Following the Deepwater Horizon disaster, effect of weathering on surface slicks, oil-soaked sands, and oil-covered rocks boulders was studied for 18 months. With time, oxygen content increased in hydrocarbon residues. Furthermore, a weathering-dependent increase an operationally defined oxygenated fraction relative to saturated aromatic fractions observed. This made up >50% mass weathered samples, had average carbon oxidation state -1.0, molecular formula (C(5)H(7)O)(n). These residues were...

Petroleum biomarkers such as hopanoids, steranes, and triaromatic steroids (TAS) are commonly used to investigate the source fate of petroleum hydrocarbons in environment based on premise that these compounds resistant biotic abiotic degradation. To test validity this context Deepwater Horizon disaster, we investigated changes induced by natural weathering crude oil discharged from Macondo Well (MW). For surface slicks collected May June 2010, other oiled samples beaches northern Gulf Mexico...

Of the estimated 5 million barrels of crude oil released into Gulf Mexico from Deepwater Horizon spill, a fraction washed ashore onto sandy beaches Louisiana to Florida panhandle. Here, we compare detailed molecular analysis hydrocarbons in oiled sands Pensacola Beach Macondo wellhead (MWO) by electrospray (ESI) and atmospheric pressure photoionization (APPI) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) identify major environmental transformation products polar,...

The 2010 Deepwater Horizon disaster introduced an unprecedented discharge of oil into the deep Gulf Mexico. Considerable uncertainty has persisted regarding oil's fate and effects in ocean. In this work we assess compound-specific rates biodegradation for 125 aliphatic, aromatic, biomarker petroleum hydrocarbons that settled to ocean floor following release from damaged Macondo Well. Based on a dataset comprising measurements up 168 distinct hydrocarbon analytes 2,980 sediment samples...

Following the Deepwater Horizon (DWH) blowout in 2010, oil floated on Gulf of Mexico for over 100 days. In aftermath blowout, substantial accumulation partially oxidized surface was reported, but pathways that formed these residues are poorly constrained. Here we provide five quantitative lines evidence demonstrating oxidation by sunlight largely accounts oil. First, residence time sunlit sea surface, where photochemical reactions occur, strongest predictor partial oxidation. Second,...

Biodegradation plays a major role in the natural attenuation of oil spills. However, limited information is available about biodegradation different saturated hydrocarbon classes surface environments, despite that oils are composed mostly saturates, due to ability conventional gas chromatography (GC) resolve this compound group. We studied eight weathered samples collected from four Gulf Mexico beaches 12–19 months after Deepwater Horizon disaster. Using comprehensive two-dimensional...

Exposures to environmental toxicants can have both immediate and long-term impacts, including those that persist into the next generation. Using Gulf killifish (Fundulus grandis), we tested whether adult progenitor exposure crude oil caused perturbations larval morphology embryonic genome-wide gene expression in their first- second-generation descendants raised clean water. We also tracked responses of additional direct exposures F1 F2 embryos. Exposure fish altered descendants. Some were...

A method has been developed for the direct determination of stable chlorine isotope composition (delta(37)Cl) organochlorines that eliminates sample preparation, achieves precision comparable to earlier techniques while improving sensitivity, and makes use benchtop gas chromatography-quadrupole mass spectrometry instruments (GCqMS). The is based on multiple injections (n = 8-10) sample, bracketed by a molecularly identical isotopic standard with known delta(37)Cl, determined using off-line...

The most abundant and problematic metal compounds in crude oil exist as organic complexes of vanadium nickel porphyrin structures derived from biological molecules (chlorophyll heme), the first petroleum biomarkers discovered by Alfred Treibs early 1930s.1 Detailed characterization type structure porphyrins is critical for development upgrading processes, but also to link source rock conditions. Because petroporphyrins concentrate heavy oils, direct challenges routine analytical techniques...

We determined in situ reductive transformation rates of tetrachloroethene (PCE) a contaminated aquifer by combining compound-specific carbon stable isotope analysis (CSIA) the contaminants with tracer-based ((3)H-(3)He) groundwater dating. With increasing distance from source, PCE was gradually transformed to trichloroethene (TCE), cis-dichloroethene (cDCE), and vinyl chloride (VC). Using isotopic enrichment factor -3.3 +/- 1.2 per thousand allowed for quantification PCE-to-TCE based on...

Chlorinated ethenes (CEs) are ubiquitous groundwater contaminants, yet there remains a need for method to efficiently monitor their in situ degradation. We report here the first field application of combined stable carbon and chlorine isotope analysis tetrachloroethene (PCE) trichloroethene (TCE) investigate biodegradation heavily contaminated aquifer. The two-dimensional Compound Specific Isotope Analysis (2D-CSIA) approach was facilitated by recently developed gas chromatography-quadrupole...

Two-dimensional compound-specific isotope analysis (2D-CSIA), combining stable carbon and chlorine isotopes, holds potential for monitoring of natural attenuation chlorinated ethenes (CEs) in contaminated soil groundwater. However, interpretation 2D-CSIA data sets is challenged by a shortage experimental Cl enrichment factors. Here, enrichments factors C (i.e., εC εCl) were determined biodegradation tetrachloroethene (PCE) trichloroethene (TCE) using microbial cultures from heavily...

About half of the surface oil floating on Gulf Mexico in aftermath 2010 Deepwater Horizon spill was transformed into oxygenated hydrocarbons (OxHC) within days to weeks. These OxHC persist for years oil/sand aggregates nearshore and beach environments, there is concern that these might represent a long-term source toxic compounds. However, because this fraction continuum transformation products are not well chemically characterized, it included current fate effect models. This challenges an...

While chemical dispersants are a powerful tool for treating spilled oil, their effectiveness can be limited by oil weathering processes such as evaporation and emulsification. It has been suggested that photo-oxidation could exacerbate these challenges. To address the role of in dispersant effectiveness, outdoor mesocosm experiments with crude on seawater were performed. Changes bulk properties molecular composition quantified to characterize over 11 days. test relative residues evaluated...

Mass transfer of organic contaminants from nonaqueous phase liquids to the aqueous can significantly modulate observable carbon isotope fractionation behavior associated with contaminant transformation. We evaluated effects kinetic interphase mass between tetradecane and water on 13C enrichment factor, ϵobs, pertinent reductive dechlorination trichloroethene (TCE) by Sulfurospirillum sp. in laboratory batch model systems containing organic, gaseous phases. propose a conceptual model, which...

The widespread use of chlorinated phenols (CPs) as a wood preservative has led to numerous contaminated sawmill sites. However, it remains challenging assess the extent in situ degradation CPs. We evaluated compound-specific chlorine and carbon isotope analysis (Cl- C-CSIA) CP biotransformation. In laboratory system, we measured isotopic fractionation during oxidative 2,4,6-trichlorophenol dechlorination by representative soil enzymes (C. fumago chloroperoxidase, horseradish peroxidase,...

Coal tar and its distilled products (e.g., creosote) are commonly applied wood preservatives asphalt sealants that have been identified as significant sources of polycyclic aromatic hydrocarbons (PAHs) to the environment. Despite predictions coal is composed hundreds compounds, few studies ventured beyond measuring select PAHs with gas chromatography–mass spectrometry (GC-MS). Expanding target analyte list will improve our capacity gauge inputs impacts organic compounds released from into...

The Late Miocene–Pliocene aged hyperarid evaporitic system of Salar Grande is a unique, halite-rich sedimentary basin in the Cordillera de la Costa Central Andes (Chile) whose bio-sedimentary record poorly understood. persistence hyperacidity over millions years, hypersalinity, and intense UV radiation make it terrestrial analogue to assess potential presence organic matter halite deposits found on Mars. We investigated occurrence distribution biomolecules along 100-m depth drill down ~ 9 Ma...

The use of stable chlorine isotopic signatures (δ(37)Cl) organochlorine compounds has been suggested as a tool to determine both their origins and transformations in the environment. Here we investigated δ(37)Cl fractionation two important pathways for enzymatic natural halogenation: chlorination by chloroperoxidase (CPO) flavin-dependent halogenases (FDH). Phenolic products CPO were highly (37)Cl depleted (δ(37)Cl = -12.6 ± 0.9‰); significantly more than all known industrially produced -7...

We used alkenes commonly found in synthetic drilling-fluids to identify sources of oil sheens that were first observed September 2012 close the Deepwater Horizon (DWH) disaster site, more than two years after Macondo well (MW) was sealed. While explorations sea floor by BP confirmed sound, they identified likely source as leakage from an 80-ton cofferdam, abandoned during operation control MW May 2010. acquired sheen samples and cofferdam analyzed them using comprehensive two-dimensional gas...