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Mercury matters: a synthesis of mercury contamination in the Northeast

 

  Contact Info:
  Charles Driscoll
Syracuse University
Department of Civil and Environmental Engineering
151 Link Hall
Syracuse, New York 13244-1190
phone: (315) 443-3434
email: ctdrisco@syr.edu

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MERCURY is a naturally occurring pollutant that can have toxic effects on fish, and on wildlife and people who consume large quantities of fish high in mercury. Hubbard Brook Research Foundation recently completed a synthesis on mercury contamination in the Northeast, including an analysis of regional mercury data and linkages to mercury policy. Mercury contamination is widespread. 44 states have mercury advisories, covering 13 million lake acres and 764,000 river miles. The widespread nature of mercury contamination is indicative of the importance of atmospheric emissions and deposition of mercury. About two thirds of mercury released to the atmospheric is from human sources (coal combustion, incinerators, industrial processes). In the Northeast, deposition of mercury has increased from 4 to 6-fold over the past century. Mercury is a global, regional and local pollutant. Human and wildlife exposure to mercury occurs due consumption of methyl mercury in fish (see figure below). Inorganic mercury from atmospheric deposition is converted to methyl mercury by bacteria, largely in wetlands and sediments. Methyl mercury bioaccumulates along the food chain (both aquatic and terrestrial), allowing for relatively low concentrations in water to be biomagnified by a million to 10 million times to toxic concentrations.

In this analysis, five known and nine suspected biological mercury hotspots were identified covering the northeastern U.S. and southeastern Canada (see map below). The biological mercury hotspots are due primarily to atmospheric mercury emissions and deposition that is amplified in: (1) sensitive watersheds, (2) reservoirs with drawn downs greater than 10.5 feet, and (3) areas near large local mercury emission sources. A modeling case study in southern New Hampshire and northeastern Massachusetts suggests that local coal-fired power plants contribute to a biological mercury hotspot. If a mercury cap-and-trade program allows emissions from large local sources to continue unabated, areas of high deposition and associated biological mercury hotspots may persist.

 Mercury cycling diagram
Map of mercury hotspots

References

Doran, P.J. 2003. Intraspecific spatial variation in bird abundance: patterns and processes. Ph.D. thesis, Dartmouth College, Hanover, NH.

Doran, P.J., and R.T. Holmes. 2005. Habitat occupancy patterns of a forest dwelling songbird: causes and consequences. Canadian Journal of Zoology 83:1297-1305.

Schwarz et al. 2002. Factors controlling spatial variation of tree species abundance in a forested landscape. Ecology 84: 1862-1878.

Stamps, J. A. 1988. Conspecific attraction and aggregation in territorial species. American Naturalist 131:329-347.

Date Prepared: July 2007