Mercury deposition in Southern New Hampshire, 2006–2009 M. A. S. Lombard1, J. G. Bryce1, H. Mao2, and R. Talbot3 1Department of Earth Sciences, University of New Hampshire, Durham, NH, 03824, USA 2Department of Chemistry, State University of New York's College of Environmental Science and Forestry, Syracuse, NY, 13210, USA 3Department of Earth and Atmospheric Sciences, University of Houston, Houston, TX, 77204, USA
Abstract. The atmospheric deposition of mercury (Hg) occurs via several mechanisms
including wet, dry, and occult processes. In an effort to understand the
atmospheric cycling and seasonal depositional characteristics of Hg,
event-based wet deposition samples and reactive gaseous Hg (RGM)
measurements were collected for approximately 3 years at Thompson Farm (TF),
a near-coastal rural site in Durham, NH, part of the University of New
Hampshire AIRMAP Observing Network. Total aqueous mercury exhibited seasonal
patterns in Hg wet deposition at TF. The lowest Hg wet deposition was
measured in the winter with an average total seasonal deposition of 1.56 μg m−2
compared to the summer average of 4.71 μg m−2.
Inter-annual differences in total wet deposition are generally linked with
precipitation volume, with the greatest deposition occurring in the wettest
year. Relationships between surface level RGM and Hg wet deposition were
also investigated based on continuous RGM measurements at TF from November
2006 to September 2009. No correlations were observed between RGM mixing
ratios and Hg wet deposition, however the ineffective scavenging of RGM
during winter precipitation events was evidenced by the less frequent
depletion of RGM below the detection level. Seasonal dry deposition of
reactive gaseous Hg (RGM) was estimated using an order-of-magnitude
approach. RGM mixing ratios and dry deposition estimates were greatest
during the winter and spring. The seasonal ratios of Hg wet deposition to
RGM dry deposition vary by up to a factor of 80.
Citation: Lombard, M. A. S., Bryce, J. G., Mao, H., and Talbot, R.: Mercury deposition in Southern New Hampshire, 2006–2009, Atmos. Chem. Phys., 11, 7657-7668, doi:10.5194/acp-11-7657-2011, 2011.