| This research studied the farmland polluted by the Acid mine drainage(Acid mine drainage,AMD)for a long time in Tongling city of Anhui province,through the investigation and studied soil background value.The conclusion is that the depth of the farmland polluted by the Acid mine drainage is mainly in the shallow layer 0?20 cm,and most of them is heavy metal pollution.In a follow-up study,five different hygrophilous plants was planted to complete the adaptive plants screening of farmland polluted by the Acid mine drainage using the plant to heavy metal tolerance mechanism,and it provides a scientific background for the restoration of contaminated soil.In order to study the effect of farmland soil profile polluted by the Acid mine drainage,the soil of paddy field polluted by the Acid mine drainage for a long time and unpolluted in Tongling mining area were studied,and elementary composition in the soil profile of paddy field(0?10 cm,10?20 cm,20?40 cm,40?60 cm,60?80 cm,80?100 cm)was determined,and the influence of the pollution of the Acid mine drainage on the physicochemical properties of paddy soil profile was investigated.The conclusion is that(1)the Acid mine drainage reduces the pH value of soil profile in the paddy field,and the value of pollution profile is lower than 6.5.(2)the soil profile conductivity,S and P content in the paddy field increasing significantly in the effect of the Acid mine drainage,and the conductivity of soil in the 0-10 cm layer was 1.91 times that of the control rice field,and the total content of S was 2.36 times.(3)The heavy metals into the fields with the Acid mine drainage mainly for Cu,Zn,Pb,As and Cr,Cu,Zn,Pb in 0?40 cm all showed a trend of enrichment,and the pollution index of Cu,Zn,Cr in 0?100 cm is greater than 1,while Pb and As mainly in 0?10 cm.(4)The Acid mine drainage accelerates the mineralization process of mineral composition in soil profile,especially the transformation of pyrite into hematite.The soil profile of Acid mine drainage was evaluated with potential ecological risk assessment,which shows that the content of PCu,PZn and PPb not less than 2.All levels of pollution are above grade 3,reaching moderate and severe levels of pollution,while As pollution only stays at 0?10 cm,and reaches level 3(mild pollution).The five kinds of wet plants,such as barracuda,yellow calamus,Zizania aquatica,canna and rice,have certain tolerance to the pollution of the Acid mine drainage,which mainly shows in:(1)The content of clay and granule in the composition of soil particles was improved,and the content of sand grains was reduced,consequently,the capacity of soil water holding,fertilizer and heat preservation was enhanced;(2)The plants absorbed a lot of nitrogen and phosphorus from the Acid mine drainage,and reduced the level of eutrophication of soil.(3)Compared with the standard of national food hygiene,the heavy metal Pb,Cd and A s in the five kinds of wet plants out of limits in different levels.The content of Pb was 8.28-13.31 times greater than national standard,Cd was 4.54-5.84 times,and As was 1.05-2.1 1 times.(4)Yellow calamus and canna was higher in five kinds of wet plants about the concentration of heavy metal pollution in the Acid mine drainage.By calculating the concentration factor of heavy metal in plant biology,the bioconcentration factor of heavy metal in plant biology,and the bioconcentration factor of effective state in heavy metal in plant biology.The results indicate that it is not suitable to grow food crops such as Zizania aquatic and rice in the polluted soil of acid mine,while non-grain corn such as yellow calamus can be used to repair the soil polluted by the Acid mine drainage.It can not only guarantee the purification ability of soil,but also beautify the environment and produce certain economic value. |
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