Chemical characterization of rainwater over Suwon region during farming and non-farming periods

Recently, special attention has been givento acid rain and its problem to environment such as acid precipitation and air pollution in East Asia.In the present study, rainwater samples werecollected from Apr to Oct (farming period) and from Nov to Mar (non-farming period) in 2009 ~ 2011. The samples were chemically characterized for the assessment of emission sources. Suwon region, a typical agricultural area in Gyeonggi province (South Korea) was chosen as a study site. The content of ionic species and theirtemporal variation were used forfactor analysis, which was used to presume the natural and anthropogenic sources depending upon the farming and non-farming periods. The cationsobserved during farming and non-farming periods were > Na+> Ca2+> K+> H+> Mg2+and Na+> N >Ca2+> H+= Mg2+> K+, respectively. The anions during farming and non-farming periods were > > Cl- and > > Cl-, respectively. While the amounts of sulfate, one of the major dissolved components of rainwater were 113.5 and 177.0 ueq.L-1, the ones of NSS- (Non-Sea Salt sulfate) were 93.7 and 87.1% during farming and non-farming periods, respectively. The comparison of observed pH values (pHobs) with the theoretical pH values (pHthe) showed that the neutralization of rainwater considerably went along during farming and non-farming periods. The highest amountof rainfall throughout the year was310.5 mmin August and its corre sponding nitrogen loading was5.03 kg·ha-1. The major ion contents for crop growth, , Ca2+, K+, Mg2+, were 49.4, 5.5, 18.1,1.4 kg·ha-1from April to October. The major contributions to the existing chemical ions in rainwaters during farming and non-farming periods were from the natural sources (sea and soil) and the anthropogenic sources (human and animal waste, vehicular emission + fossil fuels combustion), respectively.