Chemical characteristics of rainwater in karst rural areas,Guizhou Province,Southwest China

The chemical composition of rainwater has been studied in a karst rural area from September 2012 to August 2013 in Guizhou Province,Southwest China.The results indicated that the VWM value of p H was 5.4,varied from 4.6 to 6.9.Ca~(2+)and NH_4~+were the major cations,and SO_4~(2-)was the dominant anion.Neutralization factors show that the acid was mainly neutralized by Ca~(2+),NH_4~+and Mg~(2+).Investigations of correlation coefficients and enrichment factors revealed that Ca~(2+)and Mg~(2+)were mainly crust origins,and NH_4~+was from agriculture and livestock manure.SO_4~(2-)and NO_3~-were mainly from anthropogenic sources.