Abstract
Abstract. Continuous measurements of elemental (Hg0) and reactive mercury were conducted at two sites in New Hampshire during a powerful April 2007 noreaster. During the most intense period of the storm, enhancements of ~30–50 ppqv in Hg0 were observed at a coastal and a high elevation inland site. This enhancement occurred simultaneously with elevated mixing ratios of three marine tracers, CH3I, CH2Br2 and CHBr3. These observations suggest a marine source of Hg0, possibly outgassing from the ocean surface during strong turbulence. The Hg0 enhancement observed 100 km inland suggests that the impact of coastal storms on terrestrial Hg cycling may not be limited to near-shore environments. Combining Hg0 and marine tracer measurements during the storm with estimates of oceanic tracer fluxes during previous strong storms yields an order-of-magnitude estimate of the oceanic source of Hg0 during the storm (~7 ppqv h−1) which can account for the observed enhancement at the field sites.
Highlights
Mercury (Hg) has been identified as an important environmental pollutant, yet our understanding of both natural and anthropogenic emissions and environmental cycling of Hg is very limited
Pressure, relative humidity, wind speed and direction are measured at 1-minute resolution (Davis, Inc.), and marine tracers (CHBr3, CH2Br2 and CH3I) are measured at Thompson Farm (TF) with two-hour resolution using a GC system designed for dual-stage trapping without using liquid nitrogen (Sive et al, 2005)
The April 2007 noreaster developed as a low pressure system over the southwestern United States which tracked toward the east coast and northward on 15 April
Summary
Mercury (Hg) has been identified as an important environmental pollutant, yet our understanding of both natural and anthropogenic emissions and environmental cycling of Hg is very limited. Measurements in the Mediterranean Sea by Sprovieri et al (2003) indicated enhanced Hg0 compared to coastal sites (Pirrone et al, 2003) and a net source from oceanic evasion. A recent study by Mao et al (2008) suggested the ocean was a source of Hg0 by comparing ambient levels of Hg0 with a marine tracer (CHBr3) at a coastal site in the northeastern United States. In April of 2007, the mid-Atlantic and northeastern United States experienced a rare and powerful springtime noreaster; the lowest barometric (sea level) pressure recorded was 958 hPa, equivalent to that of a moderate category 3 hurricane During this event, we monitored Hg0 and RGM continuously at two sites in New Hampshire. The combination of Hg0, RGM, marine tracer and meteorological data along with concurrent Hg measurements at both inland and coastal sites during a major storm is the first data set of its kind and adds considerably to our understanding of coastal Hg cycling
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