Heavy Metal Pollution Characteristics And Environmental Risk Assessment In Wanshan Mercury Mining Area

As the largest mercury mining area in China,Wanshan Mercury Mine in Guizhou has been concerned about the release of mercury to the surrounding environment after it stopped mining.As a waste residue from large mining area,it will cause continuous harm to the local environment and human body.As the largest mercury mining area in China,Wanshan Mercury Mine in Guizhou has been concerned about the release of mercury to the surrounding environment after it stopped mining.As a waste residue from large mining area,it will cause continuous harm to the local environment and human body.This study hopes to investigate the content and morphology of heavy metal elements in the soil around Wanshan mercury mining area,explore the relationship between heavy metal sources and environmental factors,and provide reference for the subsequent heavy metal treatment project by quantifying the threat degree of heavy metal through risk assessment.To investigate the vegetation communities in abandoned mining areas,to explore the relationship between heavy metal content in local plants and heavy metal content in soil,whether there are super-enriched plants or tolerant plants,and to explore the effects of nutrient elements and environmental factors on plant enrichment of heavy metals.Investigation of heavy metal phytoremediation in abandoned mining area.Heavy metal Pb,Cd,Hg,As,Cu,Zn content and morphological distribution in soil around Wanshan mercury mining area were studied,and the compound pollution degree and potential ecological harm of heavy metals were quantified by risk assessment.The results showed that the average content of Pb was lower than the soil background value and the national soil control value(GB15618-2018)of Guizhou Province,and the Cu content exceeded the background value but was lower than the control value.Cd,Hg,As contents all exceeded soil background value and control value.3.1,3.1,1.1.5 times higher respectively,and the Zn content is close to the soil control value.The correlation analysis and PCA analysis show that As,Cu mainly comes from natural geological input;Pb,Cd,Zn comes from the release from man-made mining activities and the attachment of some natural geological associated elements;and Pb,Cd,Hg has a large proportion of non-residual fraction(Non Res).The content of heavy metals in soil and plants in Wanshan mercury mining area was determined and analyzed,and it was concluded that the whole Pb did not exceed the national standard control value,the Cd exceeded the control value,the Hg was higher than the control value in WW,EK,ZJW,and the As,Cu,Zn content was mostly higher than the soil background value.The plants are mainly Compositae,followed by legumes.the most enriched contents for Pb were Serissa japonica of alizarinaceae,Cd was Cinnamomum japonicum of camphoraceae,Hg was Phytolacca americana L,As was Pteris vittata of pteridophy,Cu was Artemisia argyi and Zn was poplar of Populus in the study of plant bioconcentration factor(BCF),we found that the maximum Pb enrichment coefficient was Serissa japonica,Cd was Populus,Hg was Rubus corchorifolius,As was Conyza canadensis,Cu was Clerodendrum bungei and Zn was Populus.The correlation analysis of bioconcentration factor and soil heavy metal content showed significant negative correlation in Hg?Cu?Zn(P<0.05).By exploring the relationship between plant heavy metals and plant nutrient elements,it was found that P-Fe,P-Mn oxide was the carrier of high quality trace metals,it had significant effect on the enrichment of most heavy metals in plants,and P-Cd had antagonistic effect on the enrichment of P-Mg.RAC analysis found that Pb?Cd are two important heavy metals in the study area except Hg.Through the correlation between elemental pollution factor Cf and different forms,it can be seen that all heavy metals are mainly contributed pollution factors by residue fraction,that is,natural background input,Cd?Hg?Cu of which there are anthropogenic input at the same time.At the PLI,it is shown that the southwest and central towns in the study area and some towns in the north belong to the higher level of comprehensive pollution.PERI evaluation shows that Hg?Cd have a high level of potential risk and the largest proportion of Hg in the RI,its high risk situation needs to be noted.Based on the evaluation of the degree of compound pollution and potential ecology in this study,Hg and Cd are the mid-point focus of the subsequent mining area management work.The plant risk index in non-carcinogenic risk assessment HI were Cyclosorus interruptus > Matteuccia struthiopteris > Chrysanthemum coronarium> Conyza canadensis>Artemisia argyi>Gynostemma pentaphyllum > Rubus corchorifolius > Pteris cretica,while urban children > urban children > rural children and rural adults were affected by different population groups caused by element Hg>Cu>Zn,The risk index of plants in carcinogenic risk LCR was as large as Conyza canadensis>Artemisia argyi>Pteris cretica > Chrysanthemum coronarium > Rubus corchorifolius >Matteuccia struthiopteris > Gynostemma pentaphyllum > Cyclosorus interruptus,and the risk of Cd>As>Pb,was the same as that of HI.Generally speaking,the content and risk of heavy metals in the soil in this investigation are still at a relatively high pollution level,of which Hg is the most obvious;there are relatively high-enrichment vegetation,but no heavy metal-rich plants are found according to the defined indicators;There is an impact on the concentration of heavy metals in plants;the ecological risk in the study area is still at a relatively high level and needs constant attention.