Isotopic composition of species-specific atmospheric Hg in a coastal environment

Abstract The isotopic composition of species-specific atmospheric mercury (Hg) was investigated in the coastal environment of Grand Bay, Mississippi, USA. Atmospheric mercury species (Hg 0 (g) , Hg II (g) and Hg (p) ) were collected individually, and analyzed for isotopic composition. Gaseous elemental Hg (Hg 0 (g) ) displayed δ 202 Hg ranging from − 3.88‰ to − 0.33‰. Aerosol Hg (Hg (p) ) displayed intermediate δ 202 Hg ranging from − 1.61‰ to − 0.12‰, while reactive gaseous Hg (Hg II (g) ) displayed positive δ 202 Hg ranging from + 0.51‰ to + 1.61‰. Significant positive mass-independent fractionation (MIF) was observed in Hg (p) (∆ 199 Hg = + 0.36‰ to + 1.36‰), while Hg 0 (g) displayed negative MIF (∆ 199 Hg = − 0.41‰ to − 0.03‰) and Hg II (g) displayed intermediate MIF (∆ 199 Hg = − 0.28‰ to 0.18‰). Positive MIF of 199 Hg and 201 Hg measured in Hg (p) is consistent with significant in-aerosol photoreduction. Significant MIF of 200 Hg was observed in all Hg species with Hg 0 (g) displaying negative ∆ 200 Hg values of − 0.19‰ to − 0.06‰ while Hg II (g) and Hg (p) displayed positive ∆ 200 Hg values of + 0.06‰ to + 0.28‰, which are similar to ∆ 200 Hg values reported by Gratz et al. (2010). These results suggest that isotope tracing of each atmospheric Hg species may be feasible during important atmospheric processes such as wet and dry deposition.