LU Aigang, LIU Hui, KANG Shichang, WANG Shao'an
A total of 74 effective precipitation samples collected from Huangbaiyuan of southern Taibai Mountain, from November, 2011 through September, 2014 were used as the research carriers. Constant inorganic ions (NH4+, Ca2+, Na+, K+, Mg2+, SO42-, NO3-, Cl-, F-) in precipitation were analyzed. The data were dealt with the trend analysis and the correlation analysis methods and the sources were explored with the enrichment factor method, the source contribution method and backward trajectory model. The results showed that cation and anion concentrations in precipitation ranked as Ca2+ > SO42- > NH4+ > NO3- > K+ > Na+ > Mg2+ > Cl- > F-; of which Ca2+ and NH4+ were the major cations, accounting for 76.21% and SO42- and NO3- are the main anions, accounting for 90.83%. The average annual equivalent cation and anion concentrations in precipitation is 404.64 μeq·L-1, higher than any other already studied stations over the worldwide, showing the typical continental and human-source interference characteristics. Affected by emission factors, meteorological factors, vegetation, precipitation and other factors, total ion concentration in precipitation showed significant seasonal differences, followed by winter > spring > autumn > summer. Source analysis results showed that 95% of SO42- and NO3- came from anthropogenic contribution; the concentrations of Ca2+ and Mg2+ were mainly from the crust sources; about a half of Na+ came from seasalt and another half of Na+ came from non-seasalt; K+ mainly from non-seasalt; F- and NH4+ almost all from anthropogenic sources. The ionization components of precipitation under different pathway were obviously different; northern air group came though Taiyuan, Shijiazhuang, Beijing, Lanzhou and other industrial cities, due to industrial coal and traffic emissions, the concentrations of SO42- and NO3- in precipitation were high and the total ion concentration was also higher than those in the southern air mass.