Policy Initiative:
Mercury Modeling

In addition to CO₂ , we are pursuing a regional perspective on persistent atmospheric toxics such as Hg.   Mercury is a contaminant in the global atmosphere that exists predominately as elemental mercury (Hg ° ) with a lifetime of 0.5-2 years [ Schroeder and Munthe, 1998].   Natural processes release about 3,000 tons Hg/year to the atmosphere compared to 3,560 tons yr -1 from anthropogenic sources [ Nriagu, 1989].   In the United States major sources are believed to be fossil fuel combustion, municipal and medical waste incineration, manufacturing and smelting, with small contributions from burning of gasoline and diesel fuels.   Wet and dry deposition processes remove Hg from the atmosphere with efficiencies that depend on the proximity of sources, the level of atmospheric oxidants, precipitation patterns, and land cover.   In particular, Xu et al. [2000] suggested that ambient concentrations and wet deposition are heavily influenced by re-emission from the natural surfaces and local, regional/global scale transport.

Many of the lakes in New England contain high levels of mercury in fish, and health warnings have been issued for fish consumption from a large number of lakes
( e.g., NH Warning ;   EPA Advisories ) .   Recent estimates indicate that 47% of the mercury deposited in the northeast U.S. originates from sources within the region, 30% from outside the region, and 23% from the global background reservoir [ U.S. EPA , 1997].   The deposition of Hg across the northeastern U.S. is estimated to be >10 micrograms per square meter per year. [ U.S. EPA , 1997; NESCAUM, NEWMOA, NEIWPCC and Canadian Ecological Monitoring Network , 1998], but there are only a few isolated measurements to verify this estimate.   Our broad expertise in measurements, data analysis, and modeling has the capacity to substantially elevate our understanding of the Hg budget in New England within the next few years.

An NCASP modeling and monitoring initiative is aimed at the development and evaluation of tools for assessing the mechanisms and contributing sources which lead to mercury pollution in the Northeastern US.    The approach will be to develop a CMAQ modeling platform, a REMSAD mercury modeling platform with source tagging capability and expand a set of atmospheric mercury measurement stations whose historical measurements will be used to validate the models.