Li Lifen, Ma Yinxin
Anhui Xiang'an Environmental Protection Corporation Ltd, Hefei, 230031, China.
College of Resources and Environment, Anhui Agricultural University, Hefei, 230036, China.
Sci Rep. 2025 Aug 3;15(1):28297. doi: 10.1038/s41598-025-14241-3.
Elucidating the impact of rhizosphere interactions on soil heavy metal accumulation and speciation is essential for accurately assessing heavy metal bioavailability and remediating contaminated soils. The rhizosphere effects of wheat on soil organic matter (SOM) content, pH levels, and Cd fractions in two Cd-contaminated soils, Ultisols (red soil) and Alfisols (yellow cinnamon soil), were studied through pot experiments using root bags. The results indicated that the rhizosphere of the red soil had a higher SOM content but a lower pH than the bulk soil. Conversely, the yellow cinnamon soil exhibited lower SOM and higher pH in the rhizosphere relative to the bulk soil. Meanwhile, Tessier sequential extraction identified Fe/Mn oxide-bound Cd (Fe/Mn-Cd; rhizosphere: 23.2%-50.7%, bulk: 35.9%-55.1%) and exchangeable Cd (Ex-Cd; rhizosphere: 31.6%-40.3%, bulk: 24.6%-33.7%) as the dominant fractions in the red soil. Similarly, the yellow cinnamon soil exhibited predominant fractions of Fe/Mn-Cd (rhizosphere: 22.4%-27.3%, bulk: 48.5%-55.9%), Ex-Cd (rhizosphere: 18.3%-49.6%, bulk: 17.5%-20.4%), and carbonate-bound Cd (Ca-Cd; rhizosphere: 8.9%-37.2%, bulk: 8.9%-20.5%). Furthermore, wheat roots tended to enhance the accumulation of Ca-Cd and residual Cd (Re-Cd) fractions, particularly under high Cd stress. Conversion sources varied by soil type: in the red soil, the primary sources were Ex-Cd and Fe/Mn-Cd, with rhizosphere processes dominated by SOM and bulk soil dynamics regulated by SOM and pH. In the yellow cinnamon soil, the sources included Ex-Cd, Fe/Mn-Cd, and OM-Cd, with rhizosphere transformations governed by SOM and bulk soil mechanisms controlled by pH. The findings are crucial for assessing Cd contamination in soil-plant environments and developing tailored phytostabilization approaches for Cd in specific soil types.
阐明根际相互作用对土壤重金属积累和形态的影响对于准确评估重金属生物有效性和修复污染土壤至关重要。通过使用根袋的盆栽试验，研究了小麦在两种镉污染土壤（老成土（红壤）和淋溶土（黄褐土））中对土壤有机质（SOM）含量、pH值和镉形态的根际效应。结果表明，红壤根际的SOM含量高于土体，但pH值低于土体。相反，黄褐土根际的SOM含量低于土体，pH值高于土体。同时，Tessier连续提取法确定铁/锰氧化物结合态镉（Fe/Mn-Cd；根际：23.2%-50.7%，土体：35.9%-55.1%）和可交换态镉（Ex-Cd；根际：31.6%-40.3%，土体：24.6%-33.7%）是红壤中的主要形态。同样，黄褐土中Fe/Mn-Cd（根际：22.4%-27.3%，土体：48.5%-55.9%）、Ex-Cd（根际：18.3%-49.6%，土体：17.5%-20.4%）和碳酸盐结合态镉（Ca-Cd；根际：8.9%-37.2%，土体：8.9%-20.5%）为主要形态。此外，小麦根系倾向于促进Ca-Cd和残留态镉（Re-Cd）形态的积累，尤其是在高镉胁迫下。转化源因土壤类型而异：在红壤中，主要来源是Ex-Cd和Fe/Mn-Cd，根际过程受SOM主导，土体动力学受SOM和pH调节。在黄褐土中，来源包括Ex-Cd、Fe/Mn-Cd和OM-Cd，根际转化受SOM控制，土体机制受pH控制。这些发现对于评估土壤-植物环境中的镉污染以及针对特定土壤类型开发定制的镉植物稳定化方法至关重要。
