[Distribution Characteristics and Sources of Metal Elements in Rainwater in Xiamen]

Forty-one metal elements, including rare earth elements and the lead isotope ratio in rain water in Xiamen were measured by inductively coupled plasma mass spectrometry. Sources of metal elements were identified by combined enrichment factor, isotope analysis, and positive matrix factorization analysis. The results showed that the concentration sequence of total metal elements in rainwater in Xiamen was winter-suburban (213.964 μg·L^-1) > winter-urban (176.357 μg·L^-1) > summer-suburban (75.401 μg·L^-1). There were seasonal and regional differences in the content of rare earth elements, and their standardized distribution patterns were inconsistent with each potential source, indicating that their sources were relatively complex. Enrichment factor analysis showed that Ni, Cu, Zn, and Cd were significantly affected by human sources, whereas Be, Ti, V, Mn, Cr, Co, Ga, Rb, Y, Cs, rare earth elements, Th, and U were mainly affected by natural sources. The result of Pb-isotopic-analysis showed that Pb in rainwater was significantly affected by coal sources with a contribution rate of 63.67%, and soil parent material, garbage incineration, motor vehicle exhaust, and cement dust with a contribution rate of 36.33%. The result of positive matrix factorization combined with the enrichment factor and isotope method showed that the metal elements in rainwater were affected by coal burning, natural sources, industry, and traffic.