Mercury Hot Spots Found in North America

[Guest guest]

January 03, 2007

Mercury " Hot Spots " Found in North America

http://www.sciam.com/print_version.cfm?articleID=EA19F960-E7F2-99DF-32460084B295\

C9EA

Aquatic ecosystems in the northeastern U.S. and southern Canada harbor

dangerous concentrations of the neurotoxin

Researchers have discovered dangerous levels of the neurotoxin mercury

(Hg) in the muscle tissue of perch and in the blood and eggs of the common

loon in aquatic ecosystems of the northeastern U.S. and southern Canada.

The finding led them to identify five " hot spots " of mercury contamination

that pose serious health risks to animals as well as humans. In addition,

elevated concentrations of the neurotoxin were found in nine other regions

labeled as " areas of concern " in the report published in the January issue

of Bioscience. High concentrations of mercury, which accumulate in the

food chain, can cause brain and nerve damage in developing fetuses and

young children.

In some areas the team of U.S. and Canadian researchers, led by

Evers of the BioDiversity Research Institute in Gorham, Maine, found perch

containing mercury levels as high as 20 times greater than the

Environmental Protection Agency's (EPA) recommended limits. A survey of

other ecosystem members discovered that 75 percent of bass and trout

sampled contained mercury levels exceeding the federal limits.

The northeastern hot spots--which include the western Adirondacks and the

middle and lower Merrimack River--share several characteristics: most can

track much of their mercury deposition to local sources such as waste

incinerators and coal-fired electricity plants. Each area contains

landscape components--like tree canopies that suck up airborne mercury

particles or wetlands that facilitate the methylation of mercury to the

toxic compound methylmercury--that concentrate the pollutant in aquatic

environments, sometimes up to one million times greater than its ambient

levels. Water manipulation, such as reservoirs, can also ratchet up

methylmercury levels, causing a decrease in the viability of wildlife

offspring. In addition, soil contamination from legacy mercury use is

another major indicator of a hot spot.

" I would say these four factors are likely responsible for biological Hg

hot spots in other parts of the country as well, " Evers surmises. " The

western U.S. and Rockies appear to have major legacy Hg problems that are

causing reproductive impairments to birds such as the clapper rail in San

Francisco Bay. "

The research team predicts its results will affect cap-and-trade

regulations implemented by the EPA in 2005 to nudge coal-fired power

plants to take steps to reduce their emissions. The cap-and-trade program

was designed to encourage the industry to put in pricey pollution controls

by allowing them to sell " credits " they received for doing so to other

plants. " Trading has the potential to lead to static or increased

emissions in some areas of the United States, " the authors write in the

report, adding that increased deposition in areas with high mercury

content will increase contamination in fish and put people who consume

that fish at higher risk of mercury poisoning.

Pointing to historical data from the Merrimack River, the authors note

that between 1997 and 2002 mercury emissions in southern New Hampshire

declined by 45 percent because of regulations on municipal incinerators.

As a result, mercury concentrations in loons decreased 64 percent, with an

accompanying decline of accumulations in perch.

" The cap-and-trade could work as long as there was an evaluation of

landscape sensitivities within a radius of 50 to 100 kilometers of the

point source, " Evers says. " I think associating monitoring stations as

part of the national Hg monitoring network is best and should at least be

placed in areas with the greatest risk. "

Responding to the new findings, the EPA issued a statement saying that

emission reductions made through its Clean Air Interstate Rule will

specifically " occur in areas where mercury deposition is currently the

highest. " The agency insists that it will keep an eye on the situation.

" EPA is, " says the statement, " working with monitoring, modeling and

mercury experts to establish a coordinated, nationwide network of

atmospheric mercury monitoring sites. "

*

The material in this post is distributed without

profit to those who have expressed a prior interest

in receiving the included information for research

and educational purposes.For more information go to:

http://www4.law.cornell.edu/uscode/17/107.html

http://oregon.uoregon.edu/~csundt/documents.htm

If you wish to use copyrighted material from this

email for purposes that go beyond 'fair use', you

must obtain permission from the copyright owner.