Liu Yanwei, Li Bingqian, Zhou Juanjuan, Li Dongqin, Liu Yuanyang, Wang Yan, Huang Weigang, Ruan Zhepu, Yao Jun, Qiu Rongliang, Chen Guikui
Guangdong Laboratory for Lingnan Modern Agriculture, Guangdong Provincial Key Laboratory of Agricultural & Rural Pollution Abatement and Environmental Safety, College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China.
Institute of Quality Standard and Monitoring Technology for Agro-products of Guangdong Academy of Agricultural Sciences, Guangzhou 501640, China.
J Hazard Mater. 2025 Mar 15;486:136988. doi: 10.1016/j.jhazmat.2024.136988. Epub 2024 Dec 25.
Naturally aged microplastics (NAMPs) are commonly found in farmland soils contaminated with heavy metals (HMs), such as arsenic (As) and cadmium (Cd); yet their combined effects on soil-plant ecosystems remain poorly understood. In this study, we investigated the toxic effects of NAMPs and As-Cd on lettuce, considering the influence of earthworm activity, and examined changes in As-Cd bioavailability in the rhizosphere. Four experimental systems were established: soil-only, soil-lettuce, soil-earthworms, and soil-lettuce-earthworms systems, with four NAMPs concentrations (0, 0.1, 0.5, 1 %). Our results showed that exposure to 0.1 % NAMPs reduced As accumulation in lettuce shoots (0.17-0.25 mg kg) and roots (1.13-1.72 mg kg), while increasing biomass and enhancing root growth by alleviating toxicity. In contrast, the combined stress of higher NAMPs concentration (0.5 %/1 %) and As-Cd caused a 28.4-58.4 % reduction in root activity, which stimulated low-molecular-weight organic acid (LMWOA) secretion in the rhizosphere, increasing the bioavailability of As and Cd and enhancing their absorption by lettuce. Partial least squares path modeling (PLS-PM) revealed that co-exposure altered LMWOA content, soil enzyme activity, and microbial community stability in the rhizosphere, ultimately influencing the bioavailability and uptake of As and Cd by lettuce.
自然老化微塑料（NAMPs）常见于受重金属（HMs）污染的农田土壤中，如砷（As）和镉（Cd）；然而，它们对土壤-植物生态系统的综合影响仍知之甚少。在本研究中，我们考虑蚯蚓活动的影响，研究了NAMPs和As-Cd对生菜的毒性作用，并检测了根际中As-Cd生物有效性的变化。建立了四个实验系统：仅土壤、土壤-生菜、土壤-蚯蚓和土壤-生菜-蚯蚓系统，设置了四个NAMPs浓度（0、0.1、0.5、1%）。我们的结果表明，暴露于0.1%的NAMPs可减少生菜地上部（0.17 - 0.25 mg kg）和根部（1.13 - 1.72 mg kg）中As的积累，同时通过减轻毒性增加生物量并促进根系生长。相反，较高浓度的NAMPs（0.5%/1%）与As-Cd的联合胁迫导致根系活性降低28.4 - 58.4%，这刺激了根际低分子量有机酸（LMWOA）的分泌，增加了As和Cd的生物有效性并增强了生菜对它们的吸收。偏最小二乘路径建模（PLS-PM）显示，共同暴露改变了根际LMWOA含量、土壤酶活性和微生物群落稳定性，最终影响了生菜对As和Cd的生物有效性及吸收。
