The Mechanism of Micro-aerobic Habitat Alteration in Controlling Rice Cadmium and Phenanthrene Uptake
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College of Environment and Resources, Xiangtan University

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Supported by the National Natural Science Foundation of China (No.22176161)

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    Abstract:

    【Objective】The unique micro-oxygen environment of the rice rhizosphere constitutes a critical hotspot that governs the transport and transformation of pollutants. However, the chemical-microbial mechanisms for absorbing cadmium(Cd) and phenanthrene uptake by manipulation of the rhizosphere micro-oxygen environment are still unclear. 【Method】This study conducted a pot experiment using the mid-season rice cultivar ""Huanghuazhan"". The dissolved oxygen content in the rhizosphere was elevated by inserting plastic droppers to investigate the mechanisms by which this modulated micro-oxygen environment inhibits the uptake of Cd and phenanthrene in rice. 【Result】The results indicated that the increased rhizospheric oxygen content (up to 1.7-fold) led to reductions in the accumulation of Cd (24.2%–61.1%) and phenanthrene (26.1%–50.6%) in rice. First, the increased oxygen content in the rice rhizosphere promoted the formation of Amorphous Ferric Iron Phosphate (AFIP-Fe) on the root surface (up to a 1.5-fold increase). This enhancement thereby strengthened the adsorption and sequestration of Cd and phenanthrene, constructing a root barrier that effectively impeded pollutant uptake. Secondly, the aerobic environment reshaped the rhizospheric microbial community structure, forming a functional microbiota dominated by core functional flora such as Sphingomonas sp. and Mycobacterium sp. Consequently, the abundance of genes related to Cd resistance and polycyclic aromatic hydrocarbon (PAH) degradation increased by 2.2 to 5.6-fold, which enhanced the microbial-mediated bio-immobilization of Cd and the biodegradation of phenanthrene. Redundancy analysis (RDA) showed that dissolved oxygen was the key environmental factor driving microbial community succession and influencing the forms of pollutants. 【Conclusion】In conclusion, this study confirms that improving the micro-oxygen environment promotes the formation of root iron plaque and functional rhizosphere microbiota, which synergistically acted to inhibit the uptake of Cd and phenanthrene in rice. These findings provide a novel theoretical basis and a potential technical approach for the safe utilization of contaminated farmland.

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ZHANG Qiming, WU Chen, YI Shengwei, CHEN Mingjie, PENG Guanwei, WU Michuan, XIE Yunhe, WU Yujun, LI Feng. The Mechanism of Micro-aerobic Habitat Alteration in Controlling Rice Cadmium and Phenanthrene Uptake[J]. Acta Pedologica Sinica,2026,63(1).

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History
  • Received:June 22,2025
  • Revised:October 05,2025
  • Adopted:October 09,2025
  • Online: October 11,2025
  • Published:
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