Joel S. Hayworth

Chemical fingerprinting of petroleum biomarkers in Deepwater Horizon oil spill samples collected from Alabama shoreline

We compare the chromatographic signatures of petroleum biomarkers in Deepwater Horizon (DH) source oil, three other reference crude oils, DH emulsified mousse that arrived on Alabamas shoreline in June 2010, and seven tar balls collected from Alabama beaches from 2011 to 2012. Characteristic hopane and sterane fingerprints show that all the tar ball samples originated from DH oil. In addition, the diagnostic ratios of various hopanes indicate an excellent match. Quantitation data for C₃₀αβ-hopane concentration levels show that most of the weathering observed in DH-related tar balls found on Alabamas beaches is likely the result of natural evaporation and dissolution that occurred during transport across the Gulf of Mexico prior to beach deposition. Based on the physical and biomarker characterization data presented in this study we conclude that virtually all fragile, sticky, brownish tar balls currently found on Alabama shoreline originated from the DH oil spill.

Long-term monitoring data to describe the fate of polycyclic aromatic hydrocarbons in Deepwater Horizon oil submerged off Alabama's beaches

The 2010 Deepwater Horizon (DWH) catastrophe had considerable impact on the ∼ 50 km long sandy beach system located along the Alabama shoreline. We present a four-year dataset to characterize the temporal evolution of various polycyclic aromatic hydrocarbons (PAHs) and their alkylated homologs trapped in the residual oil buried along the shoreline. Field samples analyzed include the first arrival oil collected from Perdido Bay, Alabama in June 2010, and multiple oil spill samples collected until August 2014. Our field data show that, as of August 2014, DWH oil is still trapped along Alabamas beaches as submerged oil, predominately in the form of surface residual oil balls (SRBs). Chemical characterization data show that various PAHs present in the spilled oil (MC252 crude) weathered by about 45% to 100% when the oil was floating over the open ocean system in the Gulf of Mexico. Light PAHs, such as naphthalenes, were fully depleted, whereas heavy PAHs, such as chrysenes, were only partially depleted by about 45%. However, the rate of PAH weathering appears to have decreased significantly once the oil was buried within the partially-closed SRB environment. Concentration levels of several heavy PAHs have almost remained constant over the past 4 years. Our data also show that evaporation was most likely the primary weathering mechanism for PAH removal when the oil was floating over the ocean, although photo-degradation and other physico-chemical processes could have contributed to some additional weathering. Chemical data presented in this study indicate that submerged oil containing various heavy PAHs (for example, parent and alkylated chrysenes) is likely to remain in the beach system for several years. It is also likely that the organisms living in these beach environments would have an increased risk of exposure to heavy PAHs trapped in the non-recoverable form of buried DWH oil spill residues.

Fate of Deepwater Horizon oil in Alabama's beach system: understanding physical evolution processes based on observational data.

The impact of MC252 oil on northern Gulf of Mexico (GOM) beaches from the 2010 Deepwater Horizon (DWH) catastrophe was extensive along Alabamas beaches. While considerable amount of cleanup has occurred along these beaches, as of August 2014, DWH oil spill residues continue to be found as surface residual balls (SRBs), and also occasionally as submerged oil mats (SOMs). Four years of field observations informing the fate and transport of DWH SRBs in Alabamas beach system are presented here, along with a conceptual framework for describing their physical evolution processes. The observation data show that SRBs containing MC252 residues currently remain in Alabamas beach system, although their relationship to SOMs is not fully known. Based on our field observations we conclude that small DWH SRBs are likely to persist for several years along the Alabama shoreline.

Evaluation of differential cytotoxic effects of the oil spill dispersant Corexit 9500

AIMS The British Petroleum (BP) oil spill has raised several ecological and health concerns. As the first response, BP used a chemical dispersant, Corexit-9500, to disperse the crude oil in the Gulf of Mexico to limit shoreline contamination problems. Nevertheless, portions of this oil/Corexit mixture reached the shoreline and still remain in various Gulf shore environments. The use of Corexit itself has become a significant concern since its impacts on human health and environment is unclear. MAIN METHODS In this study, in vitro cytotoxic effects of Corexit were evaluated using different mammalian cells. KEY FINDINGS Under serum free conditions, the LC50 value for Corexit in BL16/BL6 cell was 16 ppm, in 1321N1 cell was 33 ppm, in H19-7 cell was 70 ppm, in HEK293 was 93 ppm, and in HK-2 cell was 95 ppm. With regard to the mechanisms of cytotoxicity, we hypothesize that Corexit can possibly induce cytotoxicity in mammalian cells by altering the intracellular oxidative balance and inhibiting mitochondrial functions. Corexit induced increased reactive oxygen species and lipid peroxide levels; also, it depleted glutathione content and altered catalase activity in H19-7 cells. In addition, there was mitochondrial complex-I inhibition and increase in the pro-apoptotic factors including caspase-3 and BAX expression. SIGNIFICANCE The experimental results show changes in intracellular oxidative radicals leading to mitochondrial dysfunctions and apoptosis in Corexit treatments, possibly contributing to cell death. Our findings raise concerns about using large volumes of Corexit, a potential environmental toxin, in sensitive ocean environments.

Provenance of Corexit-related chemical constituents found in nearshore and inland Gulf Coast waters

The dispersants Corexit 9527 and Corexit 9500 were extensively used during the response to the Deepwater Horizon accident in 2010. In addition to the monitoring programs established by federal and state governments, local communities also conducted studies to determine if chemical constituents from these dispersants impacted nearshore and inland waters. One community (the City of Orange Beach, Alabama) collected water samples between September, 2010 and January, 2011, and found the dispersant-related chemicals propylene glycol, 2-butoxyethanol, and dioctyl sodium sulfosuccinate at nearshore and inland water sampling sites. In this paper, we examine their dataset in an attempt to discern the origin of these chemicals. Our assessment indicates that these compounds are unlikely to be present as a result of the use of Corexit dispersants; rather, they are likely related to point and non-point source stormwater discharge.

A Tale of Two Recent Spills—Comparison of 2014 Galveston Bay and 2010 Deepwater Horizon Oil Spill Residues

Managing oil spill residues washing onto sandy beaches is a common worldwide environmental problem. In this study, we have analyzed the first-arrival oil spill residues collected from two Gulf of Mexico (GOM) beach systems following two recent oil spills: the 2014 Galveston Bay (GB) oil spill, and the 2010 Deepwater Horizon (DWH) oil spill. This is the first study to provide field observations and chemical characterization data for the 2014 GB oil spill. Here we compare the physical and chemical characteristics of GB oil spill samples with DWH oil spill samples and present their similarities and differences. Our field observations indicate that both oil spills had similar shoreline deposition patterns; however, their physical and chemical characteristics differed considerably. We highlight these differences, discuss their implications, and interpret GB data in light of lessons learned from previously published DWH oil spill studies. These analyses are further used to assess the long-term fate of GB oil spill residues and their potential environmental impacts.

Development and application of an analytical method using gas chromatography/triple quadrupole mass spectrometry for characterizing alkylated chrysenes in crude oil samples

RATIONALE Recent advances in analytical techniques have led to the development of gas chromatography/triple quadrupole mass spectrometry methods that allow the identification of target analytes in complex environmental samples. We have employed this technology to develop a method for characterizing alkylated chrysenes, which are environmental toxins that are resistant to weathering. METHODS An Agilent 7890 gas chromatograph coupled to an Agilent 7000B triple quadrupole mass spectrometer was used. The mass spectral fragmentation of seven commercially available alkylated chrysene standards was studied under full-scan and product-ion scan conditions. The calibration curves used were in the linear range with r(2) values greater than 0.99. The recovery and limit of detection of target analytes in the samples were in the range of 80-120% and 0.11-1.09 ng/mL, respectively. RESULTS The information inferred from full-scan and product-ion scan data was combined with literature data to develop a GC/MS/MS method for the identification and quantification of C1 -, C2 -, C3 -, and C4 -chrysene homologues. The method was employed to characterize MC252 crude oil which was released during the 2010 Deepwater Horizon accident. The results showed that the chrysene concentrations estimated by the proposed method were well within the range of previously reported values. CONCLUSIONS The proposed method is useful for analyzing chrysene and its alkylated homologues in crude oil samples.

A rapid UHPLC-MS/MS method for simultaneous quantitation of 23 perfluoroalkyl substances (PFAS) in estuarine water

Per- and polyfluoroalkyl substances (PFAS) represent a large group of synthetic organic compounds which, as a result of their unique chemical properties, render them extremely recalcitrant to environmental degradation. Research concerning the environmental, ecological, and human health effects of PFAS has focused on long aliphatic chain (> C7) compounds having no ether bonds. For new, less studied, or previously unknown PFAS (≤ C7 with ether bonds), there is little to no information about their environmental behavior, transport, fate, exposure, and toxicological effects. LC-MS/MS has proven effective for detection and quantitation of some PFAS, however, straightforward analytical methods for simultaneous trace quantitation of broad mixtures of PFAS in varied complex environmental media, available to a wide range of researchers and also suitable for routine monitoring, remain critical needs. Here we describe a simple, rapid, sensitive, and reproducible quantitative analytical method for trace analysis and monitoring of 23 PFAS in estuarine water, using ultra-high performance liquid chromatography-triple quadrupole mass spectrometry (UHPLC-MS/MS). The developed MRM method allows simultaneous trace quantitation of a broad mixture of PFAS, including 13 perfluoroalkyl carboxylic acids, 8 perfluoroalkyl sulfonates, and 2 short-chain perfluoroethers. The method provides better peak resolution and peak separation, and shorter run times (method separation/total run time: 6/8 min) compared to those of existing analytical methods. Percent recoveries for the validated method ranged from 78.54 to 112.61. LOD and LOQ values ranged from 0.48 to 1.68 pg/injection and 1.71 to 5.40 pg/injection, respectively. The validated method was used for quantitative PFAS analysis of estuarine water samples collected from 16 locations within the Perdido Bay estuary in coastal Alabama.