Feasibility of Bioremediation of a Ground Water Polluted with Alkylpyridines   总被引：1，自引：0，他引：1  

Zeev Ronen  Jean-Marc Bollag  Cheng-Hsiung Hsu  James C. Young 《Ground water》1996,34(2):194-199

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Cation exchanged Fe(II) and Sr compared to other divalent cations (Ca, Mg) in the bure Callovian–Oxfordian formation: Implications for porewater composition modelling     

Christophe Tournassat  Catherine Lerouge  Philippe Blanc  Jocelyne Brendlé  Jean-Marc Greneche  Stéphane Touzelet  Eric C. Gaucher 《Applied Geochemistry》2008

Iron and Sr bearing phases were thoroughly investigated by means of spectrometric and microscopic techniques in Callovian–Oxfordian (COX) samples originating from the ANDRA Underground Research Laboratory (URL) in Bure (France). Strontium was found to be essentially associated with celestite, whereas Fe was found to be distributed over a wide range of mineral phases. Iron was mainly present as Fe(II) in the studied samples (∼93% from Mössbauer results). Most of the Fe(II) was found to be in pyrite, sideroplesite/ankerite and clay minerals. Iron(III), if present, was associated with clay minerals (probably illite, illite-smectite mixed layer minerals and chlorite). No Fe(III) oxy(hydro)xide could be detected in the samples. Strontianite was not observed either. Based on these observations, it is likely that the COX porewater is in equilibrium with the following carbonate minerals, calcite, dolomite and ankerite/sideroplesite, but not with strontianite. It is shown that this equilibrium information can be combined with clay cation exchange composition information in order to give direct estimates or constraints on the solubility products of the carbonate minerals dolomite, siderite and strontianite. As a consequence, an experimental method was developed to retrieve the cation exchanged Fe(II) in very well preserved COX samples.  相似文献   

Accretion disc outbursts: a new version of an old model   总被引：1，自引：0，他引：1  

Jean-Marie Hameury  Kristen Menou  Guillaume Dubus  Jean-Pierre Lasota  & Jean-Marc Huré 《Monthly notices of the Royal Astronomical Society》1998,298(4):1048-1060

We have developed 1D time-dependent numerical models of accretion discs, using an adaptive grid technique and an implicit numerical scheme, in which the disc size is allowed to vary with time. The code fully resolves the cooling and heating fronts propagating in the disc. We show that models in which the radius of the outer edge of the disc is fixed produce incorrect results, from which probably incorrect conclusions about the viscosity law have been inferred. In particular we show that outside-in outbursts are possible when a standard bimodal behaviour of the Shakura–Sunyaev viscosity parameter α is used. We also discuss to what extent insufficient grid resolution has limited the predictive power of previous models. We find that the global properties (magnitudes, etc.) of transient discs can be addressed by codes using a high, but reasonable, number of fixed grid points. However, the study of the detailed physical properties of the transition fronts generally requires resolutions which are out of reach of fixed grid codes. It appears that most time-dependent models of accretion discs published in the literature have been limited by resolution effects, improper outer boundary conditions, or both.  相似文献   

Symplectic Integrators: Rotations and Roundoff Errors     

Jean-Marc Petit 《Celestial Mechanics and Dynamical Astronomy》1998,70(1):1-21

We investigate the numerical implementation of a symplectic integrator combined with a rotation (as in the case of an elongated rotating primary). We show that a straightforward implementation of the rotation as a matrix multiplication destroys the conservative property of the global integrator, due to roundoff errors. According to Blank et al. (1997), there exists a KAM-like theorem for twist maps, where the angle of rotation is a function of the radius. This theorem proves the existence of invariant tori which confine the orbit and prevent shifts in radius. We replace the rotation by a twist map or a combination of shears that display the same kind of behaviour and show that we are able not only to recover the conservative properties of the rotation, but also make it more efficient in term of computing time. Next we test the shear combination together with symplectic integrator of order 2, 4, and 6 on a Keplerian orbit. The resulting integrator is conservative down to the roundoff errors. No linear drift of the energy remains, only a divergence as the square root of the number of iterations is to be seen, as in a random walk. We finally test the three symplectic integrators on a real case problem of the orbit of a satellite around an elongated irregular fast rotating primary. We compare these integrators to the well-known general purpose, self-adaptative Bulirsch–Stoer integrator. The sixth order symplectic integrator is more accurate and faster than the Bulirsch–Stoer integrator. The second- and fourth- order integrators are faster, but of interest only when extreme speed is mandatory. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

Use of seasonal trend decomposition to understand groundwater behaviour in the Permo-Triassic Sandstone aquifer,Eden Valley,UK     

Antoine E. A. Lafare  Denis W. Peach  Andrew G. Hughes 《Hydrogeology Journal》2016,24(1):141-158

The daily groundwater level (GWL) response in the Permo-Triassic Sandstone aquifers in the Eden Valley, England (UK), has been studied using the seasonal trend decomposition by LOESS (STL) technique. The hydrographs from 18 boreholes in the Permo-Triassic Sandstone were decomposed into three components: seasonality, general trend and remainder. The decomposition was analysed first visually, then using tools involving a variance ratio, time-series hierarchical clustering and correlation analysis. Differences and similarities in decomposition pattern were explained using the physical and hydrogeological information associated with each borehole. The Penrith Sandstone exhibits vertical and horizontal heterogeneity, whereas the more homogeneous St Bees Sandstone groundwater hydrographs characterize a well-identified seasonality; however, exceptions can be identified. A stronger trend component is obtained in the silicified parts of the northern Penrith Sandstone, while the southern Penrith, containing Brockram (breccias) Formation, shows a greater relative variability of the seasonal component. Other boreholes drilled as shallow/deep pairs show differences in responses, revealing the potential vertical heterogeneities within the Penrith Sandstone. The differences in bedrock characteristics between and within the Penrith and St Bees Sandstone formations appear to influence the GWL response. The de-seasonalized and de-trended GWL time series were then used to characterize the response, for example in terms of memory effect (autocorrelation analysis). By applying the STL method, it is possible to analyse GWL hydrographs leading to better conceptual understanding of the groundwater flow. Thus, variation in groundwater response can be used to gain insight into the aquifer physical properties and understand differences in groundwater behaviour.  相似文献   

Geological and geotechnical properties of the “Terres Noires” in southeastern France: Weathering, erosion, solid transport and instability     

P. Antoine  A. Giraud  M. Meunier  T. Van Asch 《Engineering Geology》1995,40(3-4):223-234

The geological formation known as the “Terres Noires” covers large areas of southeastern France, between the Rhône valley and the pre-Alpine hills. This formation consists mainly of dark marls of the basal Upper Jurassic. These marls are very susceptibility to weathering and are particularly prone to erosion, resulting in high solid transport. This paper attempts to quantify this transport in experimental catchment areas, and shows that a forest cover can play a major role in preventing this type of phenomenon. Weathering of this formation may also lead to gravity instabilities in fresh marl (although this is rare) and, much more frequently, in the surficial weathered material.  相似文献   

Microstructural criteria for reliable thermometry in low-temperature eclogites     

Jean-Marc Lardeaux  Jean-Michel Caron  Pascal Nisio  Guy Pquignot  Micheline Boudeulle 《Lithos》1986,19(3-4):187-203

Two Alpine eclogite bodies, sampled in metaophiolitic complexes of the Piemonte Zone, have been studied for geothermometry. It is demonstrated that temperature estimates, by both exchange thermometry and sizes of antiphase domains in omphacites, give rise to erratic results when the defect structures of the minerals are not taken into account. Microstructural criteria, by means of both optical and TEM microscopy, for reliable thermometry in low-temperature eclogites are disscussed. The dynamically recrystallized grains are the more suitable sites for the application of exchange thermometry, while only low-strained omphacites can be used for thermometry based on APD's.  相似文献   

Phycoperiphyton Development on an Artificial Substrate in the River Wye System,Wales, U. K. Part 2: Population Dynamics     

S. E. Antoine  K. Benson-Evans 《洁净——土壤、空气、水》1986,14(4):347-363

The temporal and spatial fluctuations of the main algal phyla and the constant species colonising Perspex slides were studied. Higher algal counts were noted during the warmer periods of the year and lower ones during the winter months. The Bacillariophyta dominated the other algal phyla and greatly affected the total biomass. The Chlorophyta were represented by a few species which were regarded as plankton fall-out. The diatom species showed various, inconsistent relationships with different environmental variables. It was concluded that not only the environmental variables affected the colonisation and growth of benthic algae, but also others, such as smoothness of the surface of the Perspex slides, duration of colonisation period, accumulation of silt and detritus on the slide, the competition for limited spaces and selectivity of the Perspex slides for certain species. Several species colonising both the Perspex slides and stone surfaces either failed to correlate significantly between themselves or were not correlated at all. Several others were only correlated significantly at some stations and not correlated at others. It was therefore concluded that the Perspex slides affected the algal species in an unpredictable manner at the different sampling sites and so rendered the method unreliable for reflecting true ecological changes.  相似文献   

Phycoperiphyton Development on an Artificial Substrate in the River Wye System,Wales, U. K. Part 1: Biomass Variation     

S. E. Antoine  K. Benson-Evans 《洁净——土壤、空气、水》1985,13(3):277-296

The phycoperiphyton on Perspex slides is investigated after an exposure for four weeks at six stations in the upper course of the River Wye System from June 1979 to June 1981. The pigment contents were between 0.1 and 48 mg/m² chlotophyll-a as well as 0.01 and 18 mg/m² phaeophytin with a unimodal or bimodal annual variation (minima in winter, maxima in April and July). The biomass was between 55 and 11,000 cells/cm² and is closely correlated with chlorophyll in the annual variation. The algal community colonizing the artificial substrate shows only a very slight similarity to that on the natural stones of the water. The SØRENSEN index lies between 0.1 and 0.7, the biomass on the artificial substrate amounts to only 0.7… 0.01 ‰, the chlorophyll quantity only 0.5… 0.007‰, the phaeophytin quantity only 1… 0.003‰ of the values on the natural stones. Therefore, the periphyton on artificial substrates represents only a more or less restricted selection of the real natural phycoperiphyton. At four of the six stations, biomass and chlorophyll are positively correlated with each other and with temperature and phosphorus concentration and negatively correlated with flow, current velocity, oxygen concentration, hardness and nitrate concentration.  相似文献   

The behavior of shape preferred orientations in metamorphic rocks: amphiboles and jadeites from the Monte Mucrone area (Sesia-Lanzo zone, Italian Western Alps)     

Benoit Ildefonse  Jean-Marc Lardeaux  Jean-Michel Caron 《Journal of Structural Geology》1990,12(8)

In the eclogitic micaschists of the Monte Mucrone area (Sesia-Lanzo zone, Italian Western Alps), we have measured in detail the eclogitic lineation at several outcrops. We present observations at the markers scale, this scale allowing the whole range of progressive deformations to be described. Populations of glaucophanes and jadeites show different statistical features which must be, at least for a part, produced by the distinct mechanical behavior for these markers during the alpine history. The glaucophanes show a positive correlation between the intensity of preferred orientation and their aspect ratio, due to a mainly rigid behavior. The observed differences in shape and orientation of jadeites also show different behavior, related to different retromorphic overprints. We briefly discuss the implications of these observations on the significance of metamorphic lineations.  相似文献