Weathering of Oil in a Surficial Aquifer          下载免费PDF全文

Mary Jo Baedecker  Robert P. Eganhouse  Haiping Qi  Isabelle M. Cozzarelli  Jared J. Trost  Barbara A. Bekins 《Ground water》2018,56(5):797-809

The composition of crude oil in a surficial aquifer was determined in two locations at the Bemidji, MN, spill site. The abundances of 71 individual hydrocarbons varied within 16 locations sampled. Little depletion of these hydrocarbons (relative to the pipeline oil) occurred in the first 10 years after the spill, whereas losses of 25% to 85% of the total measured hydrocarbons occurred after 30 years. The C_6‐30 n‐alkanes, toluene, and o‐xylene were the most depleted hydrocarbons. Some hydrocarbons, such as the n‐C_10–24 cyclohexanes, tri‐ and tetra‐ methylbenzenes, acyclic isoprenoids, and naphthalenes were the least depleted. Benzene was detected at every sampling location 30 years after the spill. Degradation of the oil led to increases in the percent organic carbon and in the δ ¹³C of the oil. Another method of determining hydrocarbon loss was by normalizing the total measured hydrocarbon concentrations to that of the most conservative analytes. This method indicated that the total measured hydrocarbons were depleted by 47% to 77% and loss of the oil mass over 30 years was 18% to 31%. Differences in hydrocarbon depletion were related to the depth of the oil in the aquifer, local topography, amount of recharge reaching the oil, availability of electron acceptors, and the presence of less permeable soils above the oil. The results from this study indicate that once crude oil has been in the subsurface for a number of years there is no longer a “starting oil concentration” that can be used to understand processes that affect its fate and the transport of hydrocarbons in groundwater.  相似文献   

Evolution of cutoffs across meander necks in Powder River,Montana, USA     

Glenn R. Gay  Hubert H. Gay  William H. Gay  Holly A. Martinson  Robert H. Meade  John A. Moody 《地球表面变化过程与地形》1998,23(7):651-662

Over a period of several decades, gullies have been observed in various stages of forming, growing and completing the cutoff of meander necks in Powder River. During one episode of overbank flow, water flowing over the down-stream bank of the neck forms a headcut. The headcut migrates up-valley, forming a gully in its wake, until it has traversed the entire neck, cutting off the meander. The river then follows the course of the gully, which is subsequently enlarged as the river develops its new channel. The complete process usually requires several episodes of high water: in only one of the five cases described herein was a meander cutoff initiated and completed during a single large flood. © 1998 John Wiley & Sons, Ltd.  相似文献   

Long-term influence of maritime access works on the distribution of cohesive sediments: analysis of historical and recent data from the Belgian nearshore area (southern North Sea)     

Michael Fettweis  Jean-Sébastien Houziaux  Isabelle Du Four  Vera Van Lancker  Cecile Baeteman  Mieke Mathys  Dries Van den Eynde  Frederic Francken  Stanislas Wartel 《Geo-Marine Letters》2009,29(5):321-330

  相似文献   

Fault throw determination using 4 component VSP: Aigion fault (Greece) case study     

Joachim Place  Charles Naville  Isabelle Moretti   《Tectonophysics》2007,440(1-4):141-158

The present paper presents the results of a technique based on Vertical Seismic Profiling (VSP) to quantify the offset of a fault in a context where seismic reflection profiles do not image any reflectors. The case study is located in Greece, in the Aigion area, on the south border of the Corinth Gulf. The Aigion fault, oriented East–West, and dipping at 60°N, has been intersected by the scientific well Aig-10 at 760 m in depth, but some uncertainty remained concerning its exact offset since the depth of the pre-rift sequence is open to debate due to the lack of subsurface data. The pre-rift consists of a Mesozoic low-porosity series (carbonates and radiolarite), while the syn-rift consists of poorly compacted conglomerates and turbidites.

Seismic diffractions on fault edges are expected to be present along the fault surface. We find that a few diffracted events are effectively recorded in P and S wave mode by the 4 components of the VSP survey, and critically refracted arrivals along the Aigion fault plane. These singular events have been used in order to refine the fault geometry and to determine its throw. Additionally, results from a 2D finite difference elastic seismic model of a single fault step geometry have been closely examined in order to illustrate the generation of the singular seismic events observed on the field data, such as P-wave and S-wave refracted and diffracted events, and support their interpretation with higher confidence. As a result, the seismic arrival patterns from full waveform seismic modelling confirm the characterisation of the main fault geometry (mainly its throw: about 200 m) in the well vicinity derived from the actual analysis of the 4 Component Aigion VSP data.  相似文献   

Preservation potential of highstand coastal sedimentary bodies in a macrotidal basin: Example from the Bay of Mont-Saint-Michel, NW France     

Isabelle Billeaud  Bernadette Tessier  Bruno Caline 《Sedimentary Geology》2007,202(4):754-775

  相似文献   

Cementation of kerogen-rich marls by alkaline fluids released during weathering of thermally metamorphosed marly sediments. Part I: Isotopic (C,O) study of the Khushaym Matruk natural analogue (central Jordan)     

Serge Fourcade  Laurent Trotignon  Philippe Boulvais  Isabelle Techer  Marcel Elie  Didier Vandamme  Elias Salameh  Hani Khoury 《Applied Geochemistry》2007

The Khushaym Matruk site in central Jordan may represent a natural analogue depicting the interaction of alkaline solutions with a clayey sedimentary formation or with clay-rich confining barriers at the interface with concrete structures in waste disposal sites. In this locality, past spontaneous combustion of organic matter in a clayey biomicritic formation produced a ca. 60 m-thick layer of cement-marble containing some of the high-temperature phases usually found in industrial cements (e.g., spurrite, brucite, and Ca-aluminate). A vertical cross-section of the underlying sediments was used in order to study the interaction between cement-marbles and neighbouring clayey limestones under weathering conditions. A thermodynamic approach of the alteration parageneses (calcite–jennite–afwillite–brucite and CSH phases) in the cement-marbles constrains the interacting solutions to have had pH-values between 10.5 and 12. Over 3 m, the sediments located beneath the metamorphic unit were compacted and underwent carbonation. They display large C and O isotopic variations with respect to “pristine” sediments from the bottom of the section. Low δ¹³C-values down to −31.4‰/PDB show the contribution of CO₂ derived from the oxidization of organic matter and from the atmosphere to the intense carbonation process affecting that particular sedimentary level. The size of the C isotopic anomalies, their geometrical extent and their coincidence with the variations of other markers like the Zn content, the structure of organic matter, the mineralogical composition, all argue that the carbonation process was induced by the percolation of high pH solutions which derived from the alteration of cement-marbles. The temperature of the carbonation process remains conjectural and some post-formation O isotopic reequilibration likely affected the newly-formed carbonate. Carbonation induced a considerable porosity reduction, both in fractures and matrixes. The Khushaym Matruk site may have some bearing to the early life of a repository site, when water saturation of the geological formations hosting the concrete structures is incomplete, enabling simultaneous diffusion of alkaline waters and gaseous CO₂ in the near field.  相似文献   

Cementation of kerogen-rich marls by alkaline fluids released during weathering of thermally metamorphosed marly sediments. Part II: Organic matter evolution,magnetic susceptibility and metals (Ti,Cr, Fe) at the Khushaym Matruk natural analogue (Central Jordan)     

Marcel Elie  Isabelle Techer  Laurent Trotignon  Hani Khoury  Elias Salameh  Didier Vandamme  Philippe Boulvais  Serge Fourcade 《Applied Geochemistry》2007

Spontaneous combustion, less than 1 Ma ago, affected a 60-m thick sediment pile of biomicrite at the Khushaym Matruck site (Jordan). The present study shows that three retrograde alteration stages occurred: weathering, thermal stress and oxidative alkaline perturbation. μ-FT-i.r. spectra of isolated kerogens and oxygen index of whole rocks indicate that oxidation of organic matter occurred down to ∼10 m beneath the metamorphosed zone at Khushaym Matruck. The occurrence of the oxidative weathering bacterially mediated, as suggested by the mass chromatograms of saturated hydrocarbons, can explain high Rock-Eval T_max values and low petroliferous potential measured along the sedimentary pile. On the other hand, the thermal extent of combustion events was limited to the first 2 m from the contact. The mean reflectance of 0.20–0.24% and porosity of ca. 50% of the grey clayey biomicrites indicate that organic matter was very immature and sediments were unconsolidated at the time of the combustion event. Using mineralogy, microscopic analyses of vegetable debris and magnetic susceptibility, a suite of characteristic points corresponding to the thermal imprint can be assessed: (i) x = 0m, T ∼ 1000 °C, (ii) x = 1 m, T ∼ 350 °C, (iii) x = 2 m, T ∼ 150 °C and (iv) x > ∼ 8 m, T ∼ 30 °C. Paleocirculation of meteoric groundwater in the ‘cement-marbles’ generated high-pH fluids that have circulated via fractures and through the matrix porosity of the underlying biomicrites but have also induced alkaline hydrolysis and oxidative attack of the organic matter. The polysaccharide/lignin ratio derived from μ-FT-i.r. analyses shows that the delignification of vegetable debris and degradation of polysaccharides progressively decline in the indurated zone, which indicates a decrease in the pH of migrating solutions. The latter also severely oxidized organic matter at 2.10 and 3.05 m as revealed by the oxygen index and induced the generation of bitumen. The spatial correlation between the oxidation levels of organic matter and the metal contents (Fe, Ti and Cr) suggests that redox reactions were responsible for the immobilization of metals in the indurated biomicrites. The intensity of these reactions is attributed to changes in the fluid flow regime within the sedimentary column.  相似文献   

Reconstitution des apports en éléments traces métalliques et bilan de leur migration dans un Luvisol sableux soumis à 100 ans d'irrigation massive par des eaux usées brutes     

Christelle Dère  Isabelle Lamy  Folkert van Oort  Denis Baize  Sophie Cornu 《Comptes Rendus Geoscience》2006,338(8):565-573

Raw wastewaters were massively spread on sandy luvisols near Paris from 1899 to 2002, leading to high trace metals (TM) pollution of soils. Mass balance calculations were performed on a soil profile to assess vertical migration of TM. The contamination was estimated by subtracting the natural pedo-geochemical background of the horizons. TM inputs were estimated using Cr as an invariant. It is shown that Pb and Cr remained in the surface horizon, while Ni, Cd, Cu and Zn migrated downward, being more or less trapped depending on the physicochemical properties of the horizons. To cite this article: C. Dère et al., C. R. Geoscience 338 (2006).  相似文献   

From the green color of eskolaite to the red color of ruby: an X-ray absorption spectroscopy study     

Émilie Gaudry  Philippe Sainctavit  Farid Juillot  Federica Bondioli  Philippe Ohresser  Isabelle Letard 《Physics and Chemistry of Minerals》2006,32(10):710-720

The best known cause for colors in insulating minerals is due to transition metal ions as impurities. As an example, Cr³⁺ is responsible for the red color of ruby (α-Al₂O₃:Cr³⁺) and the green color of eskolaite (α-Cr₂O₃). Using X-ray absorption measurements, we connect the colors of the Cr _x Al_2−x O₃ series with the structural and electronic local environment around Cr. UV–VIS electronic parameters, such as the crystal field and the Racah parameter B, are related to those deduced from the analysis of the isotropic and XMCD spectra at the Cr L_2,3-edges in Cr_0.07Al_1.93O₃ and eskolaite. The Cr–O bond lengths are extracted by EXAFS at the Cr K-edge in the whole Cr _x Al_2−x O₃ (0.07≤x< 2) solid solution series. The variation of the mean Cr–O distance between Cr_0.07Al_1.93O₃ and α-Cr₂O₃ is evaluated to be 0.01₅ Å (≈1%). The variation of the crystal field in the Cr _x Al_2−x O₃ series is discussed in relation with the variation of the averaged Cr–O distances.  相似文献   

Contribution of Secondary VOC to the Composition of Aqueous Atmospheric Particles: A Modeling Approach     

Bernard Aumont  Sasha Madronich  Isabelle Bey  Geoffrey S. Tyndall 《Journal of Atmospheric Chemistry》2000,35(1):59-75

Measurements show that 20–60% of the carbon mass present in fine atmospheric particulate matter consists of water soluble organic compounds (WSOC). However, only 5–20% of this WSOC has been identified, mainly as dicarboxylic acids. Because of their high solubility in water, multifunctional secondary compounds derived from the gas-phase oxidation of volatile organic compounds (VOC) are suspected to be key contributors to the WSOC. To test this assumption, an estimate of aqueous uptake of secondary VOC was included in a highly detailed gas-phase mechanism which treats explicitly the formation of the secondary VOC from a set of representative primary species. Simulations were conducted for 2 scenarios, representing typical rural and urban areas. It was observed that the uptake of secondary VOC can lead to WSOC mass concentrations in the range of a few C m^–3, in fairly good agreement with typical WSOC mass concentrations measured. Speciation of WSOC was found to be mainly as tri- or higher multifunctional hydroxy-carbonyl species and hydroxy-hydroperoxide-carbonyl species, in urban and rural environments, respectively. However, it was also found that taking into account only the absorption of secondary VOC does not bring the carboxylic acids mass concentration in agreement with measurements. An attempt was made to explain this discrepancy by introducing chemistry occurring within deliquescent aerosols.  相似文献