Biogenic emission of dimethylsulfide (DMS) from the North Yellow Sea, China and its contribution to sulfate in aerosol during summer

Abstract

Seawater, atmospheric dimethylsulfide (DMS) and aerosol compounds, potentially linked with DMS oxidation, such as methanesulfonic acid (MSA) and non-sea-salt sulfate (nss-SO 4 2−) were determined in the North Yellow Sea, China during July–August, 2006. The concentrations of seawater and atmospheric DMS ranged from 2.01 to 11.79 nmol l −1 and from 1.68 to 8.26 nmol m −3, with average values of 6.20 nmol l −1 and 5.01 nmol m −3, respectively. Owing to the appreciable concentration gradient, DMS accumulated in the surface water was transferred into the atmosphere, leading to a net sea-to-air flux of 6.87 μmol m −2 d −1 during summer. In the surface seawater, high DMS values corresponded well with the concurrent increases in chlorophyll a levels and a significant correlation was observed between integrated DMS and chlorophyll a concentrations. In addition, the concentrations of MSA and nss-SO 4 2− measured in the aerosol samples ranged from 0.012 to 0.079 μg m −3 and from 3.82 to 11.72 μg m −3, with average values of 0.039 and 7.40 μg m −3, respectively. Based on the observed MSA, nss-SO 4 2− and their ratio, the relative biogenic sulfur contribution was estimated to range from 1.2% to 11.5%, implying the major contribution of anthropogenic source to sulfur budget in the study area.