natural degradation
of other toxic organic material might be widespread."
The Coakley Landfill was listed in 1986 as an Environmental Protection Agency Superfund
Site because of hazardous waste content. The area was capped in 1998, a
procedure common in the rehabilitation of landfills. With data collected since
1994, the researchers were able to tie changes in arsenic levels over time to
the degradation of benzene and other organic wastes.
Bostick's coauthors on this study include Jamie deLemos, Carl Renshaw, Stefan
Stürup, and Xiahong
Feng, all with the Department of Earth Sciences.
Funding for this research was provided by the U.S. National Institutes of
Environmental Health Sciences Superfund Basic Research Program and the National Science Foundation.
By SUSAN KNAPP
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