Study On The Distribution Characteristics Of Heavy Metals In Soil-Plant System Of Water Reservoir Fluctuation Zone

In order to clarify the migration characteristics of heavy metals in the soil-plant system of the reservoir fading zone,this study carried out sample collection,heavy metal content and soil physical and chemical analysis of the soil and dominant plants in the fading zone of the Three Gorges reservoir area and part of the Jinsha River Hydropower Station.Character determination,experimental data processing and analysis,study the distribution of heavy metals in different regions,different elevations,different soil layers and different dominant plants,and evaluate the ecological risk of heavy metal pollution.On the one hand,the distribution of heavy metals in different regions is clearly defined.The migration and distribution law in the plant system reveals the main influencing factors of the effectiveness of heavy metals,on the other hand,it selects the plant species with high-efficiency heavy metal absorption and accumulation capacity and strong adaptability to the environment of the fading zone.The ecological restoration model provides a theoretical basis.The main conclusions of this study are as follows:1.The contents of Cr,Cu,Zn,Pb,Cd,and Ni in the Three Gorges Reservoir area and the Jinsha River fluctuating zone are within the safety threshold compared with the soil heavy metal risk screening value.2.The content of six heavy metals in the soil of the Three Gorges Reservoir area increased with the depth of the soil layer.The content of Cr in the soil increased first and then decreased.The content of Cu,Pb and Ni remained basically unchanged,and the content of Zn and Cd decreased slowly;As the altitude increases,the average values of Cr,Cu,Zn,Pb,Cd,and Ni all show a slowly decreasing trend.3.The correlation analysis results between the content of available heavy metals(Fe,Mn,Cu,Zn)and environmental factors(pH,organic matter)in the soil show that the soil pH and effective Mn,Cu,Zn content in the water-flooding zone of the Three Gorges reservoir area are extremely Significant positive correlation(p <0.01),the correlation coefficient between effective Fe and Mg content is small;soil organic matter is extremely significantly positively correlated with effective Fe,Cu,Zn content(p<0.01),which is related to the effective Mn content The correlation coefficient is relatively small.The soil pH of the Jinsha River fading zone is very significantly positively correlated with the contents of available Fe,Mn,Cu,and Zn;the soil organic matter is extremely significantly positively correlated with the contents of Mn,Zn,which is related to the content of Fe,Cu The impact is small.4.Based on the single pollution index method,the soil in the Three Gorges Reservoir Area was not contaminated with Cr,Cu,Zn,Pb,Cd,and Ni;the Jinsha River Recession Zone,the Zhongxiaoqing River and Xiluodu had moderate Cu pollution and Ni light Pollution degree,Jinanqiao Cu light pollution,Ni light pollution.Based on the Nemero comprehensive index method,the evaluation level of heavy metal pollution in the soil of the Three Gorges Reservoir area is grade ? and clean;the evaluation level of heavy metal pollution in the soil of the Xiaosha River,Jin'an Bridge and Xiluodu of the Jinsha River is ?,Light pollution,other areas are class ?,clean.Based on the potential ecological hazard index method,it is concluded that the Zhongshi Baozhai and Xiangxiestuaries in the Three Gorges Reservoir area are middle potential ecological risks.Potential ecological risks.5.Compared with other plants such as Bidens nigella,Setaria,sedge and velvetleaf,there are strong potentials for the restoration of heavy metal plants in the fading zone of the Three Gorges Reservoir area.Bermuda,Bidens,Onion Grass,and Goosegrass have strong repair potential for heavy metal plants.