Anthropogenic sulphate aerosols and large Cl-deficit in marine atmospheric boundary layer of tropical Bay of Bengal

作者：Sarin Manmohan^*; Kumar Ashwini; Srinivas Bikkina; Sudheer A K; Rastogi Neeraj

来源：Journal of Atmospheric Chemistry, 2010, 66(1-2): 1-10.

DOI：10.1007/s10874-011-9188-z

• Marine Aerosols
• Sulphate
• Cl-depletion
• Bay of Bengal

Our long-term study provides an unequivocal evidence for near-quantitative (80-100%) depletion of chloride from sea-salts in the marine atmospheric boundary layer (MABL) of tropical Bay of Bengal. During the late NE-monsoon (Jan-Mar), continental outflow from south and south-east Asia dominate the wide-spread dispersal of pollutants over the Bay of Bengal. Among anthropogenic constituents, SO (4) (2-) (range: 0.6-35 mu g m(-3)) is the most dominant. The non-sea-salt SO (4) (2-) (nss-SO (4) (2-) ) constitutes a major fraction (55-65%) of the aerosol water-soluble ionic composition (WSIC), whereas contribution of NO (3) (-) is relatively minor. The magnitude of Cl-deficit (with respect to its sea-salt proportion) exhibits linear increase with the excess-nss-SO (4) (2-) (excess over NH (4) (+) ). We propose that displacement of HCl from sea-salt aerosols by H2SO4 is a dominant reaction mechanism for the chloride-depletion. These results also suggest that sea-salts could serve as a potential sink for anthropogenic SO2 in the downwind polluted marine environment. Furthermore, loss of hydrogen chloride, representing a large source of reactive chlorine, has implications to the oxidant chemistry in the MABL (oxidation of hydrocarbons and dimethyl sulphide).

• 出版日期2010-6