Statistical Distribution Features and Evaluation of Ecological Risk in Superficial Sediments of Hulun Lake

The paper discusses concentrations, statistical distributions and ecological risks of seven heavy metals in superficial sediments of Hulun Lake. The highest values for heavy metal concentrations in sediments before the modern industrialization of the world and grade I criteria of the National Standard for Soil Environmental Quality were used to analyse the accumulation and potential ecological risk (PER) coefficients of heavy metals. The PER index for each sample location is also discussed. The PER index was evaluated using the method of Lars Hakanson to evaluate ecological risk. The distribution of content of heavy metal does not reveal regional distributive characteristics; the space distribution differential is small. However, three metals (i.e., Zn, Cr, Cu) exhibit the same trend. These heavy metals are highly concentrated in the northeast and southwest parts of Hulun Lake than at the entrance of the Xinkai, Wuerxun, and Kelulun rivers. Using the highest values for heavy metal concentrations in sediments before the modern industrialization of the world as reference, these heavy metals have an accumulation order of Pb > Zn > Cd > Cu > As > Cr > Hg and pollution level order of Cd > As > Pb > Cu > Hg > Cr > Zn. However, most of these heavy metals are in low risk states. Using the grade I criteria of the National Standard for Soil Environmental Quality work as reference, these heavy metals have an accumulation order of Cd > Zn > Cu > As > Pb > Cr > Hg and pollution level order of Cd > As > Hg > Cu > Pb > Cr > Zn. Cd is the potential impact element for the ecological environment in Hulun Lake.