镉砷在线蚓中的毒物-毒效动力学过程及定量模拟

李敏; 龚冰; 黄雪莹; 肖雪; 何尔凯; 仇荣亮

文章摘要

李敏,龚冰,黄雪莹,肖雪,何尔凯,仇荣亮.镉砷在线蚓中的毒物-毒效动力学过程及定量模拟[J].农业环境科学学报,2020,39(7):1451-1459.

镉砷在线蚓中的毒物-毒效动力学过程及定量模拟

Toxicokinetic-toxicodynamic processes of cadmium and arsenic in Enchytraeus crypticus

投稿时间：2020-02-26

DOI：10.11654/jaes.2020-0209

中文关键词: 镉砷毒物动力学毒效动力学剂量-效应关系

英文关键词: cadmium arsenic toxicodynamic toxicokinetic dose-response relationship

基金项目:国家自然科学基金面上项目（41977115）；广州市科技计划项目（201904010116）；高校基本科研业务费青年教师培育项目（19lgpyl50）

作者	单位	E-mail
李敏	中山大学环境科学与工程学院, 广州 510006
龚冰	上海交通大学环境科学与工程学院, 上海 200240
黄雪莹	中山大学环境科学与工程学院, 广州 510006
肖雪	中山大学环境科学与工程学院, 广州 510006
何尔凯	中山大学环境科学与工程学院, 广州 510006	heerk@mail.sysu.edu.cn
仇荣亮	广东省环境污染控制与修复技术重点实验室, 中山大学, 广州 510006 岭南现代农业科学与技术广东省实验室, 华南农业大学, 广州 510642

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中文摘要:

为探讨土壤污染物重金属镉（Cd）和类金属砷（As）在陆生生物体内的动态累积及毒性效应过程的差异性和规律性，以线蚓（Enchytraeus crypticus）为研究对象，以Cd和As为目标金属，采用室内试验和模型拟合手段定量描述两者的毒物动力学和毒效动力学过程。结果表明：线蚓体内Cd、As的累积量随着暴露浓度及时间的增加而不断上升并逐渐趋于平衡，Cd、As在暴露期间最大的累积量分别为459.6、32.91 mg·kg^-1；拟合得到的Cd总吸收速率常数K_u（1.761 mg·kg^-1·d^-1）显著大于As（0.102 mg·kg^-1·d^-1），Cd总排出速率常数K_e（0.015 d^-1）小于As（0.287 d^-1）；Cd、As对线蚓的毒性作用随着暴露时间的增加而增强，基于体外暴露浓度计算的半数致死浓度（LC₅₀）随时间的增加而降低，并在暴露约7 d后达到平衡，其最终半数致死浓度（LC₅₀∞）分别为0.314、1.253 mmol· L^-1；进一步基于体内浓度计算其体内半数致死浓度（LC_50inter），发现As的LC_50inter值基本不受暴露时间的影响，而Cd的LC_50inter值随着暴露时间的增加而上升，基于不同暴露时间下体内浓度和毒性数据整体拟合得到总的LC_50interCd（468.8 mg·kg^-1·d^-1）显著大于LC_50interAs（26.65 mg·kg^-1·d^-1）。整体上，Cd和As在线蚓体内的累积和毒性均受到时间的影响；Cd的累积能力显著强于As，基于体外暴露浓度时毒性强度Cd大于As，而体内累积的As则呈现更强的毒性效应；As的体内浓度和其动态毒性效应有很好的相关性（R²=0.75），而Cd的体内浓度不能很好地预测其毒性（R²=0.57），说明其体内浓度不能完全代表产生毒性的生物有效浓度。

英文摘要:

The dynamic accumulation and toxicity processes of a heavy metal(Cd)and metalloid(As)in terrestrial organisms were explored. In this study, laboratory experiments and a modeling approach were both applied to quantitatively describe the toxicokinetic and toxicodynamic processes of Cd and As in the soil organism Enchytraeus crypticus. The results showed that the accumulation of Cd and As in E. crypticus increased with increasing exposure concentration and time, and equilibrium was reached after a certain exposure period. The maximum body concentrations of Cd and As during the exposure period were 459.60 mg·kg^-1 and 32.91 mg·kg^-1, respectively. The estimated overall uptake rate constant(K_u)of Cd(1.761 mg·kg^-1·d^-1)was greater than that of As(0.102 mg·kg^-1·d^-1), while the elimination rate constant(K_e)of Cd(0.015 d^-1)was smaller than that of As(0.287 d^-1). Based on the external exposure concentrations, the median lethal concentration(LC₅₀)for Cd and As decreased over time and reached equilibrium after 7 d of exposure, and the ultimate LC₅₀(LC₅₀∞)of Cd (0.314 mmol·L^-1)was smaller than that of As(1.253 mmol·L^-1). When based on the body concentrations, the LC_50inter was calculated, with an almost constant LC_50inter of As, while the LC_50inter of Cd increased over time. The overall LC_50interCd(468.80 mg·kg^-1·d^-1)was significantly higher than LC_50interAs(26.65 mg·kg^-1·d^-1). Overall, the accumulation and toxicity of Cd and As were both time-dependent. The accumulation capacity of Cd in E. crypticus was greater than that of As. The toxicity of Cd was higher than that of As when based on the external concentration, while the accumulated As in the organism showed a stronger toxic effect. There was a good correlation between the dynamic toxicity and the body concentration of As(R²=0.75), but not for Cd(R²=0.57), thereby suggesting that the accumulated Cd inside the organism cannot well represent the bioavailable fraction that causes toxicity. This study emphasizes the importance of considering the exposure time and bioavailability of metals for risk assessments in the future.

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