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

February A Tale of Two Recent Spills-Comparison of 2014 Galveston Bay and 2010 Deepwater Horizon Oil Spill Residues Fang Yin 0 1 2 Joel S. Hayworth 0 1 2 T. Prabhakar Clement 0 1 2 0 Environmental Engineering Program, Department of Civil Engineering, Auburn University , Auburn, Alabama , United States of America 1 Data Availability Statement: All relevant data are within the paper 2 Academic Editor: James P. Meador, Northwest Fisheries Science Center , NOAA Fisheries, UNITED STATES 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. - Funding: This work was supported, in part, by funding received from the Alabama Emergency Management Agency (AEMA). The GC/MS/MS facility and the characterization methods were developed using grant funds received from the National Science Foundation (NSF-MRI grant #G00006697). The funding agencies had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. On March 22, 2014, on the weekend of the 25th anniversary of the catastrophic Exxon Valdez oil spill in Alaska, the bulk carrier M/V Summer Wind collided with the oil barge Kirby, near Texas City, about 50 km southeast of Houston, Texas. The accident released approximately 168,000 gallons of marine fuel oil (known as RMG-380, a highly viscous, sticky, heavy black oil) into Galveston Bay (GB). After the accident, oil residues began washing up on several beaches along GB. The oil spill also spread into the Gulf of Mexico (GOM) and within a week oil was rapidly transported by shoreline currents to the Matagorda Island Wildlife Management region, located about 200 km south of GB. By the end of March, overflight observers noted beached oil being rapidly buried under clean sand near Matagorda Island [1]. Unfortunately, oil spill incidents like these occur in GB on a regular basis: according to the Texas General Land Office, 3,954 oil spills occurred in GB between 1998 and 2010 [2]. Oil spill residues washing onto shores is a common problem for many northern GOM beach systems. In 2010, the Deepwater Horizon (DWH) accident released about 210 million Competing Interests: The authors have declared that no competing interests exist. gallons of Louisiana light sweet crude oil into the GOM impacting over 1,600 miles of shoreline, and depositing oil on Florida, Alabama, Mississippi, Louisiana and Texas beaches. Negative environmental, ecological, social, and economic consequences of this event continue today [38]. Impacted beaches and dunes, estuaries, and tidal brackish and freshwater wetlands and the numerous species inhabiting them were, and remain, at risk of long-term detrimental effects as a result the spill [36,9,10]. The amount of oil released during the GB accident was relatively small compared to the DWH accident. The physicochemical characteristics of these two oils are also different. Fuel oil released during the GB spill was a heavy, viscous, refined fluid containing low levels of volatile hydrocarbons, while oil released during the DWH accident (MC252 crude oil) was an unrefined, low viscosity, sweet crude enriched in light, volatile hydrocarbons. Another major difference between the two events is that the GB spill was a surface release discharged about a kilometer away from the nearest shoreline; while the DWH event occurred about 75 km from the nearest shoreline, about 1.5 km under water. Uniquely, large volumes of chemical dispersants were also injected subsurface during the DWH spill response. Owing to its proximity to the shoreline, GB oil weathered in marine waters for only a few hours to days before being deposited on nearby beaches. Also, the GB spill occurred close to several sensitive wildlife areas during breeding season of migratory birds and marine species. DWH oil, on the other hand, was weathered by ocean-scale processes such as volatilization, dissolution, emulsification, photo-degradation and/or biodegradation for 3 or more weeks before being deposited on northern GOM shorelines. Table 1 summarizes some of the key features of these two oil spills. The objective of this study is to compare observational and chemical characterization data of first-arrival oil samples collected from GB and DWH spill-impacted beaches. Chemical characterization efforts included the measurement of concentrations of n-alkanes, several biomarkers, five groups of alkylated polycyclic aromatic hydrocarbons (PAHs) and seventeen other PAHs. Biomarker data for the GB oil presented in this study are important since they can be used for identifying and differentiating GB residue from oil residues from other sources, and are also useful for understanding weathering levels. PAH data are useful for comparing and quantifying potential long-term environmental impacts of GB and DWH oil spill residues. Materials and Methods Organic solvents used in this study were of analytical or higher grade and were purchased from VWR International (Suwanee, GA). Silica gel (60200 m) and anhydrous sodium sulfate (ACS grade) were also purchased from VWR International. Prior to use, silica gel was activated using well-established procedures [11]. C8-C40 alkanes, pristane and phytane mixtures and Deepwater Horizon Oil Spill hexadecane-d34 were purchased from Sigma-Aldrich. Biomarkers, namely C30-hopane (17(H),21(H)-hopane), C27(R)-sterane (5,14,17(H) cholestane 20R), and C30hopane (17(H),21(H)-hopane) were purchased form Chiron, Norway. The PAH reference standard consisting of 27 different PAHs (naphthalene, 1-methylnaphthalene, 2-methylnaphthalene, 2,6-dimethylnaphthalene, 2,3,5-trimethylnaphthalene, biphenyl, acenaphthylene, acenaphthene, fluorene, phenanthrene, 1-methylphenanthrene, anthracene, dibenzothiophene, fluoranthene, pyrene, benz[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[j]fluoranthene, benzo[k]fluoranthene, benzo[e]pyrene, benzo[a]pyrene, perylene, dibenz[a,c]anthracene, dibenz[a,h]anthracene, indeno[1,2,3,-cd]pyrene and benzo[ghi]per (...truncated)