The Mechanism Of Phytoremediation Of Heavy Metals In The Environment

Hyperaccumulation of contaminated soils by heavy metal is using plant roots to accumulate heavy metals and then transfer them to shoots without destroying the soil environment, which is permanent and expanding. For simply the system and control condition exactly, this study introduced nutrition liquid to culture pants. Choosing Brassica Juncea L.Multisecta, we study the three factors that affect hyperaccumulation effect and analyze the mechanism of plants absorbing and transfering the heavy metals. We conclude:(1) Pb in plants has the obvious relativity with Pb in nutrient solution medium. When Pb concentration in nutrition solution medium is low, Pb concentration in plants is increased; when Pb concentration nutrient solution medium is to be a certainty, Pb concentration in plants will not be increased, if increasing Pb concentration outsides.(2) When the value of pH is 6-7, the biology quantity will not be effected. And at this range, the Pb concentration in plants has nothing with the pH.(3) The addition of chelator EDTA can enhance the Pb concentration in plants and the ability of transferring heavy metal from roots to shoots. When EDTA concentration in nutrient solution medium is low, with EDTA concentration increased, Pb can be absorbed with relatively steady chelated matter by plants; when EDTA concentration is too high, the Pb concentration in plants will exceed the endurance range of plants , so the plants have to reduce absorbing Pb and then Pb in plants will be decreased.(4) There are two basic countermeasure that plants endure heavy metal of high concentration, one is that plants accumulate and distribute heavy metal, and then absorb and transfer heavy metal to shoots; the other is excluding mechanism, which is that plants avoid to absorb too heavy metal to die.(5) The process of plants accumulating Pb includes the first 8-10 hours' speediness absorption and then slow chemistry deposition and cell absorb. For the integrity plants, plants absorbing and accumulating heavy metal are controlled by roots, and when the roots is excised, the control will disappear and there only has absorption.