Dimethylsulfide and its oxidation products at two sites in Brittany (France)

Dimethylsulfide (DMS), sulfur dioxide (SO,), dimethylesulfoxide (DMSO), sul fate (SO42-) and methanesulfonate (MSA) were measured at a coastal site, Po inte de Penmarc'h, over a 25 day period during May and June 1993. Measureme nts were also performed to estimate the DMS flux from the algal beds around the Penmarc'h lighthouse and from the surrounding sea water. Similar atmos pheric measurements were conducted at a second site approximately 2 km inla nd from Penmarc'h. A comparison between the 2 sites indicates similar patte rns of DRIS concentration at each site, with values at the inland site bein g generally 10-15% lower. The concentrations of the aerosol phase products such as methanesulfonic acid and sulfate are examined in the light of air m ass origins. The fraction of nss SO42- produced from biogenic sources is es timated to be less than 25%. The yield of MSA and DMSO from DMS oxidation a re assessed from their relative concentrations and estimates of their atmos pheric lifetime. (C) 1999 Elsevier Science Ltd. All rights reserved.