[Chemical characteristics and source assessment of rainwater at Shenyang]

To understand the origin and chemical characteristics of precipitation in Shenyang, about 25 rainwater samples were collected in 2007. The pH of samples varied from 4.89 to 8.02, with the volume-weighted average of 6.89. The results showed that the concentration of the sum of anions and cations in Shenyang was higher than those in southern cities such as Hangzhou, whereas the acidification of rainwater was not very serious in Shenyang. The volume-weighted average concentrations of SO4(2-) and Cl(-) were 330.00 microeq x L(-1) and 85.05 microeq x L(-1), with the percent contribution to anions of 60.32% and 15.55%, respectively. Ca2+ and NH4(+) were the main cations with contribution of 49.51% and 29.78%, respectively. The seasonal variations of ions showed that the concentrations were higher in autumn and winter than in spring and summer. 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. Results of NF indicated that NH4(+) and Ca(2+) were the dominant neutralization substances. Calculation of enrichment factors for rainwater components relative to soil and seawater indicated that SO4(2-) and NO3(-) were mostly attributed by the anthropogenic activities, 53.1% of Cl(-) originated from sea sources, and NH4(+) and K(+) came from the soils and human activities.