Risk Assessment and Source of Soil Heavy Metals in the Typical Agricultural Areas of Qinghai Province,China
The accumulation of heavy metals in soil not only causes serious ecological and environmental problems,but also migrates to the human body through the food chain,posing a direct or indirect threat to human health.In order to understand the status of heavy metal pollution in cultivated soil in Qinghai province and promote the healthy development of local agriculture,the cultivated soil in Hehuang Valley and Qaidam Basin were taken as the research object.A total of 84 samples of cultivated soil(0-20 cm)were collected,and the soil pH and the contents of five heavy metal elements,including Cu,Pb,Cr,Zn and Cd,were determined.Single factor pollution index,geo-accumulation index,Nemerow comprehensive pollution index and potential ecological risk index were used to evaluate the heavy metal pollution degree and ecological risk of the surface soil in the study area.Correlation analysis and principal component analysis were used to identify the sources of five heavy metals in cultivated soil.The results show that ① compared with the soil environmental background value of Qinghai province,only the average content of Cd in the cultivated soil of Hehuang Valley and Qaidam Basin is higher than the background value,but all the samples do not exceed the screening value of soil pollution risk of agricultural land;in Hehuang Valley and Qaidam Basin,the coefficient of variation of Cd content is the highest,reaching 40.87％and 40.07％,respectively,and the other four heavy metals are all lower than 30.00％;the contents of Cu,Pb and Zn are not significantly different between the two areas,the content of Cr in Hehuang Valley is significantly higher than that in Qaidam Basin,but the content of Cd is significantly lower than that in Qaidam Basin.② According to Nemerow comprehensive pollution index and comprehensive potential ecological risk evaluation,the cultivated soil in Hehuang Valley and Qaidam Basin is at a clean level,and the comprehensive potential ecological risk is low;according to the single potential ecological risk index,the potential ecological risk of Cd is high and reaches the medium risk level in the two areas,which is the main heavy metal element constituting the potential ecological risk of cultivated soil.③ In Hehuang Valley,Cu,Zn and Cd are mainly affected by agricultural activities such as fertilizer application and pesticides,while Pb and Cr are mainly affected by soil parent material;in Qaidam Basin,Cu and Zn are mainly affected by the weathering of parent minerals and soil erosion,while Pb,Cr and Cd are mainly affected by agricultural production and management.In summary,although the five heavy metals in the cultivated soil of Hehuang Valley and Qaidam Basin do not pose a threat to the quality of crops and human health,the impact of human activities on the accumulation of heavy metals in soil cannot be ignored,especially the impact of the use of agricultural fertilizer on the accumulation of Cd,so as to prevent soil pollution in cultivated land.
soil heavy metalcultivated landpollution degreepotential ecological riskprincipal component analysissource analysisQinghai
NETL
NSTL
万方数据
