| Cultivated land is the cornerstone of food security.Purifying the environment where agricultural products are produced and allowing people to eat with confidence are important guarantees for our national security.Proving the status and main sources of heavy metal pollution in cultivated soil in the Jinzi River Basin is crucial to the effective prevention and control of soil pollution.In this paper,eight heavy metals(Cd,Hg,As,Pb,Cr,Cu,Zn,Ni)in the topsoil of a typical cultivated land in the Jinzi River Basin of Yunnan Province were taken as the research object.The pollution characteristics and causes of pollution were analyzed by the joint application of the,and the main research results are as follows:(1)With reference to the soil background value of the study area,heavy metals Cd,Hg,As,Pb,Cr,Cu,Zn,and Ni all have different degrees of enrichment.Eight soil heavy metals were evaluated by geoaccumulation index method and potential ecological risk index method.The results showed that the accumulation degree of Cd,Pb and Cu was higher,and the accumulation degree of soil in the west bank of the study area was significantly higher than that in the east bank;Cd,Hg and The potential ecological risk index of Pb is relatively high,and the potential ecological risk index of Cd element is the highest,showing a very high potential ecological risk level as a whole;the potential ecological risk index of the soil on the west bank of the study area is significantly higher than that on the east bank.(2)According to the global trend analysis results,the soil heavy metal content in the study area showed a trend of high in the west and low in the east,but there was no obvious trend change in the north-south direction.According to the results of ordinary kriging interpolation,the distribution of Pb and Zn content in the study area is very similar,indicating that the two may have the same source;the high-value areas of each heavy metal in the study area are distributed in the area west of the Jinzi River,And it is close to industrial and mining enterprises.(3)The PMF model analyzed that there are five sources of soil heavy metals in the study area: industrial and agricultural mixture(12.15%),natural background(22.04%),gold mining and dressing(20.16%),copper mining and dressing(21.77%)and lead-zinc mining Mining and selection(23.87%);PCA-MLR model analyzed that there are two sources of soil heavy metals in the study area: industrial mixed sources(70.5%)and natural sources(29.5%).The analytical results of the two models for natural sources are very similar,both of which are the main sources of heavy metals Cr and Ni in the study area;the PMF model analyzes the mixed sources of industrial and agricultural inputs,gold mining and smelting sources,and copper mining and dressing.Both source and lead-zinc ore mining and beneficiation belong to industrial activities and are a refinement of the analytical results of the PCA-MLR model.In comparison,it is found that both the PMF model and the PCA-MLR model can better reflect the pollution sources in the study area,but the PMF model can analyze the pollution sources more precisely.(4)The following countermeasures and suggestions are put forward for the prevention and control of soil heavy metal pollution in the study area: carry out the investigation and rectification of pollution sources in cadmium-related and lead-related industries,and systematically promote the prevention and control of pollution sources;strengthen the use and management of agricultural inputs such as fertilizers,and adjust the planting structure;Safe utilization or treatment and restoration;investigation and remediation of historical solid wastes in mining areas;construction of gridded farmland plot information management system,and long-term observation of soil ecological environment. |
PDF Full Text Request