South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China; Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, 511458, China.
Department of Ecological Science, Faculty of Science, Vrije Universiteit, De Boelelaan 1085, 1081 HV, Amsterdam, the Netherlands.
Environ Pollut. 2022 May 1;300:118874. doi: 10.1016/j.envpol.2022.118874. Epub 2022 Jan 28.
Toxicokinetics may help assessing the risk of metal-contaminated soils by quantifying the development of internal metal concentrations in organisms over time. This study assessed the toxicokinetics in Enchytraeus crypticus of non-essential (Pb and Cd) and essential elements (Zn and Cu) in metal-contaminated field soils from a mining area, containing 3.49-24.3 mg Cd/kg dry soil, 433-1416 mg Pb/kg dry soil, 15.7-44.9 mg Cu/kg dry soil and 1718-6050 mg Zn/kg dry soil. Three different uptake-elimination patterns in E. crypticus were found. Both essential elements (Zn and Cu) showed fast increasing internal concentrations reaching equilibrium within 2 d in the uptake phase, without hardly any elimination after transfer to clean soil. The non-essential Cd showed a slow linear accumulation and excretion with body concentrations not reaching steady state within 21 d. Internal Pb concentrations, however, reached equilibrium within 7 d in the uptake phase. Longer exposure times in ecotoxicological tests, therefore, are required for elements like Cd. Porewater pH and dissolved organic carbon (DOC) levels were the dominant factors controlling Cd uptake from the test soils. The 21-d body Cd and Pb concentrations were best explained from 0.01 M CaCl-extractable soil concentrations. Steady-state Cu and Zn body concentrations were independent of soil exposure concentrations. Bioaccumulation factors (BAF) were low for Pb (<0.1 kg/kg), but high for Cd at 1.78-24.3 kg/kg, suggesting a potential risk of Cd biomagnification in the terrestrial food chain of the mining area ecosystem.
毒代动力学可以通过量化生物体随时间推移内部金属浓度的发展，来帮助评估受污染土壤的风险。本研究评估了采矿区受污染田间土壤中痕量元素（Pb 和 Cd）和必需元素（Zn 和 Cu）在穴居颤蚓（Enchytraeus crypticus）体内的毒代动力学，这些土壤中 Cd 的含量为 3.49-24.3mg/kg 干土，Pb 的含量为 433-1416mg/kg 干土，Cu 的含量为 15.7-44.9mg/kg 干土，Zn 的含量为 1718-6050mg/kg 干土。在穴居颤蚓中发现了三种不同的吸收-消除模式。两种必需元素（Zn 和 Cu）表现出快速增加的内部浓度，在吸收阶段 2 天内达到平衡，转移到干净的土壤后几乎没有任何消除。非必需元素 Cd 则表现出缓慢的线性积累和排泄，体内浓度在 21 天内未达到稳定状态。然而，在吸收阶段 Pb 的内部浓度在 7 天内达到平衡。因此，对于 Cd 等元素，在生态毒理学测试中需要更长的暴露时间。孔隙水 pH 值和溶解有机碳（DOC）水平是控制从测试土壤中吸收 Cd 的主要因素。21 天的体内 Cd 和 Pb 浓度与 0.01M CaCl2 可提取土壤浓度的相关性最好。稳定态 Cu 和 Zn 体内浓度与土壤暴露浓度无关。Pb 的生物积累因子（BAF）较低（<0.1kg/kg），但 Cd 的 BAF 较高（1.78-24.3kg/kg），表明 Cd 在矿区生态系统陆地食物链中具有潜在的生物放大风险。
