Influence of Dissolved Organic Matter on Cd Speciation in Rhizosphere Soil Solution and Phytoextraction by Sedum alfredii and Sedum sarmentosum
Meihua Lian1,2, Yaohua Zhang3, Lina Sun2, Xiaomin Hu1, Xiangfeng Zeng4
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1College of Resources and Civil Engineering, Northeastern University, Shenyang, Liaoning, China
2Key Laboratory of Regional Environment and Eco-Remediation, Ministry of Education,
Shenyang University, Shenyang, Liaoning, China
3Liaoning Acadeny of Geology and Mineral Resources, Shanyang, Liaoning, China
4Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology,
Chinese Academy of Sciences, Shenyang, Liaoning, China
Submission date: 2015-01-27
Final revision date: 2015-04-10
Acceptance date: 2015-04-10
Publication date: 2015-09-21
Pol. J. Environ. Stud. 2015;24(5):2035–2044
Cd contamination in soil is a global environmental issue and the remediation of contaminated soil is necessary. Phytoextraction, as a promising friendly technique, has a main drawback: low mobility and bioavailability of Cd. In this study, the influences of dissolved organic matter derived from chicken manure (DOMc), humus soil (DOMs), and rice hull (DOMr) on Cd speciation in soil solution, and the uptake of Cd by a hyperaccumulating ecotype (HE) and a non-hyperaccumulating ecotype (NHE) of Crassulaceae were investigated. After the addition of exogenous DOM and subsequent plant growth, the dissolved organic carbon (DOC) concentration increase resulted in a higher proportion of Cd-DOM complexation. Moreover, DOM derived from the chicken manure had the highest degree of Cd complex formation in rhizosphere soil, followed by DOMs and DOMr. Furthermore, because of the increasing fraction of Cd-DOM, the solvation of Cd in the soil matrix was remarkably favored. However, growth of HE decreased the dissolved Cd in rhizosphere soil solution compared to bulk soil, and may be attributed to the phytoaccumulation of Cd by HE plants. In addition, the amount of Cd phytoextracted by plants significantly increased with DOM concentration. The Cd concentrations in the HE shoots were in the range of 754.3~1234.2 mg·kg-1 (DOMc), 714.9~1015.8 mg·kg-1 (DOMs), and 656.7~900.4 mg·kg-1 (DOMr), and were 15.4~17.0, 17.4~23.9, and 16.9~22.6 times higher than the NHE samples, respectively.