Complexation with dissolved organic matter and mobility control of heavy metals in the rhizosphere of hyperaccumulator Sedum alfredii.
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.
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. Electronic address: litq@zju.edu.cn.
Tingqiang
T
Li
Qi
Q
Tao
Chengfeng
C
Liang
M J I
MJ
Shohag
Xiaoe
X
Yang
Donald L
DL
Sparks
D060146:Ecotype; D019216:Metals, Heavy / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*; D018517:Plant Roots / Q000502:physiology; D058441:Rhizosphere; D031963:Sedum / Q000502:physiology*; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*
D019216:Metals, Heavy; D012987:Soil; D012989:Soil Pollutants
Cadmium; Complexation; Dissolved organic matter; Hyperaccumulator; Lead; Zinc