The removal of dimethyl sulfide (DMS) from the atmosphere remains a mystery as reaction with iodine monoxide (IO) is ruled out by researchers from Leeds, UK. 

Scientists believe oxidation of DMS emitted from oceans is important in the production of aerosol particles that scatter solar radiation. The amount of DMS in the atmosphere can then influence the Earth's radiative balance and climate.   

Reacting with the main oxidisers, OH and NO, does not account for the rapid loss of DMS. IO, formed in the atmosphere when sunlight breaks down biogenic iodine compounds, has recently been identified as a possible alternative but Dwayne Heard and colleagues have shown this is not the case. 

Heard's group is the first to study the reaction of DMS with IO using a pulsed-laser photolysis laser-induced fluorescence system. This minimises secondary chemistry and provides a sensitive detection method for IO. 'We have shown that under atmospheric conditions of pressure and temperature the reaction is not fast enough to be important,' he said.

Hilary Crichton