Production, distribution and flux of dimethyl sulfide in the East China Sea and its contribution to atmospheric sulfate aerosols

Dimethyl sulfide (DMS) is identified as an essential biogenic sulfur compound in the ocean. Its oxidation products are thought to be important contributors to cloud condensation nuclei, thereby influencing the earth's radiative balance and climate. The concentrations of DMS and its precursor, dimethylsulfoniopropionate (DMSP) were measured in seawater and sediment pore water in the East China Sea (ECS) during summer. In addition, dissolved DMSP (DMSPd) degradation rates, DMS production and consumption rates, and sea-to-air flux of DMS were determined, and the biogenic contribution to atmospheric non-sea-salt sulfate (nss-SO42-) was evaluated in PM2.5 and PM10 aerosols over the study area. The spatial distributions of DMS and DMSP were closely related to that of chlorophyll-a and decreased from the inshore to the offshore. The concentration of DMSPd in sediment pore water was significantly higher than that in bottom water, which indicated that sediment is a net source of DMSPd for bottom water. The biological incubation experiments showed that similar to 36.0 % of decomposed DMSPd was degraded into DMS, while 78.7 % of produced DMS was consumed by bacteria within the surface water. The sea-to-air flux of DMS varied from 1.30 to 31.84 mu mol m(-2) day(-1), with an average of 7.45 +/- 6.30 mu mol m(-2) day(-1). Biogenic contributions of the ECS to total nss-SO42- were estimated to be 13.0 % +/- 9.9 % in PM2.5 and 13.5 % +/- 5.1 % in PM10 samples respectively, which indicated that marine DMS release cannot be neglected in the ECS during summer.

Automated summary

The study investigated the concentrations of DMS and DMSP in the East China Sea during summer and their contribution to atmospheric non-sea-salt sulfate. The results show that marine DMS release is an important factor in the East China Sea during summer and cannot be neglected.