Bioavailability, accumulation, translocation and transformation of Cd depend on the molar ratio of soil Se-to-Cd: Evidence from a natural SeCd rich soil-corn system

IF 8 1区环境科学与生态学 Q1 ENVIRONMENTAL SCIENCES

Science of the Total Environment Pub Date : 2025-10-22 DOI:10.1016/j.scitotenv.2025.180758

Zezhou Zhang , Yidan Wang , Wenyao Shi , Shihua Qi , Linxi Yuan

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引用次数: 0

Abstract

The existing understanding of the critical interactions between selenium and cadmium in crops grown in naturally Se–Cd-rich soils remains limited. To address this knowledge gap, this study investigated agricultural systems in naturally Se–Cd-rich areas within the Wumeng Mountain region of Guizhou, China. Samples of roots, stems and leaves, along with the corresponding rhizosphere soils of corn (Zea mays L.) in the grain-filling stage, were collected and analysed for Se and Cd concentrations and speciations. Results demonstrated significant inverse relationships among rhizosphere-soil Cd bioavailability, Cd accumulation in corn plant compartments, and increasing bioavailable Se:Cd molar ratios in soil (p < 0.05). Notably, the soil Se:Cd molar ratio was inversely correlated with Cd translocation from soil to roots (p < 0.01) while showing no significant effects on aboveground translocation (root-to-stem and stem-to-leaf, p > 0.05). These outcomes suggest that the soil Se:Cd molar ratio primarily regulates Cd accumulation at the soil–root interface, with limited impact on subsequent translocation within plant compartments. Moreover, the transformation of Cd into Cd–SeCys and Cd–SeMet occurred more frequently in the stem and leaf compared with that in the root. Furthermore, the underlying mechanism was conceptualised as comprising ‘three barriers’: SeCd complex formation in the rhizosphere (Barrier 1), Cd sequestration by the selenohydryl group (-SeH) in plant cells (Barrier 2) and Cd inhibition by phloem and nodes (Barrier 3). These findings support the use of Se:Cd molar ratios as indicators for sustainable crop safety in SeCd co-contaminated regions. This study advances the understanding of the potential mechanisms underlying the Se:Cd molar ratio and its influence on Cd toxicity in natural environments. Based on these findings, the Se:Cd molar ratios serve as an effective indicator for sustainable management of Cd contamination in agriculture.

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Cd的生物有效性、积累、转运和转化取决于土壤se -Cd的摩尔比：来自天然富硒土壤-玉米系统的证据。

在天然富硒镉土壤中生长的作物中，对硒和镉之间的关键相互作用的现有理解仍然有限。为了解决这一知识缺口，本研究调查了中国贵州乌蒙山地区天然富硒镉地区的农业系统。对灌浆期玉米的根、茎、叶及其根际土壤进行了硒、镉浓度和形态分析。结果表明，根际-土壤Cd生物有效性、玉米植株间Cd积累量与土壤生物有效性Se:Cd摩尔比增加呈显著负相关（p < 0.05）。这些结果表明，土壤硒镉摩尔比主要调控土壤-根界面的镉积累，对随后在植物区室内的转运影响有限。Cd向Cd- secys和Cd- semet的转化在茎和叶中的发生频率高于在根中的发生频率。此外，潜在的机制被概念化为包括“三个屏障”：根际形成的第二复合物（屏障1），植物细胞中硒羟基（-SeH）的Cd隔离（屏障2）以及韧皮部和淋巴结的Cd抑制（屏障3）。这些发现支持使用硒：镉摩尔比作为次生污染地区可持续作物安全的指标。本研究促进了对Se:Cd摩尔比的潜在机制及其对自然环境中Cd毒性的影响的理解。基于这些发现，硒镉摩尔比可作为农业镉污染可持续管理的有效指标。

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来源期刊

Science of the Total Environment 环境科学-环境科学

CiteScore

17.60

自引率

10.20%

发文量

8726

审稿时长

2.4 months

期刊介绍： The Science of the Total Environment is an international journal dedicated to scientific research on the environment and its interaction with humanity. It covers a wide range of disciplines and seeks to publish innovative, hypothesis-driven, and impactful research that explores the entire environment, including the atmosphere, lithosphere, hydrosphere, biosphere, and anthroposphere. The journal's updated Aims & Scope emphasizes the importance of interdisciplinary environmental research with broad impact. Priority is given to studies that advance fundamental understanding and explore the interconnectedness of multiple environmental spheres. Field studies are preferred, while laboratory experiments must demonstrate significant methodological advancements or mechanistic insights with direct relevance to the environment.