ABSTRACT
Lovelock et al. (1972) was the first to report dimethylsulfide (DMS) measurements from ocean areas and to recognize its importance for the global sulfur cycle. DMS is a semivolatile organic sulfur compound that accounts for 50% to 60% of the total natural reduced sulfur flux to the atmosphere, including emissions from volcanoes and vegetation (Andreae, 1990; Bates et al., 1992; Spiro et al., 1992). Of the total global DMS emissions, about 95% come from the oceans, with estimates of the emission ranging from 15-33 Tg S y-1 (Kettle and Andreae, 2000). All surface ocean water is supersaturated with DMS, and typical concentrations for open oceans range between 0.1 and 5 nM, but local increases can be observed in phytoplankton blooms. In the late 1980s, the hypothesis that DMS is involved in the biological regulation of global climate was put forward (Bates et al., 1987; Charlson et al., 1987). After emission to the atmosphere, DMS is oxidized to sulfur dioxide (SO2) and other products. From SO2, non-sea-salt (nss) sulfate is produced, which can form sulfate (SO4
2-) particles that act as condensation nuclei for water vapor. These nuclei affect the radiative properties of the atmosphere and clouds, with implications for climate. Higher numbers of condensation nuclei will reflect more incoming solar radiation back into space and thereby reduce the temperature on earth.
