Hydrocarbon Decay Research Articles

Post - sedimentation influence on filtration capacity reservoir rock properties (Pur-Tazov oil\\gas-bearing area)

The processes of the second mineral formation (kaolinite, carbonates and micas) were identified during the post-sedimentation transformation studies in oil\\gas deposits. Besides, quartz regeneration, solid product destructive formation processes and hydrocarbon oxidation processes were -determined. Correlation analysis of the mineralogy and petrophysics data revealed the post-sedimentation influence factors on the reservoir properties of deposits. It should be noted that the second kaolinite composition increase results in water saturation and density decrease, porosity and, especially, permeability increase. Quartz regeneration and second mica formation deteriorate the reservoir properties or poorly influence them. The hydrocarbon decay and oxidation products, as well as secondary carbonate seal the void space, replace the soluble rock debris and sharply deteriorate the reservoir properties of oil andgas deposits.

Migration and fate of ethanol-enhanced gasoline in groundwater: A modelling analysis of a field experiment

Ethanol use as a gasoline additive is increasing, as are the chances of groundwater contamination caused by gasoline releases involving ethanol. To evaluate the impact of ethanol on dissolved hydrocarbon plumes, a field test was performed in which three gasoline residual sources with different ethanol fractions (E0: no ethanol, E10: 10% ethanol and E95: 95% ethanol) were emplaced below the water table. Using the numerical model BIONAPL/3D, the mass discharge rates of benzene, toluene, ethylbenzene, xylenes, trimethylbenzenes and naphthalene were simulated and results compared to those obtained from sampling transects of multilevel samplers. It was shown that ethanol dissolved rapidly and migrated downgradient as a short slug. Mass discharge of the hydrocarbons from the E0 and E10 sources suggested similar first-order hydrocarbon decay rates, indicating that ethanol from E10 had no impact on hydrocarbon degradation. In contrast, the estimated hydrocarbon decay rates were significantly lower when the source was E95. For the E0 and E10 cases, the aquifer did not have enough oxygen to support complete mineralization of the hydrocarbon compounds to the extent suggested by the field-based mass discharge. Introducing a heterogeneous distribution of hydraulic conductivity did little to overcome this discrepancy. A better match between the numerical model and the field data was obtained assuming partial degradation of the hydrocarbons to intermediate compounds. Besides depending on the ethanol concentration, the impact of ethanol on hydrocarbon degradation appears to be highly dependent on the availability of electron acceptors.

Primor’ye as a new promising region of Russia with gold-palladium-platinum ore mineralization of a nontraditional type

The following regionally distributed contact-metamorphosed metalliferous sediments occur in association with each other in the lower part (Upper Olenekian‐Ladinian) of the Triassic siliceous formation of the Sikhote-Alin, which is enriched in carbon: manganese‐silicate (metamorphosed siliceous‐rhodochrosite) rocks, “brown cherts” (cherts with pyrophanite and spessartine), tin‐iron ores, “ilmenite‐biotite‐feld spar” (metamorphosed argillous) rocks, and “itabirites” (gold-bearing jaspers). These rocks occur in association with the products of hydrothermal regeneration composing bodies of different morphology and composition, including deposits of manganiferous skarnlike (amphibole‐pyroxene) rocks and skarns [1‐3]. Metalliferous sediments and products of their regeneration contain nickel and cobalt sulfides, arsenides, antimonides, tellurides, sulfoarsenids, sulfoantimonides and sulfotellurides, minerals of rare earth elements, thorium, uranium, barium, vanadium, and other minerals. Furthermore, reduced forms of different metals are common: native elements, solid solutions, intermetallic compounds, phosphides, and silicides. Associations of the reduced forms occur in pores and microsize fissures with organic matter. They were formed during the contact-metamorphic process under high temperatures (according to the admixture concentration level of several elements in native metals) accompanied by hydrocarbon decay and hydrogen reducing of oxidized forms. In view of the degree of the metalliferous rock distribution and the usual presence in it of minerals of Au, Ag, Pt, and Pd (a separate publication devoted to these minerals has been prepared [5]), the question of the concentration level of noble metals in these rocks becomes very important. Analyses performed earlier [1, 3] could not give an unambiguous answer to this question. Although they revealed high concentrations of Au, Pt, and Pd in separate samples, they characterized only manganese‐silicate rocks, their amount was insufficient, and reproducibility was weak. The concentrations of Au and Pt were found to be lower (one order of magnitude or more) than was expected according to the results of the investigation of mineral forms and dissolution of samples in hydrofluoric acid. The following three analytical methods have been used in the present work: fire assay with atomic absorption (AA) finishing, ICP-MS, and AA. The results of the fire assay analysis were found to contradict the data from the microprobe investigation and dissolution of samples in hydrofluoric acid. As was established during the microprobe investigation of the cinder, the losses were connected with

Assessing in situ rates of anaerobic hydrocarbon bioremediation

SummaryIdentifying metabolites associated with anaerobic hydrocarbon biodegradation is a reliable way to garner evidence for the intrinsic bioremediation of problem contaminants. While such metabolites have been detected at numerous sites, the in situ rates of anaerobic hydrocarbon decay remain largely unknown. Yet, realistic rate information is critical for predicting how long individual contaminants will persist and remain environmental threats. Here, single‐well push–pull tests were conducted at two fuel‐contaminated aquifers to determine the in situ biotransformation rates of a suite of hydrocarbons added as deuterated surrogates, including toluene‐d8, o‐xylene‐d10, m‐xylene‐d10, ethylbenzene‐d5 (or ‐d10), 1, 2, 4‐trimethylbenzene‐d12, 1, 3, 5‐trimethylbenzene‐d12, methylcyclohexane‐d14 and n‐hexane‐d14. The formation of deuterated fumarate addition and downstream metabolites was quantified and found to be somewhat variable among wells in each aquifer, but generally within an order of magnitude. Deuterated metabolites formed in one aquifer at rates that ranged from 3 to 50 µg l−1 day−1, while the comparable rates at another aquifer were slower and ranged from 0.03 to 15 µg l−1 day−1. An important observation was that the deuterated hydrocarbon surrogates were metabolized in situ within hours or days at both sites, in contrast to many laboratory findings suggesting that long lag periods of weeks to months before the onset of anaerobic biodegradation are typical. It seems clear that highly reduced conditions are not detrimental to the intrinsic bioremediation of fuel‐contaminated aquifers.

Field metabolomics and laboratory assessments of anaerobic intrinsic bioremediation of hydrocarbons at a petroleum‐contaminated site

SummaryField metabolomics and laboratory assays were used to assess the in situ anaerobic attenuation of hydrocarbons in a contaminated aquifer underlying a former refinery. Benzene, ethylbenzene, 2‐methylnaphthalene, 1,2,4‐ and 1,3,5‐trimethylbenzene were targeted as contaminants of greatest regulatory concern (COC) whose intrinsic remediation has been previously reported. Metabolite profiles associated with anaerobic hydrocarbon decay revealed the microbial utilization of alkylbenzenes, including the trimethylbenzene COC, PAHs and several n‐alkanes in the contaminated portions of the aquifer. Anaerobic biodegradation experiments designed to mimic in situ conditions showed no loss of exogenously amended COC; however, a substantive rate of endogenous electron acceptor reduction was measured (55 ± 8 µM SO4 day−1). An assessment of hydrocarbon loss in laboratory experiments relative to a conserved internal marker revealed that non‐COC hydrocarbons were being metabolized. Purge and trap analysis of laboratory assays showed a substantial loss of toluene, m‐ and o‐xylene, as well as several alkanes (C6–C12). Multiple lines of evidence suggest that benzene is persistent under the prevailing site anaerobic conditions. We could find no in situ benzene intermediates (phenol or benzoate), the parent molecule proved recalcitrant in laboratory assays and low copy numbers of Desulfobacterium were found, a genus previously implicated in anaerobic benzene biodegradation. This study also showed that there was a reasonable correlation between field and laboratory findings, although with notable exception. Thus, while the intrinsic anaerobic bioremediation was clearly evident at the site, non‐COC hydrocarbons were preferentially metabolized, even though there was ample literature precedence for the biodegradation of the target molecules.

Night‐time NO3 and OH radical concentrations in the United Kingdom inferred from hydrocarbon measurements

AbstractThe hydrocarbon decay method (Rivett et al., 2003) has been used to analyse hydrocarbon data from four contrasting sites in the United Kingdom to estimate night‐time levels of NO3 and OH. Remarkably consistent results emerge using alkenes, revealing NO3 and OH levels in the range of 0.01–10 ppt and 1 × 104 − 1 × 106 molecule cm−3, respectively. Weak seasonal cycles are observed where NO3 levels peak in spring and OH in summer. Analysis using alkanes suggests that Cl atom levels of around 2 × 104 molecule cm−3 may be present. How Cl may be formed at night in such high quantities is unknown and may not be the answer to the disparity between the two methods. Copyright © 2008 Royal Meteorological Society

Oil spill in the Río de la Plata estuary, Argentina: 2-hydrocarbon disappearance rates in sediments and soils

The 6-month assessment of the oil spill impact in the Río de la Plata described in the preceding paper [Colombo, J.C., Barreda, A., Bilos, C., Cappelletti, N., Demichelis, S., Lombardi, P., Migoya, M.C., Skorupka, C., Suárez, G., 2004. Oil spill in the Río de la Plata estuary, Argentina: 1 – biogeochemical assessment of waters, sediments, soils and biota. Environmental Pollution] was followed by a 13- and 42-month campaigns to evaluate the progress of hydrocarbon decay. Average sediment hydrocarbon concentrations in each sampling include high variability (85–260%) due to contrasting site conditions, but reflect a significant overall decrease after 3 years of the spill: 17 ± 27, 18 ± 39 to 0.54 ± 1.4 μg g −1 for aliphatics; 0.44 ± 0.49, 0.99 ± 1.6 to 0.04 ± 0.03 μg g −1 for aromatics at 6, 13 and 42 months, respectively. Average soil hydrocarbon levels are 100–1000 times higher and less variable (61–169%) than sediment values, but display a clear attenuation: 3678 ± 2369, 1880 ± 1141 to 6.0 ± 10 μg g −1 for aliphatics and 38 ± 26, 49 ± 32 to 0.06 ± 0.04 μg g −1 for aromatics. Hydrocarbon concentrations modeled to first-order rate equations yield average rate constants of total loss (biotic + abiotic) twice as higher in soils ( k = 0.18–0.19 month −1) relative to sediments (0.08–0.10 month −1). Individual aliphatic rate constants decrease with increasing molecular weight from 0.21 ± 0.07 month −1 for isoprenoids and < n-C22 to 0.10 ± 0.08 month −1 for > n-C27, similar to hopanes (0.10 ± 0.05 month −1). Aromatics disappearance rates were more homogeneous with higher values for methylated relative to unsubstituted species (0.17 ± 0.05 vs. 0.12 ± 0.05 months −1). Continued hydrocarbon inputs, either from biogenic (algal n-C15,17; vascular plant n-C27,29) or combustion related sources (fluoranthene and pyrene), appear to contribute to reduced disappearance rate. According to the different loss rates, hydrocarbons showed clear compositional changes from 6–13 to 42 months. Aliphatics disappearance rates and compositional changes support an essentially microbiologically-mediated recovery of coastal sediments to pre-spill conditions in a 3–4 year period. The lower rates and more subtle compositional changes deduced for aromatic components, suggest a stronger incidence of physical removal processes.

Removal of NOxand NOyin Asian outflow plumes: Aircraft measurements over the western Pacific in January 2002

The Pacific Exploration of Asian Continental Emission Phase A (PEACE‐A) aircraft measurement campaign was conducted over the western Pacific in January 2002. Correlations of carbon monoxide (CO) with carbon dioxide (CO2) and back trajectories are used to identify plumes strongly affected by Asian continental emissions. ΔCO/ΔCO2ratios (i.e., linear regression slopes of CO‐CO2) in the plumes generally fall within the variability range of the CO/CO2emission ratios estimated from an emission inventory for east Asia, demonstrating the consistency between the aircraft measurements and the emission characterization. Removal rates of reactive nitrogen (NOxand NOy) for the study region (altitude &lt;4 km, 124°–140°E, 25°–45°N) are estimated using the correlation with CO2, the photochemical age of the plumes, and the NOx/CO2emission ratio derived from the emission inventory. The plume age is estimated from the rates of hydrocarbon decay and hydroxyl radical (OH) concentration calculated using a constrained photochemical box model. The average lifetime of NOxis estimated to be 1.2 ± 0.4 days. Possible processes controlling the NOxlifetime are discussed in conjunction with results from earlier studies. The average lifetime of NOyis estimated to be 1.7 ± 0.5 days, which is comparable to the NOylifetime of 1.7–1.8 days that has been previously reported for outflow from the United States. This similarity suggests the importance of chemical processing near the source regions in determining the NOyabundance.

Validation of the calibration of a laser-induced fluorescence instrument for the measurement of OH radicals in the atmosphere

Abstract. An assessment of the accuracy of OH concentrations measured in a smog chamber by a calibrated laser-induced fluorescence (LIF) instrument has been made, in the course of 9 experiments performed to study the photo-oxidation of benzene, toluene, 1,3,5-trimethylbenzene, para-xylene, ortho-cresol and ethene at the European Photoreactor facility (EUPHORE). The LIF system was calibrated via the water photolysis / ozone actinometry approach. OH concentrations were inferred from the instantaneous rate of removal of each hydrocarbon species (measured by FTIR or HPLC) via the appropriate rate coefficient for their reaction with OH, and compared with those obtained from the LIF system. Good agreement between the two approaches was found for all species with the exception of 1,3,5-trimethylbenzene, for which OH concentrations inferred from hydrocarbon removal were a factor of 3 lower than those measured by the LIF system. From the remaining 8 experiments, an overall value of 1.15±0.13 (±1σ) was obtained for [OH]LIF / [OH]Hydrocarbon Decay, compared with the estimated uncertainty in the accuracy of the water photolysis / ozone actinometry OH calibration technique of 26% (1σ).

Combustion aerosol water content and its effect on polycyclic aromatic hydrocarbon reactivity

A linear relationship was observed between particle water uptake and relative humidity for aerosol samples collected on Teflon coated glass fiber filters. Gasoline soot and wood smoke sample weight increases were three to five times greater than diesel soot weight increases at comparable relative humidities. Lower limit estimates of wood smoke water content at 90% relative humidity were in the 5–10% range. Based on these results polycyclic aromatic hydrocarbon photodegradation was investigated in liquid mixtures of actual wood smoke components with water content varied from 0 to 15%. Reaction rates of benz[a]anthracene and benzo[k]fluroanthene were significantly greater in methoxyphenol mixtures with 10% water content than in mixtures which did not contain water. Benzo[a]pyrene photodegradation was not significantly different. The results indicate that combustion particle water content increases with increasing relative humidity and that PAH photodegradation rates are likely to increase with increasing particle water content. This provides an explanation for previously described smog chamber studies in which a correlation between polycyclic aromatic hydrocarbon (PAH) decay in sunlight and water vapor concentration was reported.

Effect of Composition and State of Organic Components on Polycyclic Aromatic Hydrocarbon Decay in Atmospheric Aerosols

Effect of Composition and State of Organic Components on Polycyclic Aromatic Hydrocarbon Decay in Atmospheric Aerosols

Higher hydrocarbon combustion 1. Primary process in fuel-rich acetylene combustion

Computational results are presented supporting the suggestion that the primary process in fuel-rich acetylene combustion is reaction with OH to yield ketene, and that acetylene does not decay, primarily, through the methane family. The methodology for modeling higher hydrocarbon decay is discussed.

Mechanism of hydrocarbon decay in fuel-rich secondary reaction zones

Mole fraction profiles of stable species and free radicals have been measured using molecularbeam mass spectrometry in the secondary reaction zone of a near-sooting (=1.8) 2.67 kPa benzene-oxygen-argon flame. From the measurement of H, OH, O2, H2 and H2O mole fractions and the calculation of the O-atom mole fraction from a steady-state analysis Rxns. 2, 3 and 8 are near equilibrium in the presence of hydrocarbons. Rxn. 1 does not reach equilibrium. H+O2OH+O Rxn. 1 O+H2OH+H Rxn. 2 O+H2OOH+OH Rxn. 3 H+H2OOH+H2 Rxn. 8 Three types of hydrocarbon (HC) reactions were found to be equilibrated: (I) HC's with HC free radicals via hydrogen abstraction reactions, (II) polyacetylenes with C2H2 and H2, (III) odd-numbered HC radicals with C2H2 and H2. From these equilibria, ΔHf300o(C3H2)=531±13 kJ/mol and ΔHf300o (C5H3)=568±13 kJ/mol. From the concept of a HC pool, the decay of equilibrated hydrocarbons is found to be dominated by reactions of C2H2 and C4H2 with O and OH. A rate coefficient of k=1.3±0.3×1012 cm3 mol−1 s−1 is obtained for the OH+C2H2 reaction between 1700 and 1900 K.

Hydroxyl radical measurements in a photochemical reactor by laser‐induced fluorescence

AbstractMeasurements of hydroxyl radical (HO) concentrations in ambient air by the technique of laser‐induced fluorescence have been recently reported. The present study was undertaken to provide an independent test of the validity of those measurements. A photochemical reactor was used to provide a source of HO, and the concentration of HO in the reactor was determined by the laser‐induced fluorescence technique. The HO concentration was also deduced from measured hydrocarbon decay rates in the reactor. There was agreement between the HO concentrations obtained by these two different methods, thus providing further validation of the fluorescence method. Some studies of HO fluorescence efficiency as well as of possible interferences with the fluorescence measurements are reported.