Chemical composition of aerosols over Bay of Bengal during pre-monsoon: Dominance of anthropogenic sources

• Spatial distribution of aerosol species over Bay of Bengal (BoB) during pre-monsoon.
• Significant anthropogenic influence of Indo Gangetic Plains/north India over northern BoB.
• While mass concentration of various species show high over north BoB, Mass fractions are high over mid/southeast BoB.
• First cut model for aerosol chemical composition over BoB evolved.

Total suspended particulates were collected from the marine boundary layer of Bay of Bengal (BoB) as part of the Integrated Campaign for Aerosols gases & Radiation Budget (ICARB) conducted under the Geosphere Biosphere Programme of Indian Space Research Organisation during pre-monsoon period. These samples were analyzed to quantify various chemical species and to bring out a comprehensive and quantitative picture of the chemical composition of aerosols in the marine environment of Bay of Bengal. Almost all the species showed highest mass concentration over north/head BoB. On the other hand, their mass fractions were high over mid/south BoB which has implications on the radiative forcing in this region. The source characteristics of various species were identified using specific chemical components as tracers. Presence of significant amount of non-sea-salt aerosols (~7–8 times of sea-salt) and several trace species like Ni, Pb, Zn, etc were observed in this marine environment indicating significant continental/anthropogenic influence. An approximate estimate of the contributions of anthropogenic and natural aerosols to the total aerosol mass loading showed prominence of anthropogenic component over mid and south BoB also. Based on this study first-cut aerosol chemical models were evolved for BoB region.