Aerosol iron solubility over Bay of Bengal: Role of anthropogenic sources and chemical processing

作者：Kumar Ashwini; Sarin M M^*; Srinivas Bikkina

来源：Marine Chemistry, 2010, 121(1-4): 167-175.

DOI：10.1016/j.marchem.2010.04.005

• Bay of Bengal
• Aerosols
• Aerosol iron solubility
• Mineral dust

The chemical composition (involving water-soluble inorganic constituents, crustal elements and carbonaceous species) of size-segregated aerosols (PK10 and PM2.5), collected from the marine atmospheric boundary layer (MABL) of the Bay of Bengal (BOB) during 27th Dec' 08-28th Jan' 09, has been studied to ascertain the factors controlling the spatio-temporal variability in the fractional solubility of aerosol iron. Based on the air-mass back-trajectory (AMBT) analyses and chemical proxies, continental outflow from the two major source regions has been identified, viz: (1) outflow from the Indo-Gangetic Plain (IGP) sampled over north-BoB (N-BoB); and (2) south-east Asian (SEA) outflow over south-BoB (S-BOB). A significant linear relationship among fractional Fe solubility [WS-Fe (%)] and nss-SO42- over N-BoB (characterized by higher abundance of aerosol iron (Fe-A) and SO42-) provides evidence for the acid processing of mineral dust during atmospheric transport from IGP. The enhancement in the solubility of aerosol constituents is also evident from a linear increase in nss-Ca2+ with nss-SO42-. In contrast, a temporal shift in the winds, representing the outflow from south-east Asia and aerosol composition over south-BOB, exhibit enhanced fractional solubility of aerosol Fe (range: 11.4 to 49.7%) associated with the lower abundance of dust (<100 ng m(-3) of Fe-A) and nss-SO42- (<15 mu g m(-3)). These observations suggest the dominance of combustion sources (biomass burning and fossil-fuel) in dictating the aerosol iron solubility over south Bay of Bengal. The impact of the anthropogenic sources is also ascertained based on the covariance of WS-Fe with K+ and OC (organic carbon); as well as enrichment factor of heavy metals (Pb and Cd) associated with the outflow from south-east Asia.

• 出版日期2010-8-20