Complexation with dissolved organic matter and mobility control of heavy metals in the rhizosphere of hyperaccumulator Sedum alfredii

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• 作者：Tingqiang Li ; Qi Tao ; Chengfeng Liang ; M.J.I. Shohag ; Xiaoe Yang ; Donald L. Sparks
• 关键词：Cadmium ; Complexation ; Dissolved organic matter ; Hyperaccumulator ; Lead ; Zinc
• 刊名：Environmental Pollution
• 出版年：2013
• 出版时间：November, 2013
• 年：2013
• 卷：182
• 期：Complete
• 页码：248-255
• 全文大小：401 K

文摘

The complexation of Zn, Cd and Pb with dissolved organic matter (DOM) in the rhizosphere of hyperaccumulating ecotype (HE) and a non-hyperaccumulating ecotype (NHE) of m>Sedum alfrediim> was measured using resin equilibration method. After the growth of HE m>S.?alfredii,m> the rhizosphere soil pH was reduced by 0.27-0.33 units, due to enhanced DOM derived from root exudation. For both ecotypes of m>S.?alfrediim>, the fraction of free metal as a percentage of soluble metal varied from 22.1 to 42.5 % for Zn²⁺, from 8.1 to 15.5 % for Cd²⁺, and from 4.5 to 10.4 % for Pb²⁺. Resin equilibration experiment results indicated that HE-DOM had greater ability to form complexes with Zn, Cd and Pb than NHE-DOM, Visual MINTEQ model gave excellent predictions of the complexation of Zn and Cd by DOM (m>Rm>²?>?0.97). DOM in the rhizosphere of HE m>S.?alfrediim> could significantly increase metal mobility through the formation of soluble DOM-metal complexes.