Food and Bioproduct Sciences, Univ. of Saskatchewan, Saskatoon, SK, Canada.
J Environ Qual. 2012 May-Jun;41(3):732-43. doi: 10.2134/jeq2011.0376.
A multitrophic outdoor mesocosm system was used to mimic a wetland ecosystem and to investigate the effects of glyphosate and two herbicide mixtures on wetland microbial communities. The glyphosate concentration used was 1000 times the environmentally relevant concentration (ERC). One herbicide mixture consisted of six auxin-type herbicides (2,4-D, MCPA, clopyralid, dicamba, dichlorprop, mecoprop), each at 1000 times the ERC. The second mixture was comprised of eight herbicides, including the six auxin-type herbicides as well as bromoxynil and glyphosate. For this mixture, a dose-response approach was used to treat mesocosms with the ERCs of each herbicide as the base concentration. Algal biomass and production and bacterial production and numbers for pelagic and attached communities were measured at different times over a 22-d period. The experimental results indicate that the eight-herbicide mixture, even at low concentrations, produced negative effects on microbial communities. Glyphosate on its own suppressed algal biomass and production for the duration of the study in pelagic and biofilm communities. Algal biomass and production, although initially depressed in the auxin-type herbicide treatment, were stimulated from Day 9 until experiment end. Due to their similar modes of action, the effects of this herbicide mixture appear to be a result of concentration addition. Such negative effects, however, were brief, and microbial communities recovered from herbicide exposure. Based on evidence presented in this study, it appears that glyphosate has a higher potential to inhibit primary production and chlorophyll content in pelagic and attached wetland algal communities than the auxin-type herbicide mixture.
采用多营养层户外中观系统模拟湿地生态系统，研究草甘膦和两种除草剂混合物对湿地微生物群落的影响。所用草甘膦浓度是环境相关浓度（ERC）的 1000 倍。一种除草剂混合物由六种生长素型除草剂（2,4-D、MCPA、氯吡嘧磺隆、麦草畏、二氯丙酸、甲草胺）组成，每种除草剂的浓度均为 ERC 的 1000 倍。第二种混合物由八种除草剂组成，包括六种生长素型除草剂以及溴苯腈和草甘膦。对于这种混合物，采用剂量反应方法，用每种除草剂的 ERC 作为基础浓度处理中观系统。在 22 天的时间内，不同时间测量浮游和附着群落的藻类生物量和生产力以及细菌生物量和数量。实验结果表明，即使在低浓度下，八种除草剂混合物也会对微生物群落产生负面影响。草甘膦本身在浮游和生物膜群落中抑制藻类生物量和生产力，持续整个研究过程。虽然生长素型除草剂处理最初抑制藻类生物量和生产力，但从第 9 天开始一直到实验结束，藻类生物量和生产力受到刺激。由于它们的作用模式相似，这种除草剂混合物的影响似乎是浓度加和的结果。然而，这些负面影响是短暂的，微生物群落从除草剂暴露中恢复。根据本研究提供的证据，草甘膦似乎比生长素型除草剂混合物更有潜力抑制浮游和附着湿地藻类群落的初级生产力和叶绿素含量。
