State Key Laboratory of Efficient Utilization of Arid and Semi-arid Arable Land in Northern China/ Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, PR China; Department of Analytical Chemistry, The Connecticut Agricultural Experiment Station, 123 Huntington St., New Haven, CT 06511, USA.
State Key Laboratory of Efficient Utilization of Arid and Semi-arid Arable Land in Northern China/ Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, PR China.
J Environ Manage. 2024 Jun;362:121316. doi: 10.1016/j.jenvman.2024.121316. Epub 2024 Jun 5.
Given the increasing concern over Cd contamination of agricultural soils in China, reducing the availability of the toxic metal has become an important remedial strategy. However, the lack of a unified evaluation framework complicates the assessment of remediation efficiency of different practices. Here, we evaluated the general extraction method (GEM) of available Cd in nine typical soil types by comparing extraction agents, including CaCl, EDTA, Mehlich-Ⅲ, HCl and DTPA. The safe grain concentration of different agricultural products from National Food Safety Standards Limits of Contaminants in Food (GB 2762-2022) was then applied to understand soil limited available Cd concentration based on dose-response curves. We also derived environmental risk threshold (HC) values for Cd remediation in agricultural soils by constructing species sensitivity distribution (SSD) curves. The results showed that Mehlich-Ⅲ best predicted Cd accumulation in crops (with 76.5% of explanation of grain Cd) and was selected as the GEM of soil available Cd for subsequent analyses. The regression coefficient (R) of dose-response curves fitting between Cd absorption in crop tissues and soil available Cd extracted by GEM based on 30 different crop species varied from 51.0% to 79.5%, and the derived limit concentration of soil available Cd based on standard GB 2762-2022 was 0.18-0.76 mg‧kg. An HC of 0.19 mg‧kg was then calculated, meaning that a concentration of available Cd in agricultural soil below 0.19 mg‧kg ensures that 95% of agricultural products meet the quality and safety requirements of standard GB 2762-2022. The prediction model was well verified in the field test, indicating that can correctly estimate the soil available Cd based on the content of Cd in plant. This study provides a robust scientific framework for deriving the risk threshold for Cd remediation in agricultural soils and could be quite useful for establishing soil remediation standards.
鉴于中国农田土壤中镉污染的日益加剧，降低有毒金属的有效性已成为一项重要的修复策略。然而，缺乏统一的评价框架使得不同修复措施的修复效率评估变得复杂。在这里，我们通过比较提取剂，包括 CaCl、EDTA、Mehlich-Ⅲ、HCl 和 DTPA，评估了九种典型土壤类型中有效态镉的通用提取方法（GEM）。然后，我们应用国家食品安全标准《食品中污染物限量》（GB 2762-2022）中不同农产品的安全粮食浓度，根据剂量-反应曲线了解土壤中有效态镉的限量。我们还通过构建物种敏感性分布（SSD）曲线，得出了农业土壤镉修复的环境风险阈值（HC）值。结果表明，Mehlich-Ⅲ 最能预测作物中镉的积累（解释了 76.5%的粮食镉），因此被选为土壤有效态镉的 GEM，用于后续分析。基于 30 种不同作物的组织吸收镉与 GEM 提取的土壤有效态镉之间的剂量-反应曲线拟合的回归系数（R）在 51.0%至 79.5%之间，基于标准 GB 2762-2022 得出的土壤有效态镉的限量浓度为 0.18-0.76 mg·kg。然后计算出 HC 值为 0.19 mg·kg，这意味着农业土壤中有效态镉浓度低于 0.19 mg·kg 可确保 95%的农产品符合标准 GB 2762-2022 的质量和安全要求。该预测模型在田间试验中得到了很好的验证，表明可以根据植物中镉的含量正确估计土壤有效态镉。本研究为确定农业土壤中镉修复的风险阈值提供了一个稳健的科学框架，对于制定土壤修复标准可能非常有用。
