The Tolerant Mechanisms And Phytoremediation Potential For Pb Tailing Leachate Of Several Aquatic Species

Six species of aquatic plants,Iris ensata var.hortensis,Hydrocotyle vulgaris,Nelumbo nucifera,Acorus calamus,Iris pseudacorus,Eleocharis tuberose were planted in the Pb mine tailing leachates(PbL)by pots or in the PbL pond.The research was to study the effects of PbL on the growth indexes and heavy mentals accumulations and the cultivation of aquatic plants on the water quality of cultivating medium(PbL).The results are as follows:(1)The results of the effects of PbL on the growth,anatomical structure and Pb accumulation and translocation of I.ensata var.hortensis showed that the seedling growth index decreased with PbL portions,especially when 100%PbL treatment.The seedling height,root length,leaf number root number and Dry weight were decreased significantly by 28.53%,33.50%,33.32%,28.57%and 41.62%compared with those of control.In 100%PbL treatment,leaf epidermal cells of I.ensata var.hortensis were only one or two layers and the apical epidermal cells arranged in intact but the cortical cells were not completed and dispersed with gas chamber.Pb contents in the above-ground and below-ground parts of I.ensata var.hortensis treated with 100%PbL were 115.82?g/g and 576.25?g/g,respectively,and the contents of Zn increased by 1.81and 5.99 of the control.The contents of Cu and Cd increased in a certain extent.The effects of I.ensata var.hortensis cultivation in PbL on the water qualitis were in the order:ORP>EC>removal BOD>DO.The concentrations of heavy metals in the PbL cultivation medium increased as the level of PbL enhanced.The highest value of bioconcentration factor of Pb was found in the 100%PbL treatment and was 0.416.The values of bioconcentration factor of Cu and Zn in the 100%PbL treatment were 19.33%and 80.75%higher than those of control.(2)the results of the effects of PbL on the growth,tolerant index of three aquatic species in compound cultivation showed that the gowth parameters of three species growing in the PbL were lower than those of control.However,the DW of below-ground parts in the compound cultivation with Hydrocotyle vulgaris and three species compound cultivation were significangtly increased.The DWs of above-ground and below-ground parts of H.vulgaris in compound cultivation with Nelumbo nucifera and three species compound cultivation were significangtly increased.The leaf numbers of N.nucifera in the compound cultivation with Hydrocotyle vulgaris and three species compound cultivation and the DW above-ground part in the compound cultivation with I.ensata var.hortensis were significangtly increased.The results indicated that the growth parameters of three aquatic plants wereinhibited by PbL and tolerant of three species was promoted in compound cultivation in a certain extent.(3)The results of effects of PbL stress on the water quality of three aquatic species compound cultivation showed that DO contents in the compound cultivation of three spcies were higher than that of control.The cultivation solutions of the aquatic plants cultivation were basicity.The ORP of the solutions of IPbL,NPbL,H + N and I +N treatment were higher than the control,especially I+N treatment.The removal of BOD of the solution of HH,HPbL and H+I were increase of 0.91%,1.48%and 1.37%.The least value of conductivity was found in the three species compound cultivation.Heavy metal concentrations in the solutions of cultivation of aquatic species decreased than that the PbL without cultivated plants.The Pb,Cu and Zn concentration of three species compound cultivation decreased 70.65%?90.52%and 30.77%compared with those of the control.(4)The results of six species of aquatic plants cultivated in the PbL pond of Dexing Pb Mine showed that enrichments of Pb in the underground parts from highest to the lowest were:H.vulgaris>I.pseudacorus>Acorus calamus>N.nucifera>Eleocharis tuberosa>I.Ensata var.hortensis.The accumulations of Pb in the above-ground parts of H.vulgaris and I.Ensata var.hortensis were higher than other species.The study found the Zn enrichment in underground parts of A.calamus was 21.65 times of the ground parts.Except the higher Cu contents in the above-ground part of H.vulgaris than the underground,enrichment five other aquatic plants underground portion of Cu were higher than the above-ground parts.The enrichments of Cd in the underground parts from highest to the lowest were:H.vulgaris>I.pseudacorus>E.tuberosa>A.calamus>N.nucifera>I.Ensata var.hortensis.The highest translocation factor of Pb was found in I.Ensata var.hortensis and the TF wass 0.097.The highest translocation factors of Zn and Cu and were found in H.vulgaris and the TF values were 0.22 and 1.063.The results indicated that six aquatic species could live in PbL and couldcould be used in the remediation of Pb contaminated water.The Pb accumulations of I.Ensata var.hortensis and H.vulgaris were higher than other four species.