Geochemical Characteristics And Environmental Effects Of Heavy Metal Elements In The Phosphate Rock Of Mabian,Sichuan

Human mining activities are the direct cause which make environmental damage and pollution around mines become more and more serious.Heavy metal pollution is also one of the results of mining activities.Research on heavy metal elements in the distribution of mines surrounding environment and chemical speciation of great significance for environmental studies and mine management.Based on the topic of“Comprehensive Evaluation of Environmental Effects of Mabian-Leibo Phosphorus Base in Sichuan Province”,this paper takes the Mabian Phosphorus Mine as the research object,and combines field investigation and laboratory experiments to study the geochemistry of heavy metal elements in different environmental media.Geological accumulation exponential method,the pollution load index method and index method of potential ecological harm evaluation of relevant environmental effect,BRC extraction heavy metal forms used to test and analyze the experimental results.Achieved the following results:1)The water quality samples are weakly alkaline,all located in the category 1area,which is a typical Ca-HCO₃ type water quality.The spatial distribution of heavy metals in water sediments increases the content of Cd,Pb and Zn from upstream to downstream,and the discharged sewage is an important cause of the increase of heavy metal elements in the water system;Hg and As are significantly affected by mining activities;The contents of Co,Mn,Ni and Cu are affected by slag accumulation and mining area.The elements near the water system are less released into the sediment;Cr,V and Ti are less affected by mining.The evaluation results of three evaluation methods on the environmental effects of heavy metals in sediments are basically the same.The pollution of Cd,Pb and Zn in water sediments is serious.The overall heavy metal pollution is mainly moderate pollution,and the potential risks are mainly mild to medium damage.The pollution level of the national sedimentary sediments is higher than the regional background value.2)The pH of soil samples was between 4.29 and 8.81.The spatial distribution of Cd,Pb and Zn elements has an upward trend from the inside to the outside of the mine.The content of the pits is obviously increased,which is greatly affected by mining.Hg and As are affected by mining;Co,Cr,Ni,Ti and V are less affected by mining and are affected by water flow;Cu and Mn elements are less affected by mining.Based on the national soil background value,three evaluation methods were adopted to evaluate the soil heavy metal pollution.It can be seen that the pollution of Cd,Zn and Pb elements in the soil of ma bian phosphate mine is relatively serious,and the pollution degree is mainly medium to very heavy pollution,with potential hazards above medium hazards3)All elements of atmospheric dust samples are contaminated.Among them,Cd,Pb and Zn are the most polluted,and the three samples are mainly highly polluted.4)There is a significant positive correlation between heavy metals in the root soil and leaf samples.The leaves are more likely to enrich the heavy metal elements.The stems are more likely to enrich Cu and Zn elements.Cr,Mn and Zn are high in the leaves.Fruits are the least likely to be enriched in heavy metals,and the heavy metals in the corn kernels are not exceeded.5)Zn and Cd in the sediments of the water system are mainly dissolved in weak acid,which is an active element and has a great influence on the environment.Mn and Pb are mainly in a reducible state,which has a great potential impact on the environment.Co,Ni,Cu,Cr,and As have a certain potential impact on the environment.The high proportion of Ti and V element residues has no impact on the environment.The Cd elements in the soil are mainly weakly soluble and reducible.The Zn and Pb are mainly in the reducible and oxidizable states,which have a great influence on the soil environment.Mn and Co elements are mainly in the reducible state and have a large potential impact on environment.Ni,Cu,Cr,and As have a certain potential impact on the environment.The high proportion of residual states of Ti and V has no effect on the soil environment.Relatively speaking,heavy metal elements in sediments are more active than soil.6)The release of heavy metal elements is obviously affected by mining.The heavy metal elements have obvious migration and transformation laws in different media.The heavy metal elements enter the environment with the artificial exploitation of the mine.The mine wastewater is discharged into the mine river,and heavy metal elements in the river are deposited into the water sediments.Heavy metal elements in rock and mine waste rock piles can enter the soil with rainwater,and the dust caused by mining is the main source of atmospheric heavy metals.