共存阳离子对砷、硒和钒毒性效应的影响及预测模型研究

Development of Predictive Models for Quantifying Potential Impacts of Coexisting Cations on Toxicity of As,Se,and V

为探明并量化共存阳离子存在下含氧阴离子型金属在生物体中的毒性效应,以模式植物小麦(Triticum aestivum L.)为研究对象,通过单一变量控制实验,探究了4种阳离子(Ca^(2+)、Mg^(2+)、Na^(+)和K^(+))对3种典型含氧阴离子型金属(AsO_(4)^(3-)、SeO_(3)^(2-)和VO_(4)^(3-))毒性的影响,并构建了静电作用模型来预测和评估As、Se和V的生态毒性效应与风险。结果表明,Ca^(2+)对As、Se和V毒性的影响呈现出3种不同的趋势:在相同设计浓度范围内Ca^(2+)的增加显著引起了As毒性的减弱(Adj.R^(2)=0.76,P<0.05)、V毒性的加剧(Adj.R^(2)=0.81,P<0.05),而对Se毒性却没有显著影响。当Mg^(2+)从0.20 mmol·L^(-1)增加到2.73 mmol·L^(-1)时,Se主导形态的半数有效活度值(EC_(50){HSeO_(3)^(-)})从40.40μmol·L^(-1)显著下降为27.98μmol·L^(-1),即Se毒性增强到原来的1.44倍(Adj.R^(2)=0.79,P<0.05)。静电作用理论能够很好地解释Ca^(2+)(或Mg^(2+))在显著增强V(或Se)毒性中发挥的作用,将这种静电作用影响纳入考虑成功构建了可以定量预测V(Adj.R^(2)=0.88)和Se(Adj.R^(2)=0.95)毒性的静电作用模型。研究结果弥补了目前含氧阴离子型金属生态毒性研究的不足,为含氧阴离子型金属的土壤污染生态风险评估提供了指导与参考。

To quantify the toxicity of anionic metal(loid)s in the presence of potentially competing cations,we designed a univariate experiment to investigate the influence of various cations(varying Ca,Mg,Na and K levels)on the toxicity of single anionic metal(loid)s(arsenate,selenite,and vanadate)and developed a mechanistic model to predict and evaluate the toxicity and risk of individual As,Se and V.Standard root elongation tests with wheat(Triticum aestivum L.)were performed.Results showed that the toxic effects of Ca^(2+) on As,Se and V presented three different trends.At the same concentration range,the addition of Ca^(2+) significantly reduced the toxicity of As(Adj.R^(2)=0.76,P<0.05),but aggravated the toxicity of V(Adj.R^(2)=0.81,P<0.05).There was no significant effect of Ca^(2+) on the toxicity of Se.Increasing{Mg^(2+)}from 0.20 mmol·L^(-1) to 2.73 mmol·L^(-1),the corresponding EC_(50){HSeO_(3)^(-)}decreased significantly from 40.40μmol·L^(-1) to 27.98μmol·L^(-1),that is,the toxicity of Se increased by 1.44 times(Adj.R^(2)=0.79,P<0.05).The electrostatic theories well explained the effects of Ca^(2+)(or Mg^(2+))on the significant enhancement of V(or Se)toxicity.By taking possible cation interactions into account,the electrostatic toxicity models succeeded in predicting the toxicity of Se(Adj.R^(2)=0.95)and V(Adj.R^(2)=0.88),respectively.Our findings filled the knowledge gaps on the ecological toxicity of anionic metal(loid)s,and provided guidelines for the ecological risk assessment of anionic metal(loid)s in the soil ecosystem.