Isolation Of Algae From Copper Mining Wastelands And Its Study On The Tolerance And Adsorption Of Cu²⁺ And Cd²⁺

Due to the exploitation of metal mineral resources,a large number of mining waste had been produced,which seriously polluted the surrounding environment.Therefore,people were thinking about effective ways to treat the soil pollution by heavy metals.Bioremediation is an effective method for heavy metal treatment without secondary pollution.Some studies were shown that algae had strong tolerance and adsorption capacity to heavy metals,so it could be used for remediation of heavy metal contaminated soil.The physical and chemical properties,enzyme activity and heavy metal contents of the two kinds of copper mining wastelands were analyzed and determined in Shizishan copper mine dump and Fenghuangshan copper tailings in Tongling,Anhui province.The algae in two copper mining wastelands were screened,purified and identified in the substrates.The tolerance and adsorption capacity of algae under different concentrations of Cu2+ and Cd2+ were studied,which aimed at providing theoretical basis for algae to remediate contaminated soils by heavy metals.The main results were as follows:1.The contents of heavy metals in the substrates of two abandoned copper mines were relatively high.The contents of Cu,Cd,Pb,Zn and Cr in the soil of Shizishan Copper mine were 7256.67 mg/kg,6.24 mg/kg,105.57 mg/kg,84.52 mg/kg and154.70 mg/kg respectively.Among which,the contents of Cu and Cd reached 72.56 and 20.8 times of the soil environmental quality standard.The contents of Cu,Cd,Pb,Cr and Zn in the tailings of Fenghuangshan copper tailings were 2520.16mg/kg,5.70mg/kg,412.33 mg/kg,51.23 mg/kg and 273.97 mg/kg,among which the contents of Cu,Cd,Pb and Zn are 25.20,19.00,3.44 and 1.10 times of the soil environmental quality standard respectively.The contents of Cu,Cd,Pb,Cr and Zn in the crust of copper tailings in Fenghuangshan are 2709.67 mg/kg,6.10 mg/kg,417.33 mg/kg,45.47 mg/kg and 256.13 mg/kg respectively,among which the contents of Cu,Cd,Pb and Zn were 27.10,20.3,3.48 and 1.02 times of the soil environmental quality standard respectively.The contents of nutrients in the substrates of two abandoned copper mines were low.The contents of total nitrogen,available nitrogen and available phosphorus in the soil of Shizishan copper mining dump were 0.52 g/kg,35.77 mg/kg and 3.88 mg/kg respectively,all of which were classified as level 5deficiency.The total nitrogen content in the crust and tailings of Fenghuangshan copper tailings were 0.34 g/kg and 0.11 g/kg respectively,both of which were level 6.The available nitrogen content in the crust and tailings of Fenangshan copper tailings were 86.42 mg/kg and 20.31 mg/kg,which were classified as level 5 deficiency and level 6 extreme deficiency respectively.The content of available phosphorus in the crust and tailings of Fenghuangshan copper tailings were 2.97 mg/kg and 2.83 mg/kg respectively,both of which were level 6.The contents of available potassium in the skin and tailings of Fenghuangshan copper tailings were 44.78 mg/kg and 34.82mg/kg respectively,both of which were classified as grade 5 deficiency level.2.Through the isolation,purification and identification of algae from two copper mining wastelands substrates,a total of 6 species of algae were obtained.There were C.vulgris,C.pyrenoidosa,C.ellipsoidea,S.quadricauda,W.linearis and S.bacillaris.Among them,C.vulgris,C.pyrenoidosa and S.bacillaris were the dominant algae in the mine wasteland.3.According to the tolerance of three dominant algae to Cd2+ and Cu2+,there were a certain difference in the tolerance of each algae to heavy metals.C.pyrenoidosa could still grow at Cd2+ concentration of 10 mg/Lwith strong resistance to Cd.C.vulgris and S.bacillaris could not grow normally when Cd2+ concentration was 7mg/L and 5 mg/L.C.pyrenoidosa,C.vulgris and S.bacillaris had low tolerance to Cu2+,and their maximum tolerance concentrations were 1 mg/L,1.5 mg/L and 0.5mg/L,respectively.4.When the concentration of Cd2+were10 mg/L,0.5 mg/L and 5 mg/L,the adsorption rates of Cd2+ to C.pyrenoidosa,C.vulgris and S.bacillaris reached the maximum,which were 92.77%,98.61% and 85.10%,respectively.When the concentration of Cu2+was 0.5 mg/L,the adsorption rate of Cu2+to C.pyrenoidosa,C.vulgris and S.bacillaris reached the maximum,which were 85.86%,97.31% and75.36%.5.Adsorption kinetics experiments on C.pyrenoidosa at different concentrations of Cd2+ showed that the adsorption effects of C.pyrenoidosa in the concentration of 1mg/L and 7 mg/L Cd2+ were conformed to the quasi-first-order kinetic equation,and the adsorption effects in the concentrations of 3 mg/L,5 mg/L and 7 mg/L Cd2+were conformed to the quasi-second-order kinetic equation.