Abstract:

This dataset contains the results of three intercalibration experiments using three different spectrofluorometers (Horiba Aqualog-UV-800, Turner Trilogy, and Shimadzu Spectrofluorometer RF-1501) to measure the concentration of oil in blind samples of Water Accommodated Fraction (WAFs) and Chemical Enhanced WAF (CEWAFs). The first experiment was designed to analyze a set of WAF samples from mesocosms (Wade et al. 2017) using the three different fluorometers. Water samples were measured directly (i.e., no extraction process was involved). The second set of measurements were done on the same source water samples but this time, samples were extracted with dichloromethane. The fluorescence emissions from the three instruments were recorded and compared. The second experiment consisted of the intercalibration between the Aqualog Horiba and Turner Trilogy spectrofluorometers. For this, WAF and CEWAF samples were made in deionized water (DI) as well as in natural seawater collected from the Gulf of Mexico immediately prior to starting experiments. The chemical response to oil spills: Ecological Research Forum (CROSERF) method was used to make the WAF and CEWAF (Singer et al., 2000). The third experiment consisted of the Intercalibration between Aqualog Horiba and Shimadzu spectrofluorometers. WAF and CEWAF samples from ADDOMEx 6 mesocosms study were used. WAF and CEWAF were made following Wade et al., (2017) method.

Suggested Citation:

Gopal Bera, Gerardo Gold-Bouchot, Terry L. Wade, Dawei Shi, Maya Morales-McDevitt, Noemi Ramirez-Miss, Anthony H. Knap, Antonietta Quigg. 2018. Intercalibration of the Estimated Oil Equivalence (EOE) of WAFs and CEWAFs using 3 different spectrofluorometers. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/N71G0JX8

Publications:

Bera, G., Gold-Bouchot, G., Passow, U., Wade, T. L., Shi, D., Morales-McDevitt, M., … Quigg, A. (2019). Inter-laboratory calibration of estimated oil equivalent (EOE) concentrations of a water accommodated fraction (WAF) of oil and a chemically enhanced WAF (CEWAF). Heliyon, 5(1), e01174. doi:10.1016/j.heliyon.2019.e01174

Shi, D., Bera, G., Knap, A. H., Quigg, A., Al Atwah, I., Gold-Bouchot, G., & Wade, T. L. (2020). A mesocosm experiment to determine half-lives of individual hydrocarbons in simulated oil spill scenarios with and without the dispersant, Corexit. Marine Pollution Bulletin, 151, 110804. doi:10.1016/j.marpolbul.2019.110804

Purpose:

Develop an easy method for direct measurement of WAF concentrations using instrumentation common to most laboratories.

Data Parameters and Units:

Concentration of EOE (mg/L), Concentration of EOE (microg/L), Emission (emission fluorescence units), Sample id, Spectrofluorometer

Methods:

The first experiment was designed to analyze a set of WAF samples from mesocosms (Wade et al. 2017) using three different fluorometers (Horiba Aqualog-UV-800, Turner Trilogy, Shimadzu Spectrofluorophotometer RF-1501). Water samples were measured directly i.e. no extraction process was involved. The second set of measurements were done on the same source water samples but this time, samples were extracted with dichloromethane. The fluorescence emissions from the three instruments were recorded and compared. For all of the experiments, a calibration curve was prepared with Macondo Surrogate Oil (MC 252) and this was used to quantify the EOE concentrations. Calibration points range from 0.1 mg/L to 10 mg/L of oil. Several blind WAF and CEWAF samples were measured and quantified using the calibration curve (run in each instrument). Results were compared among three instruments. When experiments were prepared for Horiba Aqualog and Turner Trilogy, WAF and CEWAF samples were made in deionized water (DI) as well as in natural seawater collected from the Gulf of Mexico immediately prior to starting experiments. To investigate whether the fluorescence intensity of hydrocarbons was impacted by dispersant, an experiment with 1 ppm solution of the single aromatic hydrocarbon, phenanthrene in both DI and natural seawater was carried out. In addition, 30 µL of Corexit was added to both solutions and measured on the Horiba Aqualog spectrofluorometer. EOE Measurement by Horiba Aqualog: The measurement of EOE on the Horiba Aqualog was carried out in two stages. First using a mid-range calibration standard (either 2 or 5 mg/L), total scanning fluorescence (TSF) and the optimal wavelengths for maximum intensity were determined at Excitation at 260 nm and Emission at 372 nm) (Bera et al., 2018; Knap et al., 2017, Wade et al., 2011; Wade et al., 2017). Second, the calibration standards were run at these determined wavelengths and emissions recorded to create a calibration curve. Samples were measured in a similar manner as the calibration standards and were quantified using the calibration curve. EOE Measurement by Turner Trilogy: Oil concentration was determined as EOE following extraction of seawater samples in dichloromethane (Wade et al. 2011) using a Trilogy fluorometer with the crude oil module 7200-63, which measures at an excitation wavelength of 365 nm and emission wavelengths of 410-600 nm. At these wavelength chlorophyll a, accessory pigments, and colored dissolved organic matter may generate artificially elevated values. By subtracting the “EOE” of the control, measured EOE were corrected for such interferences. Replicate EOE measurements were at times highly variable, reflecting the uneven distribution of dispersed oil droplets as described in (Wade et al. 2017). EOE Measurement by Shimadzu Spectrofluorophotometer RF-1501: EOE was measured using 5 mL control or treated (WAF, CEWAF) seawater diluted with 5, 10 or 15 mL dichloromethane to extract the oil. Approximately 4 mL of the dichloromethane fraction of each sample was transferred into a cuvette for EOE analysis in a Shimadzu Spectrofluorophotometer RF-1501. EOE was measured at the optimum excitation and emission wavelengths for EOE determinations of 260 and 358 nm respectively, as in Wade et al. (2011). WAF and CEWAF for the first experiment (without DCM extraction and with DCM extraction) were made following Wade et al., 2017 (Heliyon). In summary, 130L of seawater was added in a baffled recirculating tank followed by addition of 25 g of Macondo oil. In case of a CEWAF, 1:20 ratio of oil and Corexit was used. Mixing was done using a Masterflex pump and a magnetic stirrer for 24 hours. WAF and CEWAF for intercalibration experiment between Aqualog Horiba and Shimadzu were made using the similar procedure. WAF and CEWAF (including WAF1, 2 and 3) for intercalibration between Aqualog Horiba and Turner Trilogy were produced following CROSERF method (Singer et al., 2000). In summary, 100-400 mg of Macondo oil was added to 2L of seawater of DI in an aspirator bottle. Mixing was allowed for 24 hours at 300 rpm. WAF/ CEWAF were collected from a sample outlet at the bottom of the aspirator bottle.

Instruments:

Spectrofluorometers compared: Horiba Aqualog, Turner Trilogy, Shimadzu Spectrofluorophotometer RF-1501

Provenance and Historical References:

Bera, G., Parkerton, T., Redman, A., Turner, N. R., Renegar, D. A., Sericano, J. L., & Knap, A. H. (2018). Passive dosing yields dissolved aqueous exposures of crude oil comparable to the CROSERF (Chemical Response to Oil Spill: Ecological Effects Research Forum) water accommodated fraction method. Environmental Toxicology and Chemistry. doi:10.1002/etc.4263 Knap, A., Turner, N. R., Bera, G., Abigail Renegar, D., Frank, T., Sericano, J., & Riegl, B. M. (2017). Short-term toxicity of 1-methylnaphthalene to Americamysis bahia and 5 deep-sea crustaceans. Environmental Toxicology and Chemistry, 36(12), 3415-3423. doi:10.1002/etc.3926 Singer, M. M., Aurand, D., Bragin, G. E., Clark, J. R., Coelho, G. M., Sowby, M. L., & Tjeerdema, R. S. (2000). Standardization of the preparation and quantitation of water-accommodated fractions of petroleum for toxicity testing. Marine Pollution Bulletin, 40(11), 1007-1016. doi:10.1016/s0025-326x(00)00045-x 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. Monitoring and Modeling the deepwater horizon oil spill: a record-breaking enterprise, Geophysical Monograph Series, 77–82. doi:10.1029/2011gm001103 Wade, T.L., Morales-McDevitt, M., Bera, G., Shi, D., Sweet, S., Wang, B., Gold-Bouchot, G., Quigg, A. and 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), p.e00419. doi:10.1016/j.heliyon.2017.e00419

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