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Ana Horta Pedro Correia Luís Menezes Pinheiro Amílcar Soares 《Mathematical Geosciences》2013,45(5):575-590
Soil contamination assessments can be improved with new methods aimed at the accurate estimation of the volume and extension of contaminated soil to be remediated. Geostatistical models that use secondary information to characterize soil contamination are incorporated into a new integration model to provide accurate three-dimensional maps. The proposed integration model is based on a stochastic inversion approach and uses sequential indicator simulation. A two-dimensional reference image representing the areal extension of the contamination is combined with local measurements of contamination in the vertical direction, to render a three-dimensional contamination map. To demonstrate how well the integration model performs, the case study presented focuses on geophysical data and how it can be integrated with soil contamination measurements to improve the characterization of a contaminated site. The results show that the model reproduces successfully the reference image thus providing an accurate three-dimensional contamination map. 相似文献
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Evaluating the genetic effects of the invasive Ocenebra inornata on the native oyster drill Ocenebra erinacea 
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下载免费PDF全文 Eric Pante Pierre‐Yves Pascal Vanessa Becquet Amélia Viricel Benoit Simon‐Bouhet Pascale Garcia 《Marine Ecology》2015,36(4):1118-1128
Studies focusing on the effect of invasive species on the genetic diversity of native marine invertebrates remain scant. Here we report diversity among French populations of the intertidal gastropod Ocenebra erinacea (Linnaeus, 1758) sampled in the presence and absence of the invasive Ocenebra inornata (Recluz, 1851). Between 1999 and 2004, a total of 352 individuals of O. erinacea was collected from 15 sites (five of which had the invasive present) and was genotyped at the mitochondrial locus Cytochrome Oxidase 1 (cox1). No statistical difference was observed between polymorphism levels recorded within native populations exposed to the invasive, compared with populations sampled in the absence of O. inornata. No sign of native population decline was detected in response to the invader. While significant shifts in native O. erinacea population sizes have previously been reported in the literature, genetic effects may take longer to accumulate, or may be undetectable without a larger panel of genetic markers. By contrast, large genetic distances and significant population differentiation were recorded between Atlantic and Mediterranean O. erinacea samples, suggesting that these populations have distinct evolutionary histories. Comparison of genetic divergence within the closely related genus Nucella suggests that the Atlantic populations of O. erinacea and those from Thau Lagoon in the Mediterranean may belong to different species or subspecies. 相似文献
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Antoni Quetglas Aina de Mesa Francesc Ordines Amàlia Grau 《Deep Sea Research Part I: Oceanographic Research Papers》2010,57(8):999-1008
The life cycle of the two species of the deep-sea family Histioteuthidae inhabiting the Mediterranean Sea (Histioteuthis reversa and Histioteuthis bonnellii) was studied from monthly samples taken throughout the year during daytime hours by bottom trawl gears. A small sample of individuals found floating dead on the sea surface was also analyzed. Both species were caught exclusively on the upper slope at depths greater than 300 m. Their frequency of occurrence increased with depth and showed two different peaks, at 500–600 m and 600–700 m depth in H. bonnellii and H. reversa, respectively, which might indicate spatial segregation. Maturity stages were assigned using macroscopic determination and confirmed with histological analyses. Although mature males were caught all year round, no mature females were found, which suggests that their sexual maturation in the western Mediterranean takes place deeper than the maximum depth sampled (800 m). In fact, the increase in mean squid size with increasing depth in H. reversa indicates an ontogenetic migration to deeper waters. The individuals of both species found floating dead on the sea surface were spent females which had a relatively large cluster of small atresic eggs and a small number of remaining mature eggs scattered in the ovary and mantle cavity. The sizes of these females were clearly larger than the largest individuals caught with bottom trawls. A total of 12 and 7 different types of prey, belonging to three major taxonomic groups (crustaceans, osteichthyes and cephalopods), were identified in the stomach contents of H. reversa and H. bonnellii, respectively. In both species fishes were by far the main prey followed by crustaceans, whereas cephalopods were found only occasionally. The preys identified, mainly myctophids and natantian crustaceans, indicate that both histioteuthids base their diet on pelagic nictemeral migrators. 相似文献
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Bernard Bourdon Sarah Bureau Morten B. Andersen Eric Pili Amélie Hubert 《Chemical Geology》2009,258(3-4):275-287
This study investigates U-series, Sr isotopes, major and trace elements in a chalk aquifer system located in Eastern France. Soil and rock samples were collected along depth profiles down to 45 m in four localities as an attempt to investigate the weathering processes in the soil, the unsaturated zone and the saturated zone of the aquifer. Interstitial water was extracted from soils and rocks by a centrifugation technique. U-series offer a powerful tool to calculate weathering rates because the relative mobility of the U- and Th-isotopes can be precisely measured and it does not require the determination of a reference state as in other approaches. As expected, the data show very large mobile element depletion in the soil with large 230Th excess relative to 238U, while the rocks show more limited but not insignificant mobile element depletion. The U-series data have been used to constrain weathering rates based on a 1-D reactive transport model. Weathering rates in the near surface are about 10–100 times faster than at depth. However, when integrated over the depth of the cores, including the unsaturated and the saturated zones, this underground weathering represents more than 30% of the total weathering flux, assuming congruent dissolution of carbonates. The (234U/238U) ratios in interstitial water are consistent with solid samples showing 234U depletion near the surface and an excess 234U at depth. A leaching experiment performed on chalk shows that the excess 234U in natural waters percolating through carbonate rocks results both from preferential 234U leaching and direct recoil in the interstitial water. A new approach was used to derive the recoil ejection factor based on BET measurements and the fractal dimension of chalk surface. Consideration of preferential leaching and recoil allows a more accurate modeling of weathering rates. 相似文献
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Mathematical Geosciences - Iterative geostatistical seismic inversion methods are widely used to predict petro-elastic rock properties from seismic reflection data. When the model perturbation... 相似文献
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