New Jersey Water Science Center
Great Falls of the Passaic River at Paterson, N.J.
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Monitoring Mercury in Wet Deposition
Project Title:Monitoring Mercury in Wet Deposition
The purpose of this project is to obtain concentrations of total mercury in weekly precipitation samples and concentrations of methyl mercury in four-week composite samples from the existing Mercury Deposition Network (MDN) site at the Rutgers Horticultural Farm in New Brunswick over a three and a half year period starting in April 2010. Analysis of precipitation samples for total and methyl mercury is performed by Frontier Geosciences, Inc., Seattle WA, USA under contract with the National Atmospheric Deposition Programs (NADP) Mercury Deposition Network.
Statement of Problem
Worldwide industrial use of mercury in mining and manufacturing processes, as well as emission during power generation, have greatly increased concentrations of mercury in the environment. Mercury accumulates in biological tissue through complex reactions (bioaccumulation). Bacteria convert environmental inorganic mercury into methyl mercury (Me-Hg). This Me-Hg form is more toxic and more difficult to remove from bacterial systems than inorganic mercury. Any higher-level organisms that consume these bacteria also consume the Me-Hg. This cycle repeats up the food chain, with each higher predator consuming more and more Me-Hg, ultimately arriving in fish.
As humans consume fish, the Me-Hg in the fish is also consumed. Neurotoxicity is the most important health concern with mercury. Methyl mercury easily reaches the bloodstream and is distributed to all tissues; it can also cross the normally protective blood-brain barrier and enter the brain. It will also readily move through the placenta to developing fetuses, and so is of particular concern to pregnant women. Low-level exposure is linked to learning disabilities in children, along with interference in reproduction of fish-eating animals. In addition, both methyl mercury and mercuric chloride are listed by EPA as possible human carcinogens.
One of the primary ways mercury reaches land surfaces and water bodies is through atmospheric deposition, both wet and dry. Wet deposition is pollution, washed out of the atmosphere by rain. Estimates suggest mercury wet deposition accounts for 50% to 90% of the mercury load to most inland water bodies and estuaries in the U.S. Wet deposition rates are variable, and tend to have summer maximums.
Strategy and Approach
Personnel from the NJDEP Bureau of Air Quality will collect, process, and ship all precipitation samples weekly from the existing MDN site at the Rutgers Horticultural Farm in New Brunswick. From April 1st 2010 to September 31st 2013 a total of 182 samples will be collected, shipped, and analyzed for total mercury. Starting October 1st 2010 and continuing through September 31st 2013 the lab will composite subsamples from the weekly precipitations samples over 4-week periods and conduct analyses on the composite for methyl mercury (a total of 39 analyses). All coolers, sampling supplies, and blanking equipment are supplied by the MDN program on a weekly basis. NJDEP personnel will follow quality assurance procedures as specified by the MDN program (copy of QAPP is on file at NJDEP Bureau Air Quality). Data are made electronically available to the public from the NADP website http://nadp.sws.uiuc.edu/mdn/.