Urban and Rural Bulk Precipitation Chemistry

To examine the chemical composition of both urban and rural areas, we have undertaken a study during 2005–07 and have collected 580 bulk precipitation samples from nine pre-determined sites in Karnataka state, India, and analyzed them for various parameters such as pH, electrical conductivity, cations, and anions. The procedure of Standard Methods of 1995 was adopted for the analysis of the samples. The unit for all ionic concentrations is expressed in µeq?-1. To ensure accuracy of major ions, the samples were tested by ca1culating cation/anion ratios and charge balances (CB). Based on this analysis, the mean value of charge balance was found to be 3.38 and the ratio 0.90, which indicates that all the major ions were considered in the analysis. The linear correlation coefficient between measured conductivity and calculated conductivity from measured ions concentrations was 0.90. Solute concentrations generally are inversely related to the quantity of rainfall during storms; therefore, volume-weighted mean (VWM) concentrations were calculated. Determination of marine and non-¬marine components showed that Ca2+, Mg2+, K+ and SO42- ions were of non-marine origin.