Hydrocarbons to carboxyl-rich alicyclic molecules: A continuum model to describe biodegradation of petroleum-derived dissolved organic matter in contaminated groundwater plumes

David C Podgorski; Phoebe Zito; Anne M Kellerman; Barbara A Bekins; Isabelle M Cozzarelli; Donald F Smith; Xiaoyan Cao; Klaus Schmidt-Rohr; Sasha Wagner; Aron Stubbins; Robert G M Spencer

doi:10.1016/j.jhazmat.2020.123998

Hydrocarbons to carboxyl-rich alicyclic molecules: A continuum model to describe biodegradation of petroleum-derived dissolved organic matter in contaminated groundwater plumes

J Hazard Mater. 2021 Jan 15:402:123998. doi: 10.1016/j.jhazmat.2020.123998. Epub 2020 Sep 19.

Authors

Affiliations

¹ Pontchartrain Institute for Environmental Sciences, Department of Chemistry, Chemical Analysis & Mass Spectrometry Facility, University of New Orleans, New Orleans, LA 70148, USA. Electronic address: dcpodgor@uno.edu.
² Pontchartrain Institute for Environmental Sciences, Department of Chemistry, Chemical Analysis & Mass Spectrometry Facility, University of New Orleans, New Orleans, LA 70148, USA.
³ Department of Earth, Ocean and Atmospheric Science, Florida State University, Tallahassee, FL, USA; National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310, USA.
⁴ US Geological Survey, Menlo Park, CA 94025, USA. Electronic address: babekins@usgs.gov.
⁵ US Geological Survey, Reston, VA 20192, USA.
⁶ National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310, USA.
⁷ Department of Chemistry, Brandeis University, Waltham, MA 02453, USA.
⁸ Department of Earth and Environmental Sciences, Rensselaer Polytechnic Institute, Troy, NY 12180, USA; Department of Chemistry and Chemical Biology, Department of Marine and Environmental Sciences, Department of Civil and Environmental Engineering, Northeastern University, Boston, MA 02115, USA.
⁹ Department of Chemistry and Chemical Biology, Department of Marine and Environmental Sciences, Department of Civil and Environmental Engineering, Northeastern University, Boston, MA 02115, USA.

PMID: 33254831
DOI: 10.1016/j.jhazmat.2020.123998

Abstract

Relationships between dissolved organic matter (DOM) reactivity and chemical composition in a groundwater plume containing petroleum-derived DOM (DOM_HC) were examined by quantitative and qualitative measurements to determine the source and chemical composition of the compounds that persist downgradient. Samples were collected from a transect down the core of the plume in the direction of groundwater flow. An exponential decrease in dissolved organic carbon concentration resulting from biodegradation along the transect correlated with a continuous shift in fluorescent DOM_HC from shorter to longer wavelengths. Moreover, ultrahigh resolution mass spectrometry showed a shift from low molecular weight (MW) aliphatic, reduced compounds to high MW, unsaturated (alicyclic/aromatic), high oxygen compounds that are consistent with carboxyl-rich alicyclic molecules. The degree of condensed aromaticity increased downgradient, indicating that compounds with larger, conjugated aromatic core structures were less susceptible to biodegradation. Nuclear magnetic resonance spectroscopy showed a decrease in alkyl (particularly methyl) and an increase in aromatic/olefinic structural motifs. Collectively, data obtained from the combination of these complementary analytical techniques indicated that changes in the DOM_HC composition of a groundwater plume are gradual, as relatively low molecular weight (MW), reduced, aliphatic compounds from the oil source were selectively degraded and high MW, alicyclic/aromatic, oxidized compounds persisted.

Keywords: Hydrocarbon oxidation products; OPAH; Oxyhydrocarbon; Polar hydrocarbon metabolites.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Biodegradation, Environmental
Groundwater*
Hydrocarbons
Petroleum*
Water Pollutants, Chemical* / analysis

Substances

Hydrocarbons
Petroleum
Water Pollutants, Chemical