Effects of Environmental Factors on Arsenic Fractions in Plateau Lakeside Wetland Sediments.

The toxicity of arsenic (As) in different polluted areas and its effects on human and animal health is a big concern all over the world. Although a wetland ecosystem is a "green filter," this specific function would be impaired by high As content in wetland sediments. The distribution of As in wetland sediments and its linkages to environmental factors have not been fully explored. In this study, sediment samples (0-10 cm) and water samples were collected from different locations along the Yangzonghai lakeside, located in the city of Yuxi, Yunnan province of China, and were analyzed for As fractions. Results showed that As content in sediments ranged from 7.550 to 89.83 mg·kg-1 (with a mean value of 16.11 mg·kg-1). The As fractions were dominated by residual fraction (B4) (up to 62.67%), and the mean contents from high to low were: B4 (10.10) > oxidizable fraction (B3) (2.600) > acid extractable fraction (B1) (2.270) > reducible fraction (B2) (2.170). The distribution of As in sediments was mainly influenced by point-source pollution. In addition, the lack of significant correlation between As content and the different landscapes in the buffer zone of Yangzonghai lakeside indicated that the land use around the lakeside wetland (mainly non-point source pollution) may not have a significant impact on As fractions. Among environmental factors, As contents were positively (p<0.05) correlated to dicalcium phosphate (Ca2-P) and octacalcium phosphate (Ca8-P). However, phosphorus distribution revealed that phosphorus in sediments was mainly caused by non-point source pollution, and thus farmland fertilizer, domestic waste, and livestock manure should be controlled. As fractions such as B1, B2, and B3 in wetland sediments were positively correlated with dissolved oxygen (DO) and redox potential (Eh), but negatively correlated to organic matter (OM), pH, and lime-type phosphorus (Ca10-P) when the upstream area was dominated by agricultural lands, indicating that these parameters may affect the release of As into sediments. [ABSTRACT FROM AUTHOR]