Influence of crustal aerosols on wet deposition at urban and rural sites in India

The present study reports the pH and chemical composition of rain water at four urban sites of Delhi and one rural site away from Delhi. The collected samples were analysed for major cations (Ca, K, Mg , Na and NH4) and anions (SO4, NO3 and Cl). Data showed very high pH and Ca concentration at rural site which indicated the direct influence of crustal sources on rain water. It was estimated that a significant fraction of SO4 in rain water is contributed by crustal sources in this region. The association of high pH and high crustal SO4 suggested that crustal SO4 is not responsible for acidity or lowering the pH of rain water in India. Ion balance and conductivity balance for data quality assessment was observed to be within USEPA recommended limits.