State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210046, China.
J Hazard Mater. 2012 Oct 30;237-238:270-6. doi: 10.1016/j.jhazmat.2012.08.041. Epub 2012 Aug 24.
This study analyzed the toxicity of organophosphorus pesticide, dimethoate on freshwater rotifer Brachionus calyciflorus, using swimming angular and linear speed alteration as the sub-lethal endpoints. Response surface methodology (RSM) was applied in experimental design and data analysis to consider two related factors: toxic concentration, exposure time and their interaction. In general, inhibition effect of the pesticide on rotifer swimming was observed clearly at any given toxicant concentration. The highest inhibition rates in angular and linear speed were obtained in the shortest exposure time (11.36 min) and the highest dimethoate concentration (1.85 mg L(-1)). The RSM used for the analysis of treatment combinations showed that a cubic polynomial regression model was in good agreement with experimental results, with R(2)=0.992 and 0.9997, for swimming angular speed inhibition rate and linear speed inhibition rate (p<0.01, F-test, respectively). 3D reference surface plots and contour plots showed that the toxic effect was influenced not only by dimethoate concentration, but also by the exposure time. A time-step effect was observed clearly. Thus, the pesticide dimethoate had toxic stress on the swimming behavior of rotifers.
本研究采用角速度和直线速度的变化作为亚致死终点，分析了有机磷农药乐果对淡水轮虫褶皱臂尾轮虫的毒性。响应面法（RSM）被应用于实验设计和数据分析，以考虑两个相关因素：有毒浓度、暴露时间及其相互作用。一般来说，在任何给定的有毒浓度下，都能清楚地观察到农药对轮虫游动的抑制作用。在最短的暴露时间（11.36 分钟）和最高的乐果浓度（1.85mg/L）下，角速度和直线速度的抑制率最高。用于处理组合分析的 RSM 表明，三次多项式回归模型与实验结果吻合良好，对于角速度抑制率和直线速度抑制率，R(2)分别为 0.992 和 0.9997（p<0.01，F 检验）。3D 参考表面图和等高线图表明，毒性效应不仅受乐果浓度的影响，还受暴露时间的影响。明显观察到时间步长效应。因此，乐果对轮虫的游动行为具有毒性应激作用。
