University of Basel, Program Sustainability Research, Basel, Switzerland.
Aquat Toxicol. 2010 Mar 1;96(4):256-63. doi: 10.1016/j.aquatox.2009.11.001. Epub 2009 Nov 10.
Natural variability in sensitivity and pollution induced community tolerance (PICT) to atrazine, isoproturon and diuron and a mixture of these three herbicides to natural algal assemblages in mesocosms was determined. The specificity of PICT was examined by evaluating co-tolerance pattern for these photosystem-II (PSII) inhibitors. Phytoplankton communities were constantly exposed to equipotent concentrations of atrazine, isoproturon, diuron namely the 30% hazard concentration (HC(30)) obtained from species sensitivity distributions and an equitoxic mixture (Sigma3 x 1/3 x HC(30) of each herbicide) for five weeks in outdoor mesocosms. Induction of tolerance to the various herbicides was investigated by photosynthetic efficiency measurements of the algal assemblages in short-term laboratory tests. The composition of the algal communities in the various treatments was determined and ordination techniques such as the principal component analysis (PCA) were applied to log-transformed data to compare the seasonal community structure development. Temporal variation in sensitivity of the control algal assemblage to atrazine and isoproturon, but less to diuron was observed. The results further demonstrated that the control communities were in general more sensitive than the treated ones over the whole period tested indicating an enhanced tolerance of pre-exposed phytoplankton in the mesocosms. Co-tolerance was also observed for atrazine pre-exposed algal community to isoproturon, however, not vise versa. A pre-exposure to diuron induced similar tolerance to all three herbicides. A pre-exposure to the mixture treatment also lead to tolerance to isoproturon and diuron, less to atrazine. Overall, the observed co-tolerance pattern indicates that co-tolerance was not comparable between the herbicides with strong similarity in their biochemical mode of action.
自然变异性在灵敏度和污染诱导的社区对莠去津、异丙隆和西玛津的耐受性（PICT），以及这三种除草剂混合物对中观自然藻类组合的影响已被确定。通过评估这些光合系统 II（PSII）抑制剂的共耐受性模式，检验了 PICT 的特异性。浮游植物群落持续暴露于等效力浓度的莠去津、异丙隆、西玛津，即从物种敏感性分布中获得的 30%危害浓度（HC（30））和每种除草剂的等毒性混合物（Sigma3 x 1/3 x HC（30）），在户外中观实验室内进行了五周的实验。通过在短期实验室测试中对藻类组合的光合作用效率进行测量，研究了对各种除草剂的耐受性诱导。确定了各种处理中藻类群落的组成，并应用主成分分析（PCA）等排序技术对数转换数据进行比较，以比较季节性群落结构的发展。在整个测试期间，观察到对照藻类组合对莠去津和异丙隆的敏感性发生了变化，但对西玛津的敏感性变化较小。结果进一步表明，对照群落总体上比处理群落更敏感，表明中观实验室内预先暴露的浮游植物具有更高的耐受性。对于预先暴露于莠去津的藻类群落，也观察到对异丙隆的共耐受性，但反之则不然。预先暴露于西玛津会诱导对所有三种除草剂的相似耐受性。预先暴露于混合物处理也会导致对异丙隆和西玛津的耐受性，对莠去津的耐受性较小。总的来说，观察到的共耐受性模式表明，共耐受性在生化作用模式相似的除草剂之间不可比。
