Tlili Ahmed, Dorigo Ursula, Montuelle Bernard, Margoum Christelle, Carluer Nadia, Gouy Véronique, Bouchez Agnès, Bérard Annette
CEMAGREF, UR Qualité des Eaux, 3 bis Quai Chauveau CP 220, 69336 Lyon Cedex 09, France.
Aquat Toxicol. 2008 May 30;87(4):252-63. doi: 10.1016/j.aquatox.2008.02.004. Epub 2008 Feb 19.
An experimental study was undertaken to highlight the potential ecotoxicological impact of the herbicide diuron on biofilms during flooding events in a small river (Morcille) in the Beaujolais vineyard area (France). We investigated the responses of chronically contaminated biofilms exposed to short-term pulses (3 h) of diuron. Biofilms were grown in indoor microcosms that were either non-contaminated or exposed to low-level chronic contamination, and not exposed, or exposed to single or double pulses of two environmental concentrations (7 and 14 microg L(-1)) of diuron. Exposure to pollution and its impact on biofilms were assessed by measuring pesticide concentrations in biofilms, biomass parameters (chl a, AFDW), community structure (using 18S and 16S rDNA gene analysis by DGGE, and HPLC pigment analysis to target eukaryotes, bacteria and photoautotrophs, respectively) and by performing a physiological test. Control biofilms displayed very low diuron concentrations, whereas the herbicide was found in the contaminated biofilms. Nevertheless, diuron concentrations were not higher in the pulsed biofilms than in the non-pulsed ones. AFDW and chl ain vivo fluorescence increased in both microcosms during the experiment and biomass was higher in chronically exposed biofilms than in control ones. The impact on biomass was higher for the control double-pulsed biofilms than for the non-pulsed ones. Carbon incorporation by the chronically exposed biofilms was greater during the first 28 days of growth than during the first 28 days of growth in the control biofilms. Both single and double pulses inhibited carbon incorporation of all biofilm communities, especially of the control ones. Short-term inhibition of photosynthesis was never significantly different in exposed and non-exposed biofilms. Few differences in the pigment structure were found between chronically exposed and control biofilms, but pulses impacted on the pigment structure of all biofilm communities. Bacterial structural differences were observed between single-pulsed and non-pulsed biofilms, but not between double-pulsed and non-pulsed biofilms. The different pulses affected the eukaryotic community structures of the control biofilms, but not of the chronically exposed ones. Unlike the bacterial communities, the control eukaryotic communities were structurally different from the chronically exposed ones. This preliminary experimental study indicates that exposure to environmental concentrations of diuron and other agricultural contaminants and further exposure to diuron can have measurable effects on small river biofilm communities. The effects of a pulsed acute exposure to diuron on biofilms depended on whether the biofilms had previously been exposed to the same stressors or not.
开展了一项实验研究，以突出除草剂敌草隆在法国博若莱葡萄酒产区一条小河（莫尔西耶河）洪水期间对生物膜的潜在生态毒理学影响。我们研究了长期受污染的生物膜在短期（3小时）敌草隆脉冲作用下的反应。生物膜在室内微观环境中生长，这些微观环境要么未受污染，要么受到低水平的长期污染，并且未暴露、或暴露于两种环境浓度（7和14微克/升）敌草隆的单脉冲或双脉冲作用下。通过测量生物膜中的农药浓度、生物量参数（叶绿素a、无灰干重）、群落结构（分别使用变性梯度凝胶电泳通过18S和16S rDNA基因分析，以及通过HPLC色素分析来靶向真核生物、细菌和光合自养生物）以及进行生理测试，评估污染暴露及其对生物膜的影响。对照生物膜中敌草隆浓度非常低，而在受污染的生物膜中发现了这种除草剂。然而，脉冲处理的生物膜中敌草隆浓度并不高于未脉冲处理的生物膜。在实验过程中，两个微观环境中的无灰干重和叶绿素a体内荧光均增加，长期暴露的生物膜中的生物量高于对照生物膜。对照双脉冲生物膜对生物量的影响大于未脉冲处理的生物膜。长期暴露的生物膜在生长的前28天比对照生物膜在生长的前28天的碳固定量更大。单脉冲和双脉冲均抑制了所有生物膜群落的碳固定，尤其是对照生物膜。暴露和未暴露的生物膜在光合作用的短期抑制方面从未有显著差异。长期暴露的生物膜和对照生物膜之间在色素结构上几乎没有差异，但脉冲影响了所有生物膜群落的色素结构。在单脉冲和未脉冲处理的生物膜之间观察到细菌结构差异，但在双脉冲和未脉冲处理的生物膜之间未观察到。不同的脉冲影响了对照生物膜的真核生物群落结构，但未影响长期暴露的生物膜的真核生物群落结构。与细菌群落不同，对照真核生物群落与长期暴露的真核生物群落在结构上不同。这项初步实验研究表明，暴露于环境浓度的敌草隆和其他农业污染物以及进一步暴露于敌草隆会对小河生物膜群落产生可测量的影响。敌草隆脉冲急性暴露对生物膜的影响取决于生物膜之前是否曾暴露于相同的应激源。
