Heavy Metal Pollution And Potential Risk Assessment Of Soil In Vineyards In Turpan Basin

For analyzing the concentrations,environmental capacity,contamination levels,sources,and potential ecological and health risk and of heavy metals in soil of the main grape producing areas in China,a total of 101 soil samples were gathered from vineyards in Turpan Basin for analyzing the concentrations of six heavy metals,such as As,Cd,Cr,Ni,Pb,and Hg.The spatial distribution of heavy metals in vineyard soils was analyzed based on the GIS technology.The characteristics and spatial distribution of environmental capacity of heavy metals in vineyard soils were analyzed based on GIS technology and the comprehensive environmental capacity index（PI）.The static and dynamic environmental capacity of soil heavy metals in Turpan Basin were estimated by the soil environmental capacity model,the changing trend was also predicted.The contamination level was analyzed using the pollution load index（PLI）and geoaccumulation index(I_geo).Main sources of heavy metals were analyzed using correlation analysis and principal component analysis.The potential ecological risk index（RI）and ecological risk warning index(I_ER)were used to analyze the contamination and its potential ecological risk of heavy metals in vineyard soil.The potential health risk of heavy metals in vineyard soil was analyzed based on the US EPA Health Risk Assessment Model.The main conclusions of this study are as follows:1)The average concentrations of As,Cd,Cr,Ni,Pb,and Hg in vineyard soil from Turpan Basin were 9.57 mg/kg,0.19 mg/kg,59.0 mg/kg,21.60 mg/kg,13.41 mg/kg,and 0.045 mg/kg,respectively.The average concentrations of six elements in vineyard soil are lower than the limits of the National Soil Environmental Quality Standards（GB 15618—2018）,but the average concentrations of As,Cd,Cr,and Hg exceed the background values of irrigation soil in Xinjiang by factors of 1.05,1.58,1.49,and 1.15,respectively.The average concentrations of As,Cd,Cr,and Hg exceed the background values of soil in Xinjiang by factors of 1.05,1.58,1.20,and 2.65,respectively.2)The spatial distribution patterns of six elements of vineyard soil in Turpan Basin were substantially heterogeneous.In the case of As,the high concentrations were observed mainly in the eastern areas,whereas Cd was most concentrated in the southwestern area,Cr was most concentrated in the central areas.A dot-distributed pattern was discerned for Ni,whereas Pb and Hg elements were most concentrated in the areas with relatively dense population and traffic in the study area.3)The average values of single environmental capacity index of heavy metals in vineyard soils were ranked as:Ni>Pb=Hg>As>Cr>Cd.Among them,the environmental capacity of Ni fell into the high capacity level,while the environmental capacity of As,Cd,Cr,Pb,and Hg fell into the medium capacity level.The average comprehensive environmental capacity index（PI）was 0.96 which belonged to medium capacity area.On the whole,the soil environmental capacity index of heavy metals in vineyard soils hight capacity level,and the soil environmental quality is safe.PI values of heavy metals in vineyard soils from the central area of the study area were higher than those from eastern and western areas.The static annual capacity and the dynamic annual capacity showed a same order:Cr>Ni>Pb>As>Hg>Cd.The changing rates of static and dynamic annual capacity within 20～40a were higher than those of other times,and the dynamic annual capacity of each year was greater than the corresponding static annual capacity.The trend of soil environmental capacity improved.4)The pollution load index（PLI）of each element in vineyard soil is low polluted by As,Cd,Cr,and Hg elements,and slightly polluted by Ni and Pb elements,and the average value of pollution load index shows the low polluted level.The average value of I_geoof six elements in vineyard soil is ranked as:Cd>Cr>As>Hg=Pb>Ni.Among the value of I_geo of six elements,As,Ni showed no pollution,Cd,Cr,Pb showed unpollution and slightly pollution,Hg showed no pollution,slightly pollution and moderate pollution of vineyard soil in Turpan basin.In terms of contamination sources As,Cr,and Ni elements in vineyard soil were mainly natural sources,whereas Cd,Pb,and Hg elements were mainly anthropogenic sources.5)The ecological risk index of each element in vineyard soil is ranked as:Cd,As,Ni,Hg,Cr,and Pb,at the low ecological risk level.The average value of RI is 17.33,at the low ecological risk level.The average value of I_ER is-4.87,at the no warning status.6)The results of health risk assessment indicate that both the non-carcinogenic and carcinogenic health risk of six heavy metal elements in vineyard soil showed the acceptable risk level,the hand-mouth ingestion is the main pathway of daily exposure and health risk of heavy metal elements in vineyard soil in the study area.Both the non-carcinogenic and carcinogenic health risk of heavy metals for children is higher than that for adults.As and Cr elements are the main non-carcinogenic risk factors,while As is the main carcinogenic risk factor of vineyard soil in the study area.On the whole,the potential non carcinogenic and carcinogenic risk index of heavy metals in the vineyard soil in the study area is within the acceptable range.