| Mineral resources are necessary and fundamental substance for social development.The development of mineral resources led to the changes in the structure of soil environment.When the soil can't recover by its self-purification capacity,it will cause the accumulation of heavy metals and soil pollution in heavy mental.Soil pollution in heavy metal is not only difficult to control,and also brings great harm to human body through agricultural products and water.Understanding the distribution of heavy metals content in the soil and evaluating it is the necessary means of soil governance.Guangdong province is a land of rare metals and non-ferrous metals,energy and raw materials rely on the development of mineral resources.The tailings,slag,and waste water generated in mine exploration has became the major source which create soil pollution in heavy mental.On the basis of reviewing a large number of literatures about heavy metal pollution to the soil,this article studies the content and distribution of heavy mental in the soil of a certain mining area in northern Guangdong from the practice of soil pollution of a certain mining area in northern Guangdong.The author adopts Nemerow index method and the potential ecological risk assessment method to evaluate it.Based on the content and distribution of heavy mental in the soil in a certain mining area of northern Guangdong,it found that the average levels of metal elements content in the three areas distribution is area X > area Y > area Z.the rankings for times of ultra standard in Area X ranks: Cadmium > Mercury > Lead > Zinc > Arsenic > Copper,and the content of chromium and nickel don't exceed under the standard of national soil background values,the rankings for times of ultra standard in Area Y ranks ranks: Cadmium > Copper > Mercury > Lead > Zinc> Arsenic> Chromium.The content of nickel doesn't exceed under the standard of national soil background values,the rankings for times of ultra standard in Area Z: Cadmium> Copper > Mercury > Lead> Zinc >.Chromium,Arsenic and Nickel don't exceed under the standard of national and Guangdong soil background values.On the vertical distribution in three study areas,surface soil is all serious polluted.The enrichment of heavy metal is the highest.Lead,Cadmium,Zinc,Arsenic and Mercury in three areas are similar.On the vertical distribution of three areas,the rankings for the content of heavy mental: X> Y > ZIt shows that the average Nemerow index of three areas from large to small is : X(5.70)> Z(3.22)> Y(3.17)through the evaluation result of Nemerow index.The whole study area belongs to heavy pollution,the soil quality is extremely poor.Five kinds from eight heavy metals,pollution rates of lead,cadmium,zinc,copper,mercury basically reached 100%.The average Nemerow index of these heavy metals is within 1,only reaching warning level,so the pollution is small.Evaluation result shows us that,from the aspect of contamination rate,the pollution rate of Y is slightly higher than the X,Z,which proves that the pollution caused by human activity in Y slightly wider than the X,Z.From the degree of pollution,the average enrichment of X and Z is slightly above Y,proved that the enrichment degree of X,Z are bigger than Y.From the perspective of the enrichment factor of individual elements,cadmium(7.11)> mercury(4.89)> lead(4.46)> zinc(3.25)> copper(2.04).While the enrichment factor of arsenic,chromium,nickel is slightly larger than 1,the contributing value of man-made pollution is not big.Through evaluation result of potential ecological harm index,the average RI of Y,Z area both are more than 150,which belongs to moderate hazard,the average RI of X area is more than 300,which belongs to the strong hazard.In terms of potential ecological harm coefficient of single heavy metal,the potential ecological harm coefficient Er of zinc,arsenic,chromium,copper,nickel are all within 15,which have less potential harm;while the potential hazards of cadmium is the biggest,followed by mercury and lead. |
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