Chemical characteristics of atmospheric aerosols over Southwest coast of India

Abstract

Ambient aerosol samples, collected from Mangalore region in the southwest coast of India during the period of late winter (February and March) to early summer (April and May), have been analysed for water-soluble ionic species. Their abundance pattern is dominated by HCO₃^-, SO₄^2-, Na⁺, Cl^-, with minor contribution from NO₃^-, Ca²⁺, NH₄⁺, K⁺ and Mg²⁺ indicating the contribution from not only sea salt, but also from anthropogenic and dust sources; with pronounced seasonal variability. The suspended particulate matter concentration varied from 35 to 160 µg m^-3, with consistently higher values during the late winter. Back trajectory analysis suggests the origin of the air masses shifting from Indo-Gangetic Plains (during late winter) to those from the Arabian Sea and the area around Persian Gulf during April-May. Air masses passing over Northern India (Indo-Gangetic Plains) impart characteristic contribution of ionic species from fossil fuel combustion, biomass burning and eolian dust as asserted by the factor analysis. A detailed study on characterisation of aerosols from south Asian region is rather sparse but essential for modelling the effect of tropospheric aerosols on climate.