The Investigation On Soil Contaminated By Acid Mine Wastewater And A Wetland Treatment System In A Mining Area

Acid mine drainage(AMD)is a special acidic wastewater produced in the process of mining and utilization.It contains a lot of heavy metal ions and sulphates.Any discharge can lead to the destruction of the surrounding ecosystem of the mine.The environmental problems caused by it cannot be neglected.In this paper,the field of soil pollution and the microbial community structure were analyzed in order to evaluate the local soil pollution and to study the effect of wetland system on AMD treatment.The results showed that the soils surrounding acid water reservoir were seriously polluted by heavy metals such as Fe,Mn,Cd and sulfate,and the loss of nutrients such as organic matter and total nitrogen was more serious;The soil pollution degree of soil samples decreased with the increase of acid reservoir distance,soil pH,organic carbon and total nitrogen content increased gradually,soil microbial species increased gradually,and diversity index increased;The bacteria in the sampled soils are more complete.Bacillus and Lactococcus have more than 55.0% of the total bacterial flora,and Desulfuromonas and Desulfobulbus,which are involved in the metabolism of sulfur,account for more than 24.0% of the total flora;In addition,Nitrosophaera,Nitrosopumilus and Methanoregula,Methanosphaerula,which are involved in the nitrogen cycle,are the dominant species in the soil.AMD in the acid water reservoir was pretreated and discharged into the wetland system for treatment.The pH in the water environment gradually increased from 5.18 to 7.41,stabilizing at neutral;The removal rates of COD,sulfate,sulfide,Fe,Mn,Zn,Co,Ca and Mg were 63.6%,59.3%,59.8%,100%,61.8%,92.0%,48.6%,56.4% and 60.6%.The removal of heavy metals is mainly present in wetland sediments in the form of residues,and the three bioavailable forms of heavy metals are decreasing and the potential harm to the environment is smaller;there are a large number of sulfate-reducing bacteria,iron-reducing bacteria,and methanogens and so on in the wetland.They are the C,N,S,Fe elements of the cycle of the link,the organic mineralization,denitrification,methane production,heavy metal fixation and other environmental processes are closely linked,Among them,Latescibacteria,Bacillus,Optitutus and other bacteria can decompose organic matter accounted for more than 21.0% of the total bacteria;Geobacter,Azotobacter,Nitrosopumilus and other bacteria involved in nitrogen cycling accounted for 32.2% to 33.8%;Desulfobacca,Desulfarculus and Sideroxydans,Thiobacillus involved in the metabolism of sulfur and manganese were 24.0% ~ 25.8% and 21.1% ~ 27.1% of the total flora.