Chemical characterization of rainwater at a developing urban habitat of Northern India

A comprehensive study of the chemical composition of rainwater was carried out from June 1999 to September 2001 at Lucknow, India. The rainwater was found to be alkaline with a mean pH of 6.7 in winter season and 6.5 in monsoons. It was observed during the study that Ca was the most abundant ion and along with Mg and NH4 it forms equilibrium reactions with acids. Analysis of Variation (ANOVA) indicates that concentration of major ions was higher during cold climatic conditions probably due to dry season in winter leading to low dilution phenomena. The data was subjected to factor analysis based on Principal Component Analysis using the SPSS software (Version 7.5). The rotated factor matrix was employed to group variables into four factors. The first factor included Ca, Mg, SO4, NO3 and NH4 attributed to soil derivatives and biogenic activities. Factor 2 loaded with Na, K, and Cl, may be linked to emissions from traditional combustion activities. Factor 3 and 4 include Cu, Zn, Fe and Ni, which may be attributed to industrial activities and scavenging process cycles.