1000 resultados para Isotopic tracer


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参阅了大量国内外有关乔木蒸腾研究方法文献,认为乔木蒸腾量研究方法主要有二大类,即组织器官测定、单木测定;分类对典型研究方法(快速称重法、气孔计法、整株容器称重法、同位素示踪法、热脉冲法、树干热平衡法、热扩散探针法)进行了述评,对比分析了各种方法间的优缺点及其适用范围;展望了乔木蒸腾耗水作用研究方法的应用前景,认为热技术法是未来几年内的主要测定方法。

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Based on the study of the combined flooding test block of Guantao formation in Third faulted block of Yangsanmu oil field, this paper carries out the integration of reservoir precise characterization for very high water cut reservoir, establishes precise 3D geologic model for high water cut development period and states the changing law of the reservoir architecture dtiring development by combined flooding. Then, by subdivided the thick oil reservoir, the study of remaining oil saturation monitoring in fiber glass cased well and tracer monitoring is developed. According the study of multiple constrained combined flooding reservoir numerical simulation, remaining oil distribution are predicted, the methods architecture of predicting remaining oil distribution are established for fluvial facies reservoir at late development stage, develops plan is designed and adjustment associating technologies for enhancing oil recovery. On these base, related measures for tapping the potential are given, it is verified and optimized through the field former test and the good economic effect is achieved . The major achievements of this paper are as follows. The changing law of the reservoir architecture and it's property parameters is revealed, The result indicates that the temperature-pressure of the injecting material and the interaction effect of the injecting material and reservoir petrography are the main factors of the dynamic changes of the reservoir architecture. The quantitative reservoir geologic model, which is tallied with dynamic reservoir parameters of the study area, is established. Subdivided the thick oil reservoir is very important for the study of the remaining oil distribution within the thick oil reservoir. Subdivided the thick oil reservoir technology, which consists of six technologies as follow: micro-cyclic divided, flow unit method, architectural element method, high resolution log technology, high resolution-process technology for normal logging data and using the production data is presented. 3. It is established dynamic monitoring system of remaining oil saturation quantitative research which are inner and interlayer remaining oil saturation from time-lapse logging in fiber glass cased well, inter-well remaining oil saturation from the technology of isotopic tracer monitoring technology, and 4d remaining oil saturation distribution from combined flooding numerical modeling integrated by production datao The forming mechanism of remaining oil for polymer flooding and alkali/polymer combined flooding is clarified, and the plane and vertical distribution law of remaining oil after combined flooding is revealed. Predicting methods and technologies for the combined flooding reservoir of fluvial facies is developed. Combined flooding has been achieved good displacement result in the pilot of Third fault block in Yangsanmu oil field, and accumulated types of important parameters and optimum plans, this technology of combined flooding is expected to increase recovery ratio by 4.77%.

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The marine cyanobacterium Prochlorococcus, the most abundant phototrophic organism on Earth, numerically dominates the phytoplankton in nitrogen (N)-depleted oceanic gyres. Alongside inorganic N sources such as nitrite and ammonium, natural populations of this genus also acquire organic N, specifically amino acids. Here, we investigated using isotopic tracer and flow cytometric cell sorting techniques whether amino acid uptake by Prochlorococcus is subject to a diel rhythmicity, and if so, whether this was linked to a specific cell cycle stage. We observed, in contrast to diurnally similar methionine uptake rates by Synechococcus cells, obvious diurnal rhythms in methionine uptake by Prochlorococcus cells in the tropical Atlantic. These rhythms were confirmed using reproducible cyclostat experiments with a light-synchronized axenic Prochlorococcus (PCC9511 strain) culture and S-35-methionine and H-3-leucine tracers. Cells acquired the tracers at lower rates around dawn and higher rates around dusk despite > 10(4) times higher concentration of ammonium in the medium, presumably because amino acids can be directly incorporated into protein. Leucine uptake rates by cells in the S+G(2) cell cycle stage were consistently 2.2 times higher than those of cells at the G(1) stage. Furthermore, S+G(2) cells upregulated amino acid uptake 3.5 times from dawn to dusk to boost protein synthesis prior to cell division. Because Prochlorococcus populations can account from 13% at midday to 42% at dusk of total microbial uptake of methionine and probably of other amino acids in N-depleted oceanic waters, this genus exerts diurnally variable, strong competitive pressure on other bacterioplankton populations.

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Environmental tracers continue to provide an important tool for understanding the source, flow and mixing dynamics of water resource systems through their imprint on the system or their sensitivity to alteration within it. However, 60 years or so after the first isotopic tracer studies were applied to hydrology, the use of isotopes and other environmental tracers are still not routinely necessarily applied in hydrogeological and water resources investigations where appropriate. There is therefore a continuing need to promote their use for developing sustainable management policies for the protection of water resources and the aquatic environment. This Special Issue focuses on the robustness or fitness-for-purpose of the application and use of environmental tracers in addressing problems and opportunities scientifically, to promote their wider use and to address substantive issues of vulnerability, sustainability, and uncertainty in (ground)water resources systems and their management.

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Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

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The development of the seasonal phytoplankton bloom in the Ross Sea was studied during two cruises. The first, conducted in November-December 1994, investigated the initiation and rapid growth of the bloom, whereas the second (December 1995-January 1996) concentrated on the bloom's maximum biomass period and the subsequent decline in biomass. Central to the understanding of the controls of growth and the summer decline of the bloom is a quantitative assessment of the growth rate of phytoplankton. Growth rates were estimated over two time scales with different methods. The first estimated daily growth rates from isotropic incorporation under simulated in situ conditions, including 14C, 15N and 32Si uptake measurements combined with estimates of standing stocks of particulate organic carbon, nitrogen and biogenic silica. The second method used daily to weekly changes in biomass at selected locations, with net growth rates being estimated from changes in standing stocks of phytoplankton. In addition, growth rates were estimated in large-volume experiments under optimal irradiances. Growth rates showed distinct temporal patterns. Early in the growing season, short-term estimates suggested that growth rates of in situ assemblages were less than maximum (relative to the temperature-limited maximum) and were likely reduced due to low irradiance regimes encountered under the ice. Growth rates increased thereafter and appeared to reach their maximum as biomass approached the seasonal peak, but decreased markedly in late December. Differences between the major taxonomic groups present were also noted, especially from the isotopic tracer experiments. The haplophyte Phaeocystic antarctica was dominant in 1994 throughout the growing season, and it exhibited the greatest growth rates (mean 0.41/day) during spring. Diatom standing stocks were low early in the growing season, and growth rates averaged 0.100/day. In summer diatoms were more abundant, but their growth rates remained much lower (mean of 0.08/day) than the potential maximum. Understanding growth rate controls is essential to the development of predictive models of the carbon cycle and food webs in Antarctic waters.

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Results of studies in two biogeochemically active zones of the Atlantic Ocean (the Benguela upwelling waters and the region influenced by the Congo River run-off) are reported in the book. A multidisciplinary approach included studies of the major elements of the ocean ecosystem: sea water, plankton, suspended matter, bottom sediments, interstitial waters, aerosols, as well as a wide complex of oceanographic studies carried out under a common program. Such an approach, as well as a use of new methodical solutions led to obtaining principally new information on different aspects of oceanology.