Effects of Single Heavy Metal Pollution on Growth and Heavy Metal Accumulation of Juncus effuses

Effects of single element(Cu,Cd,Pb,Zn or As) pollution on growth and heavy metal accumulation of Juncus effuses were studied with pot culture.Results show that Cd,Pb and Cu stimulated growth of Juncus effuses when in the set range of low concentration,but inhibited when in the range of high concentration.As and Zn inhibited growth of Juncus effuses regardless of concentration except for As of the ground parts.The experiment also indicated that single heavy metal pollution affected yield of the biomass aboveground more significantly than yield of the biomass underground of Juncus effuses.In terms of extent of the inhabition of growth of Juncus effuses,the five heavy metals showed a decreasing order of Zn>(As>)Cu>Pb>Cd.With the decrement by 10% in biomass of Juncus effuses as a reference point,the threshold for soil Cd,Pb and Cu was set at 10,100 and 100～200 mg·kg^-1,respectively.Juncus effuses did not fit Zn-contaminated soil,and the threshold for soil As remained to be a topic that needs further study.All the heavy metals,except Cd,accumulated mainly in the roots of the plant.Regression analysis revealed that contents of Cd and Pb in the shoots and roots and As in the roots were correlated significantly with the rate of heavy metals added to the soil,showing a linear curve(P<0.05).