Chemical characteristics and sources of precipitation around Qinghai Lake valley, NW China

摘要

A total of 33 precipitation samples have been collected from individual precipitation events at the bird island, a scenic zone of Qinghai Lake Monitoring (36° 32′ ∼37° 15′N, 99° 36′ ∼100° 16′E; 3200 m a.s.l) located in the northwest of Tibetan Plateau from June 2010 to August 2010. All samples were analyzed for major cations (NH4+, Na+, K+, Ca2+ and Mg2+) and anions (F-, Cl−, NO3− and SO4−) conductivity, pH and DOC (Dissolved Organic Carbon). The pH value of precipitation ranged from 6.05 to 8.19 with a volume average value of 7.13. Ca2+ is the dominant cation in precipitation with a VWM of 125.08 µeqL−1 (1.62–664.21µeqL−1), accounting for 27% of the total cations in precipitation. HCO3− is the predominant anion with a VWM of 125.09 µeqL−1, accounting for 26% of the total anions. Correlation and Enrichment factor analysis (EF) indicate that crustal aerosols from combustion emissions of residents and continental dust, which are the major sources for these ions.