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Estimated Trends in Wet Mercury Deposition at MDN Sites
Dr. Kevin Civerolo* and Gopal Sistla
New York State Department of Environmental Conservation Division of Air Resources
625 Broadway, 2nd Floor, Albany, NY 12233-3259
| With the proposed reductions in mercury EGU emissions
in the coming years, it is instructive to examine current trends in mercury
wet deposition. To this end we used the nonparametric Seasonal Kendall
test to estimate trends at 49 MDN sites having at least seven years of
data. Preliminary analysis suggests that 18 sites experienced statistically
significant declines in mercury concentrations in wet deposition, despite
the fact that trends in precipitation at these sites, although generally
not significant, were found to be increasing at 31 of the 49 sites. There
does not appear to be any clear geographic pattern to these significant
declines, as these 18 sites were distributed across the MDN network. Changes
in mercury deposition will be compared with changes in sulfate deposition
at these locations. It will be important to continue this analysis as
more data become available and more sites are brought on-line to assess
the impacts of the Clean Air Mercury Rule and other emissions reductions
programs over the next decade.
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