Abstract:

Mesocosm experiments were performed as part of the ADDOMEx GOMRI funded program with seawater collected from the NGOM and “seeded” with microbial populations collected from coastal Texas (in Galveston Bay) in August of 2015. At the end of these experiments, exopolymeric substances (EPS) were isolated from water sampled from particles that sank to the bottom of each tank throughout the course of the experiment. The operationally-defined EPS were freeze-dried, and the freeze-dried solid material was subjected to solid-state 13C NMR spectroscopic analysis before and after dichloromethane extraction. The data contained in this dataset represents the raw chemical shift and intensity data obtained directly from the instrument.

Suggested Citation:

Pat Hatcher and Andrew Wozniak. 2017. Response of oil-degrading microbes to dispersants in a ternary system (oil-dispersant-EPS): TeCOAST, a mesocosm Test of COASTal water with microbial concentrate, Solid-state 13C NMR data for EPS. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/N7862DHD

Publications:

Hatcher, P. G., Obeid, W., Wozniak, A. S., Xu, C., Zhang, S., Santschi, P. H., & Quigg, A. (2018). Identifying oil/marine snow associations in mesocosm simulations of the Deepwater Horizon oil spill event using solid-state 13 C NMR spectroscopy. Marine Pollution Bulletin, 126, 159–165. doi:10.1016/j.marpolbul.2017.11.004

Purpose:

To investigate molecular level differences in natural EPS, EPS impacted by oil, and EPS impacted by oil and dispersant mixtures.

Data Parameters and Units:

The file names describe the sample as (either CEWAF, DCEWAF, WAF, or control) bottom particles before and after dichloromethane (DCM) extraction. Spectral Intensity = the spectral response (arbitrary units) at the given chemical shift Chemical Shift = parts per million

Methods:

The seawater used in the TeCOAST Mesocsom studies was collected on July 30, 2015 from 8 kilometers off shore south of Galveston (TX) in the Gulf of Mexico. The salinity was 34. The seawater was processed through a charcoal filter to remove large particles and debris. Four mesocosm tanks were treated in the following way. The control tank was filled with the seawater directly from the storage tank of filtered seawater. This seawater was also used to fill 130 L recirculating glass flumes (Knap et al. 1986; Knap et al. 2016 in preparation) to make water accommodated fraction (WAF) and a chemically enhanced water accommodated fraction of oil (CEWAF). The WAF was prepared by mixing a total of 24 mL (2 ml to start, 2 ml after 1 hr, then 5 ml at ~ 2, 3, 4 and 5 hrs total of 24 ml) of Macondo surrogate Marlin oil into 130 L of the seawater. Total mixing time from the start of oil addition to transfer to the mesocosms was 18 hrs. The WAF (79 L) was transferred to the WAF mesocosm tank and mixed. In order to make CEWAF, Corexit 9500 was mixed with Macando Surrogate oil in a ratio of 1:20 (Corexit to oil) and 24 mL of this mixture (2 ml to start, 2 ml after 1 hr, then 5 ml at ~ 2, 3, 4 and 5 hrs total of 24 ml) of surrogate oil plus Corexit was added to 130 L of seawater and mixed for 18 hrs. The CEWAF (79 L) was transferred to the WAF mesocosm tank and mixed. In addition a dilute CEWAF (DCEWAF) mesocosum treatment was produced by adding 9 L of CEWAF to 70 L of the original seawater for a total volume of 79 L. Light dark bottles were also filled from the WAF and CEWAF. Plankton (≥63 µm) samples were collected using a net and transferred into polycarbonate bottles. This concentrated plankton mass was introduced to each mesocsom and stirred (2 L to each tank for a final volume 81 L) immediately prior to starting the experiments. No plankton was added to the light or dark bottles. The EOE concentration for the control, WAF, DCEWAF and CEWAF at the start of the experiments were estimated as 0 mg/L, 3.4 mg/L, 3.6 mg/L and 36 mg/L, respectively. The EOE concentration of the control, WAF, DCEWAF and CEWAF mesocosms averaged for samples taken during the first 74 hours were 0 mg/L , 1.21 mg/L, 4.28 and 43.4 mg/L, respectively. All mesocosms had loses of EOE from 88 to 100%, while the bottles had losses of 56 to 74%. Estimated Oil Equivalence (EOE) The estimated oil equivalents (EOE) were determined by fluorescence (Wade et al. 2011) using Macondo surrogate oil as a standard to produce calibration curves at 5 to 7 concentrations. Water samples (5 to 20 ml) were extracted with 5 ml of dichloromethane. An aliquot of the extract was placed in a cuvette for fluorescence analyses (Horiba Scientific Aqualog Fluorometer). The EOE were determined from the calibration curve (Wade et al. 2011). Samples with florescence responses that exceeded the calibration curve were diluted so that their florescence was within the calibration range. Samples were taken at the beginning and end of the experiment and at intervals in between and at the same time point as measurements of other parameters during the experiment. EOE data can be found in corresponding GRIIDC dataset UDI: R4.x263.000:0018.

Individual Files: