Non-Seasalt Sulfate (NSS) Production by O3-Oxidation in Seasalt Aerosols under Clear Sky Conditions: Implications for Modeling of Global Marine Boundary Layer NSS and of New Particle Production
Abstract
Aqueous-phase mechanisms can explain a portion of the coarse aerosol NSS (heterogeneous O3 oxidation and halogen chemistry in the water associated with seasalt aerosols)found in the MBL. NSS data were collected at Baring Head, New Zealand during clear sky and normal cloudiness conditions. The clear sky coarse aerosols - a unique data subset - encountered little cloud, had substantial excess alkalinity from marine biogenic sources, and contained over 8 nmol NSS m-3; normal cloudiness coarse aerosols contained ~5 nmol NSS m-3. Up to 90% of the clear sky coarse aerosol NSS (70-80% for normal cloudiness cases) was due to O3-oxidation within seasalt aerosols. For typical global open ocean conditions this biogenic source introduces 100% to 150% added alkalinity beyond that from bulk seawater. The MISTRA model was used to assess the magnitude of S oxidation by O3 in seasalt aerosols due to this added alkalinity. For a doubling of alkalinity, the % contribution to S oxidation increases 2.5x, causing O3 oxidation to dominate over halogen chemistry and H2O2 oxidation. A major implication of this S oxidation by O3 in seasalt aerosols is that new particle production from biogenically-derived oceanic S is severely limited in the MBL.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2003
- Bibcode:
- 2003AGUFM.A22E..03S
- Keywords:
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- 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0305 Aerosols and particles (0345;
- 4801);
- 0312 Air/sea constituent fluxes (3339;
- 4504);
- 0315 Biosphere/atmosphere interactions;
- 0330 Geochemical cycles