Arsenic accumulation and speciation in epilithic moss collected from an abandoned mercury mining area, south-western China

Özet

Arsenic (As) is considered a carcinogenic toxin, and nonferrous metal smelting activities can release significantquantities of As, causing an increase in As levels in the environment. A total of 221 samples of moss belonging to5 species in 4 families were collected from the Wanshan District, the world third largest mercury mining area, inGuizhou Province, southwestern China, for analysis of total As (tAs) concentrations and As speciation. Theresults indicated that the tAs concentrations in these mosses ranged from 0.67 to 9.6 mg $kg^{-1}$, with an average of2.4 ± 1.7 mg $kg^{-1}$. The dominant species of As in these mosses were inorganic forms of arsenite (As(III)) andarsenate (As(V)) with a total percentage of 87%, whereas the concentrations of organic forms (monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA)) were relatively low, with percentages of 11.8% and6.0%, respectively. A significant correlation (r = 0.766, p < 0.01) was observed between As(V) and tAs. In thespatial distribution pattern of As, high concentrations of As in mosses were centralized around historical Hgretorting sites in the town of Wanshan, the villages of Gouxi and Yanwuping and sites downwind of theselocations, suggesting that historical intensive Hg mining activities might be the most possible source of atmospheric As.