Bromide content of sea-salt aerosol particles collected over the Indian Ocean during INDOEX 1999

Gabriel, R., von Glasow, R., Sander, R., Andreae, M. O. and Crutzen, P. J. (2002) Bromide content of sea-salt aerosol particles collected over the Indian Ocean during INDOEX 1999. Journal of Geophysical Research, 107 (D19). INX2 31-1-INX2 31-9. ISSN 2156-2202

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Abstract

Bromide can be depleted from sea-salt aerosol particles in the marine boundary layer (MBL) and converted to reactive gas-phase species like Br, BrO, and HOBr, which affect ozone chemistry. Air pollution can enhance the bromine release from sea-salt aerosols and thus inject additional bromine into the MBL. During the winter monsoon the northern Indian Ocean is strongly affected by air pollution from the Indian subcontinent and Asia. As part of the Indian Ocean Experiment (INDOEX), aerosol particles were sampled with stacked filter units (SFU) on the NCAR Hercules C-130 aircraft during February-March 1999. We determined the vertical and latitudinal distribution of the major inorganic aerosol components (NH4+, Na+, K+, Mg2+, Ca2+, Cl−, NO3−, SO42−) and the Br− content of the coarse aerosol to examine the role of the bromine release on the gas-phase chemistry in the marine boundary layer over the tropical Indian Ocean. The aerosol mass and composition varied significantly with air mass origin and sampling location. In the northern part of the Indian Ocean (5°–15°N, 66°–73°E), high concentrations of pollution-derived inorganic species were found in the marine boundary layer extending from the sea surface to about 1.2 km above sea level. In this layer, the average mass concentration of all aerosol species detected by our technique was comparable to pollution levels observed in industrialized regions. In the Southern Hemisphere (1°–9°S, 66°– 73°E), the aerosol concentrations rapidly declined to remote background levels. A chloride loss from the coarse aerosol particles was observed in parallel to the latitudinal gradient of the non sea salt SO42− burden. In most of the samples, Br− was depleted from the sea-salt aerosols. However, we found an enrichment in bromide in aerosols affected by air masses originating over strong pollution sources in India (Bombay, Calcutta). In these cases the additional pollution-derived Br from organo-halogen additives in petrol outweighs the release of sea-salt bromine.

Item Type:	Article
Faculty \ School:	Faculty of Science > School of Environmental Sciences
UEA Research Groups:	Faculty of Science > Research Groups > Volcanoes@UEA (former - to 2018) Faculty of Science > Research Groups > Marine and Atmospheric Sciences (former - to 2017) Faculty of Science > Research Groups > Meteorology, Oceanography and Climate Dynamics (former - to 2017) Faculty of Science > Research Groups > Atmospheric Chemistry (former - to 2018) Faculty of Science > Research Groups > Climate, Ocean and Atmospheric Sciences (former - to 2017) Faculty of Science > Research Groups > Centre for Ocean and Atmospheric Sciences
Depositing User:	Rachel Snow
Date Deposited:	06 Apr 2011 12:32
Last Modified:	17 Jul 2024 00:12
URI:	https://ueaeprints.uea.ac.uk/id/eprint/28219
DOI:	10.1029/2001JD001133

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