The Phytoremediation Experimental Study Of Root Tuber Plants And Tuber Plants For Pb、Cd Contaminated Soil

Soil pollution of Pb and Cd is very serious in our country, but existing repair methodscan’t fully meet our requirements. In order to ensure the economic value of the land, at thesame time to repair the contaminated soil, we conducted a series of experiments. The Pb,Cd uptake character of Ipomoea batatas and Potato and their absorption coefficient、transfer coefficient potential in the phytoremediation of Pb, Cd–contaminated soil werestudied with different concentrations of single heavy metal pollutants (Cd or Pb) andCd-Pb compounded pollutants added into pot soil. The results indicate that:（1）Low concentrations of soil Pb can accelerate the growth of Ipomoea batatas, butwhen the concentrations of soil Pb exceed350mg/kg, high levels of Pb will inhibit thegrowth. Along with the rise of soil Cd level, the output of Ipomoea batatas risen first, thendeclined after the level of0.7mg/kg. But there no apparent effect to the growth conditionof Ipomoea batatas aboveground. According to Cd-Pb compounded pollution, the outputand the aboveground biomass of Potato all decreased with the concentrations increase.（2）The concentrations of different Ipomoea batatas tissues Pb increased with the soilPb levels rise, but the absorptive capacity of Pb are all decreased, and the sequence ofdifferent tissues is root>outer root sheath>stem>leaves>root core. According to Potato, thesequence of different tissues is root>leaves>stem>outer root sheath>root core.Theconcentrations of different Ipomoea batatas and potato tissues Cd increased with the soilCd levels rise, too. The absorptive capacity of Cd are all decreased. The Ipomoea batatasabsorptive capacity of Pb and Cd are all higher than potato. The Ipomoea batatas andpotato absorptive capacity of Pb are all lower than that of Cd.（3）Under the conditions of single heavy metal pollutants (Cd or Pb), theconcentrations of Cd, or Pb absorbed in the body of Ipomoea batatas and potato weresignificantly positively related to the heavy metals added in soil. Under the conditions ofCd-Pb compounded pollution, Cd and Pb levels were mainly affected by different Cd or Pbconcentrations added into soil and affected by a cross action of Cd-Pb secondly. The crossaction of Cd and Pb in the absorption and transference showed that Cd inhibited the Pbabsorption of the roots. The low concentrations of Pb accelerated the Cd absorption ofroots. On the other hands, high concentrations of Pb inhibited the Cd uptake into roots.（4）When the concentrations of Pb in soil lower than300mg/kg, that of Cd lowerthan0.7mg/kg, although Ipomoea batatas can’t be used as a hyperaccumulator plant, but it can be used as industrial starch, and have a higher economic value. When theconcentrations of Pb and Cd in soil are higher, Ipomoea batatas and potato can’t be used asa hyperaccumulator plant too, it just can be used to produce industrial starch.