Abstract:

In this project, Macondo surrogate and heavy crude oil (bitumen) underwent biodegradation in a microcosm for 0-15 days. Both fractionated to yield structurally defined fractions: saturates, 1-ring, 2-ring, 3-ring, 4-ring, and 5+ring aromatics. The fractions with acceptable yields underwent biodegradation as well, to determine each structural class's contribution to the transformation products. Products were analyzed for DOC (dissolved organic carbon), and by Fourier-transform ion cyclotron resonance mass spectrometer (FT-ICR MS) for molecular-level changes. This dataset supports the publication: Niles, S. F., Chacón-Patiño, M. L., Chen, H., McKenna, A. M., Blakney, G. T., Rodgers, R. P., & Marshall, A. G. (2019). Molecular-Level Characterization of Oil-Soluble Ketone/Aldehyde Photo-Oxidation Products by Fourier Transform Ion Cyclotron Resonance Mass Spectrometry Reveals Similarity Between Microcosm and Field Samples. Environmental Science & Technology, 53(12), 6887–6894. doi:10.1021/acs.est.9b00908

Suggested Citation:

Huan Chen, Amy M. McKenna, Ryan P. Rodgers. 2019. Microcosm study: Laboratory measurements of biodegradation. Distributed by: Gulf of Mexico Research Initiative Information and Data Cooperative (GRIIDC), Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/n7-3d8b-0860

Publications:

Niles, S. F., Chacón-Patiño, M. L., Chen, H., McKenna, A. M., Blakney, G. T., Rodgers, R. P., & Marshall, A. G. (2019). Molecular-Level Characterization of Oil-Soluble Ketone/Aldehyde Photo-Oxidation Products by Fourier Transform Ion Cyclotron Resonance Mass Spectrometry Reveals Similarity Between Microcosm and Field Samples. Environmental Science & Technology, 53(12), 6887–6894. doi:10.1021/acs.est.9b00908

Purpose:

To reveal Ox products generated by biodegradation (laboratory-based) and analyzed by Fourier-transform ion cyclotron resonance mass spectrometer (FT-ICR MS).

Data Parameters and Units:

The dataset contains biodegradation time, type of oil, and transformation products targeted. The main parameters are as follows: Number of Peaks = Number of Peaks on Full Spectrum with signal magnitude greater than six times the baseline root-mean-square noise % R. A. = Percent Relative Abundance DBE = double bond equivalents - number of aromatic rings plus double bonds to carbon % R. A.(No Hits Discarded) = Percent Relative Abundance with Non-Classified Peaks Removed A. M. W. average = Relative abundance weighted average molecular weight A.W. average C# = relative abundance weighted average carbon number A.W. average DBE = average number of double bond equivalents A.W. average H/C = relative abundance weighted average hydrogen-to-carbon ratio A.W. average O/C = relative abundance weighted average oxygen-to-carbon ratio A.W. average N/C = relative abundance weighted average nitrogen-to-carbon ratio Sum R. A. = Sum of Relative Abundance for all mass spectral peaks RMS Error = Root Mean Square Error PosESI = Positive Electrospray Ionization NegESI = Negative ion electrospray ionization APPI = atmospheric pressure photoionization

Methods:

The initial concentration of crude: 385 µL of oil in 50 mL artificial seawater. Microcosm examines the biodegradation process was established by dispensing 385 µL of the Macondo crude oil (MC252, NIST 2779) in 50 mL autoclave-sterilized 70% artificial seawater (ASW) (Instant Ocean Aquarium Systems, Inc., Mentor, OH, USA). The amount of oil generated 120µm oil films. The experiments were replicated in triplicate. The experiment is using bacterial pulication captured on 0.2 μm membrane filters from live seawater from the Gulf of Mexico (Lat. N 29° 54' 49.6''; Long. W 84° 30' 41.7''; Temperature 23.1°C; Salinity 30.8 ppt; pH; Dissolved oxygen 5..21 mg L-1). Control microcosms consist of sterile ASW and oil and are bacteria free. Test and control microcosm flasks were wrapped with foils to prevent photooxidation, incubated (Thermo Scientific MaxQ 4000 orbital shaker) and shaken (110 rpm) at 23 °C. At each time point (t=0, t=10, t=20, t=30), water layer of the microcosms was transferred to a sterile container with a sterile glass pipette. Water fractions were then filtered through 0.2 µm membrane filters to remove the microbial population. 20 mL of the samples were acidified to pH 2 with HCl and the water-soluble organics were extracted by the solid-phase extraction described by Dittmar et al., (2008). Acidified samples were loaded on to a Bond Elute PPL (Agilent Technologies) stationary phase cartridge. Each sample was then desalted with pH 2 water and eluted with methanol at a final concentration of 100 ug mL-1 prior to Fourier-transform ion cyclotron resonance mass spectrometer (FT-ICR MS) analysis. Extraction blank and solvent blank were included.

Instruments:

The FT-ICR mass spectrometer is custom-built with a 9.4 tesla superconducting magnet.

Provenance and Historical References:

Dittmar, Thorsten, Koch, Boris, Hertkorn, Norbert, Kattner, Gerhard, ( 2008), A simple and efficient method for the solid‐phase extraction of dissolved organic matter (SPE‐DOM) from seawater, Limnol. Oceanogr. Methods, 6, doi:10.4319/lom.2008.6.230.

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