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351.
Marta Zossi de Artigas Patricia Fernandez de Campra 《Journal of Atmospheric and Solar》2010,72(7-8):565-569
Trends in total column ozone have been analyzed in terms of the equatorial zonal wind. We used zonal monthly mean total ozone from Total Ozone Mapping Spectrometer (TOMS) and monthly mean zonal wind in the equatorial stratosphere at 30 hPa to define the phases of the quasi-biennial oscillation (QBO). Total column ozone trends have been assessed during the period 1979–2004, for both Hemispheres, and for each month, under three conditions considering, all the ozone dataset, ozone values during easterly phase and ozone values during westerly phase of the QBO. When the whole dataset is considered, negative trends are observed. From low to midlatitudes a zonal pattern is noticed with increasing negative values toward higher latitudes. When the data is filtered according to the QBO phase, statistically significant positive trends appear in the westerly case during January to May at low latitudes .The trend pattern in the case of the easterly phase presents more negative values. 相似文献
352.
Ernesto Heredia‐Zavoni Sandra Santa‐Cruz Francisco L. Silva‐González 《地震工程与结构动力学》2015,44(13):2241-2260
A formulation is developed for modal response analysis of multi‐support structures using a random vibration approach. The spectral moments of the structural response are rigorously decomposed into contributions from spectral moments of uncoupled modal responses. An advantage of the proposed formulation is that the total dynamic response can be obtained on the basis of mode by mode uncoupled analyses. The contributions to the total response from modal responses under individual support ground motions and under cross‐correlated pairs of support ground motions can be recognized explicitly. The application and performance of the formulation is illustrated by means of an example using a well‐established coherency spectrum model and widely known power spectra models, such as white noise and Kanai–Tajimi. The first three spectral moments of displacement, shear, and bending moment responses are computed, showing that the formulation produces the same results as the exact solution. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
353.
Luis F.O.Silva Ismael L.Schneider Paulo Artaxo Yuleisy Núñez-Blanco Diana Pinto Érico M.M.Flores Leandro Gómez-Plata Omar Ramírez Guilherme L.Dotto 《地学前缘(英文版)》2022,(1):376-387
Air pollution has become an important issue,especially in Caribbean urban areas,and,particulate matter(PM)emitted by different natural and anthropogenic sources causes environmental and health issues.In this work,we studied the concentrations of PM10 and PM2.5 sources in an industrial and port urban area in the Caribbean region of Colombia.PM samples were collected within 48-h periods between April and October 2018 by using a Partisol 2000 i-D sampler.Elemental geochemical characterization was performed by X-ray fluorescence(XRF)analysis.Further,ionic species and black carbon(BC)were quantified by ion chromatography and reflectance spectroscopy,respectively.Using the Positive Matrix Factorization(PMF)receptor model,the contributions of PM sources were quantified.The average concentration of PM10 was 46.6±16.2μg/m3,with high concentrations of Cl and Ca.For PM2.5,the average concentration was 12.0±3.2μg/m3,and the most abundant components were BC,S,and Cl.The receptor model identified five sources for PM10 and PM2.5.For both fractions,the contributions of marine sea spray,re-suspended soil,and vehicular traffic were observed.In addition,PM2.5 included two mixed sources were found to be fuel oil combustion with fertilizer industry emissions,and secondary aerosol sources with building construction emissions.Further,PM10 was found to also include building construction emissions with re-suspended soil,and metallurgical industry emissions.These obtained geochemical atmospheric results are important for the implementation of strategies for the continuous improvement of the air quality of the Caribbean region. 相似文献
354.
A. Cachada S. M. Rodrigues C. Mieiro E. Ferreira da Silva E. Pereira A. C. Duarte 《Environmental Geology》2009,57(1):91-98
This study aims at assessing the extent of total mercury (Hg) contamination in urban and agricultural soils under long-term
influence of a chlor-alkali plant, located at about 1 km away from a town centre. Moreover, it aims at identifying the main
factors controlling Hg contents’ distribution and associated potential hazards to environment and human health. The median
value of total Hg for soil surface layer (0–10 cm) was 0.20 mg/kg (data ranging from 0.050 to 4.5 mg/kg) and for subsurface
layer (10–20 cm) 0.18 mg/kg (data ranging from 0.046 to 3.0 mg/kg). The agricultural area showed higher Hg concentrations
(ranging from 0.86 to 4.5 mg/kg) than urban area (ranging from 0.05 to 0.61 mg/kg), with some results exceeding target values
set by the Dutch guidelines. Mercury concentrations observed in the studied area are more likely to be associated with the
influence of the chlor-alkali plant and with the use of historically contaminated sludges and water from a nearby lagoon in
agriculture, than to the impacts of urban development. The statistical correlations between Hg concentrations and soil properties
suggest that anthropogenic metal sources should influence the spatial distribution more than the geological properties. Although
the Hg emissions were drastically reduced 10 years ago, the area under influence of the chlor-alkali plant is still facing
potential health and environmental threats arising from soil contamination. 相似文献
355.
This paper shows the potential of gravity data to map a buried landfill bottom topography. To this end, a gravity inversion
method is presented for estimating the landfill’s bottom depths at discrete points assuming a decrease of the density contrast
with depth according to a hyperbolic law. The method’s efficiency was tested using synthetic data from simulated waste landfills,
producing estimated bottom topographies very close to the true ones. The method’s potentiality has been further evaluated
in applying it to the gravity data from the abandoned Thomas Farm Landfill site, Indiana, USA, whose bottom topography is
known. The estimated topography showed close agreement with the known Thomas Farm Landfill’s bottom topography. 相似文献
356.
Paulo Pinheiro da Silva Leonardo Salayandía Aída Gándara Ann Q. Gates 《Earth Science Informatics》2009,2(4):249-269
The realization of an international cyberinfrastructure of shared resources to overcome time and space limitations is challenging
scientists to rethink how to document their processes. Many known scientific process requirements that would normally be considered
impossible to implement a few years ago are close to becoming a reality for scientists, such as large scale integration and
data reuse, data sharing across distinct scientific domains, comprehensive support for explaining process results, and full
search capability for scientific products across domains. This article introduces the CI-Miner approach that can be used to
aggregate knowledge about scientific processes and their products through the use of semantic annotations. The article shows
how this aggregated knowledge is used to benefit scientists during the development of their research activities. The discussion
is grounded on lessons learned through the use of CI-Miner to semantically annotate scientific processes in the areas of geo-sciences,
environmental sciences and solar physics: A use case in the field of geo-science illustrates the CI-Miner approach in action. 相似文献
357.
Ignez de Pinho Guimarães Adejardo F. da Silva Filho Daniel Brito de Araújo Cícera Neysi de Almeida Elton Dantas 《Gondwana Research》2009,15(1):98-110
The Solânea Complex (572 ± 8 Ma) comprises various intrusions that total 200 km2. It cuts Palaeoproterozoic migmatized orthogneisses of the Serrinha–Pedro Velho Complex, which is part of the São José do Campestre Massif, North Tectonic Domain of the Borborema Province, NE Brazil. It is a post-collisional intrusion constituted of coarse-grained biotite–amphibole monzogranites, fine-grained leucogranites and diorites. Major, trace and rare earth elements data, used to constrain the origin and nature of these rocks, indicate that the monzogranites display chemical features of weakly peraluminous ferro-potassic trans-alkaline granitoids, similar to coeval occurrences described in eastern Nigerian. Sm–Nd data together with the whole rock geochemical data suggest that: (I) the monzogranites were generated by partial melting of tonalitic gneiss from the lower crust, leaving behind a granulitic residue; (II) the diorites originated by partial melting of an enriched lithospheric mantle; (III) the evolution of the Solânea Complex involved magma mixing between the monzogranites and diorites. K-feldspar and amphibole fractionation appear to have occurred during the evolution of the monzogranites.Leucogranites constituting an elliptical shaped intrusion (80 km2), the Dona Inês Pluton, are intruded to the north of the Solânea Complex. They also occur as small intrusions cross-cutting the border of the Solânea Complex. Geochemical and isotopic data suggest that the leucogranites were generated by melting of crustal Palaeoproterozoic rocks. Rb–Sr data gave an age of 544 ± 16 Ma.Trans-alkaline magmatism is associated with ductile–brittle deformation in the Serrinha–Pedro Velho Complex of the São José do Campestre Massif. This event follows the peak of an extensional-related high-temperature metamorphism (upper amphibolite to granulite facies), with estimated age of 578 to 574 Ma. If a pre-Gondwana reconstruction is considered, this event is seen to extend to the African side of Gondwana in eastern Nigeria. 相似文献
358.
M. Assafin R.P. Campos D.N. da Silva Neto A.H. Andrei 《Planetary and Space Science》2008,56(14):1882-1887
Ground-based observations of faint satellites nearby their planets with 1-2 m class telescopes usually do not allow for high quality astrometry and photometry, due to saturation by the primary or to poor S/N ratio on the satellite images, generally embedded on the scattered light of the planet. Earth-based observations of the Uranus satellites’ upcoming mutual events in 2007-2008 are no exception. In most cases, the event will take place at 4 arcs or less from the planet, with “planet minus satellite” brightness differences of 10 magnitudes. So as to make feasible the observations of these important phenomena, we have developed a prototype of a coronagraph of simple design making use of good quality commercial optical systems. Pilot tests made with this coronagraph with a telescope of show that it is possible to obtain S/N ratios of 50 or higher for 10 s exposures, for satellites as close as 2 Uranus radii from the planet center. We have also developed numerical algorithms which perform digital coronagraphy in the images, with the elimination of the influence of the planets’ scattered light. This procedure considerably improves the S/N ratio of the satellite images (with or without a coronagraph instrument) and shall be applied in the reduction of the observations of the Uranus events so as to achieve the highest possible photometric and astrometric quality. 相似文献
359.
Débora V. Franco Wilson F. Jardim Julien F. C. Boodts Leonardo M. Da Silva 《洁净——土壤、空气、水》2008,36(1):34-44
Perspectives, advances and environmental aspects concerning electrochemical ozone production applied to water purification are presented and discussed in relation to the conventional corona process (silent electric discharge). Ozone generated using a laboratory‐made electrochemical reactor was applied for the discoloration/degradation of dyes used in the Brazilian textile industry and for degradation of endocrine disruptors. A constant ozone load of 0.35 ± 0.02 g/h was used throughout. The study, concerning color removal from dye solutions, revealed that total discoloration is rapidly achieved. The degradation rate of the textile dyes evaluated by TOC is little affected by the dye composition and considerably influenced by the pH and ozonation time. Analysis of the COD/TOC‐ratio indicates that ozonation increases oxidation feasibility of the organic matter (dye by‐products) when compared to the original compounds. Ozonation of mixed aqueous solutions containing different endocrine disruptors revealed these compounds are totally degraded with a very high removal rate. 相似文献
360.