Ministry of Education, Key Laboratory of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310029, China.
J Hazard Mater. 2011 Sep 15;192(3):1616-22. doi: 10.1016/j.jhazmat.2011.06.086. Epub 2011 Jul 5.
Pot experiments were conducted to investigate the changes of the dissolved organic matter (DOM) in the rhizosphere of hyperaccumulating ecotype (HE) and non-hyperaccumulating ecotype (NHE) of Sedum alfredii and its effects on Zn and Cd sorption by soils. After planted with HE, soil pH in the rhizosphere reduced by 0.5-0.6 units which is consistent with the increase of DOM. The hydrophilic fractions (51%) in DOM from the rhizosphere of HE (HE-DOM) was much greater than NHE-DOM (35%). In the presence of HE-DOM, Zn and Cd sorption capacity decreased markedly in the following order: calcareous clay loam>neutral clay loam>acidic silty clay. The sorption isotherms could be well described by the Freundlich equation (R(2)>0.95), and the partition coefficient (K) in the presence of HE-DOM was decreased by 30.7-68.8% for Zn and 20.3-59.2% for Cd, as compared to NHE-DOM. An increase in HE-DOM concentration significantly reduced the sorption and increased the desorption of Zn and Cd by three soils. DOM derived from the rhizosphere of the hyperaccumulating ecotype of S. alfredii could significantly reduce metal sorption and increase its mobility through the formation of soluble DOM-metal complexes.
采用盆栽试验研究了东南景天超积累生态型（HE）和非超积累生态型（NHE）根际溶解有机质（DOM）的变化及其对土壤吸附 Zn 和 Cd 的影响。与 NHE 相比，HE 根际土壤 pH 降低了 0.5-0.6 个单位，这与 DOM 的增加是一致的。HE 根际 DOM 的亲水组分（51%）明显大于 NHE-DOM（35%）。在 HE-DOM 的存在下，Zn 和 Cd 的吸附容量按以下顺序显著降低：钙质粘土、中性粘壤土、酸性粉砂粘壤土。吸附等温线可以用 Freundlich 方程很好地描述（R(2)>0.95），与 NHE-DOM 相比，HE-DOM 存在时 Zn 的分配系数（K）降低了 30.7-68.8%，Cd 的分配系数（K）降低了 20.3-59.2%。HE-DOM 浓度的增加显著降低了三种土壤对 Zn 和 Cd 的吸附，并增加了它们的解吸。东南景天超积累生态型根际产生的 DOM 可通过形成可溶性 DOM-金属配合物显著降低金属的吸附，并增加其迁移性。
