Enhanced mobilization of Cd from commercial pigments in the rhizosphere of flooded lowland rice

文献类型： 外文期刊

第一作者： Liu, Zhaodong

作者： Liu, Zhaodong;Fang, Wen;Ji, Rong;Li, Hanbing;Yin, Daixia;Luo, Jun;Liu, Zhaodong;Williams, Paul N.;Han, Chao;Ren, Jinghua;Fan, Jian;Xu, Hongting

作者机构：

关键词： Cd mobilization; Rice rhizosphere; DGT; Planar-optode

期刊名称：SCIENCE OF THE TOTAL ENVIRONMENT （ 影响因子：7.963； 五年影响因子：7.842 ）

ISSN： 0048-9697

年卷期： 2022 年 807 卷

页码：

收录情况： SCI

摘要： Although yellow Cd pigments (Cd-YP), widely used in industrial colorants, are considered inert, increasing evidence suggests once released into the environment, photobleaching/weathering mobilizes Cd from these pigments posing a pollution threat. Although general redox conditions and biotic/microbial activity are known to be important factors in determining Cd release, how spatial trends and specific soil processes regulate the Cd-YP behavior are poorly understood. Using plant rhizotrons in controlled environmental conditions, this study investigated the behavior of Cd-YP amendments matched to levels (15 mg kg-1) representative of contaminated soils in Yixing, China. Using high-resolution two-dimensional diffusive-gradient-in-thin-films (HR-2D-DGT), planar-optode (PO) multilayer systems alongside targeted soil and porewater sampling for chemical analysis the biogeochemistry associated with Cd mobilization from Cd-YP rice rhizospheres were determined. The results showed that there was a significant release of Cd into soil porewaters (51.5 mu g L-1), but this reduced by 90.9% and stabilized over time (after 6-days). HR-2D-DGT ion-maps revealed pronounced spatial variances. The flux-maxima for Cd, which located within aerobic-rhizosphere zones, was 9 to 19-fold higher than in associated anoxic bulk soil. In general, zones of radial O2 loss (ROL)/higher redox conditions and lower pH were associated with Cd release, with S2- to SO42- transitions marking the boundaries of high-flux areas. Some isolated colocalization of Fe and Cd hotspots were observed in lateral root regions, but on-the-whole Fe/Mn and Cd release were not linked. In addition, microniche development was also an important feature of Cd mobilization due to soil heterogeneity. (c) 2021 Elsevier B.V. All rights reserved.

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