Gaseous (DMS, MSA, SO2, H2SO4 and DMSO) and particulate (sulfate and methanesulfonate) sulfur species during the MINOS campaign: 1. Experimental data

H. Bardouki1, H.Berresheim2, J. Sciare3, G. Kouvarakis1, M.Vrekoussis1, C. Economou1, N. Mihalopoulos1

1 University of Crete - Environmental Chemical Processes Laboratory (ECPL), P.O Box 1470, 71409 Heraclion, Greece (mihalo@chemistry.uoc.gr)
2 Deutscher Wetterdienst Meteorologisches Observatorium (DWD)
3 LSCE, CEA Saclay, France


Dimethyl sulfide (DMS) is the principal and most abundant biogenic organic sulfur compound entering the atmosphere, where it undergoes photo-oxidation by OH, XO (X=halogen atom) and NO3 radicals and produces sulfur dioxide (SO2), dimethylsulfoxide (DMSO) and methanesulfonic acid (MSA). These compounds undergoe gas phase and/or heterogeneous reactions leading to the formation of aerosol species (non-sea-salt sulphate and methanesulfonate (MS-)), contributing to Earth's radiation budget by backscattering solar radiation to space and controlling the cloud condensation nuclei formation (Charlson et al., 1987).
During a field experiment performed during July-August 2001 in Crete in the frame of MINOS campaign, DMS and all the major oxidation products have been identified under moderately polluted marine conditions. DMS mixing ratios range from values near the detection limit (0.12nmol/m3) to 5.55nmol/m3 (136 pptv) (on 31st of July) with a mean value of 0.88nmol/m3. DMS present a well defined diurnal variation with higher values during daytime and a clear minimum (in most cases near to the detection limit) during night. A second minimum was observed in most cases around 1500 (LT). DMS oxidation products in gas phase (SO2, DMSO and MSA) have been identified with time resolution of 5 min (MSA) - 3 h (SO2, DMSO) and showed mean values of 42.22 nmol/m3, 0.07 nmol/m3 and 6.5E6 (median: 1.3E6) molecules cm-3 respectively. In addition SO4 and MSA have been also identified in aerosol phase with mixing ratios ranging from 64.13nmol/m3 and 0.47nmol/m3 respectively. The aim of this work is to present i) the levels and the variations of the main compounds involved in the biogenic sulphur cycle and ii) to understand the factors controlling their variability.