Researchers David Gay, coordinator of the National Atmospheric
Deposition Program, Illinois State Water Survey, and Jeffrey
Levengood, wildlife toxicologist with the Illinois Natural
History Survey, and their colleagues selected fish common to two
rural streams in Illinois. In 2006 and 2007, fish were collected
from Panther Creek in Jasper County, considered a "high mercury"
site due to mercury levels reported previously, and from Saline
Branch Ditch in Champaign County, considered a "low mercury"
Findings showed that as predicted, fish from Panther Creek
had higher concentrations of mercury than did those from Saline
Branch Ditch. Although there were no point sources of mercury
upstream in either location, there are more and larger power
plants in the vicinity of Panther Creek than around Saline
Although the history of land use, the makeup of soils in the
area and a wider stream corridor at Panther Creek could all
contribute to the observed findings, "our results are consistent
with the higher wet deposition of mercury in the area and the
state's sport fish consumption advisories for Jasper and
neighboring counties, which indicate higher mercury loads in
large species of fish in this region," Levengood said.
To examine mercury concentrations over time, the researchers
also tested preserved blackstripe topminnows collected in 1900
and 1961 from Panther Creek. They found a dramatic decrease (64
percent) in mercury levels from the turn of the century to the
early 1960s, which is consistent with the changing use of coal
during that time period.
The most prevalent anthropogenic sources of mercury
historically were domestic heating and industry, although coal
was also used to power locomotives and steam shovels, and was
even used in medications and beauty products and to make hats.
This changed with the discovery of petroleum and advent of
coal-fired power plants. In Illinois, most of the coal
production and use was, and still is, located in the southern
and western portions of the state.
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Mercury concentrations in the fish from Panther Creek increased
slightly between 1961 and 2006. The researchers surmised that this
could be due to landscape changes that have taken place in that time
frame, such as the advent of intensive row crop agriculture and
continued conversion of more natural habitats to farmland. Such
changes would allow mercury deposited atmospherically for many years
to leach into streams at a faster rate.
As a pollutant, mercury can stay in the atmosphere for years, Gay
said. Distributed by rain and wind, mercury found in Illinois
streams may originate from both local and distant sources.
"If mercury is in a water body, there is no guarantee that it is
only from a local source," Gay said. "The difficulty is in
distinguishing among sources."
Mercury monitoring is important in setting regulatory benchmarks
and for measuring the success of environmental controls. The
researchers hope to conduct a more intensive study of mercury in
small fish from various locations in Illinois.
The results of the study, "Mercury in small Illinois fishes:
Historical perspectives and current issues," were recently published
in the international journal Environmental Monitoring and Assessment
(Volume 185(8):6485-6494). David Soucek and Chris Taylor of the
Illinois Natural History Survey were co-authors.
[Text from file received
Institute, University of Illinois]