The Physiological Growth And Enrichment Effect Of Submerged Plants In Cu And Pb Contaminated Sediment Under Different Planting Patterns

Poyang Lake is the largest freshwater lake in China.It is located in the northwestern part of the Jiangxi Province.It is rich in mineral resources in the basin.It is east of Raohe River.The middle and lower reaches of the Le'an River and reaches of the Rao River in the upper have the largest Dexing Copper Mine and Lead Mountain Lead-Zinc Mine.With the development of industry and the acceleration of urbanization in Jiangxi Province,the aquatic environment of Poyang Lake wetland has been polluted by heavy metals such as Cu and Pb.Therefore,The Cu,Pb polluted sediments of the Raohe River in Poyang Lake wetland and its dominant species,Vallisnera natans,Hydrilla verticillata and Ceratophyllum demersum,were used as experimental materials.studying the growth and development,physiological ecology and bioaccumulation response of submerged plants in heavy metal Cu and Pb contaminated sediments can provide a theoretical basis for repairing aquatic environment pollution similar to rivers and lakes.Simulate static water bodies using white transparent plastic buckets,and cultivate submerged plants for72 days,a total of 4 stages(18/stage),with contaminated sediment from Raohe,and explore different plantings from the aspects of growth,physiological ecology and bioaccumulation of Vallisnera natans,Hydrilla verticillata and Ceratophyllum demersum.The physiological growth and enrichment effects of submerged plants in the sediment environment of Cu,Pb(about 280 mg/kg Cu,about 250 mg/kg Pb)in the River wetland of Poyang Lake.The results show:(1)Effects of single and mixed plants on plant growth and development.(P<0.05).The plants can grow naturally in the Cu and Pb composite sediment environment of the river beach.The total fresh weight,dry weight and plant height of the V.natans,H.verticillata and C.demersum are in the order of H.verticillata > V.natans > C.demersum;The ratio of dry to fresh weight is C.demersum > V verticillata > H.verticillata.The results showed that there was a significant difference in growth and development between the single species of V.natans,H.verticillata and C.demersum(P<0.05).Both V.natans and H.verticillata(1:1)and H.verticillata and C.demersum(1:1)C.demersum increased the fresh weight,plant height and dry weight of V.natans,H.verticillata and C.demersum.The fresh weight of V.natans,H.verticillata and C.demersum increased by6.82%,4.63% and 4.77%,respectively;the plant height increased by 17.9%,15.0% and3.3%;the dry weight increased by 2.43%,2.21% and 2.44.%;indicates that the mixed plants in a suitable ratio promotes the growth and development of submerged plants.(2)The growth,physiological and ecological enrichment responses of V.natans,H.verticillata and C.demersum in different culture stages were significantly different(P<0.05).In the second stage(mid-July to the end of July),the fresh weight increase,net height increase,growth rate and chlorophyll content of the V.natans and H.verticillata werethe largest,while the C.demersum was in the third stage(end of July to mid-August)the biggest.Under the single plant,Y(II),Fv/Fm and qN of V.natans and H.verticillata showed a trend of increasing first and then decreasing with the increase of culture time,while qP showed an increasing trend;C.demersum Fv/Fm,qP and qN It has been increasing,and Y(II)has increased first and then decreased.Under each planting,the V.natans and H verticillata 1:1 Fv/Fm and qP in each culture stage were higher than the single plant.The light energy activity utilization rate of plants from mid-August to End of July was higher than other time periods.Under the various plantings,in the first stage,the net amount of Cu and Pb in the sediment,the reduction of Cu and Pb and the bioconcentration factor in the sediment were the largest,while the H.verticillata in the second stage and the C.demersum in the three stage are the biggest.(3)The effect of submerged plant on the repair of heavy metals Cu and Pb can be improved under suitable mixing ratio.The V.natans and H.verticillata(1:1)increased the Cu enrichment factor by 16.37% and 21.3%,respectively,and the enrichment factor was higher than that of Pb.V.natans and H.verticillata(2:1)and V.natans and C.demersum(2:1)increased by 22.6% and 22.4%,respectively,compared with single H.verticillata,while the mixed H.verticillata was not significantly different to Pb.The removal rate of Cu and Pb in sediments by submerged plants is Cu >Pb.V.natans and H.verticillata(1:1)had the highest removal rates of Cu and Pb,reaching 82.13% and 54.21%,respectively.The remaining mixed plants removal rate exceeding 60% was V.natans and Ceratophyllum(1:2),V.natans and C.demersum(2:1),V.natans and C.demersum(1:1),V.natans and C.demersum(1:2),and better than a single plant.After 72 days of culture of the three submerged plants,the Cu content in the sediment changed from the original Soil Environmental Quality Standard(GB15618-1995)Grade ? to Grade II,while the Pb in the sediment decreased by 50%.The degree of Cu-Pb Compound pollution has decreased significantly.