Spatial distribution and source analysis of airborne trace metal deposition using moss biomonitoring in Huai’an, China

Terrestrial mosses are tracers for studying atmospheric trace metal deposition and pollution. Here, Al, Fe, Zn, Mn, Ba, Cu, V, Cr, Pb, Ni, Co, and Cd concentrations in mosses from Huai’an, China, were measured to investigate their contamination level, spatial distribution, and sources. The average concentration of all the metals (except Ni) was much higher than those in Albania, a “hotspot” of toxic metal contamination in Europe. The pollution degree of the metals varied significantly: moderate contamination by Al, Fe, Mn, Zn, Cr, V, and Cd; slight contamination by Ba, Cu, Ni, and Pb; and suspected contamination by Co. Based on the Nemerow index (PN), only 8% of the moss samples were graded as moderate pollution, while the remaining 92% were rated as heavy pollution, with Cd and Zn contributing the most. The potential ecological risk index (RI) indicated a moderate potential ecological risk from the metals in Huai’an, with the atmosphere most heavily polluted by Cd. Further, the positive matrix factorization (PMF) model was applied to confirm the metal contamination sources and allocate their source contributions in Huai’an mosses. The results showed that the source contributions of industrial activities related to metal smelting, textile dyestuff and agricultural activities, mining development, natural source, and coal burning and traffic emission accounted for 28.86%, 20.29%, 19.83%, 17.98%, and 13.04%, respectively.