Estimation of Non-Marine Fractions of Ions in Rainwater at Three Sites of Different Characteristics in Haryana State (India)

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Non-marine sulphate (SO42−) has a significant influence on the pH of rainwater. This study reports the wet deposition of major ions at three sites having different land use and land cover (LULC) characteristics in Haryana state, located in the agriculturally dominated northwestern part of India. The sites Hisar (urban), Bahadurgarh (industrial), and Meham (semi-urban) had an average pH of rainwater of 5.94, 6.32, and 6.38, respectively. The sum of ionic constituents (i.e., Na+, NH4+, K+, Ca2+, Mg2+, F−, Cl−, NO3−, and SO42−) was found higher at the industrial site (309.9 µeq L–1) as compared to the urban (225.6 µeq L–1) and semi-urban (255.7 µeq L–1) sites with dominant contribution of NH4+ ions. Calculation of ratios of major ions to Na+ to compare the standard Na+ ratios of seawater at all the sites indicated a significant influence of non-marine sources. Source apportionment was carried out using principal component analysis (PCA) which indicated that anthropogenic activities such as coal combustion or industrial emissions were the key sources at the industrial and urban sites. Fertilizer application and its volatilization was observed as a potential source of NH3 at the semi-urban site which is expected due to prominent agricultural activities. Ca2+ and SO42− both were associated significantly with non-marine sources at all three sites. The non-marine fraction was further differentiated into anthropogenic and crustal-associated portions using soil Ca2+ ratios. The anthropogenic/crustal ratios of nss-SO42− were calculated as 0.41, 0.32, and 0.28 at urban, industrial, and semi-urban sites respectively. These ratios were inversely with pH explaining low pH at higher anthropogenic/crustal ratios. This approach of calculation of non-marine crustal associated and anthropogenic SO42− is very important to assess acidification prospects in the region.