根际环境的调节与重金属污染土壤的修复

根际环境的pH和Eh会产生影响土壤中重金属的化学过程。pH的变化影响到重金属的固定和活化，根际的酸化能够活化大多数重金属，使其毒性增强；反之，则固定大多数重金属，减轻其毒性。Eh的变化可改变重金属的价态和存在形态，使其毒性减弱或增强。根分泌物可从多方面影响金属的毒性和有效性，如改变根际环境的pH值和Eh来改变金属的存在形态和活度；与金属络合或者吸附、包埋金属污染物；通过影响根际微生物特征来改变金属的毒性。根际环境中微生物能改变金属离子存在形态，其代谢产物能对金属离子产生沉淀、螯合等作用。土壤脲酶对重金属污染最敏感，可以用于监测土壤重金属污染。调控根际环境，可以有效地调节土壤中重金属污染物的活度、毒性及其转移，对重金属污染土壤起到修复作用。

Regulation of rhizosphere and remediation of polluted soil by heavy metal

Eh and pH of rhizosphere can influence the chemical processes of heavy metals in soil. pH specially exerts impact on the immobilization and activation of heavy metals. Acidification of the rhizosphere could activate the heavy metals and increase their toxicity. Eh can change the forms of heavy metal or immobilize heavy metals reducing their toxicity. Root exudates can also affect the toxicity and availability of heavy metals in many ways, such as changing pH and Eh in rhizosphere; absorbing or embedding heavy metals. Root exudates can also change the toxicity of heavy metals by affecting the microorganisms in rhizosphere. Microorganisms living in rhizosphere can change the forms of metal ions. Products of microorganism metabolism can deposit and chelated heavy metals. Therefore, controlling rhizosphere can regulate the activity, toxicity and transfer of heavy metals in soil.