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Class conflicts, Ash argues, were muted and relatively insignificant before the war when most whites had enough to eat and adequate shelter. Class conflict erupted during the war as lower-class white Richmonders struggled with food shortages and inflation. Keywords: Southern U.S. cities; class conflict; white supremacy; ethnicity; social history EN Southern U.S. cities class conflict white supremacy ethnicity social history 686 689 4 04/12/22 20220501 NES 220501 Strickland, Jeff (2015). [Extracted from the article]

The C 20 isoprenoid crocetane (2,6,11,15-tetramethylhexadecane) is an environmental diagnostic biomarker that can be used as a proxy for both anaerobic methane oxidation and photic zone euxinia. Crocetane co-elutes with its isomer phytane (2,6,10,14-tetramethylhexadecane) on many gas chromatographic capillary columns, making the detection of crocetane analytically challenging. The separation of crocetane and phytane is reported here using: (i) a one-dimensional gas chromatography (GC) method and (ii) a comprehensive two-dimensional gas chromatography (GC×GC) chiral method. The one-dimensional method employs a (14% cyanopropyl-phenyl)-methylpolysiloxane (DB-1701) capillary GC stationary phase where crocetane and phytane elute isothermally. This resulted in the highest resolution reported to date on a non-chiral column and allows for the analysis of both crocetane and conventional biomarkers in a single injection. The GC×GC chiral method reported here is capable of separating crocetane from phytane in whole oils without any pre-separation work, diminishing any effects and potential losses associated with sample preparation. [ABSTRACT FROM AUTHOR]

A representative substrate scope investigation for an enantioselective catalytic ketone-reduction has been performed as a single reaction on a mixture containing equimolar amounts of nine (9) prototypical compounds. The resulting analyte pool containing 18 potential products from nine different reactions could all be completely resolved in a single chromatographic injection using comprehensive two-dimensional gas chromatography (GC?GC) with time-of-flight mass spectrometry, allowing for simultaneous determination of percent conversion and enantiomeric excess for each substrate. The results obtained for an enantioselective iron-catalyzed asymmetric transfer hydrogenation using this one-pot/single-analysis approach were similar to those reported for the individualized reactions, demonstrating the utility of this strategy for streamlining substrate scope investigations. Moreover, for this particular catalyst, activity and selectivity were not greatly affected by the presence of other ketones or enantioenriched reduced products. This approach allows for faster and greener analyses that are central to new reaction development, as well as an opportunity to gain further insights into other established transformations. [ABSTRACT FROM AUTHOR]

Reviews of the articles "The Geographic Imagination of Civil War-Era American Fiction" by Matthew Wilkens, which appeared in the "American Literary History," and "Space, Nation and the Triumph of Region: A View of the World from Houston" by Cameron Blevins are presented.

Traditional tools for routine environmental analysis and forensic chemistry of petroleum have relied almost exclusively on gas chromatography-mass spectrometry (GC-MS), although many compounds in crude oil (and its transformation products) are not chromatographically separated or amenable to GC-MS due to volatility. To enhance current and future studies on the fate, transport, and fingerprinting of the Macondo well oil released from the 2010 Deepwater Horizon disaster, we created an extensive molecular library of the unadulterated petroleum to compare to a tar ball collected on the beach of Louisiana. We apply ultrahigh resolution Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry to identify compositional changes at the molecular level between native and weathered crude oil samples and reveal enrichment in polar compounds inaccessible by GC-based characterization. The outlined approach provides unprecedented detail with the potential to enhance insight into the environmental fate of spilled oil, improved toxicology, molecular modeling of biotic/abiotic weathering, and comprehensive molecular characterization for petroleum-derived releases. Here, we characterize more than 30 000 acidic, basic, and nonpolar unique neutral elemental compositions for the Macondo well crude oil, to provide an archive for future chemical analyses of the environmental consequences of the oil spill. [ABSTRACT FROM AUTHOR]

Abstract: Higher plant biomarkers occur in various compound classes with an array of isomers that are challenging to separate and identify. Traditional one-dimensional (1D) gas chromatographic (GC) techniques achieved impressive results in the past, but have reached limitations in many cases. Comprehensive two-dimensional gas chromatography (GC×GC) either coupled to a flame ionization detector (GC×GC–FID) or time-of-flight mass spectrometer (GC×GC–TOFMS) is a powerful tool to overcome the challenges of 1D GC, such as the resolution of unresolved complex mixture (UCM). We studied a number of Tertiary, terrigenous oils, and source rocks from the Arctic and Southeast Asia, with special focus on angiosperm biomarkers, such as oleanoids and lupanoids. Different chromatographic separation and detection techniques such as traditional 1D GC–MS, metastable reaction monitoring (GC–MRM-MS), GC×GC–FID, and GC×GC–TOFMS are compared and applied to evaluate the differences and advantages in their performance for biomarker identification. The measured 22S/(22S +22R) homohopane ratios for all applied techniques were determined and compare exceptionally well (generally between 2% and 10%). Furthermore, we resolved a variety of angiosperm-derived compounds that co-eluted using 1D GC techniques, demonstrating the superior separation power of GC×GC for these biomarkers, which indicate terrigenous source input and Cretaceous or younger ages. Samples of varying thermal maturity and biodegradation contain higher plant biomarkers from various stages of diagenesis and catagenesis, which can be directly assessed in a GC×GC chromatogram. The analysis of whole crude oils and rock extracts without loss in resolution enables the separation of unstable compounds that are prone to rearrangement (e.g. unsaturated triterpenoids such as taraxer-14-ene) when exposed to fractionation techniques like molecular sieving. GC×GC–TOFMS is particularly valuable for the successful separation of co-eluting components having identical molecular masses and similar fragmentation patterns. Such components co-elute when analysed by 1D GC and cannot be resolved by single-ion-monitoring, which prevents accurate mass spectral assessment for identification or quantification. [Copyright &y& Elsevier]

Recent studies have shown that membrane-water partition coefficients of organic chemicals can be used to predict bioaccumulation and type I narcosis toxicity more accurately than the traditional KOW-based approach. In this paper, we demonstrate how comprehensive two-dimensional gas chromatography (GC × GC) can be used to estimate such membrane-water partition coefficients (KPLWs), focusing in particular on phosphatidyl choline based lipids. This method performed well for a set of 38 compounds, including polycyclic aromatic hydrocarbons, polychlorinated benzenes and biphenyls, and substituted benzenes including some phenols and anilines. The average difference between the estimated and the measured log KPLW values of 0.47 log units is smaller than in the case of a log KOW correlation approach but larger than seen using a polyparameter linear free energy relationship based approach. However, the GC × GC based method presents the advantage that it can be applied to mixtures of chemicals that are not completely identified, such as petroleum hydrocarbon mixtures. At the same time, our application of the GC × GC method suffered larger errors when applied to certain hydrogen bonding compounds due to the inability of the GC × GC capillary columns phases that we used to interact with analytes via hydrogen bond donation/electron acceptance. [ABSTRACT FROM AUTHOR]

Abstract: 18α(H)-, 18β(H)-oleanane and lupane are angiosperm-derived biomarkers that are used as age indicators for the Late Cretaceous onwards when the first proliferation of angiosperms occurred. In addition, the 18α(H)-/18β(H)-oleanane ratio is employed as a thermal maturity parameter of crude oil. However, evidence has shown that accurate quantification of these compounds has been impeded by inadequate chromatographic separation by traditional one-dimensional gas chromatography. In this study, we present the separation of 18α(H)-, 18β(H)-oleanane and lupane with comprehensive two-dimensional gas chromatography (GC×GC). Furthermore, it was observed that 18β(H)-oleanane elutes earlier than 18α(H)-oleanane in second dimension (polarity) which we attribute to steric hindrance effects. Two GC conditions have been developed in order to achieve baseline separation of the triterpenoids of interest in complex mixtures such as sediment extracts and crude oils. [Copyright &y& Elsevier]

Abstract: Contamination of coastal marine sediments with polycyclic aromatic hydrocarbons is pervasive, with major sources including anthropogenic activity and natural seepage. Biodegradation serves as a major hydrocarbon sink with evaporation and dissolution responsible for the removal of low boiling range compounds and photo-oxidation acting on many multi-substituted aromatic compounds. In this work, first-order rate constants for aerobic biodegradation were quantified for naphthalene (N), benzothiophene (BT) and their alkylated congeners (1–4 carbon substituents (C1–C4)) in laboratory experiments with oil laden marine sediments from a natural seep. Rate constants were used as proxies for microbial preference, which follows the order: naphthalene>C1N>C2N>C1BT>C2BT>benzothiophene>C3BT>C3N>C4BT>C4N, with some overlap. The application of comprehensive two dimensional gas chromatography further enabled separation and quantification of multiple structural isomers for C2N–C4N and C2BT–C4BT, with 7–12 isomers resolved for each C2N–C4N and 4–7 isomers resolved for each C2BT–C4BT. A strong isomeric biodegradation preference was noted within each of these compound classes, with rate constants varying as much as a factor of 2 for structural isomers of the same compound class. Each isomer was consumed to a low, but non-zero concentration, suggesting that their residual load in sediment may be proportional to the number of structural isomers originally present, in addition to the pattern and the number of alkyl substitutions. The simultaneous first-order biodegradation rates observed for 52 aromatic hydrocarbons resolved in this study, along with reference compounds such as n-alkanes, lends support to the concept of broad scale metabolic specificity during aerobic biodegradation of petroleum. [Copyright &y& Elsevier]

Abstract: Halogenated 1′methyl-1,2′-bipyrroles (MBPs) have been identified worldwide in marine mammals. Here we present the tentative identification of previously undetected MBP congeners in Delpinus delphis blubber using gas chromatography/electron capture negative ion mass spectrometry (GC/ECNI-MS) and comprehensive two-dimensional gas chromatography/time of flight mass spectrometry (GC×GC/TOF-MS). This is the first report of 26 congeners. The presence of numerous partially halogenated congeners suggests that they are either biosynthesized concomitantly with their perhalogenated counterparts or that their dehalogenation products can also bioaccumulate. The newly found compounds fit the geographic trend that has been previously noted. That is, samples from the Atlantic Ocean are dominated by the more brominated congeners while those from the Pacific are dominated by the more chlorinated congeners. [Copyright &y& Elsevier]

Hydrocarbon mass transfers to the atmosphere and water column drive the early weathering of oil spills and also control the chemical exposures of many coastal wildlife species. However, in the field, mass transfer rates of individual hydrocarbons to air and water are often uncertain. In the Part 1 companion to this paper, we used comprehensive two-dimensional gas chromatography (GC x CC) to identify distinct signatures of evaporation and dissolution encoded in the compositional evolution of weathered oils. In Part 2, we further investigate patterns of mass removal in GC x GC chromatograms using a mass transfer model. The model was tailored to conditions at a contaminated beach on Buzzards Bay, MA, after the 2003 Bouchard 120 oil spill. The model was applied to all resolved hydrocarbon compounds in the C11-C24 boiling range, based on their GC x CC-estimated vapor pressures and aqueous solubilities. With no fitted parameters, the model successfully predicted GC x CC chromatogram patterns of mass removal associated with evaporation, water-washing, and diffusion-limited transport. This enabled a critical field evaluation of the mass transfer model and also allowed mass apportionment estimates of hundreds of individual hydrocarbon compounds to air and water. Ultimately, this method should improve assessments of wildlife exposures to oil spill hydrocarbons. [ABSTRACT FROM AUTHOR]

Historically, the thousands of compounds found in oils constituted an ‘unresolved complex mixture’ that frustrated efforts to analyze oil weathering. Moreover, different weathering processes inflict rich and diverse signatures of compositional change in oil, and conventional methods do not effectively decode this elaborate record. Using comprehensive two-dimensional gas chromatography (GC x GC), we can separate thousands of hydrocarbon components and simultaneously estimate their chemical properties. We investigated 13 weathered field samples collected from the Bouchard 120 heavy fuel oil spill in Buzzards Bay, Massachusetts in 2003. We first mapped hydrocarbon vapor pressures and aqueous solubilities onto the compositional space explored by GC x GC chromatograms of weathered samples. Then we developed methods to quantitatively decouple mass loss patterns associated with evaporation and dissolution. The compositional complexity of oil, traditionally considered an obstacle, was now an advantage. We exploited the large inventory of chemical information encoded in oil to robustly differentiate signatures of mass transfer to air and water. With this new approach, we can evaluate mass transfer models (the Part 2 companion to this paper) and more properly account for evaporation, dissolution, and degradation of oil in the environment. [ABSTRACT FROM AUTHOR]

Abstract: Comprehensive two-dimensional gas chromatography with flame ionization detection (GC×GC-FID) was used to measure alkene-based drilling fluids in crude oils. Compared to one-dimensional gas chromatography, GC×GC-FID is more robust for detecting alkenes due to the increased resolution afforded by second dimension separations. Using GC×GC-FID to analyze four oil samples from one reservoir contaminated with the same drilling fluid, C15, C16, C17, C18 and C20 alkenes were identified. The drilling fluid that contaminated these samples also differed from another commercially obtained fluid, which only contained C16 and C18 alkenes. These results should motivate the petroleum industry to consider GC×GC-FID for measuring drilling fluids. [Copyright &y& Elsevier]

Abstract: Natural abundance, molecular-level 14C analysis was combined with comprehensive gas chromatography (GC×GC) to investigate, in situ, the role of intrinsic biodegradation in the loss of petroleum hydrocarbons from the rocky, inter-tidal zone impacted by the Bouchard 120 oil spill. GC×GC analysis indicated accelerated losses of n-alkane components of the residual petroleum hydrocarbons between day 40 and day 50 after the spill. 14C analysis of bacterial phospholipid fatty acids (PLFA) from the impacted zone on day 44 showed that the polyunsaturated fatty acids attributed to the photoautotrophic component of the microbial community had the same Δ14C as the local dissolved inorganic carbon (DIC), indicating that this DIC was their carbon source. In contrast there was significant Δ14C depletion in the saturated and mono-unsaturated PLFA indicating incorporation of petroleum carbon. This correlation between the observed accelerated n-alkane losses and microbial incorporation of Δ14C-depleted carbon directly demonstrated, in situ, that intrinsic biodegradation was affecting the petroleum. Since the majority of organic contaminants originate from petroleum feed-stocks, in situ molecular-level 14C analysis of microbial PLFA can provide insights into the occurrence and pathways of biodegradation of a wide range of organic contaminants. [Copyright &y& Elsevier]

Comprehensive two-dimensional gas chromatography (GC × GC) provides nearly complete composition data for some complex mixtures such as petroleum hydrocarbons. However, the potential wealth of physical property information contained in the corresponding two-dimensional chromatograms is largely untapped. We developed a simple but robust method to estimate GC × GC retention indices for diesel-range hydrocarbons. By exploiting n- alkanes as reference solutes in both dimensions, calculated retention indices were insensitive to uncertainty in the enthalpy of gas-stationary-phase transfer for a suite of representative diesel components. We used the resulting two-dimensional retention indices to estimate the liquid vapor pressures, aqueous solubilities, air-water partition coefficients, octanol-water partition coefficients, and vaporization enthalpies of a nearly complete set of diesel fuel hydrocarbons. Partitioning properties were typically estimated within a factor of 2; this is not as accurate as some previous estimation or measurement methods. However, these relationships may allow powerful and incisive analysis of phase-transfer processes affecting petroleum hydrocarbon mixtures in the environment. For example, GC × GC retention data might be used to quantitatively deconvolve the effects of water washing and evaporation on environmentally released diesel fuels. [ABSTRACT FROM AUTHOR]

In surface seawater, dissolved copper (Cu) is predominantly bound by a small pool of strong ligands, with further complexation by a larger pool of weaker ligands. Although the chemical structure of both classes of ligands observed in the open ocean remains unknown, it is believed that the stronger ligands are of biological origin, and it has been hypothesized that they are thiols. Using precolumn derivatization high-performance liquid chromatography electrospray ionization ion-trap mass spectrometry, we found that the ubiquitous coccolithophorid Emiliania huxleyi constitutively produces two previously uncharacterized thiols, arginine-cysteine and glutamine--cysteine, in high intracellular concentrations. E. huxleyi exudes these novel thiols, along with cysteine, in response to increased Cu concentrations in the growth media. Furthermore, stable Cu (I) complexes with the exuded thiols were observed in the growth media using matrix-assisted laser desorption time-of-flight mass spectrometry following size exclusion chromatography. Additionally, E. huxleyi appears to utilize these novel thiols in nitrogen storage and assimilation, as they are rapidly synthesized upon nitrogen addition to a nitrogen-depleted culture. The identification of specific ligands produced by this organism will facilitate further linkages between this likely source and the pools of Cu-binding ligands observed in surface seawater, while the discovery of novel thiols signifies the presence of unique and previously unknown biochemical pathways in E. huxleyi. [ABSTRACT FROM AUTHOR]

In 1837, Angelina and Sarah Grimké, daughters of a South Carolina planter turned abolitionist orators, each penned a series of public letters in which they attacked the rigid distinctions that their culture drew between the masculine and the feminine. In "Letters to Catherine Beecher" and "Letters on the Equality of the Sexes," each sister argued that contemporary sex roles that characterized white men as political and economic actors in the public sphere while relegating white women to the private sphere of the home amounted to a perversion of God's plan. According to them, notions of manhood gave men a charter for the exercise of tyranny and selfishness, pride and arrogance, lust and brutal violence.

Reviews several Websites about U.S. history. georgewashington.si.edu; harpweek.com; americanhistory.si.edu.

Focuses on the criticisms made by journalist William Sloane Kennedy against his antagonist Thomas Wentworth Higginson in the essay 'Euphrasy and Rue for T.W. Higginson.' Attacks made by Kennedy against the friends of Higginson; Qualities distinguishing working from middle class; Use of phallacism in a heterosexual context to explain eroticism.

Reviewed: The Black Hearts of Men: Radical Abolitionists and the Transformation of Race. Stauffer, John.

Reviewed: Truth Stranger Than Fiction: Race, Realism, and the U.S. Literary Marketplace. Rohrbach, Augusta.

Analytical techniques for chemical analysis of oil, oil photochemical and biological transformation products, and dispersants and their biodegradation products benefited significantly from research following the 2010 Deepwater Horizon (DWH) disaster. Crude oil and weathered-oil matrix reference materials were developed based on the Macondo well oil and characterized for polycyclic aromatic hydrocarbons, hopanes, and steranes for use to assure and improve the quality of analytical measurements in oil spill research. Advanced gas chromatography (GC) techniques such as comprehensive two-dimensional GC (GC × GC), pyrolysis GC with mass spectrometry (MS), and GC with tandem MS (GC-MS/MS) provide a greater understanding at the molecular level of composition and complexity of oil and weathering changes. The capabilities of high-resolution MS (HRMS) were utilized to extend the analytical characterization window beyond conventional GC-based methods to include polar and high molecular mass components (>400 Da) and to provide new opportunities for discovery, characterization, and investigation of photooxidation and biotransformation products. Novel separation approaches to reduce the complexity of the oil and weathered oil prior to high-resolution MS and advanced fluorescence spectrometry have increased the information available on spilled oil and transformation products. HRMS methods were developed to achieve the required precision and sensitivity for detection of dispersants and to provide molecular-level characterization of the complex surfactants. Overall, research funding following the DWH oil spill significantly advanced and expanded the use of analytical techniques for chemical analysis to support petroleum and dispersant characterization and investigations of fate and effects of not only the DWH oil spill but future spills. [ABSTRACT FROM AUTHOR]

BACKGROUND: The association of historical redlining policies, a marker of structural racism, with contemporary heart failure (HF) risk among White and Black individuals is not well established. METHODS: We aimed to evaluate the association of redlining with the risk of HF among White and Black Medicare beneficiaries. Zip code–level redlining was determined by the proportion of historically redlined areas using the Mapping Inequality Project within each zip code. The association between higher zip code redlining proportion (quartile 4 versus quartiles 1–3) and HF risk were assessed separately among White and Black Medicare beneficiaries using generalized linear mixed models adjusted for potential confounders, including measures of the zip code–level Social Deprivation Index. RESULTS: A total of 2 388 955 Medicare beneficiaries (Black n=801 452; White n=1 587 503; mean age, 71 years; men, 44.6%) were included. Among Black beneficiaries, living in zip codes with higher redlining proportion (quartile 4 versus quartiles 1–3) was associated with increased risk of HF after adjusting for age, sex, and comorbidities (risk ratio, 1.08 [95% CI, 1.04–1.12]; P <0.001). This association remained significant after further adjustment for area-level Social Deprivation Index (risk ratio, 1.04 [95% CI, 1.002–1.08]; P =0.04). A significant interaction was observed between redlining proportion and Social Deprivation Index (P interaction<0.01) such that higher redlining proportion was significantly associated with HF risk only among socioeconomically distressed regions (above the median Social Deprivation Index). Among White beneficiaries, redlining was associated with a lower risk of HF after adjustment for age, sex, and comorbidities (risk ratio, 0.94 [95% CI, 0.89–0.99]; P =0.02). CONCLUSIONS: Historical redlining is associated with an increased risk of HF among Black patients. Contemporary zip code–level social determinants of health modify the relationship between redlining and HF risk, with the strongest relationship between redlining and HF observed in the most socioeconomically disadvantaged communities. [ABSTRACT FROM AUTHOR]

With the expansion of offshore petroleum extraction, validated models are needed to simulate the behaviors of petroleum compounds released in deep (>100 m) waters. We present a thermodynamic model of the densities, viscosities, and gas-liquid-water partitioning of petroleum mixtures with varying pressure, temperature, and composition based on the Peng-Robinson equation-of-state and the modified Henry's law (Krychevsky-Kasarnovsky equation). The model is applied to Macondo reservoir fluid released during the Deepwater Horizon disaster, represented with 279-280 pseudocomponents, including 131-132 individual compounds. We define >n-C8 pseudocomponents based on comprehensive two-dimensional gas chromatography (GC × GC) measurements, which enable the modeling of aqueous partitioning for n-C8 to n-C26 fractions not quantified individually. Thermodynamic model predictions are tested against available laboratory data on petroleum liquid densities, gas/liquid volume fractions, and liquid viscosities. We find that the emitted petroleum mixture was ~29-44% gas and ~56-71% liquid, after cooling to local conditions near the broken Macondo riser stub (~153 atm and 4.3 °C). High pressure conditions dramatically favor the aqueous dissolution of C¹-C4 hydrocarbons and also influence the buoyancies of bubbles and droplets. Additionally, the simulated densities of emitted petroleum fluids affect previous estimates of the volumetric flow rate of dead oil from the emission source. [ABSTRACT FROM AUTHOR]

In spite of significant advancements towards understanding the dynamics of petroleum hydrocarbon degrading microbial consortia, the impacts (direct or indirect via grazing activities) of bacterivorous protists remain largely unknown. Microcosm experiments were used to examine whether protistan grazing affects the petroleum hydrocarbon degradation capacity of a deep-sea sediment microbial community from an active Gulf of Mexico cold seep. Differences in n -alkane content between native sediment microcosms and those treated with inhibitors of eukaryotes were assessed by comprehensive two-dimensional gas chromatography following 30–90 day incubations and analysis of shifts in microbial community composition using small subunit ribosomal RNA gene clone libraries. More biodegradation was observed in microcosms supplemented with eukaryotic inhibitors. SSU rRNA gene clone libraries from oil-amended treatments revealed an increase in the number of proteobacterial clones (particularly γ-proteobacteria) after spiking sediments with diesel oil. Bacterial community composition shifted, and degradation rates increased, in treatments where protists were inhibited, suggesting protists affect the hydrocarbon degrading capacity of microbial communities in sediments collected at this Gulf of Mexico site. [ABSTRACT FROM AUTHOR]

In the present study, we investigated the possibility of identifying the source oils of exposed fish using ratios of bicyclic sesquiterpane (bicyclane) chemical biomarkers. In the event of an oil spill, identification of source oil(s) for assessment, or for litigation purposes, typically uses diagnostic ratios of chemical biomarkers to produce characteristic oil "fingerprints." Although this has been applied in identifying oil residues in sediments, water, and sessile filtering organisms, so far as we are aware this has never been successfully demonstrated for oil‐exposed fish. In a 35‐day laboratory trial, juvenile Lates calcarifer (barramundi or Asian seabass) were exposed, via the diet (1% w/w), to either a heavy fuel oil or to Montara, an Australian medium crude oil. Two‐dimensional gas chromatography with high‐resolution mass spectrometry and gas chromatography–mass spectrometry were then used to measure selected ratios of the bicyclanes to examine whether the ratios were statistically reproducibly conserved in the fish tissues. Six diagnostic bicyclane ratios showed high correlation (r2 > 0.98) with those of each of the two source oils. A linear discriminatory analysis model showed that nine different petroleum products could be reproducibly discriminated using these bicyclane ratios. The model was then used to correctly identify the bicyclane profiles of each of the two exposure oils in the adipose tissue extracts of each of the 18 fish fed oil‐enriched diets. From our initial study, bicyclane biomarkers appear to show good potential for providing reliable forensic fingerprints of the sources of oil contamination of exposed fish. Further research is needed to investigate the minimum exposure times required for bicyclane bioaccumulation to achieve detectable concentrations in fish adipose tissues and to determine bicyclane depuration rates once exposure to oil has ceased. Environ Toxicol Chem 2023;42:7–18. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC. [ABSTRACT FROM AUTHOR]

We used alkenes commonly found in synthetic drilling-fluids to identify sources of oil sheens that were first observed in September 2012 close to the Deepwater Horizon (DWH) disaster site, more than two years after the Macondo well (MW) was sealed. While explorations of the sea floor by BP confirmed that the well was sound, they identified the likely source as leakage from an 80-ton cofferdam, abandoned during the operation to control the MW in May 2010. We acquired sheen samples and cofferdam oil and analyzed them using comprehensive two-dimensional gas chromatography. This allowed for the identification of drilling-fluid C16- to C18-alkenes in sheen samples that were absent in cofferdam oil. Furthermore, the spatial pattern of evaporative losses of sheen oil alkanes indicated that oil surfaced closer to the DWH wreckage than the cofferdam site. Last, ratios of alkenes and oil hydrocarbons pointed to a common source of oil found in sheen samples and recovered from oil-covered DWH debris collected shortly after the explosion. These lines of evidence suggest that the observed sheens do not originate from the MW, cofferdam, or from natural seeps. Rather, the likely source is oil in tanks and pits on the DWH wreckage, representing a finite oil volume for leakage. [ABSTRACT FROM AUTHOR]

Following the Deepwater Horizon disaster, the effect of weathering on surface slicks, oil-soaked sands, and oil-covered rocks and boulders was studied for 18 months. With time, oxygen content increased in the hydrocarbon residues. Furthermore, a weathering-dependent increase of an operationally defined oxygenated fraction relative to the saturated and aromatic fractions was observed. This oxygenated fraction made up >50% of the mass of weathered samples, had an average carbon oxidation state of -1.0, and an average molecular formula of (C5H7O)n. These oxygenated hydrocarbon residues were devoid of natural radiocarbon, confirming a fossil source and excluding contributions from recent photosynthate. The incorporation of oxygen into the oil's hydrocarbons, which we refer to as oxyhydrocarbons, was confirmed from the detection of hydroxyl and carbonyl functional groups and the identification of long chain (C10-C32) carboxylic acids as well as alcohols. On the basis of the diagnostic ratios of alkanes and polycyclic aromatic hydrocarbons, and the context within which these samples were collected, we hypothesize that biodegradation and photooxidation share responsibility for the accumulation of oxygen in the oil residues. These results reveal that molecular-level transformations of petroleum hydrocarbons lead to increasing amounts of, apparently recalcitrant, oxyhydrocarbons that dominate the solvent-extractable material from oiled samples. [ABSTRACT FROM AUTHOR]

Abstract: Sedimentary organic matter in hydrothermal systems can be altered by high temperature fluids to generate petroleum. The saturated and aromatic fractions of these hydrothermal oils are compositionally similar to conventional oil with the exception that they often contain higher concentrations of polycyclic aromatic hydrocarbons (PAH) as well as substantial mixtures of coeluting organic compounds that produce dramatically rising signal on the baseline of gas chromatograms termed unresolved complex mixtures (UCMs). Little is known about the compounds that compose UCMs and why or how they form. This is in part due to an inability to discriminate between in situ and migrated components that characterize the petroleum generated in hydrothermal systems. However, UCMs are also a product of the limitations imbedded in analytical separation techniques. With the advent of comprehensive two-dimensional gas chromatography (GC×GC), a revision of what should constitute molecular complexity needs to be considered. We address these problems by comparing the molecular compositions of the maltene fractions of three previously published hydrothermal petroleum samples using time of flight-mass spectrometry (GC×GC–ToF-MS) and 12 hydrothermal petroleum samples in cores from three locales using comprehensive two-dimensional gas chromatography with flame ionization detection (GC×GC–FID). The sediment cores were collected from Middle Valley, located off the axis of the Juan de Fuca Ridge, and the Escanaba Trough, along the Gorda Ridge, both in the NE Pacific Ocean, as well as from the Guaymas Basin in the Gulf of California. We define a UCM in GC×GC data to be a condition in which ⩾25% of the detected peaks within a chromatographic area coelute in either the first or second dimension. In turn, complex (CM) and simple mixtures (SM) are defined as having 5–24% and <5% coelution, respectively. All CM and UCMs were dominated by an array of configurational isomers, which becomes increasingly aromatic with higher molecular weight. We relate this to a multi-molecular complexity metric (MCM) by quantitatively comparing the difference in total peak variance and peak density for a GC×GC chromatogram. MCM values correlate with biomarker thermal maturity ratios for the Escanaba Trough and Guaymas Basin samples indicating that molecular complexity in these hydrothermal environments is in part a function of burial temperatures. Partial Least Squares (PLS) linear regression was applied to the total number of peak retention times as a proxy for the bulk molecular differences between each hydrothermal oil sample. Differences in the sample regressions correlate with the thermal maturity and the degree of PAH alkylation, indicating that this technique can be used to assess the degree of oxidative weathering due to dehydrogenation and hydrocarbon cracking. Subtracted chromatograms were then used to quantitatively track all of the individual molecular changes within the pyrolytic regime at Escanaba Trough. These subtracted chromatograms indicate that high molecular weight PAHs are highly mobile in hydrothermal fluids and may represent a phase partitioning that is occurring at greater depths. This phase condenses just below the seafloor to form an UCM in the near surface sediments. Saturated hydrocarbon biomarkers, such as hopanes, steranes and biphytanes are less mobile and more prone to being cracked and/or aromatized prior to migration toward the ocean floor. Together these techniques suggest that the molecular complexity of hydrothermal petroleum maximizes during the early stages of thermal maturation. The diversity of compounds forming these UCMs then decreases with increasing dehydrogenation, dealkylation and condensation reactions associated with elevated thermal stress and exposure to oxidants within the hydrothermal fluids. [Copyright &y& Elsevier]

Abstract: The accurate establishment of oil similarity is a longstanding problem in petroleum geochemistry and a necessary component for resolving the architecture of an oil reservoir. Past limitations have included the excessive reliance on a relatively small number of biomarkers to characterize such complex fluids as crude oils. Here we use multiway principal components analysis (MPCA) on large numbers of specific chemical components resolved with comprehensive two-dimensional gas chromatography-flame ionization detection (GC×GC–FID) to determine the molecular relatedness of eight different maltene fractions of crude oils. MPCA works such that every compound eluting within the same first and second dimension retention time is quantitatively compared with what elutes at that same retention times within the other maltene fractions. Each maltene fraction and corresponding MPCA analysis contains upwards of 3500 quantified components. Reservoir analysis included crude oil sample pairs from around the world that were collected sequentially at depth within a single well, collected from multiple depths in the same well, and from different depths and different wells but thought to be intersected by the same permeable strata. Furthermore, three different regions of each GC×GC–FID chromatograms were analysed to evaluate the effectiveness of MPCA to resolve compositional changes related to the source of the oil generating sediments and its exposure to biological and/or physical weathering processes. Compositional and instrumental artefacts introduced during sampling and processing were also quantitatively evaluated. We demonstrate that MPCA can resolve multi-molecular differences between oil samples as well as provide insight into the overall molecular relatedness between various crude oils. [Copyright &y& Elsevier]

Abstract: Persistent organic pollutants such as halogenated aromatic hydrocarbons (HAHs) biomagnify in food webs and accumulate to high concentrations in top predators like odontocete cetaceans (toothed whales). The most toxic HAHs are the 2,3,7,8-substituted halogenated dibenzo-p-dioxins and furans, and non-ortho-substituted polychlorinated biphenyls (PCBs), which exert their effects via the aryl hydrocarbon receptor (AHR). Understanding the impact of HAHs in wildlife is limited by the lack of taxon-specific information about the relative potencies of toxicologically important congeners. To assess whether Toxic Equivalency Factors (TEFs) determined in rodents are predictive of HAH relative potencies in a cetacean, we used beluga and mouse AHRs expressed in vitro from cloned cDNAs to measure the relative AHR-binding affinities of ten HAHs from five different structural classes. The rank order of mean IC50s for competitive binding to beluga AHR was: TCDD

Abstract: Determination of connectivity is of primary importance in petroleum reservoir characterization. Lack of connectivity can occur when the communication between two oil-producing zones is restricted. This subsurface condition is referred to as reservoir compartmentalization. Recognition of compartmentalization is often achieved by establishing whether two or more oils have the same molecular composition and hence are consistent with an equilibrium condition within a reservoir. Gas chromatography (GC) is one standard technique used to measure oil similarity. However, it is severely limited in the number of compounds that can be resolved in fluids as complex as oil. Comprehensive two-dimensional gas chromatography (GC×GC) greatly expands the resolution of compounds in such complex mixtures. In this study, GC×GC was used to compare the molecular compositions of two pairs of oil samples collected directly at depth within a reservoir drill hole. The first pair was sequentially sampled at the same depth and should represent the same oil. The second pair was collected from two different wells that were intersected by a permeable sedimentary horizon. The four samples were compared to each other and to a control sample using a novel comparative technique involving the separation of oil compositions into compound classes that are compared across a series of retention index ranges. These techniques were used to determine the compositional similarity of two or more oils, providing a more complete compositional comparison than possible with gas chromatography–mass spectrometry (GC–MS) and GC–flame ionization detection (GC–FID). [Copyright &y& Elsevier]

Standards, total lipid extracts and crudely fractionated samples as well as extensively purified alkenone references were analyzed by conventional single column gas chromatography (GC), selective two-dimensional GC (GC–GC), comprehensive two-dimensional GC (GC×GC) and high resolution mass spectrometry (HRMS). U37K′ indices, defined as [C37:2]/[C37:2+C37:3], for independently analyzed standards showed GC–GC average accuracy of 0.014 and precision ±0.008 and HRMS average accuracy of 0.001 and precision ±0.007. The HRMS limit of precision is approximately ±0.008 for “real world samples” applied to the MS probe at greater than a few nanograms of the lesser alkenone component. Both of the two-dimensional GC techniques and HRMS indicate the presence of coeluting compounds in typical alkenone fractions that are not resolved by single dimensional GC. U37K′ indices measured by GC–GC, GC×GC and HRMS for total lipid extracts were generally observed to have lower U37K′ indices than their purified alkenone fractions. [Copyright &y& Elsevier]

Abstract Anthropogenic molecular markers were used to assess chemicals inputs and ecological risks associated from multiple sources to sediments in one of the largest tropical mangrove forests of South America, with a particular focus on lesser studied compounds resulting from rural activities. Total concentrations ranged from 23.4 to 228.2 ng g−1 for polycyclic aromatic hydrocarbons (∑ PAHs), 750.4 to 5912.5 ng g−1 for aliphatic hydrocarbons (∑ AHs), 32.4 to 696.6 ng g−1 for pesticides (∑ pesticides), 23.1 to 2109.7 ng g−1 for coprostanol and sterols (∑ sterols), 139.3 to 580.2 ng g−1 for naturals hormones (∑ natural hormones) and 334.1 to 823.4 ng g−1 for synthetics hormones (∑ synthetic hormones). The PAHs and AHs used as traditional anthropogenic markers showed a mixture between natural and anthropogenic sources, related mainly to inputs from higher plants, phytoplankton and both, biomass and petroleum combustion. Rural activities linked to agricultural pest control are the predominant source of pesticides, although minor inputs from pesticides used in urban public health campaigns and household activities were also detected. Synthetic hormones levels are two to three orders of magnitude greater than natural hormones levels and no correlations were observed between the main sewage markers and synthetic hormone concentrations, rural activities such as animal husbandry, which use drugs in management, may be the predominant anthropogenic sources of these compounds in the region. Traditional markers failed to detect ecological risks in rural areas, where synthetic substances (e.g. pesticides and hormones) are widely used and introduced in the environment. Graphical abstract Unlabelled Image Highlights • Traditional anthropogenic markers are not sufficient for distinguishing inputs from rural agricultural activities. • First observations of high levels of synthetic hormones in an area with rural activities linked to animal husbandry. • Traditional organic markers failed to detect ecological risks in rural areas. • Synthetics hormones and pesticides are able to trace the influence of multiple anthropogenic activities from rural activities. [ABSTRACT FROM AUTHOR]

Abstract A recent paper delineated the variations in crude oil in five oilfields (seven reservoirs); large differences in biodegradation and water washing were reported in accord with expectations of the spill-fill sequence of trap filling [1]. Here, the deepest oilfield, Catcher, with the best quality crude oil is examined in detail. Among different oilfields, the extent of water washing is tightly coupled to the extent of (ongoing) biodegradation. Moreover, in-reservoir gradients of biodegradation and water washing are also highly correlated supporting the previous finding that, for cases of ongoing biodegradation, water washing can be assisted by biodegradation. Further support for this process is obtained with a detailed analysis of alkylbenzenes and alkylnaphthalenes that show elimination in accordance with water solubility, yet scale with the extent of biodegradation. Ongoing biodegradation accelerates water washing; once water-soluble components enter the aquifer, they are consumed by microbes maintaining a flux of these components into the aquifer and eliminating the corresponding need for (slow) diffusion of these components away from the oil-water contact. In addition, the oil gradient in the Catcher oilfield is affected by the change in biodegradation of the crude oil spilling into Catcher from a deeper, subsiding reservoir causing a large gradient at the top of the oil column. Factors that determine oil type in charge are discussed. This paper extends the range of measurement of water washing in these reservoirs to a factor 10,000 in water solubility. All data herein are consistent with biodegradation and biodegradation-assisted water washing occurring in reservoir, not in migration. [ABSTRACT FROM AUTHOR]

Coastal ecosystems are facing increasing anthropogenic stressors, including rapid urbanization rates and extensive fossil fuel usage. Nevertheless, the distribution of hydrocarbons in the Brazilian semi-arid region remains relatively uncharacterized. In this study, we analyzed ten surface sediment samples (0–2 cm) along the banks of the Acaraú River to assess the chronic contributions of aliphatic and aromatic hydrocarbons. The Acaraú River is a crucial riverine-estuarine area in the semi-arid region of Northeast Brazil. Ultrasound-assisted extraction and gas chromatograph coupled to a mass spectrometer were used to identify target compounds: 45 PAHs, 27 n -alkanes (C 10 –C 38), and two isoprenoids. At most stations, the predominant grain size was sand, and the organic carbon content was less than 1%. The total n -alkanes concentration ranged from 14.1 to 170.0 μg g−1, while individual pristane and phytane concentrations ranged from not detected (nd) to 0.4 μg g−1 and nd to 0.7 μg g−1, respectively. These concentrations resemble those found in unpolluted sediments and are lower compared to samples from urbanized coastal areas. The total USEPA PAHs concentration varied from 157.8 to 1364 ng g−1, leading to the characterization of sediment samples as moderately polluted. Based on diagnostic ratios calculated from both alkane and PAH concentrations, the sediment samples were predominantly deriving from pyrolytic sources, with some contribution from petrogenic sources. The most abundant group was 5-ring PAHs (mean: 47.3 ± 36.7%), followed by 3-ring PAHs (mean: 17.9 ± 13.7%). This predominance indicates a pyrolytic origin of hydrocarbons in the Acaraú River. The concentrations reported here were representative of the level of background hydrocarbons in the region. Regarding the sediment quality assessment, BaP TPE calculated for the Acaraú River ranged from 13.2 to 1258.4 ng g−1 (mean: 409.3 ± 409.4 ng g−1). When considering site-specific sediment quality values for the coast of the state of Ceará, half of the stations are classified as strongly contaminated, and toxic effects are expected to occur (SQGq >0.25) for the ∑16 PAHs measured in the samples, especially due to dibenz [a,h]anthracene concentrations. [Display omitted] • Aliphatic and aromatic hydrocarbons were determined in surface sediment samples in Brazilian semi-arid. • Aliphatic hydrocarbon assessments point to both biogenic and petrogenic sources. • PAH diagnostic ratios were generally indicative of a pyrolytic origin. • Half of the stations in the Acaraú River are classified as heavily contaminated and toxicity was associated mainly with dibenz [a,h]anthracene. • Findings provide baseline data for further research on chronic pollution in semi-arid region. [ABSTRACT FROM AUTHOR]

Following the Deepwater Horizon (DWH) blowout in 2010, oil floated on the Gulf of Mexico for over 100 days. In the aftermath of the accumulation of partially oxidized surface oil was reported, but the pathways that formed these oxidized residues are poorly constrained. Here we provide five quantitative lines of evidence demonstrating that oxidation by sunlight largely accounts for the partially oxidized surface oil. First, residence time on the sunlit sea surface, where photochemical reactions occur, was the strongest predictor of partial oxidation. Second, two-thirds of the partial oxidation from 2010 to 2016 occurred in less than 10 days on the sunlit sea surface, prior to coastal deposition. Third, multiple diagnostic biodegradation indices, including octadecane to phytane, suggest that partial oxidation of oil on the sunlit sea surface was largely driven by an abiotic process. Fourth, in the laboratory, the dominant photochemical oxidation pathway of DWH oil was partial oxidation to oxygenated residues rather than complete oxidation to CO2. Fifth, estimates of partial photo-oxidation calculated with photochemical rate modeling overlap with observed oxidation. We suggest that photo-oxidation of surface oil has fundamental implications for the response approach, damage assessment, and ecosystem restoration in the aftermath of an oil spill, and that oil fate models for the DWH spill should be modified to accurately reflect the role of sunlight. [ABSTRACT FROM AUTHOR]

Optimization of production depends heavily on crude oil composition and its variation within and across multiple reservoirs. In particular, asphaltene content has enormous impact on crude oil viscosity and the economic value of reservoir fluids. Thus, it is important to understand the primary controls on crude oil composition and asphaltene distributions in reservoirs. This paper examines a complex oilfield in the North Sea that contains seven separate reservoirs. The crude oil is believed to have spilled from deeper into shallower reservoirs during reservoir charging. In-situ asphaltene content is measured by downhole fluid analysis (DFA) and is generally consistent with a spill-fill sequence in reservoir charging. Detailed compositional analysis of crude oil samples by comprehensive two-dimensional gas chromatography (GC × GC) was used to determine the extent of water washing, biodegradation and thermal maturity among the reservoirs. Increased biodegradation and water washing in the shallower reservoirs is consistent with a spill-fill sequence. Aromatic and alkylated aromatic compounds decrease according to a combination of water solubility and susceptibility to biodegradation in the shallower reservoirs. Four thermal maturity biomarker ratios show that the shallower reservoirs contain less mature oil, consistent with a spill-fill sequence. The combination of DFA for bulk compositional analysis and GC × GC for detailed compositional analysis combined with geochemical interpretation is an effective tool to unravel complex oilfield scenarios. [ABSTRACT FROM AUTHOR]

Unconventional natural gas development (UNGD) generates large volumes of wastewater, the detailed composition of which must be known for adequate risk assessment and treatment. In particular, transformation products of geogenic compounds and disclosed additives have not been described. This study investigated six Fayetteville Shale wastewater samples for organic composition using a suite of one- and two-dimensional gas chromatographic techniques to capture a broad distribution of chemical structures. Following the application of strict compound-identification-confidence criteria, we classified compounds according to their putative origin. Samples displayed distinct chemical distributions composed of typical geogenic substances (hydrocarbons and hopane biomarkers), disclosed UNGD additives (e.g., hydrocarbons, phthalates such as diisobutyl phthalate, and radical initiators such as azobis(isobutyronitrile)), and undisclosed compounds (e.g., halogenated hydrocarbons, such as 2-bromohexane or 4-bromoheptane). Undisclosed chloromethyl alkanoates (chloromethyl propanoate, pentanoate, and octanoate) were identified as potential delayed acids (i.e., those that release acidic moieties only after hydrolytic cleavage, the rate of which could be potentially controlled), suggesting they were deliberately introduced to react in the subsurface. In contrast, the identification of halogenated methanes and acetones suggested that those compounds were formed as unintended byproducts. Our study highlights the possibility that UNGD operations generate transformation products and underscores the value of disclosing additives injected into the subsurface. [ABSTRACT FROM AUTHOR]

Widespread bottom trawling on the NW Iberian shelf causes chronic sediment and habitat disturbance. The few studies that have investigated vessel-modified sedimentary-structure and texture of the seabed have typically classified their results as being either impacted by trawling or not. This study indicates that bottom trawling can result in a sequence of vastly different effects to the lithology of seabed sediment, which have in turn different ecological consequences. Here, we combined very high-resolution spatial bottom-trawling data with sedimentological (grain size, porosity) and geochemical datasets (excess 210 Pb, 3D petroleum fingerprinting) to study sediment disturbance, including sorting and mixing. Our results were used to develop five conceptual disturbance scenarios: minimal seabed effects, sediment overturning, complete sediment mixing, sediment grading and layering, and loss of sediment. Considering that bottom trawling is a widespread and growing global fishing technique, such impacts need to be considered in the management of habitat conservation as well as in the reconstruction of late Holocene climate history from shallow-water deposits, not just on the NW Iberian shelf, but also globally. [ABSTRACT FROM AUTHOR]

Hundreds of organic chemicals are used during natural gas extraction via high-volume hydraulic fracturing (HVHF). However, it is unclear whether these chemicals, injected into deep shale horizons, reach shallow groundwater aquifers and affect local water quality, either from those deep HVHF injection sites or from the surface or shallow subsurface. Here, we report detectable levels of organic compounds in shallow groundwater samples from private residential wells overlying the Marcellus Shale in northeastern Pennsylvania. Analyses of purgeable and extractable organic compounds from 64 groundwater samples revealed trace levels of volatile organic compounds, well below the Environmental Protection Agency's maximum contaminant levels, and low levels of both gasoline range (0-8 ppb) and diesel range organic compounds (DRO; 0-157 ppb). A compound-specific analysis revealed the presence of bis(2-ethylhexyl) phthalate, which is a disclosed HVHF additive, that was notably absent in a representative geogenic water sample and field blanks. Pairing these analyses with (i) inorganic chemical fingerprinting of deep saline groundwater, (ii) characteristic noble gas isotopes, and (iii) spatial relationships between active shale gas extraction wells and wells with disclosed environmental health and safety violations, we differentiate between a chemical signature associated with naturally occurring saline ground-water and one associated with alternative anthropogenic routes from the surface (e.g., accidental spills or leaks). The data support a transport mechanism of DRO to groundwater via accidental release of fracturing fluid chemicals derived from the surface rather than subsurface flow of these fluids from the underlying shale formation. [ABSTRACT FROM AUTHOR]

The sinking of the Deepwater Horizon in the Gulf of Mexico led to uncontrolled emission of oil to the ocean, with an official government estimate of ~5.0 million barrels released. Among the pressing uncertainties surrounding this event is the fate of ~2 million barrels of submerged oil thought to have been trapped in deep-ocean intrusion layers at depths of ~1,000-1,300 m. Here we use chemical distributions of hydrocarbons in >3,000 sediment samples from 534 locations to describe a footprint of oil deposited on the deep-ocean floor. Using a recalcitrant biomarker of crude oil, 17α(H),21β(H)-hopane (hopane), we have identified a 3,200-km² region around the Macondo Well contaminated by ~1.8 ± 1.0 × 106 g of excess hopane. Based on spatial, chemical, oceanographic, and mass balance considerations, we calculate that this contamination represents 4-31% of the oil sequestered in the deep ocean. The pattern of contamination points to deep-ocean intrusion layers as the source and is most consistent with dual modes of deposition: a "bathtub ring" formed from an oil-rich layer of water impinging laterally upon the continental slope (at a depth of ~900-1,300 m) and a higher-flux "fallout plume" where suspended oil particles sank to underlying sediment (at a depth of ~1,300-1,700 m). We also suggest that a significant quantity of oil was deposited on the ocean floor outside this area but so far has evaded detection because of its heterogeneous spatial distribution. [ABSTRACT FROM AUTHOR]

Biodegradation plays a major role in the natural attenuation of oil spills. However, limited information is available about biodegradation of different saturated hydrocarbon classes in surface environments, despite that oils are composed mostly of saturates, due to the limited ability of conventional gas chromatography (GC) to resolve this compound group. We studied eight weathered oil samples collected from four Gulf of Mexico beaches 12-19 months after the Deepwater Horizon disaster. Using comprehensive two-dimensional gas chromatography (GC×GC), we successfully separated, identified, and quantified several distinct saturates classes in these samples. We find that saturated hydrocarbons eluting after n-C22 dominate the GC-amenable fraction of these weathered samples. This compound group represented 8-10%, or 38-68 thousand metric tons, of the oil originally released from Macondo well. Saturates in the n-C22 to n-C29 elution range were found to be partly biodegraded, but to different relative extents, with ease of biodegradation decreasing in the following order: n-alkanes > methylalkanes and alkylcyclopentanes+alkylcyclohexanes > cyclic and acyclic isoprenoids. We developed a new quantitative index designed to characterize biodegradation of >n-C22 saturates. These results shed new light onto the environmental fate of these persistent, hydrophobic, and mostly overlooked compounds in the unresolved complex mixtures (UCM) of weathered oils. [ABSTRACT FROM AUTHOR]

Highlights: [•] Asphaltene structures in Yen-Mullins model enable EoS for asphaltene gradients. [•] Flory-Huggins-Zuo EoS predicts asphaltene gradients in oilfield reservoirs. [•] ‘Downhole fluid analysis’ measures fluid gradients in oilfield reservoirs. [•] Oilfield studies show new science and new technology resolve major field issues. [•] Traditional chemical methods corroborate new analyses. [Copyright &y& Elsevier]

To assess the potential impact of the Deepwater Horizon oil spill on offshore ecosystems, 11 sites hosting deep-water coral communities were examined 3 to 4 mo after the well was capped. Healthy coral communities were observed at all sites >20 km from the Macondo well, including seven sites previously visited in September 2009, where the corals and communities appeared unchanged. However, at one site 11 km southwest of the Macondo well, coral colonies presented widespread signs of stress, including varying degrees of tissue loss, sclerite enlargement, excessmucous production, bleached commensal ophiuroids, and covering by brown flocculent material (floc). On the basis of these criteria the level of impact to individual colonies was ranked from 0 (least impact) to 4 (greatest impact). Of the 43 corals imaged at that site, 46% exhibited evidence of impact onmore than half of the colony,whereas nearly a quarter of all of the corals showed impact to >90% of the colony. Additionally, 53% of these corals' ophiuroid associates displayed abnormal color and/or attachment posture. Analysis of hopanoid petroleumbiomarkers isolated from the floc provides strong evidence that this material contained oil from the Macondowell. The presence of recently damaged and deceased corals beneath the path of a previously documented plume emanating from the Macondo well provides compelling evidence that the oil impacted deep-water ecosystems. Our findings underscore the unprecedented nature of the spill in terms of its magnitude, release at depth, and impact to deep-water ecosystems. [ABSTRACT FROM AUTHOR]