Study on water-soluble ionic composition of PM10 and related trace gases over Bay of Bengal during W_ICARB campaign

Abstract

Aerosol (PM10) samples were collected and its precursor gases, i.e., NH3, NO, NO2, and SO2 measured over Bay of Bengal (BoB) during winter months of December 2008 to January 2009 to understand the relationship between particular matter (PM) and precursor gases. The observations were done under the winter phase of Integrated Campaign on Aerosols, gases and Radiation Budget (W_ICARB). The distribution of water-soluble inorganic ionic composition (WSIC) and its interaction with precursor gases over BoB are reported in present case. Average atmospheric concentration of NH3, NO, NO2, and SO2 were recorded as 4.78 ± 1.68, 1.89 ± 1.26, 0.31 ± 0.14, and 0.80 ± 0.30 μg m−3, whereas WSIC component of PM10, i.e., NH4 +, SO4 2−, NO3 −, and Cl− were recorded as 1.96 ± 1.66, 8.68 ± 3.75, 1.92 ± 1.75, and 2.48 ± 0.78 μg m−3, respectively. In the present case, abundance of nss-SO4 2− in the particulate matter is recorded as 18 %. It suggests the possibility of long-range transport as well as marine biogenic origin. Higher SO4 2−/(SO2 + SO4 2−) equivalent molar ratio during the campaign indicates the gas-to-particle conversion with great efficiency over the study region.