July 24, 2008
Mercury Declining in Hudson’s Fish
By Delthia Ricks, Newsday, Melville, N.Y.
Jul. 24--Mercury levels in several varieties of Hudson River fish have declined significantly over the past three decades, Stony Brook researchers have found in an analysis that points to dramatically decreasing concentrations of industrial pollution.
Heavy-metal contaminants -- particularly mercury -- mounted up in the Hudson throughout most of the 20th century because of increasing dependence on the river for industry and commerce.
Now, after years of state regulation and federally mandated clean-up, mercury concentrations have declined two- to threefold in fish, proof that impeding the flow of heavy metals into the river can have a demonstrable effect on wildlife, scientists say.
Striped bass, yellow perch, largemouth bass, smallmouth bass and carp all have lower levels of mercury than in the 1970s, said Jeffrey Levinton, distinguished professor in ecology and evolution at Stony Brook University.
Mercury in Hudson River fish, Levinton said, is now at a pre-1950s level -- before the defense contractor that manufactured the Nike anti-ballistic missile released its effluent into the river.
"The decline we've seen in fish is mostly because there is less [mercury] input into the Hudson," Levinton said yesterday. "Back 30 years ago, more trash was burned, coal was burned and there were a number of industrial inputs."
Even though coal is organic, it can contain contaminants, such as mercury, which seep into coal beds through groundwater and the atmosphere, he said.
Levinton's mercury study did not undertake the larger and more technically difficult analysis of measuring amounts of the metal in the Hudson itself. "It is hard to measure mercury accurately in water. It is possible to measure it in sediment, and it has declined," he said about his research of the river's sediment.
He and Stony Brook colleague Sharon Pochron outline their findings in next month's issue of Environmental Toxicology and Chemistry.
Levinton explained that tracing the source of contaminants was difficult because some varieties of fish have an extraordinary range. Hudson bass tagged by Stony Brook scientists, for instance, have been found as far south as Virginia and as far north as Nova Scotia.
Despite the positive findings, mercury is still present in Hudson fish, and the question now is pinpointing the metal's source. Currently, all analyses point upstream, he said, possibly from the Adirondack watershed or an as-yet unidentified industrial source.
Striped bass, yellow perch, largemouth and smallmouth bass, and carp collected from New York City to the Adironack watershed, a concentration of bodies of water upstate, all have lower levels of mercury thatn in the 1970s.
What they found
Analysis of Department of Environmental Conservation data on mercury levels in a variety of fish fillets showed mercury contamination declined between 1970 and 2005. The data involved fish along much of the Hudson River.
The findings don't affect a state Health Department warning to eat striped bass from the Hudson no more than once a month.
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