@inproceedings{01GZXWMEMS7V0QSD5V8QT0XT5G,
  abstract     = {{Recently, dissolved organic carbon (DOC) was found to regulate the ecotoxicity of fluoroquinolone antibiotic ciprofloxacin (CIP). Through the various interactions, CIP molecules bound to DOC increase in molecular size and polarity, which inhibits them from traversing the membrane system of aquatic organisms and decreases the observed ecotoxicity of CIP. As the brownification of many freshwater ecosystems is predicted to rise due to climate change, the importance of DOC on the bioavailability of CIP in nature might increase consequently. In this study, we investigated how DOC of different origins affects CIP bioavailability to cyanobacteria using a cyanobacteria toxicity test performed with Microcystis aeruginosa PCC7806. The bioavailability was expressed by the ecotoxicity of CIP observed in test media dissolved with different DOC compounds: (1) freshwater DOC in the naturally occurring states, collected from six rivers and lakes in Europe, (2) processed DOC extracted from the river Schwarzbach, and (3) commercial DOC product Suwannee River organic matter. The impact of DOC wasquantified via describing the CIP+/- -DOC interaction using a binding constant (K d,CIP+/- ), which was related to the concentration of DOC and the ultraviolet (UV) light absorbance test media at 350 nm (A 350). Observations showed that the composition of DOC clearly affected the ecotoxicity of CIP. When around 11 mg L -1 different DOC compounds were present, the 50% effect concentration of CIP (EC50) varied by 10-fold, between 1.4 μg L -1 and 15.2 μg L -1 . Thus, DOC concentration alone is not sufficient to predict CIP bioavailability. Rather, the A 350 of the test media demonstrated a significant positive correlation with the observed EC50, while the absorption coefficient (ε350) correlated significantly with the K ,d,CIP+/- . Our findings suggest that the light absorbance of natural water might be a better predictor for the impact of both processed and unprocessed DOC on CIP bioavailability.}},
  articleno    = {{P-We163}},
  author       = {{Zhang, Qiyun and Demeestere, Kristof and De Schamphelaere, Karel}},
  booktitle    = {{SETAC Europe, 33rd Annual Meeting, Abstracts}},
  issn         = {{2309-8031}},
  language     = {{eng}},
  location     = {{Dublin, Ireland & online}},
  pages        = {{P-We163:414--P-We163:414}},
  title        = {{UV-light absorbance of natural water regulates the bioavailability of ciprofloxacin to cyanobacteria}},
  year         = {{2023}},
}