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1.
A new seafloor lander module, the Gas Monitoring Module (GMM), has been developed for continuous and long-term measurements of methane concentration in seawater at the benthic boundary layer, as a result of marine environmental geology and technology synergy. The module is designed to host a series of sensors controlled and managed by a data acquisition and control system able to perform first-level data quality checks. The prototype includes semiconductor methane sensors, an H2S sensor and a CTD for temperature, salinity, pressure recording, as well as interfaces for additional sensors. The GMM can be linked to submarine cables for real-time data transmission to onshore operators and is suitable for long-term monitoring of natural gas emissions from seafloor or leakages from pipelines and boreholes.  相似文献   

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Croatia is a country of tourism, and this is primarily due to its position by the warm Adriatic Sea, its varying and picturesque landscapes, its diverse and generally favorable climate for tourism, its rich Mediterranean and Central European cultural heritage and its proximity to the leading European consumer countries.In the international tourism market, Croatia presents itself with the slogan A Small Country for a Great Vacation, because its 4.8 million inhabitants and surface area of 56,538 km2 place Croatia in the ranks of the world's smaller countries. Its significance is increased by an additional 33,200 km2 of territorial waters, of which a large part is considered internal waters because of its location within the limits of a series of islands.The tourism offering of Croatia is very diverse, but its basis is formed by three differing and mutually complimentary regions, through their natural characteristics and cultural heritage: coastal, montane and Pannonian and peri-Pannonian Croatia. The total tourism offering of Croatia includes 900,000 beds, of which over one-fifth are in hotels or similar places, two-fifths are in private rooms and one-third in camps.The tradition of tourism in Croatia is over one hundred years old, and according to the number of foreign tourists it is ranked as the fifth country for tourism in southern Europe.  相似文献   

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Conventional methods for investigating soil heavy metal contamination based on raster sampling and chemical analysis are time consuming and relatively expensive. Reflectance spectroscopy within the visible-near-infrared (VNIR) region is known for being rapid, convenient, and accurate. Due to low abundance, heavy metals in soils cannot exhibit their inherently spectral features. The objective of this study were (1) to examine the possibility of reflectance spectra as a rapid method to assess Ni, Cr, Cu, Hg, Zn, As, Pb, and Cd in soils, and (2) to explore the mechanism by which to predict spectrally featureless heavy metals. Two research areas located in the south (120 samples) and north (61 samples) of Nanjing City were researched. Reflectance spectra of the samples were recorded on a Perkin-Elmer Lambda 900 spectrophotometer. Partial least-square regression (PLSR) approach was used to develop calibration equations between the spectral data and measured values for heavy metals. The prediction results of the two areas were consistent. Except for Cd all the other elements could be successfully predicted using the reflectance spectra. The prediction accuracy for Ni, Cr, and Cu was highest, while that for Hg and Cd was lowest. In order to further explore the physicochemical mechanism behind the relations between reflectance spectra and heavy metals, one more principal component analysis (PCA) was done for nine elements (eight heavy metals and Fe). The results of PCA for the both areas were also consistent. Loading plot of factors 1 and 2 from the results of PCA showed that Ni, Cr and Cu, the prediction accuracy of which was highest, were clustered together with Fe. For the other elements that were less correlated with Fe, their prediction accuracy was also lower than that of the three elements. Fe is spectrally active and can exhibit its absorption features. Therefore, the inter-correlation between heavy metals and spectrally active total Fe is the major mechanism by which to predict spectrally featureless trace metals. This study for the two areas showed the potential of reflectance spectra to predict microelements in soils.  相似文献   

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The paper proposes—and argues in favor of an alternative model to account for the dipole geomagnetic field in which a hitherto unrecognized piezomagnetic effect is the actual cause. This model offers a plausible explanation for the observed field reversals, the westward drift, and the secularly decreasing field strength. It is consistent with recent satellite data, and capable of generalization to planets other than Earth. It also accounts for the fact that the dipole axis is displaced from the geographic axis, and that the center of the dipole is displaced from the geographic center.  相似文献   

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Coupled thermal–hydrological–mechanical (THM) processes in the near field of deep geological repositories can influence several safety features of the engineered and geological barriers. Among those features are: the possibility of damage in the host rock, the time for re-saturation of the bentonite, and the perturbations in the hydraulic regime in both the rock and engineered seals. Within the international cooperative code-validation project DECOVALEX-2015, eight research teams developed models to simulate an in situ heater experiment, called HE-D, in Opalinus Clay at the Mont Terri Underground Research Laboratory in Switzerland. The models were developed from the theory of poroelasticity in order to simulate the coupled THM processes that prevailed during the experiment and thereby to characterize the in situ THM properties of Opalinus Clay. The modelling results for the evolution of temperature, pore water pressure, and deformation at different points are consistent among the research teams and compare favourably with the experimental data in terms of trends and absolute values. The models were able to reproduce the main physical processes of the experiment. In particular, most teams simulated temperature and thermally induced pore water pressure well, including spatial variations caused by inherent anisotropy due to bedding.  相似文献   

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Based on former conceptual models of vulnerability, this paper aims to improve the quantitative model for regional vulnerability assessment by analyzing in-depth the relation between vulnerability, exposure, coping capacity, and resilience. Taking the mountain settlements in the upper reaches of Min River, China, as a case study, the method of Contributing Weight Superposition (CWS) is applied in establishing both a model and a system for the vulnerability assessment of elements at risk. The CWS approach consists of 13 index factors including population, economic and road densities, building and farmland coverage, hazard-affected areas, urbanization rate, and GDP per capita. Accordingly, a debris flow hazard vulnerability zoning map was obtained and the assessment results show that the distribution of high and comparatively high vulnerability zones, where economic activities are considerably high, has a close correlation to the topography of the catchment and population characteristics. The results thus may serve as a pertinent guidance for settlement relocation, population distribution readjustment, and management to prevent and reduce hazards in the upper reaches of Min River and beyond.  相似文献   

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《Geochimica et cosmochimica acta》1999,63(13-14):1891-1903
To evaluate how the land carbon reservoir has been acting as a sink to the anthropogenic CO2 input to the atmosphere, it is important to study how plants in natural forests physiologically adjust to the changing atmospheric conditions. This has been studied intensively using controlled experiments, but it has been difficult to scale short-term observations to long-term ecosystem-level response. This paper derives variations of plant intrinsic water-use efficiency from natural trees for the past 100–200 years using carbon isotope chronologies. This parameter may potentially cause an increase in plant growth rate by improving the efficiency of plant water use, especially in arid environments. Attempts were made to isolate the variations of intrinsic water-use efficiency as a function of only the CO2 concentration of the atmosphere. The intrinsic water-use efficiency of almost all trees increased with increasing atmospheric CO2 concentration. This is caused by an increase in the carbon assimilation rate (A) and/or a decrease in the stomatal conductance (g). The increase in plant intrinsic water-use efficiency may imply an increase in plant transpiration efficiency which may have a direct connection with changes in plant biomass.  相似文献   

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GRIDA3 (Shared Resources Manager for Environmental Data Analysis and Applications) is a multidisciplinary project designed to deliver an integrated system to forge solutions to some environmental challenges such as the constant increase of polluted sites, the sustainability of natural resources usage and the forecast of extreme meteorological events. The GRIDA3 portal is mainly based on Web 2.0 technologies and EnginFrame framework. The portal, now at an advanced stage of development, provides end-users with intuitive Web-interfaces and tools that simplify job submission to the underneath computing resources. The framework manages the user authentication and authorization, then controls the action and job execution into the grid computing environment, collects the results and transforms them into an useful format on the client side. The GRIDA3 Portal framework will provide a problem-solving platform allowing, through appropriate access policies, the integration and the sharing of skills, resources and tools located at multiple sites across federated domains.  相似文献   

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A number of trace elements have been determined spectrographically in the rocks and minerals of the Skaergaard intrusion, East Greenland. The original basic magma from which the varied rocks of the complex were developed is shown to have had a normal trace element composition. The sorting out of the trace elements into the various mineral series produced by strong fractional crystallization of the original basic magma is traced in detail by means of analyses of the separated minerals. Certain of the trace elements (Cr, Ni) are shown to be strongly concentrated in the early rocks so that later fractions have little or none of them; other elements (P, V, Cu, Sc, Mn, S) reach maximum values in the middle, or late middle stages represented by certain olivine-free gabbros and ferrogabbros; other elements (Li, Zr, Y, La, Ba, Rb) tend to remain in the residual liquid during fractionation and are thus abundant in the latest granite fraction. Still other trace elements (Co, Sr, Ga, Mo) show only small changes in amount throughout the series. Of these Co is a little more abundant in the early and middle stages, Sr in the middle stages, Ga in the later stages and Mo in the early and later but not in the middle stages. The distribution of the trace elements in the rocks is considered in relation to the varying composition of the minerals produced by the fractional crystallization processes and an attempt is made to discuss the mineral compositions in terms of crystal chemical concepts.The Skaergaard sequence of differentiation from gabbros, through ferrogabbros, to granite is considered to be a common trend of fractionation of basic magma at high levels in the crust, and the observed changes in trace element composition are therefore regarded as having wide geochemical significance. The trace element composition of the intermediate Skaergaard differentiates is significantly different from that of diorites reported by other workers and suggests that diorites have had some other origin than by fractionation of basic magma. On the other hand the trace element composition of many granites resembles that of the granite fraction produced in the Skaergaard intrusion.  相似文献   

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The solid solution sanmartinite (ZnWO4)—cuproscheelite (CuWO4) has been studied using Cu 2p X-ray absorption spectroscopy. While a single L3 absorption peak is observed for CuWO4, two distinct L3 absorption peaks with a separation of ~0.8 eV are observed for the intermediate samples in the solid solution. The two peaks represent distinct Cu sites: one with all CuO6 next nearest neighbours in the (Cu,Zn)O6 chains, another having at least one ZnO6 next nearest neighbour. Both sites show a linear increase in covalency as a function of increasing Cu-content. The relative intensities of the two absorption peaks is dependent upon the Cu-content and has been used to model the site occupancies. The results reveal that the local structural effects can be associated with a composition-dependent structural phase transition from P2/c (ZnWO4) to P $\bar 1$ (CuWO4). Deviations from a single-site model are explained in terms of the local environments, and evidence for site preferences and local clustering are explored.  相似文献   

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The contamination of soils has a direct impact on human health. The ecological risk assessment for heavy metal contamination of agricultural soils (ERAHMCA) is of vital importance. Although the overall concentrations of PTEs in the soils are usually taken into consideration a important factor of assessment for PTEs contamination, this study, by taking it into consideration that the main-path for ecological risk of heavy metal contamination of agricultural soil is soil-vegetation-man, intr…  相似文献   

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A selection of evidence, including a carbon isotopic excursion, iridium anomaly, fullerenes (C60 and C70) with trapped noble gasses, microspherules and shocked quartz, is discussed in this paper. All the evidence in hand favors the hypothesis that the PTB event was probably related to an extraterrestrial cause, and the impact would lead to great physical change, including large volcanic eruptions. on the earths surface. The ET markers for the CTB event could be considered only as an example, and cannot be taken as a unique standard of an ET event.  相似文献   

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