Long-term Changes of Rainwater Quality in the Industrial Corridor of Visakhapatnam,India

Abstract

The industrial expansion during the twenty-year period of 1983 to 2003 had shown its impact on rainwaters of Visakhapatnam. The ionic contents of SO $_4$ , NH $_4$ , NO $_3$ , Ca, Na and Cl along with pH and electrical conductivity are analysed for the rainwaters of Visakhapatnam industrial corridor during the period. The analysis shows that the atmospheric dust is more in summer rains than in the post-monsoon period, when the same had been washed down. However, unabated increase of air pollution over the two decades is indicated by the steady rise of conductivity of rainwater. The ratio between Ca $^+$ + NH $_4^+$ and NO $_3^-$ + SO $_4^-$ shows values consistently less than one, indicating the rise of acidic nature, in spite of the neutralization due to alkaline agents like Ca and NH $_4$ . Gradual decline of pH of rainwater forecasts an impending acidic rain in near-future.