Hunter Wesley, Xu Yiping, Spurlock Frank, Gan Jay
Department of Environmental Sciences, University of California, Riverside, California 92521, USA.
Environ Toxicol Chem. 2008 Mar;27(3):568-75. doi: 10.1897/07-335.1.
Pyrethroid insecticides are widely used in both agricultural and urban environments. Pyrethroids have been frequently detected in California, USA, stream bed sediments. Pyrethroids are strongly hydrophobic so their bioavailability is determined by their sorption to sediment. In the present study, we used disposable polydimethylsiloxane (PDMS) fibers to sample from the freely dissolved (effective) permethrin concentration that governs bioaccumulation and toxicity, and tested the correlation of those measurements with uptake by Chironomus tentans. In sediments that were incrementally diluted with silica sand, both PDMS fiber and organic carbon (OC) normalized sediment concentrations were highly correlated with C. tentans permethrin uptake. However, for multiple sediments with OC ranging from 1.4 to 27%, C. tentans permethrin uptake showed a better correlation with PDMS fiber concentrations than sediment OC-normalized concentrations. We conclude that the qualitative properties of sediment OC influence permethrin phase distribution and therefore the bioavailability of permethrin in sediment-water systems. Consequently selective methods such as PDMS fibers yield improved estimates of bioaccumulation and toxicity as such methods detect freely dissolved permethrin concentrations in the sediment.
拟除虫菊酯类杀虫剂在农业和城市环境中都有广泛应用。在美国加利福尼亚州的河床沉积物中经常检测到拟除虫菊酯。拟除虫菊酯具有很强的疏水性，因此它们的生物利用度取决于其在沉积物上的吸附情况。在本研究中，我们使用一次性聚二甲基硅氧烷（PDMS）纤维从控制生物累积和毒性的自由溶解（有效）氯菊酯浓度中进行采样，并测试了这些测量值与摇蚊幼虫摄取量之间的相关性。在用硅砂逐步稀释的沉积物中，PDMS纤维浓度和有机碳（OC）归一化沉积物浓度均与摇蚊幼虫的氯菊酯摄取量高度相关。然而，对于有机碳含量在1.4%至27%之间的多种沉积物，摇蚊幼虫的氯菊酯摄取量与PDMS纤维浓度的相关性比沉积物OC归一化浓度更好。我们得出结论，沉积物有机碳的定性性质会影响氯菊酯的相分布，从而影响氯菊酯在沉积物 - 水系统中的生物利用度。因此，像PDMS纤维这样的选择性方法能够更准确地估计生物累积和毒性，因为此类方法能够检测沉积物中自由溶解的氯菊酯浓度。
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