Naddy R B, Klaine S J
Department of Environmental Toxicology and Clemson Institute of Environmental Toxicology, Clemson University, Pendleton, SC 29670, USA.
Chemosphere. 2001 Nov;45(4-5):497-506. doi: 10.1016/s0045-6535(01)00019-4.
Due to the episodic nature in which organisms are exposed to non-point source pollutants, it is necessary to understand how they are affected by pulsed concentrations of contaminants. This is essential, as standard toxicity tests may not adequately simulate exposure scenarios for short-lived hydrophobic compounds, such as chlorpyrifos (CPF), a broad-spectrum organophosphate insecticide. Studies were conducted with 7-day old Daphnia magna for 7 days to evaluate the effect of pulse frequency and interval among multiple CPF exposures. Daphnids were exposed to a total exposure of either 12 h at 0.5 microg/l or 6 h at 1.0 microg/l nominal CPF, respectively, in all studies. For interval studies, D. magna were exposed to two pulses of CPF at each concentration, with 0-96-h intervals between pulses. For frequency studies, D. magna were exposed to each CPF concentration altering the pulse scheme by decreasing the exposure duration but increasing the number of pulses, keeping the total exposure time the same. The pulse interval between multiple pulses in these experiments was 24 h. Our results suggest that D. magna can withstand an acutely lethal CPF exposure provided that there is adequate time for recovery between exposures.
由于生物体接触非点源污染物具有间歇性，因此有必要了解它们如何受到污染物脉冲浓度的影响。这至关重要，因为标准毒性测试可能无法充分模拟短寿命疏水性化合物（如广谱有机磷杀虫剂毒死蜱（CPF））的暴露场景。对7日龄大型溞进行了为期7天的研究，以评估多次CPF暴露之间的脉冲频率和间隔的影响。在所有研究中，大型溞分别在0.5微克/升的浓度下暴露12小时或在1.0微克/升的名义CPF浓度下暴露6小时。在间隔研究中，大型溞在每个浓度下暴露于两个CPF脉冲，脉冲之间的间隔为0至96小时。在频率研究中，大型溞暴露于每个CPF浓度，通过缩短暴露持续时间但增加脉冲数量来改变脉冲方案，保持总暴露时间相同。这些实验中多个脉冲之间的脉冲间隔为24小时。我们的结果表明，只要暴露之间有足够的恢复时间，大型溞就能承受急性致死性CPF暴露。
