Molecular-Level Composition and Acute Toxicity of Photosolubilized Petrogenic Carbon

To examine the molecular-level composition and acute toxicity per unit carbon of the petroleum-derived dissolved organic matter (DOMHC) produced via photo-oxidation, heavy and light oils were irradiated over seawater with simulated sunlight. Increases in dissolved organic carbon concentrations as a...

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Bibliographic Details
Published in:Environmental science & technology 2019-07, Vol.53 (14), p.8235-8243
Main Authors: Zito, Phoebe, Podgorski, David C, Johnson, Joshua, Chen, Huan, Rodgers, Ryan P, Guillemette, François, Kellerman, Anne M, Spencer, Robert G. M, Tarr, Matthew A
Format: Article
Language:English
Subjects:
Acute toxicity
Aliphatic compounds
Aromatic compounds
Carbon
Chemical analysis
Composition
Dissolved organic carbon
Dissolved organic matter
Factor analysis
Fluorescence
Inhibition
Mass spectrometry
Mass spectroscopy
Microtox
Oil
Organic Chemicals
Oxidation
Oxygen compounds
Petroleum
Photooxidation
Seawater
Toxicity
Water analysis
Water Pollutants, Chemical
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Summary:To examine the molecular-level composition and acute toxicity per unit carbon of the petroleum-derived dissolved organic matter (DOMHC) produced via photo-oxidation, heavy and light oils were irradiated over seawater with simulated sunlight. Increases in dissolved organic carbon concentrations as a function of time were associated with changes in the DOMHC composition and acute toxicity per unit carbon. Parallel factor analysis showed that the fluorescent dissolved organic matter (FDOM) composition produced from the heavy oil became more blue-shifted over time, while the light oil produced a mixture of blue- and red-shifted components similar to FDOM signatures. Ultrahigh-resolution mass spectrometry reveals that the composition of the DOMHC produced from both heavy and light oils was initially relatively reduced, with low O/C. With time, the composition of the DOMHC produced from the heavy oil shifted to unsaturated, high-oxygen compounds, while that produced from the light oil comprised a range of high O/C aliphatic, unsaturated, and aromatic compounds. Microtox assays suggest that the DOMHC initially produced is the most toxic (62% inhibition); however, after 24 h, a rapid decrease in toxicity decreased linearly to 0% inhibition for the heavy DOMHC and 12% inhibition for the light DOMHC at extended exposure periods.
ISSN:0013-936X
1520-5851
DOI:10.1021/acs.est.9b01894