Changes in ecotoxicity of naphthalene and alkylated naphthalenes during photodegradation in water

• Published in: Chemosphere (Oxford) Vol. 222; pp. 656 - 664
• Main Authors: Kang, Hyun-Joong, Jung, Yerin, Kwon, Jung-Hwan
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01-05-2019
• Subjects: Aliivibrio fischeri; Alkylated naphthalenes; Alkylation; Ecotoxicology - methods; Gas Chromatography-Mass Spectrometry; Luminescent Measurements; Mixture toxicity; Naphthalenes - toxicity; Oil spill; Petroleum Pollution - analysis; Petroleum Pollution - prevention & control; Photodegradation; Photodegradation products; Photolysis; Polycyclic Aromatic Hydrocarbons - toxicity; Water Pollutants, Chemical - radiation effects; Photodegradation; Oil spill; Mixture toxicity; Alkylated naphthalenes; Photodegradation products
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2019.01.153

Crude oil released into the environment contains many polycyclic aromatic hydrocarbons (PAHs). Alkylated PAHs are more abundant than unsubstituted PAHs and their toxicity is also of serious concern. Among the various physical, chemical, and biological weathering processes of crude oils, photodegradation is one of the most important for determining the environmental fate of oil residues. In this study, the photodegradation rate constants of naphthalene and alkylated naphthalenes were determined under simulated laboratory conditions at different temperature. Changes in the luminescence inhibition of Aliivibrio fischeri, as an indicator of the baseline toxicity, were observed in photodegradation mixtures. The major transformation products were also identified by gas chromatography–mass spectrometry. The photodegradation of naphthalene and the eight alkylated naphthalenes was described well by pseudo-first-order kinetics regardless of experimental temperature. The measured toxicity of the reaction mixtures obtained by photodegradative weathering slightly increased initially and then decreased with further weathering. In all cases, the observed toxicity was greater than accounted for by the parent compounds, indicating that the photodegradation products also contributed significantly to the overall toxicity of the mixtures. The identified photodegradation products were mostly oxygenated compounds such as alcohols, aldehydes, ketones, and quinones, which warrant further investigation.
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•Toxicity changes of Naph and alkyl-Naph by photodegradation were studied.•The observed photodegradation was well-explained by pseudo-first-order kinetics.•The observed toxicity of Naph and alkyl-Naph was decreased by photodegradation.•The toxic contribution by photodegradation products was significant.•The identified photodegradation products were mainly oxygenated forms.