General and specific growth marks in pegmatite beryls     

Giorgio Graziani  Sergio Lucchesi  Eugenio Scandale 《Physics and Chemistry of Minerals》1990,17(5):379-384

Growth marks of pegmatite beryls can be divided into general and specific in relation to their types and distributions. Dislocation absence and growth bands have been recognized as general growth marks of the environment while minor element concentrations and optical anomalies as specific to the local growth medium.  相似文献   

Particle-size distribution of inorganic water soluble ions in the venezuelan savannah atmosphere during burning and nonburning periods     

Eugenio Sanhueza  Alberto Rondón 《Journal of Atmospheric Chemistry》1988,7(4):369-388

The results presented are the first complete analysis of inorganic soluble ions in a tropical savannah region. Atmospheric particles were collected in six rural Venezuelan savannah sites. Concentrations and size distribution of NO₃ ^–, SO₄ ^2-, CI^–, PO₄ ^3-, NH₄ ⁺, Na⁺, K⁺, Ca²⁺ and Mg²⁺ were determined in samples collected with Hi Vol samplers equipped with five-stage cascade impactors. Concentrations were higher in the dry season, with a maximum during the burning periods. Using Na⁺ as a reference, the results show a deficit of Cl^– and, with the exception of Mg²⁺, an enrichment of all other ions with respect to marine aerosols. Significant variations were observed in particle-size distribution between different periods. Various pairs of ions present similar size distributions: SO₄ ^2- and NH₄ ⁺; Cl^– and Na⁺; PO₄ ^3- and K⁺; Ca²⁺, Mg²⁺ and NO₃ ^–; indicating that the ions were produced by the same source and/or were involved in similar atmospheric processes. Possible primary sources, the gas-to-particle atmospheric process, environmental implication of long-range transport of nutrients during dry seasons, etc., are discussed.  相似文献   

Surface ozone measurements in the Venezuelan tropical savannah     

Eugenio Sanhueza  Kathleen H. Octavio  Alfonso Arrocha 《Journal of Atmospheric Chemistry》1985,2(4):377-385

A one-year set of surface ozone measurements in a four-station network located in the Venezuelan savannah is reported. The diurnal ozone variation is typical of continental stations with a maximum in the afternoon, when vertical turbulent mixing is strongest. The annual O₃ average concentration, based on the monthly averages of daily maxima, was 17±2 ppb, which is in good agreement with values reported for similar latitudes. The boundary-layer ozone levels did not fall below 8 ppb, in contrast with previous sporadic measurements made in tropical latitudes. No evidence was found that mesoscale O₃ downdrafts in the ITCZ in the South American continent are an important source of surface ozone. Finally, it is suggested that the relatively high ozone levels observed at the end of the dry season are probably of photochemical origin.  相似文献   

On the mathematics of storage routing     

Cheng-Nan Chang  Eugenio Da Motta Singer  Antonis D. Koussis 《Journal of Hydrology》1983,61(4):357-370

Some mathematical aspects of storage routing are investigated analytically and through numerical simulation. The minimum size of the time interval required to eliminate computed values at the beginning of the outflow hydrograph falling below the initial steady flow rate is given for two routing schemes. The stability behavior of a refined Muskingum scheme is explored; it is found that values of the weighting coefficient up to 1.0 may be used with appropriately specified time intervals. The concept of “relative” storage is analyzed and it is shown that it is unnecessary when the correct initial condition of the storage is considered. The classical best straight-line fit procedure between storage and weighted discharge is investigated. In an example case, it is demonstrated that this method of system identification is not reliable. The possibility of using discharge-dependent parameters is discussed.  相似文献   

Most similar neighbor imputation of forest attributes using metrics derived from combined airborne LIDAR and multispectral sensors     

Ruben Valbuena  Ana Hernando  Jose Antonio Manzanera  Eugenio Martínez-Falero  Antonio García-Abril  Blas Mola-Yudego 《International Journal of Digital Earth》2018,11(12):1205-1218

In the context of predicting forest attributes using a combination of airborne LIDAR and multispectral (MS) sensors, we suggest the inclusion of normalized difference vegetation index (NDVI) metrics along with the more traditional LIDAR height metrics. Here the data fusion method consists of back-projecting LIDAR returns onto original MS images, avoiding co-registration errors. The prediction method is based on non-parametric imputation (the most similar neighbor). Predictor selection and accuracy assessment include hypothesis tests and over-fitting prevention methods. Results show improvements when using combinations of LIDAR and MS compared to using either of them alone. The MS sensor has little explanatory capacity for forest variables dependent on tree height, already well determined from LIDAR alone. However, there is potential for variables dependent on tree diameters and their density. The combination of LIDAR and MS sensors can be very beneficial for predicting variables describing forests structural heterogeneity, which are best described from synergies between LIDAR heights and NDVI dispersion. Results demonstrate the potential of NDVI metrics to increase prediction accuracy of forest attributes. Their inclusion in the predictor dataset may, however, in a few cases be detrimental to accuracy, and therefore we recommend to carefully assess the possible advantages of data fusion on a case-by-case basis.  相似文献   

Cross-twinning in a natural spinel from Sri Lanka     

Rosa Anna Fregola  Eugenio Scandale 《Physics and Chemistry of Minerals》2007,34(8):529-541

A modified cross-twinning growth mechanism is put forward to explain the anomalous morphology of a spinel multiple-twin from Sri Lanka, flattened crosswise the twin planes. Cross-twinning in spinel was found also in other specimens from Pegu (Myanmar), and the results were published in a previous paper. This particular type of twinning is derived from the combination of cyclic twinning with lamellar twinning, so that these samples may be thought of as partial fivelings (cubic cyclic {111} twins with five components sharing a common <110> pseudo-fivefold axis). In the present paper, the sample from Sri Lanka has been suitably cut with the aim of focusing the study on the cross-twinning region. The transformation matrices that link the orientation states of each couple of twin components have been determined by means of White Beam Synchrotron Radiation Topography. They showed that the specimen is made up of four twin components (A, B, C and D), with three twin planes: and They also showed that the cross-twinned individuals (B and D) actually are not twinned to each other, and that a simple crystallographic relationship holds between them. X-ray diffraction topography by conventional source allowed to image the crossing-region and to determine that the cross-twinned individuals are in contact through a semi-coherent boundary, with twinning dislocations contributing to relieve the coherency strains. Electron probe microanalyses with wave dispersive spectroscopy showed that the chemical composition is almost homogeneous, at least within the spatial resolution limit of this technique. The similar growth features observed in the spinel sample from Sri Lanka and in those from Myanmar are interpreted as growth marks, indicators of a similar origin: in both cases they are found in impure dolomitic marbles. In particular, the specimen from Sri Lanka results from the interaction of thermal and metasomatic effects due to contact metamorphism. An unusual stepped morphology of the face close to the twin boundary, possibly due to corrosion and re-growth processes acted preferentially at a re-entrant corner by metasomatic fluids, is interpreted as indicator of a metasomatic event that succeeded to the crystal growth, the latter occurred by thermal effect.

Rosa Anna FregolaEmail:

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The Gulf of California: Review of ecosystem status and sustainability challenges     

Salvador E. Lluch-Cota  Eugenio A. Aragón-Noriega  David Aurioles-Gamboa  Richard C. Brusca  Roberto Cortés-Altamirano  Alfonso Esquivel-Herrera  Michel E. Hendrickx  Hugo Herrera-Cervantes  Miguel Lavín  Daniel B. Lluch-Cota  Silvio G. Marinone  Sofia Ortega-García  Alejandro Parés-Sierra  Mauricio Ramírez-Rodríguez  Richard A. Schwartzlose  Arturo P. Sierra-Beltrán 《Progress in Oceanography》2007,73(1):1-26

The Gulf of California is unique because of its geographical location and conformation. It hosts diverse ecosystems and important fisheries that support industry and provide livelihood to coastal settlements. It is also the site of interests and problems, and an intense interaction among managers, producers, and conservationists. In this report, we scrutinize the abiotic (hydrography, climate, ocean circulation, and chemistry) and biotic (phyto- and zooplankton, fish, invertebrates, marine mammals, birds, and turtles) components of the marine ecosystem, and some particular aspects of climate variability, endemisms, harmful algal blooms, oxygen minimum layer, and pollution. We also review the current conditions and conflicts around the main fisheries (shrimp, small and large pelagic fishes, squid, artisanal and sportfishing), the most important human activity in the Gulf of California. We cover some aspects of management and conservation of fisheries, especially the claimed overexploitation of fish resources and the ecosystems, and review proposals for creating networks of marine protected areas. We conclude by identifying main needs for information and research, particularly the integration of data bases, the implementation of models and paleoreconstructions, establishment of monitoring programs, and the evaluation of fishing impacts and management actions.  相似文献   

Patterns of Posidonia oceanica (L.) Delile Beds around the Island of Ischia (Gulf of Naples) and in Adjacent Waters     

Paolo  Colantoni  Paolo  Gallignani  Eugenio  Fresi Francesco  Cinelli 《Marine Ecology》1982,3(1):53-74

Abstract. Posidonia oceanica prairies have been studied and mapped around the Island of Ischia and in adjacent waters. Prairies were found to cover an area of 15.7 km² and to be distributed between 0.5 and 39 m depth. The observed distribution is comparable to those reported by previous authors indicating that prairies have not undergone remarkable regressions in the last 50 years. Patterns recorded within the beds and at their lower limits, as indicated also by their sediments characteristics, are correlated to hydrodynamic energy. Two main types of water motion are responsible for the different types of erosive features: a) steady currents flowing parallel to the coast; b) rip-, wave induced currents flowing normal to the coast.  相似文献   

Assessment of toxicological health risk of trace metals in vegetables mostly consumed in Punjab,Pakistan     

Zafar Iqbal Khan  Kafeel Ahmad  Muhammad Ashraf  Nadia Shoaib  Rukhsana Parveen  Zahara Bibi  Irfan Mustafa  Ijaz Rasool Noorka  Hafiz Muhammad Tahir  Nudrat Aisha Akram  Muhammad Fahad Ullah  Rabia Yaqoob  Vincenzo Tufarelli  Mariano Fracchiolla  Eugenio Cazzato 《Environmental Earth Sciences》2016,75(5):433

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Digital Urban Morphometrics: Automatic Extraction and Assessment of Morphological Properties of Buildings     

Cláudio Carneiro  Eugenio Morello  Thomas Voegtle  François Golay 《Transactions in GIS》2010,14(4):497-531

The aim of this article is to present a method to calculate the morphological properties of the built environment using LiDAR (light detection and ranging) data, geographic information systems (GIS) data and three‐dimensional (3D) models of cities as a source of information. A hybrid approach that takes into account different types of inputs and consequently evaluates the accuracy of each type of used data is presented. This work is intended to give a first response to the lack of a comprehensive and accurate procedure that uses LiDAR data in order to automatically derive precise morphological properties, such as volumes and surfaces (façades and roofs) of buildings. The method was tested on two case‐study areas in the Geneva region with different characteristics, one in the old town along the Rhone River and the other on the CERN campus. A statistical analysis that compares the results of the computation with the 3D model of the built environment was used to validate the results, complemented by significance statistical tests. Outcomes showed that the proposed method to derive morphological properties can reach high levels of accuracy, thus enhancing the potential uses of LiDAR data for numerous applications, typically for the assessment of the urban environmental quality (UEQ) at the city and district scale, such as the estimation of the potential deployment of renewable energies in the built environment and the determination and monitoring of several urban indicators.  相似文献