Abstract
Abstract. We conducted measurements of Hg0 and RGM at two inland sites, Thompson Farm (TF) and Pac Monadnock (PM), and a marine site (Appledore Island (AI)) from the UNH AIRMAP observing network in New Hampshire in 2007. Measurements of other important trace gases and meteorological variables were used to help understand influences on the atmospheric Hg budget in New England. Seasonal variation in both species observed at TF and PM is attributable to such factors as seasonal variation in deposition strength, meteorological conditions and biogenic emissions. Hg0 and RGM varied diurnally at TF, particularly in spring, following the trend in air temperature and jNO2 and suggesting photochemical production of RGM. The diurnal patterns of Hg0 and RGM at AI during summer were nearly opposite in phase, with Hg0 decreasing through late afternoon, suggesting more significant photochemical oxidation of Hg0 to RGM in the marine environment, likely due to the presence of marine halogen compounds. A significant relationship of RGM with SO2 at TF suggests a strong contribution of RGM from anthropogenic sources. Significant levels of halogen compounds measured at TF in previous studies, as well as similar Hg0 levels and Hg0-CO ratios at TF and AI may suggest that similar air masses are prevalent at these sites.
Highlights
Mercury (Hg) has been identified as a potentially hazardous contaminant
A full year of Hg0 and RGM measurements were conducted at two inland sites, Thompson Farm (TF) and Pac Monadnock (PM), from the UNH AIRMAP observing network in New Hampshire throughout 2007, and at a marine site, Appledore Island (AI), during summer
Measurements of other trace gases, e.g., carbon monoxide (CO), CO2, O3, NOy, and SO2, and meteorological variables were employed in order to better explain this variation as well as natural and anthropogenic controls on the atmospheric Hg budget in New England
Summary
A primary source of RGM is combustion, which comprises at least 50% and 60% of total Hg emissions from coal-fired power plants (Carpi, 1997) and municipal waste combustors respectively. Three recent studies undertook year-round measurements of Hg0, RGM and particulate Hg in Quebec, Canada (P4o0issant et al, 2005), the Ohio River Valley (Yatavelli et al, 2006), and in urban and rural sites in Michigan (Liu et al, 2007) These studies revealed imprints of both local and regional sources on atmospheric Hg and showed clear diurnal and seasonal variation in Hg0 and RGM. Hampshire (UNH) conducts year-round, continuous air quality measurements at a network of sites in rural New England, USA These sites are downwind of major urban and industrial pollution sources in the US northeastern corridor. These sites are downwind of major urban and industrial pollution sources in the US northeastern corridor. Mao et al (2008), using multiple years of continuous AIRMAP measurements of Hg together with a suite of trace gases, showed distinct diurnal variability and seasonality in Hg0 mixing ratios and quantified the regional background level of Hg0 as well as the anthropogenic influence in Northern New
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