Heavy metals distribution and ecological risk assessment of dust and soil in opencast mine of east Junggar basin in Xinjiang

The opencast mine of east Junggar basin in Xinjiang is the largest self-contained coalfield in China, the ecological environment of the opencast was very fragile because of its arid climate and poor soil. In this study, 50 soil and dust samples in opencast mine were collected in order to explore the heavy metals spatial distribution and different between soil and dust of the coal mining. The content of zinc (Zn), copper (Cu), chromium (Cr), lead (Pb), mercury (Hg) and arsenic (As) were measured and the ecological risk was assessed by pollution load index, geo-accumulation index and potential ecological risk index. Results showed that the content of dust heavy metals was higher than soil generally, As were exceeded the standard limited most seriously, Pb were most slight and has no ecological risk. Ecological risk of Cu,Cr,Hg were both higher in soil and dust,but dust face more severe ecological risk. Correlation analysis showed that Zn,Cu,Cr may the associated elements and As may come from coal combustion. The main contamination elements were Cr,Hg and As in study area,and others elements prevention should be considered.