Distribution Characteristics and Pollution Evaluation of Heavy Metals in Water Environment of Taiyangshan Wetland in Ningxia

The concentrations of As, Cd, Hg, Pb, Cr, Cu, Mn and Zn in water bodies and surface sediments were monitored to explore the pollution condition of heavy metals in the water environment of Taiyangshan National Wetland Park in Ningxia in winter, spring, summer and autumn of 2019. Multivariate statistical methods were used to analyze the temporal and spatial heterogeneity of heavy metals in the water environment, and Nemerow Comprehensive Pollution Index Method and Geo-accumulation Index Method were used to assess the pollution status of heavy metals in the water environment. The results show that the heavy metal contents of the waterbody were generally at low level and only the Hg content exceeded the Ⅲ class surface water standard of the "Environmental Quality Standard for Surface Water (GB 3838-2002)". The surface sediments were seriously polluted by heavy metals except for Cr, which did not exceed the soil background value of Ningxia. The contents of heavy metals in water and sediments were higher in the east part of the lake and lower in the south part of the lake. The heavy metal pollution level of the waterbody as a whole was low by usinig Nemerow Comprehensive Pollution Index Method. While the most serious pollution was found in the west part of the lake and in winter. Among the heavy metals, Hg contributed the most to the pollution. By using the Geo-accumulation Index Method, it was found that the surface sediment was most seriously polluted in winter and Hg contributed the most to the pollution.