College of Environment and Ecology, Chongqing University, Campus B 83 Shabeijie, Shapingba, Chongqing, 400045, China; Center of Space Exploration, Ministry of Education, Chongqing University, Campus A 174 Shazhengjie, Shapingba, Chongqing, 400044, China.
College of Environment and Ecology, Chongqing University, Campus B 83 Shabeijie, Shapingba, Chongqing, 400045, China.
Chemosphere. 2023 Nov;342:140042. doi: 10.1016/j.chemosphere.2023.140042. Epub 2023 Sep 1.
Owing to complex changes in the soil environment, determining cadmium (Cd) phytoavailability is challenging. We devised a soil-wheat system to monitor alterations in soil pH, electrical conductivity (EC), and Cd transformation under various rates of calcium chloride and/or low-molecular-weight organic acids (LMWOAs) addition. The findings indicate that decreasing soil pH value, increasing soil EC value, and Cd transformation affect the phytoextraction of Cd. The exchangeable Cd and transformation of Cd under shifts in soil pH and EC contribute differentially to the phytoextracted Cd. The level of potentially phytoavailable Cd was identified through complete wheat cultivation in which the soil pH decreased by 0.47 unit and soil EC increased by 600-1000 μS cm, resembling the concentration of 0.01 M LMWOAs extractable Cd, when transitioning from paddy to dryland soil. Based on considering the phytoextracted Cd as the phytoavailable Cd throughout a complete wheat growth term, the threshold for phytoavailable Cd in soil, ensuring the safety of wheat grain (limit: 0.1 mg kg), is determined to be 2.90 μg kg. Maintaining control over Cd phytoavailability in soil emerges as the key factor in ensuring the safety of wheat grain cultivation.
由于土壤环境的复杂变化，确定镉（Cd）的植物可利用性具有挑战性。我们设计了一个土壤-小麦系统，以监测在不同氯化钙和/或低分子量有机酸（LMWOAs）添加速率下土壤 pH、电导率（EC）和 Cd 转化的变化。研究结果表明，降低土壤 pH 值、增加土壤 EC 值和 Cd 转化会影响 Cd 的植物提取。土壤 pH 和 EC 变化下可交换 Cd 和 Cd 的转化对植物提取的 Cd 有不同的贡献。通过完全种植小麦来确定潜在的可植物提取 Cd 水平，其中土壤 pH 值下降 0.47 个单位，土壤 EC 值增加 600-1000 μS cm，类似于从水田到旱地土壤时 0.01 M LMWOAs 可提取 Cd 的浓度。基于在整个完整的小麦生长期间将植物提取的 Cd 视为可利用的 Cd，确保小麦籽粒安全（限量：0.1 mg kg）的土壤中可利用 Cd 的阈值被确定为 2.90 μg kg。控制土壤中 Cd 的植物可利用性是确保小麦籽粒安全种植的关键因素。
