Gustavson K, Møhlenberg F, Schlüter L
DHI, Water and Environment, Agern Allé 11, DK-2970 Hørsholm, Denmark.
Arch Environ Contam Toxicol. 2003 Jul;45(1):48-58. doi: 10.1007/s00244-002-0079-9.
To improve risk estimates for herbicides in streams, the sensitivity of natural periphyton communities to four herbicides (metribuzin, hexazinone, isoproturon, and pendimethalin) was examined in experiments including varying exposure duration and a recovery phase. Effect parameters included assimilation of 14C and concentration of diagnostic pigments as proxies for photosynthetic activity and algal group composition, respectively. The results indicated that isoproturon, metribuzin, and hexazinone affected the photosynthetic activity of periphyton at distinctly lower concentrations than the effect concentrations published for standard single-species growth-tests with phytoplankton species. Pendimethalin did not show effects on the photosynthetic activity of periphyton at the concentrations tested. The effect concentration (EC50) of isoproturon and metribuzin decreased by one to two orders of magnitude when the duration of exposure increased from 1 h to 24 h, while hexazinone had a stimulating effect on the photosynthetic activity of periphyton after 1 h exposure and inhibiting effect after 24 h exposure. The photosynthetic activity after exposure to metribuzin for 1, 2, 6, 18, 23, or 48 h recovered almost completely after 48 h in herbicide-free water. However, different periphyton groups responded differently to metribuzin exposure: Chlorophytes were severely affected by exposure and did not recover, whereas diatoms and especially cyanobacteria recovered well. Overall the study showed that the effects of herbicides on periphyton are strongly affected by the duration of exposure, and even short-term exposure may have distinct effects on the periphyton community.
为了改进河流中除草剂的风险评估，在包括不同暴露持续时间和恢复期的实验中，研究了天然周丛生物群落对四种除草剂（嗪草酮、异恶草酮、异丙隆和二甲戊灵）的敏感性。效应参数分别包括14C同化量和诊断色素浓度，作为光合活性和藻类群落组成的指标。结果表明，异丙隆、嗪草酮和异恶草酮对周丛生物光合活性的影响浓度明显低于已公布的浮游植物标准单物种生长试验的效应浓度。在所测试的浓度下，二甲戊灵对周丛生物的光合活性没有影响。当暴露时间从1小时增加到24小时时，异丙隆和嗪草酮的效应浓度（EC50）降低了一到两个数量级，而异恶草酮在暴露1小时后对周丛生物的光合活性有刺激作用，在暴露24小时后有抑制作用。在无除草剂的水中暴露于嗪草酮1、2、6、18、23或48小时后的光合活性在48小时后几乎完全恢复。然而，不同的周丛生物群体对嗪草酮暴露的反应不同：绿藻受到暴露的严重影响且无法恢复，而硅藻尤其是蓝藻恢复良好。总体而言，该研究表明除草剂对周丛生物的影响受暴露持续时间的强烈影响，即使是短期暴露也可能对周丛生物群落产生明显影响。
