Impact of climate change on the hydrogeology of two basins in northern France     

Florence Habets  Julien Boé  Michel Déqué  Agnès Ducharne  Simon Gascoin  Ali Hachour  Eric Martin  Christian Pagé  Eric Sauquet  Laurent Terray  Dominique Thiéry  Ludovic Oudin  Pascal Viennot 《Climatic change》2013,121(4):771-785

This study presents an analysis of climate-change impacts on the water resources of two basins located in northern France, by integrating four sources of uncertainty: climate modelling, hydrological modelling, downscaling methods, and emission scenarios. The analysis focused on the evolution of the water budget, the river discharges and piezometric heads. Seven hydrological models were used, from lumped rainfall-discharge to distributed hydrogeological models, and led to quite different estimates of the water-balance components. One of the hydrological models, CLSM, was found to be unable to simulate the increased water stress and was, thus, considered as an outlier even though it gave fair results for the present day compared to observations. Although there were large differences in the results between the models, there was a marked tendency towards a decrease of the water resource in the rivers and aquifers (on average in 2050 about ?14 % and ?2.5 m, respectively), associated with global warming and a reduction in annual precipitation (on average in 2050 +2.1 K and ?3 %, respectively). The uncertainty associated to climate models was shown to clearly dominate, while the three others were about the same order of magnitude and 3–4 times lower. In terms of impact, the results found in this work are rather different from those obtained in a previous study, even though two of the hydrological models and one of the climate models were used in both studies. This emphasizes the need for a survey of the climatic-change impact on the water resource.  相似文献   

Axisymmetric compression of a Mohr–Coulomb medium around a circular hole     

A. L. Florence  L. E. Schwer 《国际地质力学数值与分析法杂志》1978,2(4):367-379

An analytical solution is presented for the stress and strain fields in a Mohr–Coulomb material in plane strain around a circular hole when it is compressed by an axisymmetric far-field pressure. It is shown that several solutions arise involving one to three plastic zones depending on the values of Poisson's ratio and the friction angle. The solution chosen for presentation was obtained and used to validate the functioning of the Mohr–Coulomb yield condition that was added to the NONSAP finite element code. Stress and strain field comparisons are made.  相似文献   

Stable carbon isotopic compositions of intact polar lipids reveal complex carbon flow patterns among hydrocarbon degrading microbial communities at the Chapopote asphalt volcano     

Florence Schubotz  Julius S. Lipp  Marcus Elvert  Kai-Uwe Hinrichs 《Geochimica et cosmochimica acta》2011,75(16):4399-3574

Seepage of asphalt forms the basis of a cold seep system at 3000 m water depth at the Chapopote Knoll in the southern Gulf of Mexico. Anaerobic microbial communities are stimulated in the oil-impregnated sediments as evidenced by the presence of intact polar membrane lipids (IPLs) derived from archaea and Bacteria at depths up to 7 m below the seafloor. Detailed investigation of stable carbon isotope composition (δ¹³C) of alkyl and acyl moieties derived from a range of IPL precursors with distinct polar head groups resolved the complexity of carbon metabolisms and utilization of diverse carbon sources by uncultured microbial communities. In surface sediments most of the polar lipid-derived fatty acids with phosphatidylethanolamine (PE), phosphatidylglycerol (PG) and diphosphatidylglycerol (DPG) head groups could be tentatively assigned to autotrophic sulfate-reducing bacteria, with a relatively small proportion involved in the anaerobic oxidation of methane. Derivatives of phosphatidyl-(N)-methylethanolamine (PME) were abundant and could be predominantly assigned to heterotrophic oil-degrading bacteria. Archaeal IPLs with phosphate-based hydroxyarchaeols and diglycosidic glyceroldibiphytanylglyceroltetraethers (GDGTs) were assigned to methanotrophic archaea of the ANME-2 and ANME-1 cluster, respectively, whereas δ¹³C values of phosphate-based archaeols and mixed phosphate-based and diglycosidic GDGTs point to methanogenic archaea. At a 7 m deep sulfate-methane transition zone that is linked to the upward movement of gas-laden petroleum, a distinct increase in abundance of archaeal IPLs such as phosphate-based hydroxyarchaeols and diglycosidic archaeol and GDGTs is observed; their δ¹³C values are consistent with their origin from both methanotrophic and methanogenic archaea. This study reveals previously hidden, highly complex patterns in the carbon-flow of versatile microbial communities involved in the degradation of heavy oil including hydrocarbon gases that would not have been evident from classical compound-specific isotope analyses of either bulk IPL or apolar lipid derivatives.  相似文献   

Internal pore measurements on macroperforate planktonic Foraminifera as an alternative morphometric approach     

Monica Constandache  Florence Yerly  Silvia Spezzaferri 《Swiss Journal of Geoscience》2013,106(2):179-186

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Retention behaviour of humic substances onto mineral surfaces and consequences upon thorium (IV) mobility: case of iron oxides     

Pascal Reiller  Valrie Moulin  Florence Casanova  Christian Dautel 《Applied Geochemistry》2002,17(12)

The influence of humic acids (HA) on the retention of Th(IV) onto the surface of Fe oxides has been investigated. Thorium (IV) is here considered as an analogue of tetravalent radionuclides (Zr, Hf, U, Np, Pu). Hematite (α–Fe₂O₃) and gœthite (α–FeOOH) have been chosen as model phases because of their widespread presence in the earth's crust. Retention experiments were performed by batch procedure at constant ionic strength and varying pH in the range 2–10; the HA concentration varied in the range 1–100 mg l⁻¹. Compared with the former data obtained on the retention of Th(IV) with the same hematite sample free of HA, the study of a ternary system (i.e. hematite–HA–Th), clearly shows the influence of HA on the retention mechanisms of Th(IV) even in neutral to slightly alkaline medium. In particular, it is illustrated that the retention of Th(IV) onto Fe oxides closely depends upon the ratio between humic and surface (Fe oxide) sites. This ratio has to be greater than a critical value in order to impede the sorption of Th(IV).  相似文献   

Late Pleistocene to Holocene sedimentation and hydrocarbon seeps on the continental shelf of a steep,tectonically active margin,southern California,USA   总被引：1，自引：0，他引：1  

Amy E. Draut  Patrick E. Hart  Thomas D. Lorenson  Holly F. Ryan  Florence L. Wong  Ray W. Sliter  James E. Conrad 《Marine Geophysical Researches》2009,30(3):193-206

Small, steep, uplifting coastal watersheds are prolific sediment producers that contribute significantly to the global marine sediment budget. This study illustrates how sedimentation evolves in one such system where the continental shelf is largely sediment-starved, with most terrestrial sediment bypassing the shelf in favor of deposition in deeper basins. The Santa Barbara–Ventura coast of southern California, USA, is considered a classic area for the study of active tectonics and of Tertiary and Quaternary climatic evolution, interpretations of which depend upon an understanding of sedimentation patterns. High-resolution seismic-reflection data over >570 km² of this shelf show that sediment production is concentrated in a few drainage basins, with the Ventura and Santa Clara River deltas containing most of the upper Pleistocene to Holocene sediment on the shelf. Away from those deltas, the major factor controlling shelf sedimentation is the interaction of wave energy with coastline geometry. Depocenters containing sediment 5–20 m thick exist opposite broad coastal embayments, whereas relict material (bedrock below a regional unconformity) is exposed at the sea floor in areas of the shelf opposite coastal headlands. Locally, natural hydrocarbon seeps interact with sediment deposition either to produce elevated tar-and-sediment mounds or as gas plumes that hinder sediment settling. As much as 80% of fluvial sediment delivered by the Ventura and Santa Clara Rivers is transported off the shelf (some into the Santa Barbara Basin and some into the Santa Monica Basin via Hueneme Canyon), leaving a shelf with relatively little recent sediment accumulation. Understanding factors that control large-scale sediment dispersal along a rapidly uplifting coast that produces substantial quantities of sediment has implications for interpreting the ancient stratigraphic record of active and transform continental margins, and for inferring the distribution of hydrocarbon resources in relict shelf deposits.  相似文献   

Grand Activity Minima and Maxima via Dual Dynamos     

Ölçek  Deniz  Charbonneau  Paul  Lemerle  Alexandre  Longpré  Gabriel  Boileau  Florence 《Solar physics》2019,294(7):1-9

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Lake levels in the southern Bolivian Altiplano (19°–21°S.) during the Late Glacial based on diatom studies     

Florence Sylvestre  Simone Servant-Vildary  Marc Fournier  Michel Servant 《International Journal of Salt Lake Research》1995,4(4):281-300

This study is focused on the endorheic Uyni-Coipasa Basin located in the southern Bolivian Altiplano. Stratigraphical and fossil diatom studies based on a detailed radiocarbon chrnology revealed six phases in water-level changes and paleosalinity variations. At 15,430±80 yr B.P., lacustrine conditions settled in the southern Bolivian Altiplano. A saline lake, characterized by benthic meso-metasaline species, reached +4 m altitude above the present bottom of the basin. After 15,430±80 yr B.P., the level rapidly rose to +27 m, as suggested by a tychoplanktonic mesosaline flora. Between 14,500 years and 13,000 years, finely lanminated sediments at +32 m contained successively a dominance of epiphytic mesosaline to hypersaline species and tychoplanktonic oligosaline diatoms, indicating weak fluctuations in water-level and salinity. At 13,000 years, strong changes in the diatom flora occurred; epiphytic oligo-hypersaline diatoms were replaced by planktonic meso-polysaline species. They indicate a deep salt lake (the lake reached +100 m). After 12,000 years, the lake level abruptly dropped, as suggested by fluviatile sediments with a benthic mesopolysaline diatom flora. The main lake was replaced by shallow saline ponds. A wet pulse occurred at 11,400 years, characterized by low water level (+7 m) and high salinity. This lacustrine phase remained until 10,400 yr B.P. These data indicate changes in Precipitation minus Evaporation (P-E). Our regional interpretations are based on a comparison with teh available data on the northern (Lake Titicaca) and southern (Lipez are) Bolivian Altiplano and on the northern Chilean Altiplano (Atacama Desert).  相似文献   

Determination of the chemical forms of dissolved cadmium, lead and copper in seawater     

G.E. Batley  T.M. Florence 《Marine Chemistry》1976,4(4):347-363

The chemical forms of Cd, Pb and Cu in seawater have been examined using a novel scheme which permits the quantification of up to seven different species of one metal. The concentration of each species was calculated from measurements using anodic stripping voltammetry of labile and total metal in samples which were (a) untreated, (b) UV irradiated, (c) passed through a chelating resin column, and (d) UV irradiated then passed through a chelating resin column. In the sample studied, the major proportion of Cd, Pb and Cu was found to be associated with organic and inorganic colloidal species. Less than half of the bound Pb and Cu was readily exchangeable with added ²¹⁰Pb and ⁶⁴Cu.  相似文献   

Reproductive success as an indicator of genotoxicity in the polychaete worm, Neanthes arenaceodentata     

Florence L. Harrison  Susan L. Anderson 《Marine environmental research》1989,28(1-4)

The effects on reproduction of single or chronic exposure to the direct-acting mutagen, radiation, were evaluated using Neanthes arenaceodentata as the model animal. In the first set of experiments, mated pairs were irradiated when oocytes were visible in the female and were given a single dose of either 0·5, 1·0, 2·0, 5·0, 10 or 50 Gy. In the second set of experiments, lifetime exposure was initiated upon the spawning of the P₁ female and was terminated upon the spawning of the F₁ female; the average total doses (0·55, 6·5 and 54 Cy) were delivered at a rate of 0·19, 2·1 or 17 mGyH⁻¹. Our results on embryo abnormalities and mortalities indicated that lethal mutations were most likely induced in the germ cells and had an adverse effect on reproductive success by reducing the survival of early life stages. Except for those mated pairs exposed acutely to 10 or 50 Gy or exposed chronically to 17 mGyh⁻¹, there was no evidence of gamete killing. However, evidence was obtained for mutagen-damage accumulation in developing gametes from continuous exposure to radiation.  相似文献