Abstract:
In this project, seawater obtained from Galveston Bay, containing plankton but filtered to exclude zooplankton and debris, was mixed with either water accommodated fraction (WAF) or chemically enhanced WAF (CEWAF) in mesocosm tanks. A control experiment containing neither WAF nor CEWAF was also conducted. After fixed periods of incubation tanks were destructively sampled for marine snow. Marine oil snow samples were subjected to solid-state 13C nuclear magnetic resonance (NMR) spectroscopic analysis. The data contained in this dataset represents the raw chemical shift and intensity data directly from the instrument and the processed peak relative abundance used for analysis. Other related Fourier transform ion cyclotron mass spectrometry (FTICR-MS) data is available under GRIIDC Unique Dataset Identifiers (UDIs) R4.x263.000:0051.
Suggested Citation:
Waggoner, Derek; Hatcher, Patrick. 2019. Molecular level characterization of oil and aggregate oxidation products: Mesocosm LTMOSE, a Long Term Marine Oil Snow Experiment, Nuclear magnetic resonance (NMR) data. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/n7-h48m-xk08
Data Parameters and Units:
The dataset consists of the seven excel files. The excel files “M5 Control Day 4 NMR”, “M5 Control Day 16 NMR”, “M5 DCEWAF BF Day 16 NMR”, “M5 DCEWAF Day 4 NMR”, “M5 WAF Day 4 NMR”, and “M5 WAF Day 16 NMR” contains spectra obtained from marine snow extracted from different mesocosm at different times of the experiment. All files include raw chemical shift and intensity data; Chemical shift = parts per million; Spectral Intensity = the spectral response (arbitrary units) at the given chemical shift. The excel file “M5 NMR peak areas” provides chemical shifts in parts per million (ppm) that correspond to the integrated areas.
All files are named as follows: M5 (part of the 5th mesocosm experiment conducted); the treatment used: Control, water accommodated fraction (WAF) or diluted chemically enhanced WAF (DCEWAF); Day ‘x’ (Time from the start of the experiment to when the sample was collected). BF = biofilm collected and analyzed separately.
Methods:
To make WAF, 25 mL of Macondo surrogate oil was poured into 6 baffled recirculating tanks containing 130L seawater and mixed aggressively for 4 hours to create a “high energy” WAF (Knap et al. 1983). The WAF was then introduced into the WAF mesocosm tanks, filled to 104L, and mixed. From these tanks, 3.5 L WAF was removed for hydrocarbon analyses.
Corexit was mixed with oil in a ratio of 1:20 to make diluted chemically enhanced water accommodated fraction (DCEWAF). Then 25 mL of this mixture (5 ml every 5 min for 25 min) of surrogate oil plus Corexit was added to a baffled recirculating tank containing ~130 L of seawater which was not vigorously mixed for 4 hrs prior to being loaded into the mesocosm tanks. From these CEWAF tanks, 5L was removed for other analyses (3.5 L hydrocarbon analyses). DCEWAF was prepared by mixing 10.4 L of CEWAF with 93.6 L of the original seawater for a total volume of 104 L. This concentrated plankton mass was introduced to each of the tanks (1.5 L to each tank which contained 104L of treated seawater, total volume of seawater 105.5L per tank) immediately prior to starting the experiments. Banks of lights were placed behind each of the glass mesocosm tanks and a 12:12 light/dark cycle employed. The first three control and WAF mesocosms were sampled day 1 and sacrificed day 4 for a quantitative marine snow collection. The second set of triplicate Control and WAF mesocosms were sampled day 8 and scarified day 16 for a quantitative marine snow collection. Days 1 and 8 only surrounding seawater samples were collected through a 5 cm diameter Teflon faucet, positioned 10 cm from the bottom of each mesocosm. Days 4 and 16 the whole tank was sacrificed after collection of surrounding seawater, to quantitatively sample all sunken marine snow.
From these DCEWAF tanks, 5L was removed for other analyses (4 L hydrocarbon analyses). The estimated oil equivalents (EOE) were determined using Macondo surrogate oil as the calibration standard (Wade et al. 2011) for the fluorescence analyses (Horiba Scientific Aqualog Fluorometer). The EOE mean concentration of the six treatments for the control, WAF and DCEWAF at the start of the experiments were below detection (0.05), 2.15, and 2.62 mg/L, respectively very close to the target concentrations. Marine snow extraction protocol: Gulf of Mexico seawater was used for the mesocosm experiment, LTMOSE, a Long Term Marine Oil Snow Experiment, and aliquots of the same treatments were used to fill 6L glass roller tanks which ran in parallel. On days 4 and 16, when mesocosm and roller tanks were sacrificed for sampling, see mesocosm method, the marine snow that had sedimented to the tank bottoms was sampled. After carefully removing the top portion of water, the last 20 L of each tank was collected. Sample aliquots were gently filtered onto combusted, pre-weighed, GFF (glass fiber) filters of 1 L from each of the mesocosm tanks and 30 mL from each roller table tank. These were frozen to preserve them for analyses at the Hatcher Lab, where the organic material was extracted with DCM (dichloromethane).
Provenance and Historical References:
Knap, A. H., Sleeter, T. D., Dodge, R. E., Wyers, S. C., Frith, H. R., & Smith, S. R. (1983). The effects of oil spills and dispersant use on corals. Oil and Petrochemical Pollution, 1(3), 157–169. doi:10.1016/s0143-7127(83)90134-5
Wade, T.L., Sweet, S.T., Sericano, J.L., Guinasso, N.L., Diercks, A.R., Highsmith, R.C., Asper, V.L., Joung, D., Shiller, A.M., Lohrenz, S.E. and Joye, S.B. (2011). Analyses of Water Samples From the Deepwater Horizon Oil Spill: Documentation of the Subsurface Plume. Geophysical Monograph Series, 77–82. doi:10.1029/2011gm001103
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