Biogenic Sulphate, Sulphur Dioxide and Methanesulphonic Acid Ratios over the North Atlantic
Abstract
Methanesulphonic acid (MSA) and sulphate are the end products of two different oxidation pathways of atmospheric dimethylsulphide (DMS). Sulphate aerosols can act as cloud condensation nuclei that affect incoming solar radiation and thus climate. The branching ratio cannot be measured using sulphate concentrations alone due to anthropogenic sulphate contributions. Stable isotope techniques, however, can be used to define continental and biogenic emissions, determine the origin of sulphate in aerosol samples and provide insight into DMS oxidation. Size segregated aerosol filters, sulphur dioxide and atmospheric DMS were collected during the summer 2003 Canadian Surface Ocean Lower Atmospheric Study (C-SOLAS) over the North Atlantic. Isotope values along with sulphate, MSA and cation concentrations were analysed. Non-sea salt (NSS) sulphate concentrations where as high as 11000 ng/m3. Biogenic sulphate concentrations ranged between 100 and 800 ng/m3 while biogenic sulphur dioxide concentrations ranged between 20 and 4000 ng/m3. Polluted air masses see an increase in biogenic sulphur dioxide indicating an influence of human activity on the oxidation pathways of DMS. MSA and biogenic sulphur dioxide concentrations are compared to the biogenic sulphate to explore the branching ratio.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2006
- Bibcode:
- 2006AGUFM.A53A0159S
- Keywords:
-
- 0305 Aerosols and particles (0345;
- 4801;
- 4906);
- 0315 Biosphere/atmosphere interactions (0426;
- 1610);
- 0454 Isotopic composition and chemistry (1041;
- 4870);
- 0488 Sulfur cycling;
- 3339 Ocean/atmosphere interactions (0312;
- 4504)