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Validating biomarkers of creosote phototoxicity to the aquatic macrophyte Lemna gibba

Conference ·
OSTI ID:218434
 [1]; ;  [2]; ;  [3]
  1. Boston Univ., MA (United States). Dept. of Biology
  2. Univ. of Guelph, Ontario (Canada). Centre for Toxicology
  3. Univ. of Waterloo, Ontario (Canada). Dept. of Biology
The authors are developing and validating photosynthetic biomarker assays of creosote toxicity that are predictive of events at the population level in cultures of the floating aquatic macrophyte, Lemna gibba (G-3). Creosote was introduced as a liquid both at full strength, and in the form of a commercially available creosote `oil` (ca. 50% creosote) at doses ranging from 1--300 ppm ({micro}L/L, v/v). Because UV light enhances the toxicity of PAHs, plants also were incubated both under visible light, and under simulated solar radiation (SSR) which mimics UV levels found in natural sunlight. Static renewal (8-day) toxicity bioassays were performed, and the results from population-level endpoints (day 8 population growth and plant chlorophyll content) were compared to chlorophyll fluorescence induction assays (an index of photosystem 11 quantum yield). Population growth rates demonstrated that similar to individual PAHs, creosote in both forms exhibited UV-enhanced phototoxicity. Chlorophyll content and chlorophyll fluorescence induction parameters also were inhibited by creosote, and closely corresponded to functional responses of population growth inhibition after sufficient acclimation. Additionally, the two forms of creosote differed both with respect to overall toxicity, and with respect to their phototoxicity in the presence of UV light. Full strength creosote was at least 50% more toxic than the creosote oil, and the phototoxic effects of SSR vs. visible light were significantly more pronounced both with respect to population-level results, and to fluorescence induction results. Fluorescence induction, therefore, is a rapid and sensitive biomarker for the phototoxicity of a PAH mixture that is consistent with results from more traditional growth-based toxicity bioassays.
OSTI ID:
218434
Report Number(s):
CONF-9511137--; ISBN 1-880611-03-1
Country of Publication:
United States
Language:
English