Heavy Metals Risk Assessment And Bacterial Community Characteristics Of Soil-Crops In Typical Coal Mining Area Of Liupanshui

Liupanshuicity in Guizhou Province is an important coal mining base in South west China,with abundant coal resources.It is also a residential area of ethnic minorities with a large population and rich and colorful traditional ethnic cultures.Liupanshui coal mining area is a typical karst mountain mining area,and its ecosystem is fragile and easy to be damaged,and it is di fficult to recover after being damaged.Long-term coal mining activities must have certain influence on the soil-crop health around the mining area.In this study,Investigate the influence of the living habits of the minorities around the mining area on the environment,the soil and crops around a typical coal mining area in Liupanshui were taken as the research object to analyze the distribution characteristics,ecological risks and health risks of heavy metals in agricultural soils around the mining area.Research field of different land use types of soil enzyme activity,bacterial community characteristics,proven mining area soil and crops affected by heavy metal pollution and ecological risk degree,clarify affect mine main environmental factors of soil enzyme activity,bacterial community,understand the mining area of different land use types change law of soil quality,so as to provide scientific basis for restoration of mining area soil management,help the minority areas of ecological civilization construction.The main results are as follows:（1）The survey found that the minorities in the mining area have a strong ideas of environmental protection,attach great importance to the protection of the ecological environment,and have kept many traditional customs to protect the ecological environment.All ethnic groups live in harmony with the environment,and the daily life of villagers around the mining area has not caused serious impact on the environment.（2）The content of heavy metal elements in the farmland soil around the mining area was Zn（213.82mg/kg）>Cu（156.43mg/kg）>Cr（127.45mg/kg）>Ni（82.85mg/kg）>Pb（56.73mg/kg）>As（18.89mg/kg）,the contents of Cr,Ni,Cu,Zn,Pb and As were all higher than the background value of heavy metals in Guizhou soil,which were 1.51,2.52,5.82,2.46,1.81 and 1.18 times,respectively.The spatial distribution characteristics of heavy metals show that heavy metals are enriched seriously in the fields around gangue hills and washing plants.The average single pollution index of eac h heavy metal was Cu（5.82）> Ni（2.52）> Zn（2.46）> Pb（1.81）> Cr（1.51）> As（1.18）,Cu showed a heavy pollution level,Ni and Zn showed a light pollution level,Pb,Cr and As showed a slight pollution level.The comprehensive pollution is at the level of severe pollution.The comprehensive potential ecological risk index of heavy metals in the study area is 68.02,which has reached the level of slight harm.The results of geological accumulation index evaluation show that: Cu,Ni,Zn,Pb are slightly polluted,and Cr,As are clean.Among them,Cu and Ni contributed the most to comprehensive potential ecological risk（RI）,and were the most significant ecological risk factors in the study area.On the whole,the farmland soils around the mining area are in a slight harm degree,and the main pollution of heavy metals in the soil comes from human mining activities.（3）The risk of heavy metal-rich crops in mining area to human health is: sorghum >Corn >Cabbage>Onion>Chili peppers.Among the effects of crops on adult health,sorghum is in the degree of chronic poisoning,and other crops are in the degree of harm that has a greater impact on human health.The health hazards of heavy metals in various crops to children have reached the level of chronic poisoning,which is much higher than the health hazards to adults.（4）Mining area of different land use types in the soil water content,TN,TP,effective phosphorus and ammonium nitrogen and nitrate in cultivated land,forest land were higher content,and show the content of surface soil content is higher than that of deep soil,the content of the reclamation area District relative to a minimum,the highest content of soil organic matter in reclamation area District,characterized by deep content higher than the surface content.The activities of soil enzymes were higher in woodla nd,residential area and cultivated land,but lower in reclaimed area.The activities of leucine aminopeptidase and phosphatase in soil were relatively high,while the activities of cellulase were relatively low.The enzyme activities in the surface soil were higher than those in the deep soil at different depths.Soil moisture content,NO₃^-（-N）,NH₄⁺（-N） and enzyme activities were significantly positively correlated,while organic matter,total nitrogen and other physical and chemical factors were significantly n egatively correlated with enzyme activities.Heavy metals such as Mn,Hg and Cu were negatively correlated with soil enzyme activities.The results showed that soil water content and nitrate nitrogen were the main environmental factors promoting the growth o f enzymes,while environmental factors such as SOM and TN could inhibit the activity of enzymes,and heavy metals such as Mn and Hg that exceeded the standard could also inhibit the activity of enzymes.（5）The dominant phyla and genus of bacteria in soils of different land use types and soils at different depths in the mining area showed little difference.The dominant phyla were Proteobacteria,Actinobacteria,Acidobacteria,Chloroflexi and Planctomycetes.The major classifications were Saccharimonadaceae_unclassified,Bradyrhizobium,Peliomonas,Subgroup_6unclassified,etc.The bacterial diversity in different land use types of soil was as follows: Washing plant cultivated land > arable land of Gangue-2> arable land of Washing> arable land of Gangue-1>plant cultivated land of Gangue-1> Residential >reclamation area of Gangue-2> reclamation area of gangue-2;The bacterial diversity in different depth of soil showed as topsoil>Deep.Soil moisture content,p H and AP were significantly related to soil bacterial community,which were the main environmental factors affecting the diversity of soil bacterial community Soil enzymes were closely related to bacterial colony,and leucine aminopeptidase（LAP）,β-1,4-acetyl-glucosidase（NAG）,β-1,4-glucosidase（BG）and cellulodiglycolytic enzyme（CBH）were significantly positively correlated with Patescibacteria.β-1,4-glucosidase（BG）and cellulodisylhydrolase（CBH）were negatively correlated with the WS2 microflora,and β-1,4-xylosidase（BX）was also negatively correlated with Chlorobi.Zn,Cu,Pb,Mn and other heavy metals were significantly negatively correlated with Bacteroidetes and Patescibacteria,and positively correlated with Acidobacteria,Planctomycetes,Gemmatimonadetes.Heavy metals Cr,Ni and Hg were negatively correlated with Bacteroidetes,Actinobacteria,Planctomycetes and other dominant bacteria.On the whole,the Soil enzyme activity,heavy metals Cr,Hg and Pb had significant e ffects on the bacterial community.In summary,heavy metals pollution in the soil around the mining area is serious,and heavy metals in crops have posed a threat to human health,so management and rectification should be strengthened.Soil physical and chemical factors,soil enzymes and soil bacteria are closely related and can influence each other.Soil enzyme activity and bacterial community in mining area are mainly affected by soil heavy metal s,water content,available phosphorus,organic matter and other environmental factors.