Study On The Spatial Distribution And Migration Law Of Heavy Metals In The Soil Around Typical Coal Gangue Accumulation

Water and soil environmental pollution caused by coal gangue accumulation is one of the main manifestations of environmental pollution in mining areas.Studying and revealing the characteristics and laws of the release of heavy metals from coal gangue accumulation areas to surrounding soil have important scientific significance and practical value for the scientific and effective management of mining area environment..The thesis is characterized by "single point breakthrough"(a total of 100 soil samples were collected through field investigations,and 3200 data were obtained in laboratory experiments).The study focused on the typical gangue accumulation area in mining area,revealing Cu,Hg,Cr,As,The distribution characteristics of the total and morphology of the five heavy metals in Pb,clarified the migration rules of the five heavy metals,established a migration prediction model of the migration of the five heavy metals,and evaluated the degree of heavy metal pollution,potential ecological risks and human health risks,forming the following main in conclusion:(1)The spatial distribution of the total amount of heavy metals in the soil around the coal gangue mountain:Cu,Hg,Cr,As,Pb five heavy metals in the surface soil and deep soil all show a trend of decreasing as the distance from the coal gangue mountain increases,Eventually approaching the background value,of which Cu and Hg mainly show a three-stage change of"slow-fast-return to natural background value",Cr,As and Pb mainly show a two-stage distribution of "fast-return to natural background value";distribution The characteristics from high to low are:southeast>positive east>northeast>true south>southwest.(2)Analysis of heavy metal forms in the soil around coal gangue:Heavy metal Cu is mainly in the residue state(34.4%?55.17%)and organically bound state(29.18%?37.86%).Most of the residue state means that it is not easy to migrate and organically bound state The high level is due to the fact that Cu generally exists in the form of Cu+and Cu2+in the compound,and it is easy to form complexes and chelates with inorganic and organic active groups;Hg is mainly in the form of residue(44.17%?69.92%)and organic Combined state(25.7%?38.93%),Heavy metal Cr is mainly in the residue state(71.05%?90.17%),As is mainly in residue state(69.87%?86.41%),Pb is mainly in residue state(39.18%?52.60%)and iron manganese oxide combined state(33.44%?39.96%).(3)The spatial distribution and morphological analysis of total heavy metals reveals the migration characteristics of heavy metals in the soil:horizontally,the potential migration capacity changes from strong to weak in order:southeast>positive east>northeast>positive south>southwest;Cu,Hg,Cr As the distance increases,the five heavy metals,As and Pb,the migration ability gradually weakens,and the maximum migration distance is determined.The maximum migration distance of the Hg element in the ES direction reaches 300m.In the vertical direction,as the depth increases,the migration ability of heavy metals shows a downward trend;the migration model of the total amount and distance of heavy metals in different directions and depths is established by the exponential distribution model,and the migration amount of heavy metals with distance,The migration prediction model of depth,angle and change of organic matter can predict and simulate the distribution and migration of heavy metals in the soil around coal gangue mountains through mathematical expressions.(4)Evaluation of heavy metal pollution in the soil around coal gangue:the single-factor index pollution assessment method is used to divide the surface soil and deep soil around the coal gangue into six different polluted areas in detail;through the potential ecological risk assessment results,different The extent of potential ecological risk areas and the determination of ecological safety limits.The safety limits for potential ecological risks of heavy metals in surface soil and deep soil are 200m and 150m,respectively,indicating that Hg element is the most important potential risk factor;There are significant human intolerable carcinogenic and non-carcinogenic risks.