Ministry of Education Key Laboratory of Environmental Remediation and Ecological Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China; Department of Plant and Soil Sciences, University of Delaware, Newark, DE 19717, USA.
Environ Pollut. 2013 Nov;182:248-55. doi: 10.1016/j.envpol.2013.07.025. Epub 2013 Aug 10.
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 Sedum alfredii was measured using resin equilibration method. After the growth of HE S. alfredii, the rhizosphere soil pH was reduced by 0.27-0.33 units, due to enhanced DOM derived from root exudation. For both ecotypes of S. alfredii, the fraction of free metal as a percentage of soluble metal varied from 22.1 to 42.5% for Zn(2+), from 8.1 to 15.5% for Cd(2+), and from 4.5 to 10.4% for Pb(2+). 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 (R(2) > 0.97). DOM in the rhizosphere of HE S. alfredii could significantly increase metal mobility through the formation of soluble DOM-metal complexes.
采用树脂平衡法测定了超积累生态型（HE）和非超积累生态型（NHE）东南景天根际中溶解态有机物（DOM）与 Zn、Cd 和 Pb 的络合作用。HE 东南景天生长后，由于根系分泌物中 DOM 的增加，根际土壤 pH 值降低了 0.27-0.33 个单位。对于两种生态型的东南景天，Zn(2+)的自由金属分数（占可溶金属的百分比）变化范围为 22.1%至 42.5%，Cd(2+)为 8.1%至 15.5%，Pb(2+)为 4.5%至 10.4%。树脂平衡实验结果表明，HE-DOM 与 Zn、Cd 和 Pb 形成配合物的能力大于 NHE-DOM，Visual MINTEQ 模型对 DOM 与 Zn 和 Cd 的络合作用给出了极好的预测（R(2)>0.97）。HE 东南景天根际 DOM 可通过形成可溶性 DOM-金属配合物显著增加金属的迁移性。
