[Distributions of Arsenic Species in Different Eutrophic Waters of Lake Taihu and Their Relations to Environmental Factors].

A detailed field survey of arsenic species and water quality parameters was conducted in different eutrophicated regions of Lake Taihu (Zhushan Bay, Meiliang Bay, Gonghu Bay and Southern Taihu) in summer and winter. Furthermore, spatial and seasonal distributions of arsenic species and their relations to water quality parameters were investigated with multivariate analysis techniques. Higher average contents of total arsenic (TAs), arsenate[As(Ⅴ)], arsenite[ As(Ⅲ)] and methylarsenicals [sum of monomethylarsenic acid (MMA) and dimethylarsenic acid (DMA)] were observed in northern regions (including Zhushan Bay, Meiliang Bay, and Gonghu Bay) (TAs:2.58-3.34 μg·L, As(Ⅴ):1.37-2.34 μg·L, As(Ⅲ):0.53-0.64 μg·L, methylarsenicals:0.16-0.36 μg·L), compared to those in Southern Taihu (1.73, 1.10, 0.31, 0.10 μg·L). The results exhibited obvious spatial characteristics of arsenic species in the surface water of Lake Taihu. Besides, average values of TAs, As(Ⅴ), As(Ⅲ) and methylarsenicals in summer were 3.40, 2.06, 0.73 and 0.25 μg·L, respectively, higher than those in winter (1.78, 1.10, 0.30, 0.17 μg·L), reflecting significant seasonal characteristics of arsenic distribution. Factor analysis revealed the significant relationships of TAs and As(Ⅴ) with several water quality parameters, which suggested that spatial and seasonal distributions of TAs and As(Ⅴ) in Lake Taihu were affected by external pollution and internal arsenic release from sediments. Redundancy analysis further indicated significant effects of total phosphorus (TP) and total iron (TFe) on the distributions of TAs and As(Ⅴ). At the mean time, the above statistical analyses exhibited that As(Ⅲ) and methylarsenicals were positively correlated with chlorophyll-a (Chl-a). A large amount of microalgae could accumulate As(Ⅴ) and transform it more strongly to As(Ⅲ) and methylarsenicals in eutrophic regions when compared to mesotrophic region,especially in summer, reflecting the regulation of microalgae on arsenic biotransformation.