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31.
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Marie‐Jeanne Teil Martine Blanchard Cendrine Dargnat Karen Larcher‐Tiphagne Marc Chevreuil 《水文研究》2007,21(18):2515-2525
The occurrence and fate of six phthalate esters were investigated in the River Seine and two tributaries in the Paris area, at six sites from upstream to downstream, throughout different seasons, with special attention given to a flood episode. At all sites, except the River Marne, whatever the period, diethylhexyl phthalate (DEHP) displayed the highest concentration (0·323–0·779 µg l?1 as mean values), followed by di‐n‐butyl phthalate (DnBP; 0·211–0·526 µg l?1 as mean values), which is consistent with the production pattern. High phthalate concentrations appeared to be related to population density and industrial distribution. The strongest values were located downstream from wastewater treatment plant effluent inputs. Seasonal variations were closely related to river flow and air and water temperature. The annual evolution of phthalates was linked to the hydrological conditions. During the flood episode at Paris, the DEHP concentration displayed a sharp increase (260 to 1123 ng l?1) occurring 9 days before the flood peak. The simultaneous fluctuations of NH4, typical of domestic origin, and of DEHP suggests a similar origin from combined sewer overflows for both compounds. Other elevated values corresponded to the highest precipitation amounts, and demonstrated the contribution of non‐point‐source runoff and wastewater overflow to DEHP inputs. The DEHP concentration relationship with river flow displayed a clockwise hysteresis loop, corresponding to a ‘first‐flush’ effect in which the finite supplies are swept along in the early stage of the flood. Annual fluxes for 2004 at Paris were 2257 kg of DEHP and 1613 kg of DnBP. The flood period seemed to have a minor impact on annual phthalate transport (29·5% and 41% of the total for DEHP and for DnBP, respectively), which is contrary to annual suspended solids transport (69%). Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
33.
In many parts of the world, groundwater users regularly face serious resource-depletion threat. At the same time, “groundwater overexploitation” is massively cited when discussing groundwater management problems. A kind of standard definition tends to relegate groundwater overexploitation only as a matter of inputs and outputs. However, a thorough state-of-the-art analysis shows that groundwater overexploitation is not only a matter of hydrogeology but also a qualification of exploitation based on political, social, technical, economic or environmental criteria. Thus, an aquifer with no threat to groundwater storage can rightly be considered as overexploited because of many other prejudicial aspects. So, why is groundwater overexploitation so frequently only associated with resource-depletion threat and so rarely related to other prejudicial aspects? In that case, what really lies behind the use of the overexploitation concept? The case of the Kairouan plain aquifer in central Tunisia was used to analyze the way that the overexploitation message emerges in a given context, how groundwater-use stakeholders (farmers, management agencies and scientists) each qualify the problem in their own way, and how they see themselves with regard to the concept of overexploitation. The analysis shows that focusing messages on overexploitation conceals the problems encountered by the various stakeholders: difficulties accessing water, problems for the authorities in controlling the territory and individual practices, and complications for scientists when qualifying hydrological situations. The solutions put forward to manage overexploitation are at odds with the problems that arise locally, triggering tensions and leading to misunderstandings between the parties involved. 相似文献
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Résumé L'étude palynologique des schistes permiens du groupe Copacabana de la région de Cuzco (Pérou) a permis d'isoler une association composée de 40 espèces de spores et de pollen correspondant à 32 genres différents. On y relève la présence de quelques espèces qui sont d'excellents marqueurs stratigraphiques des couches de passage du Permien inférieur au Permien supérieur. La comparaison avec les associations connues dans d'autres régions: Argentine, Brésil, Uruguay, Afrique de l'Ouest, Inde et Australie, situe incontestablement cette microflore péruvienne dans la province phytogéographique du Gondwana. On y mentionne d'autre part, quelques affinités avec les flores de l'Angaride (Bassin de la Pechora, U.R.S.S.).
The palynologie study of the Permian shales of the Copacabana group in the Cuzco area (Peru) allows the authors to identify an association composed of 40 species of spores and pollens corresponding to 32 different genera. The presence of some species constituting excellent stratigraphie markers for the transition from the Lower to the Upper Permian is to be noted. A comparison with the associations of other countries such as Argentina, Brazil, Uruguay, Western and South Africa, India and Australia incontestably sets this Peruvian microflora in the phytogeographic Gondwana Province. Otherwise, some affinities with the florae of Angaride (Pechora basin, U.R.S.S.) are to be mentionned.
Zusammenfassung Nach palynologischen Methoden untersuchte permische Tonschieferproben der Copacabana-Schiehten aus dem Raum Cuzco (Peru) lieferten eine aus 40 Arten und 32 verschiedenen Gattungen bestehende Sporen- und Pollen-Assoziation. Bemerkenswert ist das Vorhandensein einiger Arten, die für die übergangsschichten vom unteren zum oberen Perm vorzügliche Leitfossilien darstellen. Aus dem Vergleich dieser palynologischen Assoziation mit jenen aus den Regionen Argentinien, Brasilien, Uruguay, West- und Süd-Afrika, Indien und Australien ergibt sich eindeutig, da\ die peruanische Mikroflora zum paleobotanischen Gondwanabereich gehört. Darüber hinaus wird noch auf Ähnlichkeiten mit Angarafloren desselben Zeitalters hingewiesen.
( , ) 40 32 . , . , , , , , . , .相似文献
36.
Joseph O. Ebeniro William P. O'Brien Jr. F. Jeanne Shaub 《Marine Geophysical Researches》1986,8(4):363-382
Five seismic refraction lines, 70–90 km long, were shot in the South Florida Platform region of the Gulf of Mexico using digital ocean-bottom seismographs. Apparent velocities and depths were calculated from the refracted arrivals using a flat-layer model for the region. The two dominant refractors have apparent compressional-wave velocity ranges of 5.6 to 5.9 km s–1 and 6.2 to 6.7 km s–1. On the Sarasota Arch, the depth to the top of a 5.8–5.9km/s layer is 3–4 km below sea level. This depth corresponds to the depth to the crystalline basement. The basement dips to the north and to the south from the arch, with velocity of the upper crust increasing from 5.8–5.9 km s–1 to a maximum of 6.7 km s–1 at a depth of 6.3 km. Under the continental slope, the crust has presumably been thinned and extended. The deepest refractor has an apparent velocity of about 7.5 km s–1 at a depth of 25 km. The thickness of the crustal section and the absence of any mantle arrivals in these long refraction profiles on the platform suggest that thick continental crust underlies the South Florida Platform. A north-south cross-section through the platform suggests the presence of two structural highs separated by a portion of the South Florida Basin, which contains at least 5 km of sediment. 相似文献
37.
Wood Nathan Jones Jeanne M. Yamazaki Yoshiki Cheung Kwok-Fai Brown Jacinta Jones Jamie L. Abdollahian Nina 《Natural Hazards》2019,95(3):505-528
Natural Hazards - Population vulnerability from tsunamis is a function of the number and location of individuals in hazard zones and their ability to reach safety before wave arrival. Previous... 相似文献
38.
The influence of sediment resuspension on the degradation of phenanthrene in flow-through microcosms 总被引：1，自引：0，他引：1
The effect of sediment resuspension on the mineralization of phenanthrene was examined in microcosms and sediment slurries. In computer-controlled, flow-through microcosms, 14C-phenanthrene-amended sediments were resuspended into overlying oxic water at frequencies of 12, 4, 1, 0.25 and 0 d(-1). In slurry bottle experiments 14C-phenanthrene-amended sediments were continuously resuspended under oxic (excess air headspace) and anoxic (N2 headspace) conditions and mineralization was measured at periods from 2 h to 7 days. Our main findings were: (1) mineralization rate constants from the microcosms ranged from 0.001 to 0.01 d(-1) and increased with frequency of resuspension, (2) these rates fell between those measured in oxic and anoxic slurries and were predicted within a factor of 2.5 by a model in which mineralization depended on the degree of oxygen exposure, and (3) the phenanthrene-degrading bacterial community was more active in resuspended sediments incubated in the microcosms than in sediments which were not resuspended, or which were stored under refrigeration. We conclude from these experiments that the effects of sediment resuspension on phenanthrene degradation are consistent with a primary role of average oxygen exposure, and also an alteration in the PAH-degrading activity of microbial populations. 相似文献
39.
Understanding plant water use patterns is crucial for comprehending the dynamics of the soil–plant-atmosphere continuum and evaluating the adaptability of plants across diverse ecosystems. However, there remains a gap in our comprehension of non-halophyte plants' water uptake patterns and driving factors in temperate coastal regions. For this reason, we used locust trees (a widely planted non-halophyte tree species in northern China) as a study subject. We collected water isotope data (δ2H and δ18O) for locust trees xylem and soil over two consecutive growing seasons. The MixSIAR model was used along with five distinct sets of input data (single isotopes, uncorrected dual isotopes, and corrected dual isotopes incorporating δ2H data obtained by soil water line or cryogenic vacuum distillation methods) to infer water utilization patterns. The results indicated that locust trees primarily absorb shallow soil water (0–20 cm, 29.4% ± 16.9%) and deep soil water (120–180 cm, 24.7% ± 5.8%). Pearson's correlation analysis revealed the key driving factors behind water uptake patterns were vegetation transpiration and soil salinity. Remarkably, the build up of salts in the lower soil layer (60–120 cm) hinders the absorption of water by plants. To prevent high salt concentrations from affecting water uptake in non-halophyte plants, we recommend implementing sufficient irrigation from March to April each year to meet the water needs of plant growth and regulate the accumulation of salts in various soil layers. This study reveals the dynamic water utilization strategy of non-halophyte plants in temperate coastal regions, offering valuable information for water resources management. 相似文献
40.
Henny A.J. Van Lanen Gregor Laaha Daniel G. Kingston Tobias Gauster Monica Ionita Jean‐Philippe Vidal Radek Vlnas Lena M. Tallaksen Kerstin Stahl Jamie Hannaford Claire Delus Miriam Fendekova Luis Mediero Christel Prudhomme Ekaterina Rets Renata J. Romanowicz Sébastien Gailliez Wai Kwok Wong Mary‐Jeanne Adler Veit Blauhut Laurie Caillouet Silvia Chelcea Natalia Frolova Lukas Gudmundsson Martin Hanel Klaus Haslinger Maria Kireeva Marzena Osuch Eric Sauquet James H. Stagge Anne F. Van Loon 《水文研究》2016,30(17):3097-3104