Missing methyl chloride found

Methyl chloride (CH₃Cl) is one of the largest natural sources of ozone-depleting compounds — accounting for approximately 15% of the atmospheric chlorine content. But, measurements of CH₃Cl emissions from coastal lands in the tropics suggest there is a significant shortfall in the observed atmospheric chloride concentrations and that emitted from plants. In 14 March Nature, Yoko Yokouchi and colleagues at the National Institute for Environmental Studies, Ibaraki, Japan show that CH₃Cl emissions from some common tropical plants can make up this shortfall (Nature 2002, 416:163-165).

Yokouchi et al. examined the rate of CH₃Cl emission from varieties of Dipterocarpaceae and ferns in the Tropical Rainforest Glass House at Tsukuba Botanical Gardens. They used capillary gas chromatography and mass spectrometry and measured volatile organic compound concentrations from the observation catwalk within the glasshouse (4m high) and from an area outside and upwind of the glasshouse.

Inside the glasshouse CH3Cl concentration was ~ ...