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SOURCES OF MERCURY WET DEPOSITION IN EASTERN OHIO, USA
Citation:
KEELER, G. J., M. S. LANDIS, G. A. NORRIS, E. CHRISTIANSON, AND J. T. DVONCH. SOURCES OF MERCURY WET DEPOSITION IN EASTERN OHIO, USA. ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, Vol 40(19):5874-5881, (2006).
Impact/Purpose:
The overall research objective of this task is to improve our understanding of the emission, transport, transformation, and deposition of atmospheric mercury. Information garnered from this research is used to improve and evaluate EPA deterministic models that are used to investigate the (i) relative impact to local, regional, and global sources to atmospheric mercury deposition, and (ii) benefits of various emission reduction scenarios.
Description:
In the fall of 2002, an enhanced air monitoring site was established in Steubenville, Ohio as part of a multi-year comprehensive mercury monitoring and source apportionment study to investigate the impact of local and regional coal combustion sources on atmospheric mercury deposition in the Ohio River Valley. This study deployed advanced monitoring instrumentation, utilized innovative analytical techniques, and applied state-of-the-art statistical receptor models. This paper will present wet deposition data and source apportionment modeling results from daily event precipitation samples collected during the calendar years 2003-2004. The volume-weighted mean mercury concentrations for 2003 and 2004 were 14.0 and 13.5 ng L-1, and total annual mercury wet deposition was 13.5 and 19.7 µg m-2, respectively. Two new EPA implemented multivariate statistical models, Positive Matrix Factorization (PMF) and Unmix, were applied to the data set and six sources were identified. The dominant contributor to the mercury wet deposition was found by both models to be coal combustion (~70%). Meteorological analysis also indicates that a majority of the mercury deposition found at the Steubenville site was due to local and regional sources.