排序方式： 共有28条查询结果，搜索用时 15 毫秒
11.
Robert Barouki Manolis Kogevinas Karine Audouze Kristine Belesova Ake Bergman Linda Birnbaum Sandra Boekhold Sebastien Denys Celine Desseille Elina Drakvik Howard Frumkin Jeanne Garric Delphine Destoumieux-Garzon Andrew Haines Anke Huss Genon Jensen Spyros Karakitsios Jana Klanova Paolo Vineis 《Chemie der Erde / Geochemistry》2012
The outbreak of COVID-19 raised numerous questions on the interactions between the occurrence of new infections, the environment, climate and health. The European Union requested the H2020 HERA project which aims at setting priorities in research on environment, climate and health, to identify relevant research needs regarding Covid-19. The emergence and spread of SARS-CoV-2 appears to be related to urbanization, habitat destruction, live animal trade, intensive livestock farming and global travel. The contribution of climate and air pollution requires additional studies. Importantly, the severity of COVID-19 depends on the interactions between the viral infection, ageing and chronic diseases such as metabolic, respiratory and cardiovascular diseases and obesity which are themselves influenced by environmental stressors. The mechanisms of these interactions deserve additional scrutiny. Both the pandemic and the social response to the disease have elicited an array of behavioural and societal changes that may remain long after the pandemic and that may have long term health effects including on mental health. Recovery plans are currently being discussed or implemented and the environmental and health impacts of those plans are not clearly foreseen. Clearly, COVID-19 will have a long-lasting impact on the environmental health field and will open new research perspectives and policy needs. 相似文献
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The aim of this work is to quantify some of the complex relationships between drainage area characteristics (such as bedrocks and quaternary deposits) and lake water quality (pH, alkalinity, conductivity, and hardness). Seventysix drainage lakes, mainly oligotrophic, are described with respect to drainage area characteristics, morphometry, and water chemistry. The DAZ (drainage area zonation) method has been used to describe the drainage areas. The method utilizes a weighting system to reduce the impact of land types with increasing distance from the lake. The most significant parameter governing the water chemistry parameters seems to be the percentage of open land (cultivated land and/or meadows) in the drainage areas. High percentage leads to high pH, alkalinity, conductivity, and hardness. The correlations concerning alkalinity and pH are improved using the DAZ method. No significant relationships between bedrock geology of the drainage areas and lake water chemistry have been recorded. 相似文献
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X-ray difffaction and differential thermal (DTA) techniques were applied to evaluate the semi-quantitative mineralogical composition of a deep black soil profile from India. X-ray investigations revealed the predominance fo a smectic mineral throughout the profile. The mineral gave its main dehydroxylation peak between 532°C (Mg-sat.) and 550° (K-sat.), indicating that it belonged to the nontronite-beidellite series. The concentration of this mineral decreased with increasing particle size, i.e. increasing concentration of feldspars and amphiboles. In addition, illite, iron-rich chlorite, quartz, attapulgite, sepiolite and some mixed-layer minerals were detected.
The effect of cation (Mg++, Ca++, K+) saturation on the intensity, symmetry and temperature of the DTA peaks is discussed. Abnormal behaviour of double dehydroxylation in two clay fractions was found to be due to the abundance of Mg++ cations in the exchangeble positions K+ and Ca++-saturation of the clays did not produce this effect. 相似文献
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A simple steady-state photochemical model is developed in order to determine typical molecular oxygen concentrations for a comprehensive range of primitive abiotic atmospheres. Carbon dioxide is assumed to be the dominant constituent in these atmospheres since CO2 photodissociation may potentially result in the enhancement of the O2 partial pressure. The respective effects of the H2O content, temperature, eddy diffusion coefficient and UV flux on the results are investigated. It is shown that for any pressure at the surface, the partial pressure of molecular oxygen does not exceed 10 mbar. The peculiar case of a runaway greenhouse which has possibly taken place on Venus is qualitatively envisaged. Although O2 is basically absent in the present Venus atmosphere, a transient presence in a primitive stage cannot be ruled out. Possible mechanisms for O2 removal in such an atmosphere are reviewed. At the present stage, we think that the detection of large O2 amounts would be at least a good clue for the presence of life on an extrasolar planet. 相似文献
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Philippe Paillou Mathieu Schuster Stephen Tooth Tom Farr Ake Rosenqvist Sylvia Lopez Jean-Marie Malezieux 《Earth and Planetary Science Letters》2009,277(3-4):327-333
Over the last few decades, remote sensing has revealed buried river channels in a number of regions worldwide, in many cases providing evidence of dramatic paleoenvironmental changes over Cenozoic time scales. Using orbital radar satellite imagery, we mapped a major paleodrainage system in eastern Libya, that could have linked the Kufrah Basin to the Mediterranean coast through the Sirt Basin, possibly as far back as the middle Miocene. Synthetic Aperture Radar images from the PALSAR sensor clearly reveal a 900 km-long river system, which starts with three main tributaries (north-eastern Tibesti, northern Uweinat and western Gilf Kebir/Abu Ras) that connect in the Kufrah oasis region. The river system then flows north through the Jebel Dalmah, and forms a large alluvial fan in the Sarir Dalmah. The sand dunes of the Calanscio Sand Sea prevent deep orbital radar penetration and preclude detailed reconstruction of any possible connection to the Mediterranean Sea, but a 300 km-long link to the Gulf of Sirt through the Wadi Sahabi paleochannel is likely. If this connection is confirmed, and its Miocene antiquity is established, then the Kufrah River, comparable in length to the Egyptian Nile, will have important implications for the understanding of the past environments and climates of northern Africa from the middle Miocene to the Holocene. 相似文献
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In this paper an explicit pseudo-linear estimator for Doppler-bearing tracking is proposed. It overcomes the problems with the bias of earlier pseudo-linear estimators and with the nonlinear frequency measurement equation by using another representation than the Cartesian one and by using the logarithm of the frequency, respectively. It is fast, inherently stable, and easy to implement. The Doppler shift is, for a nonmoving own-ship, determined by the target velocities, while the bearing rate is determined by the same velocities divided by the range. The special representation in this paper uses this difference in behavior to give fast and bias free estimation of the range. Instead of iterating a weighted feast squares problem using bearing and frequency measurements simultaneously, the true bearings and the course are estimated in a bearings only step followed by a frequency only step, which estimates range and frequency. The range estimate then gives the speed estimate. Modifications for scenarios with multiple emitted frequency lines and/or for frequency lines that disappear during parts of a scenario are shown 相似文献
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The rare carth elements are determined in vivianite concretions and surrounding clay sediments. Approximately 3/4 of the rare earth elements in the clay is present in adsorbed state. The concentration of REE in the pore water is calculated from the composition of the vivianite, assuming a diffusion model for the formation of the concretions and lower solubility of the rare earth elements above the concretions than in the pore water at some distance from the concretions. The concentrations thus calculated are similar to published values for ocean water. 相似文献
19.
Forest degradation is a global phenomenon and while being an important indicator and precursor to further forest loss, carbon emissions due to degradation should also be accounted for in national reporting within the frame of UN REDD+. At regional to country scales, methods have been progressively developed to detect and map forest degradation, with these based on multi-resolution optical, synthetic aperture radar (SAR) and/or LiDAR data. However, there is no one single method that can be applied to monitor forest degradation, largely due to the specific nature of the degradation type or process and the timeframe over which it is observed. The review assesses two main approaches to monitoring forest degradation: first, where detection is indicated by a change in canopy cover or proxies, and second, the quantification of loss (or gain) in above ground biomass (AGB). The discussion only considers degradation that has a visible impact on the forest canopy and is thus detectable by remote sensing. The first approach encompasses methods that characterise the type of degradation and track disturbance, detect gaps in, and fragmentation of, the forest canopy, and proxies that provide evidence of forestry activity. Progress in these topics has seen the extension of methods to higher resolution (both spatial and temporal) data to better capture the disturbance signal, distinguish degraded and intact forest, and monitor regrowth. Improvements in the reliability of mapping methods are anticipated by SAR-optical data fusion and use of very high resolution data. The second approach exploits EO sensors with known sensitivity to forest structure and biomass and discusses monitoring efforts using repeat LiDAR and SAR data. There has been progress in the capacity to discriminate forest age and growth stage using data fusion methods and LiDAR height metrics. Interferometric SAR and LiDAR have found new application in linking forest structure change to degradation in tropical forests. Estimates of AGB change have been demonstrated at national level using SAR and LiDAR-assisted approaches. Future improvements are anticipated with the availability of next generation LiDAR sensors. Improved access to relevant satellite data and best available methods are key to operational forest degradation monitoring. Countries will need to prioritise their monitoring efforts depending on the significance of the degradation, balanced against available resources. A better understanding of the drivers and impacts of degradation will help guide monitoring and restoration efforts. Ultimately we want to restore ecosystem service and function in degraded forests before the change is irreversible. 相似文献
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Although the dynamical evolution of magnetic clouds (MCs) has been one of the foci of interplanetary physics for decades, only few studies focus on the internal properties of large-scale MCs. Recent work by Wang et al. (J. Geophys. Res. 120, 1543, 2015) suggested the existence of the poloidal plasma motion in MCs. However, the main cause of this motion is not clear. In order to find it, we identify and reconstruct the MC observed by the Solar Terrestrial Relations Observatory (STEREO)-A, Wind, and STEREO-B spacecraft during 19?–?20 November 2007 with the aid of the velocity-modified cylindrical force-free flux-rope model. We analyze the plasma velocity in the plane perpendicular to the MC axis. It is found that there was evident poloidal motion at Wind and STEREO-B, but this was not clear at STEREO-A, which suggests a local cause rather than a global cause for the poloidal plasma motion inside the MC. The rotational directions of the solar wind and MC plasma at the two sides of the MC boundary are found to be consistent, and the values of the rotational speeds of the solar wind and MC plasma at the three spacecraft show a rough correlation. All of these results illustrate that the interaction with ambient solar wind through viscosity might be one of the local causes of the poloidal motion. Additionally, we propose another possible local cause: the existence of a pressure gradient in the MC. The significant difference in the total pressure at the three spacecraft suggests that this speculation is perhaps correct. 相似文献