Gaseous (DMS, MSA, SO2, H2SO4 and DMSO) and particulate (sulfate and methanesulfonate) sulfur species over the northeastern coast of Crete H. Bardouki1, H. Berresheim2, M. Vrekoussis1, J. Sciare3,4, G. Kouvarakis1, K. Oikonomou1,4, J. Schneider3, and N. Mihalopoulos1 1Environmental Chemical Processes Laboratory (ECPL), Department of Chemistry, University of Crete, P.O Box 1470, 71409 Heraklion, Greece 2Deutscher Wetterdienst (DWD), Meteorological Observatory, Hohenpeissenberg, Germany 3Max-Planck Institute for Chemistry, Biogeochemistry Division, Mainz, Germany 4now at LSCE, Orme des Merisiers, Bat 709, CE Saclay, 91191 Gif-sur-Yvette Cedex, France
Abstract. A detailed study of the levels, the temporal and diurnal variability of the main
compounds involved in the biogenic sulfur cycle was carried out in Crete (Eastern
Mediterranean) during the Mediterranean Intensive Oxidant Study (MINOS) field
experiment in July-August 2001. Intensive measurements of gaseous dimethylsulfide
(DMS), dimethylsulfoxide (DMSO), sulfur dioxide (SO2), sulfuric
(H2SO4) and methanesulfonic acids (MSA) and particulate sulfate
(SO42-) and methanesulfonate (MS-) have been performed during the campaign.
Dimethylsulfide (DMS) levels ranged from 2.9 to 136 pmol·mol-1 (mean value of
21.7 pmol·mol-1) and showed a clear diurnal variation with daytime maximum. During
nighttime DMS levels fall close or below the detection limit of 2
pmol·mol-1. Concurrent measurements of OH and NO3 radicals during the campaign indicate that
NO3 levels can explain most of the observed diurnal variation of DMS. Dimethylsulfoxide
(DMSO) ranged between 0.02 and 10.1 pmol·mol-1 (mean value of
1.7 pmol·mol-1) and presents a diurnal variation similar to that of
DMS. SO2 levels ranged from 220 to 2970 pmol·mol-1 (mean value of
1030 pmol·mol-1), while nss-SO42- and MS- ranged from 330 to
7100 pmol·mol-1, (mean value of 1440 pmol·mol-1) and 1.1 to
37.5 pmol·mol-1 (mean value of 11.5 pmol·mol-1) respectively.
Of particular interest are the measurements of gaseous MSA and H2SO4. MSA ranged
from below the detection limit (3x104) to 3.7x107
molecules cm-3, whereas H2SO4 ranged between
1x105 and 9.0x107 molecules cm-3. The measured
H2SO4 maxima are among the highest reported in literature and can be attributed to high
insolation, absence of precipitation and increased SO2 levels in the area. From the concurrent
SO2, OH, and H2SO4 measurements a sticking coefficient of
0.52±0.28 was calculated for H2SO4. From the concurrent MSA, OH, and DMS measurements the yield of gaseous MSA from
the OH-initiated oxidation of DMS was calculated to range between
0.1-0.4%. This low MSA yield implies that gaseous MSA levels can not account for the observed
MS- levels. Heterogeneous reactions of DMSO on aerosols should be considered to explain the
observed levels of MS-.
Citation: Bardouki, H., Berresheim, H., Vrekoussis, M., Sciare, J., Kouvarakis, G., Oikonomou, K., Schneider, J., and Mihalopoulos, N.: Gaseous (DMS, MSA, SO2, H2SO4 and DMSO) and particulate (sulfate and methanesulfonate) sulfur species over the northeastern coast of Crete, Atmos. Chem. Phys., 3, 1871-1886, doi:10.5194/acp-3-1871-2003, 2003.