Wenzhou Medical College, Wenzhou, China.
PLoS One. 2011 Jan 5;6(1):e15794. doi: 10.1371/journal.pone.0015794.
Synthetic pyrethroid insecticides have generated public concerns due to their increasing use and potential effects on aquatic ecosystems. A modeling system was developed in this study for simulating the transport processes and associated sediment toxicity of pyrethroids at coupled field/watershed scales. The model was tested in the Orestimba Creek watershed, an agriculturally intensive area in California' Central Valley. Model predictions were satisfactory when compared with measured suspended solid concentration (R(2) = 0.536), pyrethroid toxic unit (0.576), and cumulative mortality of Hyalella azteca (0.570). The results indicated that sediment toxicity in the study area was strongly related to the concentration of pyrethroids in bed sediment. Bifenthrin was identified as the dominant contributor to the sediment toxicity in recent years, accounting for 50-85% of predicted toxicity units. In addition, more than 90% of the variation on the annual maximum toxic unit of pyrethroids was attributed to precipitation and prior application of bifenthrin in the late irrigation season. As one of the first studies simulating the dynamics and spatial variability of pyrethroids in fields and instreams, the modeling results provided useful information on new policies to be considered with respect to pyrethroid regulation. This study suggested two potential measures to efficiently reduce sediment toxicity by pyrethroids in the study area: [1] limiting bifenthrin use immediately before rainfall season; and [2] implementing conservation practices to retain soil on cropland.
合成拟除虫菊酯杀虫剂由于其使用量的增加及其对水生生态系统的潜在影响而引起了公众的关注。本研究开发了一个模拟模型系统，用于模拟在田间/流域尺度上拟除虫菊酯的输运过程及其相关的沉积物毒性。该模型在加利福尼亚州中央谷农业密集地区的奥雷斯蒂马溪流域进行了测试。将模型预测值与实测悬浮固体浓度（R²=0.536）、拟除虫菊酯毒性单位（R²=0.576）和淡水溞累积死亡率（R²=0.570）进行比较，结果令人满意。结果表明，研究区域的沉积物毒性与底泥中拟除虫菊酯的浓度密切相关。联苯菊酯被确定为近年来导致沉积物毒性的主要因素，占预测毒性单位的 50-85%。此外，每年最大拟除虫菊酯毒性单位的 90%以上的变异归因于降水和灌溉季节后期联苯菊酯的前期使用。作为第一个模拟田间和溪流中拟除虫菊酯动态和空间变异性的研究之一，该模拟结果提供了有关拟除虫菊酯监管方面需要考虑的新政策的有用信息。本研究提出了两种在研究区域有效降低拟除虫菊酯沉积物毒性的潜在措施：[1]限制在雨季前使用联苯菊酯；[2]实施保护措施以保留农田土壤。
