title: Characterization of dissolved organic matter in the rhizosphere of hyperaccumulator Sedum alfredii and its effect on the mobility of zinc.
abstract: Pot experiments were performed to investigate the characteristics of dissolved organic matter (DOM) in the rhizosphere soil of hyperaccumulating ecotype (HE) and a non-hyperaccumulating ecotype (NHE) of Sedum alfredii and its effects on the mobility of zinc (Zn). DOM was fractionated using XAD resins into six fractions. The acid fraction was the predominant component of DOM in the rhizosphere of S. alfredii, with hydrophilic acid (HiA), hydrophilic base (HiB), and hydrophilic neutral (HiN) in HE-DOM being 1.6, 1.9, and 1.2 times higher respectively, as compared to NHE-DOM. ATR-FTIR results showed that DOM in the rhizosphere of S. alfredii consisted of a mixture of hydroxylated and carboxylic acids, and HE-DOM exhibited more CO, OH, CC and CO functional groups than NHE-DOM. Resin equilibration experiment results indicated that DOM from the rhizosphere of both ecotypes of S. alfredii had the ability to form complexes with Zn, whereas the degree of complexation was significantly higher for HE-DOM (60%) than NHE-DOM (42%). The addition of HE-DOM significantly (P<0.05) increased the solubility of four Zn minerals while NHE-DOM was not as effective at the same concentration. It was concluded that DOM derived from the rhizosphere of hyperaccumulating ecotype of S. alfredii could significantly increase Zn mobility through the formation of soluble DOM-metal complexes, this might be one of the important mechanism by which S. alfredii is involved in activating metal in rhizosphere.
authors.affiliation: Ministry of Education Key Laboratory of Environmental Remediation and Ecological Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, China. litq@zju.edu.cn
authors.forename: Tingqiang
authors.initials: T
authors.lastname: Li
authors.forename: Zhenghao
authors.initials: Z
authors.lastname: Xu
authors.forename: Xuan
authors.initials: X
authors.lastname: Han
authors.forename: Xiaoe
authors.initials: X
authors.lastname: Yang
authors.forename: Donald L
authors.initials: DL
authors.lastname: Sparks
mesh_terms: D001673:Biodegradation, Environmental; D009038:Motion; D009930:Organic Chemicals / Q000737:chemistry*; D058441:Rhizosphere; D031963:Sedum / Q000378:metabolism*; D012989:Soil Pollutants / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D012995:Solubility; D015032:Zinc / Q000032:analysis / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D009930:Organic Chemicals; D012989:Soil Pollutants; D015032:Zinc