Oceanic influence on atmospheric mercury at coastal and inland sites: A springtime noreaster in New England

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, CH2Br 2 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 Hg 0 during the storm (∼7 ppqv h−1) which can account for the observed enhancement at the field sites.