Journal
ENVIRONMENTAL POLLUTION
Volume 220, Issue -, Pages 105-111Publisher
ELSEVIER SCI LTD
DOI: 10.1016/j.envpol.2016.09.028
Keywords
Coupling; High-resolution mass spectrometry; Humic acid; Laccase; Metal cations; Triclosan
Categories
Funding
- Special Fund for Agro-scientific Research in Public Interest, China [201503107]
- Natural Science Foundation of Jiangsu Province of China [BK20130030]
- Research project of environmental protection in Jiangsu Province, China [2015023]
- CSC scholarship
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Triclosan (TCS) is a broad-spectrum antimicrobial agent that is found extensively in natural aquatic environments. Enzyme-catalyzed oxidative coupling reactions (ECOCRs) can be used to remove TCS in aqueous solution, but there is limited information available to indicate how metal cations (MCs) and natural organic matter (NOM) influence the environmental fate of TCS during laccase-mediated ECOCRs. In this study, we demonstrated that the naturally occurring laccase from Pleurotus ostreatus was effective in removing TCS during ECOCRs, and the oligomerization of TCS was identified as the dominant reaction pathway by high-resolution mass spectrometry (HRMS). The growth inhibition studies of green algae (Chlamydomonas reinhardtii and Scenedesmus obliquus) proved that laccase-mediated ECOCRs could effectively reduce the toxicity of TCS. The presence of dissolved MCs (Mn2+, Al3+, Ca2+, Cu2+, and Fe2+ ions) influenced the removal and transformation of TCS via different mechanisms. Additionally, the transformation of TCS in systems with NOM derived from humic acid (HA) was hindered, and the apparent pseudo first-order kinetics rate constants (k) for TCS decreased as the HA concentration increased, which likely corresponded to the combined effect of both noncovalent (sorption) and covalent binding between TCS and humic molecules. Our results provide a novel insight into the fate and transformation of TCS by laccase-mediated ECOCRs in natural aquatic environments in the presence of MCs and NOM. (C) 2016 Elsevier Ltd. All rights reserved.
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