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西南喀斯特岩溶区次生风化性农田中存在重金属累积异常，但作物中重金属的累积与土壤背景值并未表现出显著相关性。本研究以川东平原典型喀斯特岩溶区为研究对象，采集了176组土壤和水稻籽粒样品，系统分析其理化性质、Cd和As的含量及迁移富集特征，并评估国家标准（GB 15618—2018）在该区的适用性。结果表明，研究区土壤pH值范围为4.49～8.94，整体呈中性偏酸，局部显著酸化。Cd平均含量为0.26 mg/kg，高于全国（0.15 mg/kg）和成都平原（0.207 mg/kg）背景值，且有效态Cd（平均0.12 mg/kg）生物有效性较高；As平均含量为4.39 mg/kg，低于全国及成都平原背景值，但在酸性土壤中存在活化风险。水稻籽粒中Cd超标率为8%，显著低于土壤潜在风险比例（21%）;As超标率较低，但其累积与土壤pH值呈显著负相关，酸化条件下累积风险增加。进一步相关性分析表明，土壤pH值、有机质（SOM）和Fe-Mn氧化物是影响Cd和As迁移富集的关键因子。其中，酸化会增强Cd和As的释放与富集，而较高的Fe-Mn氧化物和SOM含量可显著降低其生物有效性。基于以上结果，本研究提出了喀斯特岩溶区土壤Cd安全利用的针对性风险管控建议，为我国西南地区开展区域化的土壤污染风险评估与管控标准研究提供了科学依据，并为制定更加合理的土壤安全利用评价体系提供了数据支撑。
Abstract：In the Karst belt of Southwest China,secondary weathered farmland frequently contains anomalously high heavy-metal inventories,yet crop uptake does not track local geochemical background. To clarify the controls on Cd and As mobility in this setting,176 paired topsoil-rice-grain samples were collected across a typical Karst sector of the Eastern Sichuan Plain. Physicochemical parameters,total and labile metal pools,and grain enrichment were determined,and the protective value of the current national standard(GB 15618—2018) was tested. Soils were neutral to slightly acidic overall(pH 4. 49-8. 94),but conspicuous hot-spots of acidification(pH<5. 5) occurred. Mean total Cd(0. 26 mg/kg) exceeded both the national(0. 15 mg/kg) and Chengdu Plain(0. 207 mg/kg) backgrounds;exchangeable Cd averaged 0. 12 mg/kg,indicating high bioavailability. Mean total As(4. 39 mg/kg) lay below regional backgrounds,yet speciation modelling suggested re-mobilisation risk once pH drops below 5. Grain Cd surpassed the food-safety limit in 8% of samples,far less than the 21% of soils classified as high-risk. Arsenic over-limit rates were low,but grain As rose sharply with decreasing soil pH value(r=-0. 62,P<0. 01). Multiple regression and structural equation modelling identified soil pH value,organic-matter content(SOM) and Fe/Mn-oxide abundance as the dominant factors governing metal transfer. Acidification promoted desorption of both elements,whereas elevated SOM and Fe/Mn oxides immobilised them. We propose pH-neutralisation combined with organic-amendment and Fe/Mn-oxide supplementation as targeted,low-cost management to secure safe production on Cd-contaminated karst soils. The data provide a quantitative basis for revising regional screening values and for building a site-specific soil-safety evaluation framework in Southwest China.
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基本信息:
DOI：10.20236/j.CJIAC.2026.01.001
中图分类号:X826;X825
引用信息:
[1]吴佳妮,杨杰,杨宇慧,等.川东平原喀斯特岩溶区土壤-水稻系统中Cd、As风险评价[J].中国无机分析化学,2026,16(01):1-13.DOI:10.20236/j.CJIAC.2026.01.001.
基金信息:
国家自然科学基金青年科学基金C项目(42507360); 重庆市自然科学基金面上项目(4322500247); 成都市科技创新研发项目(2025-YF05-00596-SN)~~
2025-10-28
2025-10-28
2025-10-28