The biodegradable S,S-ethylenediaminedisuccinic acid (EDDS) is a promising chelant for chelant-assisted phytoextraction of trace metals in polluted soil. The interactions between EDDS and trace metals/major elements in the soil affect the metal bioavailability and their subsequent phytoextraction efficiency. This study aimed to investigate the macroscopic and molecular-level interactions of EDDS with Cu in the rhizosphere and non-rhizosphere of a Cu-polluted agricultural soil. A multi-interlayer rhizobox planted with ryegrass was used to simulate the transport of EDDS and Cu from the non-rhizosphere to rhizosphere soils. The results showed that EDDS (5 mM kg⁻¹) significantly dissociated Cu (285–690 fold), Fe (by 3.47–60.2 fold), and Al (2.43–5.31 fold) from the soil in comparison with a control group. A combination of micro-X-ray fluorescence, X-ray absorption near-edge structure spectroscopy, and sequential extraction analysis revealed that EDDS primarily chelated the adsorbed fraction of Cu by facilitating the dissolution of goethite. Moreover, as facilitated by ryegrass transpiration, CuEDDS was moved from the non-rhizosphere to rhizosphere and accumulated in ryegrass. In situ processes of Cu extraction and transport by EDDS in the rhizosphere were further elucidated with chemical speciation analysis and geochemical modeling methods.

可生物降解的S，S-乙二胺二琥珀酸（EDDS）是一种有前途的螯合剂，可用于螯合剂辅助污染土壤中微量金属的植物提取。EDDS与土壤中微量金属/主要元素之间的相互作用影响金属的生物利用度及其随后的植物提取效率。这项研究旨在研究EDDS与Cu在铜污染的农业土壤的根际和非根际的宏观和分子水平的相互作用。用黑麦草种植的多层中间根际盒子模拟了EDDS和Cu从非根际土壤向根际土壤的迁移。结果表明，EDDS（5 mM kg ^-1）与对照组相比，土壤中的铜（285-690倍），铁（3.47-60.2倍）和铝（2.43-5.31倍）显着解离。微X射线荧光，X射线吸收近边缘结构光谱和顺序萃取分析的结合表明，EDDS通过促进针铁矿的溶解而主要螯合了铜的吸附级分。此外，在黑麦草蒸腾作用的促进下，CuEDDS从非根际移至根际并积累在黑麦草中。利用化学形态分析和地球化学建模方法进一步阐明了根际EDDS在根际中Cu的原位提取和迁移过程。