USDA-ARS National Sedimentation Laboratory, Oxford, MS 38655, USA.
Arch Environ Contam Toxicol. 2011 Feb;60(2):261-71. doi: 10.1007/s00244-010-9596-0. Epub 2010 Sep 3.
The toxicity of a nutrient-pesticide mixture in nonvegetated and vegetated sections of a constructed wetland (882 m² each) was assessed using Hyalella azteca 48-h aqueous whole-effluent toxicity bioassays. Both sections were amended with a mixture of sodium nitrate, triple superphosphate, diazinon, and permethrin simulating storm-event agricultural runoff. Aqueous samples were collected at inflow, middle, and outflow points within each section 5 h, 24 h, 72 h, 7 days, 14 days, and 21 days postamendment. Nutrients and pesticides were detected throughout both wetland sections with concentrations longitudinally decreasing more in vegetated than nonvegetated section within 24 h. Survival effluent dilution point estimates-NOECs, LOECs, and LC₅₀s-indicated greatest differences in toxicity between nonvegetated and vegetated sections at 5 h. Associations of nutrient and pesticide concentrations with NOECs indicated that earlier toxicity (5-72 h) was from permethrin and diazinon, whereas later toxicity (7-21 days) was primarily from diazinon. Nutrient-pesticide mixture concentration-response assessment using toxic unit models indicated that H. azteca toxicity was due primarily to the pesticides diazinon and permethrin. Results show that the effects of vegetation versus no vegetation on nutrient-pesticide mixture toxicity are not evident after 5 h and a 21-day retention time is necessary to improve H. azteca survival to ≥90% in constructed wetlands of this size.
采用水生大型溞（Hyalella azteca）48 小时水相整体暴露毒性生物测定法，评估了营养-农药混合物在人工湿地（各 882 平方米）无植被和植被区的毒性。两个区均添加了模拟暴雨水体农业径流的硝酸钠、过磷酸钙、二嗪磷和氯菊酯混合物。在每个区的进水、中间和出水口，于加标后 5 小时、24 小时、72 小时、7 天、14 天和 21 天采集水相样品。在整个湿地各区都检测到了营养物和农药，24 小时内，植被区的浓度纵向比无植被区下降更快。在非植被区和植被区之间，生存液稀释点估计值-NOEC、LOEC 和 LC₅₀值在 5 小时时显示出最大的毒性差异。营养物和农药浓度与 NOEC 值的相关性表明，早期毒性（5-72 小时）来自氯菊酯和二嗪磷，而后期毒性（7-21 天）主要来自二嗪磷。利用毒性单位模型对营养-农药混合物浓度-效应进行评估表明，H. azteca 的毒性主要归因于农药二嗪磷和氯菊酯。结果表明，在 5 小时后，植被与无植被对营养-农药混合物毒性的影响并不明显，需要 21 天的停留时间才能提高这种大小的人工湿地中水生大型溞的生存至≥90%。
