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31.
The Military Survey Department (MSD) of the United Arab Emirates (UAE) undertook an airborne gravity survey project for the marine area of the country in 2009, especially to strengthen the marine and coastal geoid in the near-shore regions. For the airborne gravity survey, 5 km spacing coast-parallel flight lines were planned and surveyed. These lines were supplemented by cross-lines in order to assess the quality of the airborne gravity surveys. The flight lines were extended 10 km, spacing lines further offshore. A Beech King Air 350 aircraft was used for the surveys, collecting data at a typical flight speed of 170 knots and a typical flight elevation of 900–1500 m, depending on weather conditions and topography. Gravity was measured with a ZLS-modified LaCoste and Romberg gravimeter (S-99), augmented with a Honeywell strap-down inertial navigation system unit. The estimated accuracy for the airborne gravity data is better than 2.0 mGal r.m.s., as judged from the airborne track crossovers. The new airborne gravimetry data changed the UAE coastal geoid by up to 30 cm in some regions, highlighting the importance of airborne gravity coastal surveys.  相似文献   
32.
 The use of ocean floor basalt chemistry as a tool to investigate mantle composition and processes requires that we work with basalts that have been modified little since leaving the mantle. One source of such basalts is melt inclusions trapped in primitive crystals. However, obtaining information from these melt inclusions is complicated by the fact that melt inclusions in natural basalts are essentially always altered by post-entrapment crystallization. This requires that we develop techniques for reconstructing the original trapped liquid compositions. We conducted a series of experiments to reverse the effects of post-entrapment crystallization by re-heating the host crystals to their crystallization temperature. For these experiments we used plagioclase crystals separated from a single Gorda Ridge lava. The crystallization temperature for these crystals was determined by a set of incremental re-heating experiments to be ∼1240–1260° C. The inclusions are primitive, high Ca-Al basaltic melts, saturated with plagioclase, olivine and Al-rich chromite at low pressure. The inclusion analyses can be linked to the host lava composition by low pressure fractionation. The major element composition of the re-homogenized melt inclusions within each crystal is relatively constant. However, the incompatible element analyses have extremely wide ranges. The range of La/Sm and Ti/Zr from inclusions analyzed from a single sample from the Gorda Ridge exceeds the range reported for lavas sampled from the entire ridge. The pyroxene compositions predicted to be in equilibrium with the melt inclusion trace element signature cover much of the range represented by pyroxenes from abyssal peridotites. The volumetric proportions of the magmas entering the base of the crust can be evaluated using frequency distribution of melt inclusion compositions. This distribution suggests that the array of magmas was skewed towards the more depleted compositions, with little evidence for an enriched component in this system. This pattern is more consistent with a dynamic flow model of the mantle or of a passive flow model where the melts produced in the peripheral areas of the melting regime were not focused to the ridge. Received: 5 January 1995 / Accepted: 13 June 1995  相似文献   
33.
Pliocene to recent volcanic rocks from the Bulusan volcanic complex in the southern part of the Bicol arc (Philippines) exhibit a wide compositional range (medium- to high-K basaltic-andesites, andesites and a dacite/rhyolite suite), but are characterised by large ion lithophile element enrichments and HFS element depletions typical of subduction-related rocks. Field, petrographic and geochemical data indicate that the more silicic syn- and post-caldera magmas have been influenced by intracrustal processes such as magma mixing and fractional crystallisation. However, the available data indicate that the Bicol rocks as a group exhibit relatively lower and less variable 87Sr/86Sr ratios (0.7036–0.7039) compared with many of the other subduction-related volcanics from the Philippine archipelago. The Pb isotope ratios of the Bicol volcanics appear to be unlike those of other Philippine arc segments. They typically plot within and below the data field for the Philippine Sea Basin on 207Pb/204Pb versus 206Pb/204Pb and 208Pb/204Pb versus 206Pb/204Pb diagrams, implying a pre-subduction mantle wedge similar to that sampled by the Palau Kyushu Ridge, east of the Philippine Trench. 143Nd/144Nd ratios are moderately variable (0.51285–0.51300). Low silica (<55 wt%) samples that have lower 143Nd/144Nd tend to have high Th/Nd, high Th/Nb, and moderately low Ce/Ce* ratios. Unlike some other arc segments in the Philippines (e.g. the Babuyan-Taiwan segment), there is little evidence for the involvement of subducted terrigenous sediment. Instead, the moderately low 143Nd/144Nd ratios in some of the Bicol volcanics may result from subduction of pelagic sediment (low Ce/Ce*, high Th/Nd, and high Th/Nb) and its incorporation into the mantle wedge via a slab-derived partial melt.  相似文献   
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Biofiltration has shown to be a promising technique for handling malodours arising from process industries. The present investigation pertains to the removal of hydrogen sulphide in a lab scale biofilter packed with biomedia, encapsulated by sodium alginate and poly vinyl alcohol. The experimental data obtained under both steady state and shock loaded conditions were modelled using the basic principles of artificial neural networks. Artificial neural networks are powerful data driven modelling tools which has the potential to approximate and interpret complex input/output relationships based on the given sets of data matrix. A predictive computerised approach has been proposed to predict the performance parameters namely, removal efficiency and elimination capacity using inlet concentration, loading rate, flow rate and pressure drop as the input parameters to the artificial neural network model. Earlier, experiments from continuous operation in the biofilter showed removal efficiencies from 50 to 100 % at inlet loading rates varying up to 13 g H2S/m3h. The internal network parameter of the artificial neural network model during simulation was selected using the 2k factorial design and the best network topology for the model was thus estimated. The results showed that a multilayer network (4-4-2) with a back propagation algorithm was able to predict biofilter performance effectively with R2 values of 0.9157 and 0.9965 for removal efficiency and elimination capacity in the test data. The proposed artificial neural network model for biofilter operation could be used as a potential alternative for knowledge based models through proper training and testing of the state variables.  相似文献   
37.
Climate Dynamics - Analyzing December–February (DJF) precipitation in the southern tropical Andes—STA ($$12^{\circ }\,\hbox {S}$$–$$20^{\circ }\,\hbox {S}$$; &gt; 3000...  相似文献   
38.
This study investigated the removal of two model pharmaceutically active compounds (PhAcs), viz., ibuprofen and triclosan, in lab‐scale engineered floodplain filtration (EFF) system. Biodegradation experiments were performed to acquire knowledge about the degradation of the targeted PhAcs, at an initial concentration of 350 µg/L. Biodegradation results showed that the two compounds were bio‐transformed to >70% after 15 days of incubation. Column tests were performed in a statistically significant manner to determine the adsorptive potential of the suggested filler layer in the EFF (C/C0), by varying the flow rate and initial concentration of the compound. It was observed based on the F and p‐values that the main effects (F = 3163, p < 0.005) were more significant than the interactive effects (F = 9561, p < 0.05) for both ibuprofen and triclosan removal. Besides, by performing the Student's “t” test, it was concluded that the flow rate plays a major role in determining the rapidness of achieving complete breakthrough than the initial concentration of both the compounds. The data obtained from column studies under biotic conditions indicated that the removal mechanism for PhAcs is mainly biotransformation based, and that an EFF system may be effectively used to remove these emerging compounds during ground water recharge for water recycling.  相似文献   
39.
Georeferenced user-generated datasets like those extracted from Twitter are increasingly gaining the interest of spatial analysts. Such datasets oftentimes reflect a wide array of real-world phenomena. However, each of these phenomena takes place at a certain spatial scale. Therefore, user-generated datasets are of multiscale nature. Such datasets cannot be properly dealt with using the most common analysis methods, because these are typically designed for single-scale datasets where all observations are expected to reflect one single phenomenon (e.g., crime incidents). In this paper, we focus on the popular local G statistics. We propose a modified scale-sensitive version of a local G statistic. Furthermore, our approach comprises an alternative neighbourhood definition that enables to extract certain scales of interest. We compared our method with the original one on a real-world Twitter dataset. Our experiments show that our approach is able to better detect spatial autocorrelation at specific scales, as opposed to the original method. Based on the findings of our research, we identified a number of scale-related issues that our approach is able to overcome. Thus, we demonstrate the multiscale suitability of the proposed solution.  相似文献   
40.
Suspended particles and dissolved substances in water provide reactive surfaces, influence metabolic activity and contribute to the net sediment deposition. It therefore plays an important part in the ecology and quality of the water mass. The water quality in reservoirs is crucial and it is naturally maintained by flushing and sedimentation, which continuously remove phosphorus from the water. In some reservoirs, however, these removal processes are countered by recycling of ions which could play a key role to start and/or maintain the eutrophic state. The combination of macro‐, trace‐ and microanalysis techniques can be useful to trace pollution sources through a chemical fingerprint, whether be during an acute environmental disaster or a long‐term release of pollutants. The water quality and total metal content of reservoir sediments were assessed in a reservoir, situated in the capital of the Paraná State, in the South‐Eastern part of Brazil. The goal of this paper was to determine the metal presence in the sediment and metal and ionic speciation in the Green River reservoir water. Water and bed sediment samples, collected from various sites during 2008 and 2009, were investigated using XRF, ICP‐OES, ICP‐MS, XRD and zeta potential measurements. Based on the results, the heavy metal concentration and chemical composition of the suspended matter in the water samples, as well as the sediment's chemical composition will be discussed.  相似文献   
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