To investigate the fog chemistry along the Yangtze River basin, a field observation experiment was performed from Shanghai to Wuhan during November 2015. Fifteen fog water samples were collected by using a three-stage Caltech Active Strand Cloud water Collector(CASCC). The three-stage CASCC was mounted on the board of a ship. PH, electrical conductivity(EC), H_2O_2,HCHO, S(IV), ten inorganic ions, seven organicacids and sixteen trace metal elements were measured in this study. The p H of fog water samples ranged from weakly acidic(pH 4.3) to weakly alkaline(pH 7.05) and the EC ranged from 32.4 to 436.3 μS/cm. The main cations in fog water were NH+4 and Ca^(2+), accounting for 12.35% and 29.07% of those inorganic ions,respectively. In addition, SO_4^(2-) and NO_(-3) contributed to 25.52% and 12.93% to total anion concentrations respectively. Moreover, the dominant kinds of organicacids were formate and oxalate, occupying 45.28% and 28.03% of the total organicacids, respectively. For trace metal elements in fog samples, Al, Fe, Zn, and Ba revealed 34.6%, 16.4%, 19.3%, and 20.9%contributions to these sixteen trace element concentrations, respectively. The results indicated that pollutants were mainly from human activities, including fossil fuel combustion,biomass burning, steel-making, stone quarrying and sand digging. Besides, natural sources including natural background levels and long-range transport of sea salt particles also aggravated the pollution levels in the fog events along the Yangtze River.
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