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

Abstract

Environmental context Dimethyl sulfide is an important biogenic gas, released from ocean to atmosphere, which contributes to aerosol formation and can therefore affect global climate. Studies on dimethyl sulfide in both seawater and atmosphere have linked the atmospheric chemistry of dimethyl sulfide with its circulation in the marine environment. This study showed that these biogenic emissions contribute to the sulfur cycle and particulate production, deepening our understanding of their role in the East China Sea. Abstract 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 ~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 μmol m−2 day−1, with an average of 7.45 ± 6.30 μmol 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.