Zeng Qingru

Characteristics and evaluation of As pollution in the sediments of medium-small scale lakes in Lake Dongting Plain

Spatial distribution of arsenic(As) concentrations of sediments collected form ten medium-small scale lakes in Lake Dongting Plain was investigated,and the As pollution degree was evaluated using the geo-accumulation index.Average value of As sediment concentration from 10 lakes was 15.8 mg/kg,which varied from 10.1 to 33.7 mg/kg.It indicated that As sediment contamination was relative low.As to spatial distributions,the average contents of As in the superficial sediments were from high to low in the sequence of Yueyang South Lake,Bajiao Lake,Huanggai Lake,Anle Lake,Maoli Lake,Liuye Lake,Dong Lake,Shanpo Lake,Datong Lake,and Beimin Lake.As concentrations in the lake basins were from low to high in sequence of Lishui catchment(13.1mg/kg),Ouchi catchment(13.4mg/kg),Yuanshui catchment(16.2mg/kg),and lakes at outlet areas of Dongting Lake(22.4mg/kg).Degree of As pollution in lake sediments aggravated gradually from the upstream to the downstream of Lake Dongting drainage.Sediment sample analysis from 4 cores(Datong Lake,Huanggai Lake,Bajiao Lake and Shanpo Lake) showed that As had accumulated in sediments and increased from the bottom to the surface(30-0cm).Geo-accumulation index analysis showed that pollution level at 22 sites from eight lakes were none,and 7 sites from five lakes were at Level I.As a whole of Lake Dongting drainage,As pollution level in the superficial sediments was low.