Major ionic composition of aerosol, rainwater and its impact on surface and sub-surface waters, in and around Mangalore, west coast of India

Physicochemical characteristics of dissolved components from environmental samples have been studied in order to understand the impact of atmospheric pollution from aerosols and rain on surface and sub-surface waters, at industrialised urban areas in and around Mangalore, southwest coast of India. Comparatively, the H+ ion deposition from the atmosphere was moderately higher than that for other places of the west coast of India, excepting some highly industrialised locations. The major ions in aerosols and rainwater were found to be derived predominantly from the sea-salt owing to strong winds prevailing over the sea over this region. From rain to river substantial enrichment of cations was observed due to leaching processes. Further leaching of ions was well noticed from river water to the sub-surface water, as major cations are higher by factors of 2.6, 2.8, 4.2 and 5.0, respectively. Sulphate and NO3- concentrations were higher in the sub-surface waters, particularly in the densely populated areas around Mangalore probably due to sewage/effluent contamination. The pH of sub-surface waters (5.98 +/- 1.03) were significantly lower than that in rain and river waters ( 6.16 +/- 0.75 and 7.12 +/- 0.79), implying fallout of acidic species particularly during the non-monsoon seasons.