Data Parameters and Units:
All text files include raw mass lists of m/z values (m = mass; z = charge of the ion) and their peak intensities (arbitrary units).
All excel files includes processed data with chemical molecular formulas, including m/z = the measured mass to charge ratio of the identified peak (m= mass; z= charge of the ion); PeakHeight = the spectral intensity of the identified peak (in arbitrary units); Type = elemental formula type, CHO= formula containing carbon, hydrogen, and oxygen; CHON = formula containing carbon, hydrogen, oxygen, and nitrogen; CHOS = formula containing carbon, hydrogen, oxygen, and sulfur; CHONS = formula containing carbon, hydrogen, oxygen, nitrogen, and sulfur; CHOP = formula containing carbon, hydrogen, oxygen, and phosphorus; CHOSP = formula containing carbon, hydrogen, oxygen, sulfur, and phosphorus; CHONP = formula containing carbon, hydrogen, oxygen, nitrogen, and phosphorus; C = carbon abundance; H-1 = proton abundance; H = hydrogen abundance; N = nitrogen abundance; O = oxygen abundance; S = sulfur abundance; P = phosphorus abundance; exact mass = molecular weight.
The files are labelled according to the different experimental treatments: control and diluted chemically enhanced water accommodated fraction of oil (DCEWAF). Data file naming convention includes the mesocosm experiment number (M7), treatment (control, DCEWAF), time since the start (in days). For example, “M7_DCEWAF_Day1.csv” is the FTICR-MS for diluted chemically enhanced water accommodated fraction of oil at time Day 1 from May 2019 Mesocosm 7 experiment.
Methods:
Marine snow from control samples and marine oil snow (MOS) from DCEWAF samples were extracted with dichloromethane (DCM) solvent. DCM extracts were diluted with methanol (MeOH) to a final ratio of MeOH: DCM as 2:1 (v/v), and analyzed by Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) coupled with negative ion mode electrospray ionization (ESI), using an Apollo II ESI source coupled to a Bruker Daltonics 12 T Apex Qe FTICR-MS housed at the Old Dominion University COSMIC facility. Samples were infused into the instrument by a syringe pump at 2 uL/min. Ions accumulated in the hexopole for 3.0 s before being transferred to the ICR cell. Analysis of 300 transients was coadded. Mass-to-charge data for peaks with signal-to-noise ratios greater than 4 were used to assign molecular formulas to peaks in each sample using an in-house Matlab (The MathWorks Inc., Natick, MA) program following the formula assignment rules established previously (References 1 & 2).
The seawater used in the Test of Coastal water with coastal microbial concentrate (TeCOAST) mesocosm studies was collected ~0.5 km offshore south of Galveston (Texas) on May 7, 2019, from the Gulf of Mexico. Water was settled in large tanks to remove large particles and debris before collection. A plankton concentrate was collected nearby in Galveston Bay using a mesh size of 63 µm plankton net; 2 L of this “concentrate” was added to all mesocosm treatments, immediately prior to the start of the experiment to make a final volume of 102 L per mesocosm. The control tank was filled with the seawater directly from the storage tank of filtered seawater plus the added plankton concentrate. This seawater was also used to fill recirculating glass flumes (References 2, 3, & 4) to make water accommodated fraction (WAF) and a chemically enhanced water accommodated fraction of oil (CEWAF). A PTFE stopcock 10 cm off the bottom of the tank was used for sampling. The oil used was Macondo “surrogate” oil from the Marlin Platform Dorado and the dispersant used was Corexit. The WAF mixture was prepared by mixing 25 mL oil with ~130 L seawater in a stirring baffled recirculating borosilicate glass tanks of 170 L capacity (43 × 88 × 44 cm) and allowed to equilibrate over 24 hours. After that, only the aqueous phase at the bottom layer (no surface slick: the WAF fraction) was removed and added to the mesocosm tanks. CEWAF was made by adding dispersant to the oil at a ratio of oil‐to‐dispersant of 20:1. The DCEWAF was prepared by diluting the CEWAF with seawater.
Provenance and Historical References:
[1] Stubbins, A., Spencer, R. G. M., Chen, H., Hatcher, P. G., Mopper, K., Hernes, P. J., Mwamba, V. L., Mangangu, A. M., Wabakanghanzi, J. N. & Six, J. (2010). Illuminated darkness: Molecular signatures of Congo River dissolved organic matter and its photochemical alteration as revealed by ultrahigh precision mass spectrometry. Limnology and Oceanography, 55(4), 1467–1477. doi:10.4319/lo.2010.55.4.1467
[2] Wozniak, A. S., Prem, P. M., Obeid, W., Waggoner, D. C., Quigg, A., Xu, C., Santschi, P.H., Schwehr, K.A. & Hatcher, P. G. (2019). Rapid Degradation of Oil in Mesocosm Simulations of Marine Oil Snow Events. Environmental Science & Technology, 53(7), 3441–3450. doi:10.1021/acs.est.8b06532
[3] Knap, A. H., Burns, K. A., Dawson, R., Ehrhardt, M., & Palmork, K. H. (1986). Dissolved/dispersed hydrocarbons, tarballs and the surface microlayer: Experiences from an IOC/UNEP Workshop in Bermuda, December 1984. Marine Pollution Bulletin, 17(7), 313–319. doi:10.1016/0025-326x(86)90217-1
[4] Wade, T. L., Morales-McDevitt, M., Bera, G., Shi, D., Sweet, S., Wang, B., Gold-Bouchot, G., Quigg., A. & Knap, A. H. (2017). A method for the production of large volumes of WAF and CEWAF for dosing mesocosms to understand marine oil snow formation. Heliyon, 3(10), e00419. doi:10.1016/j.heliyon.2017.e00419
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