title: [Chemical characterization of rainwater in a karst rural site: a case study of Puding, China].
abstract: Rainwater samples of a karst rural site in Puding County, Guizhou Province, China over a period of one year (2008) were collected and the major ion concentrations were measured. The pH of samples varied from 4.6 to 7.1 and volume-weighted mean was 5.7. Ca2+ was the dominant cation in rainwater and volume-weighted mean was 303.2 microeq x L(-1). It accounted for 34%-88% of the total cations in the studied rainwater samples. SO4(2-) and NO3- were the main anions, and their volume-weighted mean were 281.2 microeq x L(-1) and 69.9 microeq x L(-1), respectively. The sum of SO4(2-) and NO3- accounted for 63%-93% of the total anions in the studied rainwater samples. Investigations of fractional acidity (FA), neutralization factors (NF), and correlation coefficients among ionic constituents indicated that high pH values were controlled by the neutralization caused by the alkaline materials but not by the absence of acidic materials. Studies of the origins of major ions showed that Ca2+ was from the terrestrial source, e. g. crustal dust and human activities, and NH4+ and K+ were from the soils and human acidities, while SO4(2-) and NO3- were mainly originated from anthropogenic sources.
authors.affiliation: State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China. wuqixin@mails.gyig.ac.cn
authors.forename: Qi-Xin
authors.initials: QX
authors.lastname: Wu
authors.forename: Gui-Lin
authors.initials: GL
authors.lastname: Han
authors.forename: Fa-Xiang
authors.initials: FX
authors.lastname: Tao
authors.forename: Yang
authors.initials: Y
authors.lastname: Tang
mesh_terms: D015258:Acid Rain / Q000032:analysis*; D002681:China; D004784:Environmental Monitoring; D006863:Hydrogen-Ion Concentration; D011891:Rain / Q000737:chemistry*
chemical_list: D015258:Acid Rain