摘要/Abstract
实际环境中农药与其代谢产物常常共存, 农药和代谢产物之间的联合毒性(协同或拮抗)直接影响农药的环境风险评估. 农药敌敌畏(A)在环境中主要有三种代谢产物(二氯乙醇(B)、二氯乙酸(C)、磷酸二甲酯(D)), 在不同环境条件下其浓度组成有多种变化, 与敌敌畏形成多种混合物. 本文应用优化实验设计方法从中优选5条具有不同浓度配比的混合物射线, 选择水生生物青海弧菌(Vibrio qinghaiensis sp.-Q67)和土壤生物秀丽线虫(Caenorhabditis elegans)为受试生物, 通过微板毒性分析方法测试母体A及其代谢产物B、C、D以及它们的混合物射线在不同暴露时间及不同浓度水平下对青海弧菌的发光抑制毒性和对秀丽线虫的致死毒性, 应用含95%观测置信区间的组合指数评估各混合物射线在不同暴露时间下联合毒性随混合物浓度水平的变化. 结果表明: 对青海弧菌, 母体A及2个代谢产物C和D对Q67的发光抑制毒性不随时间变化而变化, 但代谢产物B在12 h的毒性显著大于0.25 h, 且母体A无论在哪个暴露时间其毒性都大于代谢产物. 对秀丽线虫, A与B、C及D的致死毒性不随时间而变化. A、C及D的毒性基本相同, 且均显著大于B. 5条混合物射线在不同浓度水平下, 在12 h对青海弧菌的发光抑制毒性显著大于0.25 h. 无论在0.25 h或12 h, 混合物射线对青海弧菌的联合毒性均是低浓度加和与高浓度拮抗. 对于秀丽线虫, 5条射线的毒性均不随时间而变化. 在2个时间点的联合毒性除射线R2和R5具有轻微拮抗外, 其它都是浓度加和.
关键词: 农药, 多元混合物, 均匀设计射线法, 基本浓度组成, 时间依赖毒性
Pesticides and their metabolites often coexist in the real environment. The combined toxicity (synergism or antagonism) between pesticide and metabolites directly affects the environment risk assessment of pesticide. Dichlorvos (A) has three main metabolites, 2,2-dichloroethanol (B), 2,2-dichloroacetic acid (C) and dimethyl phosphate (D), in water and soil environment. Under different environmental conditions, metabolites with various concentration compositions form a variety of mixtures with dichlorvos. In this paper, five mixture rays with different mixture ratios were selected by optimal experimental design method. A typical aquatic (Vibrio qinghaiensis sp. -Q67) and a soil organisms (Caenorhabditis elegans) were selected as the tested organisms. The photoluminescence inhibitory toxicity (IT) of parent A and its metabolites B, C and D as well as their mixtures to Q67 and the lethal toxicity (LT) to C. elegans at different exposure time and concentration levels were determined by microplate toxicity analysis. The combination index with 95% observation-based confidence intervals was used to evaluate the change of combined toxicity of each mixture ray under different exposure times and the concentration levels. The results showed that the ITs of parent A and two metabolites C and D to Q67 do not change with the exposure time, but the IT of metabolite B at 12 h is significantly larger than that at 0.25 h. However, at two exposure times, the IT of parent A is greater than that of any of metabolites. The LTs of A and B, C and D to C. elegans do not change with the exposure time. The LTs of A, C and D to C. elegans are basically the same and significantly greater than that of B. The ITs of five mixture rays to Q67 at 12 h are significantly greater than those at 0.25 h at various concentration levels. The combined toxicities of the mixture rays to Q67 are concentration additive at low concentration levels and antagonistic at high concentration levels whether at 0.25 h or 12 h. For C. elegans, the LTs of five mixture rays at various concentration levels do not basically change with the exposure time. At two exposure times (12 h and 24 h), the combined toxicities of mixture rays are concentration additive except for the slight antagonism in the rays of R2 and R5.
Key words: pesticide, multicomponent mixture, uniform design ray, basic concentration composition, time-dependent toxicity
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