Chemical Characteristics and Source Assessment of Atmospheric Precipitation in Urumqi
ZHONG Yuting;LIU Xinchun;FAN Zi'ang;LU Hui;HE Fang;QU Tao;Institute of Desert Meteorology,CMA;Key Laboratory of Tree-ring Physical and Chemical Research of China Meteorological Administration/Xinjiang Laboratory of Tree Ring Ecology;The Operational Department of Xinjiang Meteorological Bureau;Midong District Meteorological Bureau;
Precipitation is the important collector of primary and secondary pollutants in the atmosphere, is the best scavenger of the removal of particulate and gaseous pollutants in the atmosphere. To understand the chemical characteristics of precipitation in Urumqi, about 51 precipitation samples were collected in 2010. The p H of samples varied from 5.6 to 7.77 with the average of 6.19, and the conductivity varied from 18.7 to 172.5 μs·cm~(-1) with the average of 57.73μs·cm~(-1). Ca~(2+) is one of the most main cation with the average of 887.43 μeq·L~(-1), while SO_4~(2-) is one of the most main anion with the average of 430.47 μeq·L~(-1). Acid-causing substance of precipitation in Urumqi is mainly sulfate. The seasonal variations of ions showed that the concentrations were the highest in autumn and the lowest in winter. Fractional acidity(FA)was 0.001, which indicates that99.9% of the precipitation acidity were neutralized by alkaline composition. Results of neutralization factors(NF)indicated that Ca~(2+) was the dominant neutralization substance. The correlation analysis,enrichment factor(EF) and sources indicated that SO_4~(2-) and NO_3~-were mostly attributed by the anthropogenic activities, K+came from soils and biomass burning, Mg~(2+)originated from soils and Clwas mainly contributed by sea sources.