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

摘要

Continuous measurements of elemental (Hg0) and reactive mercury wereconducted at two sites in New Hampshire during a powerful April 2007noreaster. During the most intense period of the storm, enhancements of~30–50 ppqv in Hg0 were observed at a coastal and a highelevation inland site. This enhancement occurred simultaneously withelevated mixing ratios of three marine tracers, CH₃I, CH₂Br₂and CHBr₃. These observations suggest a marine source of Hg0,possibly outgassing from the ocean surface during strong turbulence. TheHg0 enhancement observed 100 km inland suggests that the impact ofcoastal storms on terrestrial Hg cycling may not be limited to near-shoreenvironments. Combining Hg0 and marine tracer measurements during thestorm with estimates of oceanic tracer fluxes during previous strong stormsyields an order-of-magnitude estimate of the oceanic source of Hg0during the storm (~7 ppqv h−1) which can account for theobserved enhancement at the field sites.