Vertical distribution of dimethylsulphide in the marine atmosphere

Abstract

Dimethylsulphide (DMS) is excreted into sea water by marine phytoplankton and then transferred across the air/sea interface into the atmospheric boundary layer1–5. This process represents about one-half of the world's estimated natural sulphur emissions6, which are comparable in magnitude to the SO2 emissions from fossil-fuel burning7. The distribution and chemical reactions of DMS in the marine surface boundary layer have been described in detail elsewhere8. Here we present the first data on the vertical distribution of DMS in the marine troposphere. Our observations agree well with the distributions predicted by a two-dimensional model calculation which includes convective transport and chemical processes. This agreement supports the validity of our previous estimate of ∼40 Tg S yr−1 for the input of DMS from the oceans to the atmosphere and suggests that the oxidation of DMS can contribute significantly to the SO2 levels observed in the free troposphere.