Metal accumulation by plant species growing on a mine contaminated site in Mexico     

Ofelia Morton-Bermea  Juan Miguel Gómez-Bernal  María Aurora Armienta  Rufino Lozano  Elizabeth Hernández-Álvarez  Francisco Romero  Javier Castro-Larragoitia 《Environmental Earth Sciences》2014,71(12):5207-5213

The present work aims to assess the efficiency of heavy metal accumulation of native species growing in contaminated soils in the mining district of Taxco, Mexico. Soil and tailing sampling was conducted in three study sites: La Concha, El Fraile, and a control site. The study localities present diverse metal concentrations with significant differences in their proportion in the geochemical fractions. Results show that species Cupressus lindleyi and Juniperus deppeana accumulate Zn and Mn in anomalous concentrations at La Concha, where Zn is present in soluble fractions. Manganese, despite not being present mostly in the soluble fraction in soils and tailings, seems to have been increased in the soluble fraction after the plant growth. In contrast, samples of the same species taken at El Fraile and in the control site, where Zn and Mn are mainly contained in the residual fraction, do not show an anomalous enrichment. Other analyzed species growing under the same contamination conditions in La Concha (Jacaranda mimosifolia and Psidium guajava) do not show anomalous concentrations. These facts confirm the Zn and Mn accumulation capacity of C. lindleyi and Ju. deppeana, which depends on their accumulation ability and on the concentration of these elements in the soluble fraction.  相似文献   

An Algebra for Spatiotemporal Data: From Observations to Events     

Karine Reis Ferreira  Gilberto Camara  Antônio Miguel Vieira Monteiro 《Transactions in GIS》2014,18(2):253-269

Recent technological advances in geospatial data gathering have created massive data sets with better spatial and temporal resolution than ever before. These large spatiotemporal data sets have motivated a challenge for Geoinformatics: how to model changes and design good quality software. Many existing spatiotemporal data models represent how objects and fields evolve over time. However, to properly capture changes, it is also necessary to describe events. As a contribution to this research, this article presents an algebra for spatiotemporal data. Algebras give formal specifications at a high‐level abstraction, independently of programming languages. This helps to develop reliable and expressive applications. Our algebra specifies three data types as generic abstractions built on real‐world observations: time series, trajectory and coverage. Based on these abstractions, it defines object and event types. The proposed data types and functions can model and capture changes in a large range of applications, including location‐based services, environmental monitoring, public health, and natural disasters.  相似文献   

Stars beyond galaxies: the origin of extended luminous haloes around galaxies     

Mario G. Abadi †  Julio F. Navarro ‡  Matthias Steinmetz 《Monthly notices of the Royal Astronomical Society》2006,365(3):747-758

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The Herschel PACS photometer calibration     

Markus Nielbock  Thomas Müller  Ulrich Klaas  Bruno Altieri  Zoltán Balog  Nicolas Billot  Hendrik Linz  Koryo Okumura  Miguel Sánchez-Portal  Marc Sauvage 《Experimental Astronomy》2013,36(3):631-660

We present a flux calibration scheme for the PACS chopped point-source photometry observing mode based on the photometry of five stellar standard sources. This mode was used for science observations only early in the mission. Later, it was only used for pointing and flux calibration measurements. Its calibration turns this type of observation into fully validated data products in the Herschel Science Archive. Systematic differences in calibration with regard to the principal photometer observation mode, the scan map, are derived and amount to 5 ? 6 %. An empirical method to calibrate out an apparent response drift during the first 300 Operational Days is presented. The relative photometric calibration accuracy (repeatability) is as good as 1 % in the blue and green band and up to 5 % in the red band. Like for the scan map mode, inconsistencies among the stellar calibration models become visible and amount to 2 % for the five standard stars used. The absolute calibration accuracy is therefore mainly limited by the model uncertainty, which is 5 % for all three bands.  相似文献   

Spatial and temporal distribution of landlocked Galaxias maculatus and Galaxias platei (Pisces: Galaxiidae) in a lake in the South American Andes     

Juan P. Barriga  Miguel A. Battini  Patricio J. Macchi  Daniela Milano  Victor E. Cussac 《新西兰海洋与淡水研究杂志》2013,47(2):345-359

Galaxiids are present in many of the Andean lakes in southern South America. We studied landlocked Galaxias maculatus (Jenyns) and Galaxias platei Steindachner populations in a deep oligotrophic lake (Lake Gutiérrez, Patagonia, Argentina). Their temporal and spatial distribution, intralacustrine movements (horizontal and vertical), and spawning periods were analysed using several sampling techniques (ichthyoplankton net, seine net, gill net, and baited benthic taps). We identified the early life stages of both species based on their morphology and otolith shape. The free embryos of both species migrate to the limnetic zone, where they coexist as larvae, facing the same food availability and probably the same predation risk. Each species then moves on to its own juvenile and adult habitat: the littoral and benthic zone for G. maculatus and only the deeper benthic zone for G. platei. Their adult habitats and part of their spawning periods partly overlap.  相似文献   

Rural gentrification in Catalonia, Spain: A case study of migration, social change and conflicts in the Empordanet area   总被引：4，自引：0，他引：4  

Miguel Solana-Solana 《Geoforum》2010,41(3):508-517

The intensity of rural depopulation in Catalonia has diminished since the 1980s. New population growth patterns are occurring in rural areas, basically due to immigration. Although there has been a certain awareness of the magnitude of this process and its territorial distribution, little is known about the protagonists in this immigration and the impact on rural municipalities. Results are presented from a study of the immigration process in a group of rural inland municipalities close to the Costa Brava, a Mediterranean coastal region with extensive tourism. The great beauty of the landscape and the existence of housing stock that is being abandoned but remains desirable have led to a population influx from Catalonia’s large urban areas, especially Barcelona, purchasing these homes as a primary or secondary residence.This has led to rehabilitation of the housing stock, but also to higher housing prices and the resulting exodus of the young local population that cannot afford them; a potential source of conflict between the local population and the newcomers. The study is based on census data and statistical records, as well as extensive fieldwork, including interviews with local residents, newcomers and key informants.  相似文献   

Modern analogues for Miocene to Pleistocene alkali basaltic phreatomagmatic fields in the Pannonian Basin: “soft-substrate” to “combined” aquifer controlled phreatomagmatism in intraplate volcanic fields Research Article     

Károly Németh  Shane J. Cronin  Miguel J. Haller  Marco Brenna  Gabor Csillag 《Central European Journal of Geosciences》2010,2(3):339-361

The Pannonian Basin (Central Europe) hosts numerous alkali basaltic volcanic fields in an area similar to 200 000 km². These volcanic fields were formed in an approximate time span of 8 million years producing smallvolume volcanoes typically considered to be monogenetic. Polycyclic monogenetic volcanic complexes are also common in each field however. The original morphology of volcanic landforms, especially phreatomagmatic volcanoes, is commonly modified. by erosion, commonly aided by tectonic uplift. The phreatomagmatic volcanoes eroded to the level of their sub-surface architecture expose crater to conduit filling as well as diatreme facies of pyroclastic rock assemblages. Uncertainties due to the strong erosion influenced by tectonic uplifts, fast and broad climatic changes, vegetation cover variations, and rapidly changing fluvio-lacustrine events in the past 8 million years in the Pannonian Basin have created a need to reconstruct and visualise the paleoenvironment into which the monogenetic volcanoes erupted. Here phreatomagmatic volcanic fields of the Miocene to Pleistocene western Hungarian alkali basaltic province have been selected and compared with modern phreatomagmatic fields. It has been concluded that the Auckland Volcanic Field (AVF) in New Zealand could be viewed as a prime modern analogue for the western Hungarian phreatomagmatic fields by sharing similarities in their pyroclastic successions textures such as pyroclast morphology, type, juvenile particle ratio to accidental lithics. Beside the AVF two other, morphologically more modified volcanic fields (Pali Aike, Argentina and Jeju, Korea) show similar features to the western Hungarian examples, highlighting issues such as preservation potential of pyroclastic successions of phreatomagmatic volcanoes.  相似文献   

Dynamics of contaminants in phosphogypsum of the fertilizer industry of Huelva (SW Spain): From phosphate rock ore to the environment     

Rafael Pérez-López  José Miguel Nieto  Israel López-Coto  Juan Luis Aguado  Juan Pedro Bolívar  María Santisteban 《Applied Geochemistry》2010

The dynamics of trace elements from phosphate rock ore to the environment in a phosphoric acid plant located in SW Spain and the impact of phosphogypsum wastes were investigated through total digestion and BCR-sequential extraction. Based on total concentration, element transfer factors as criteria for examining the potential environmental risk of waste with respect to ore rock were calculated, and it was observed that most trace elements are only transferred into phosphogypsum at rates of 2–12%. However, based on those concentrations that are likely to be most readily mobile in the environment, phosphogypsum acts as a higher emission source of contaminants than the original rock. About 100 million tonnes of phosphogypsum are stack-piled in a dump of 1200 ha over salt-marshes of an estuary formed by the confluence of the Tinto and Odiel rivers. Phosphogypsum has been applied, at the recommended rate of 20–25 t/ha since 1978–2001, to improve fertility and reduce Na saturation in agricultural soils of the Guadalquivir river valley (140 km²). Phosphogypsum capacity as a source of mobile contaminants in three environmental scenarios (water leaching, exposure to oxidising and reducing conditions) was quantified by combining sequential extraction and waste mass. The amounts of mobile contaminants that could be released for every tonne of phosphogypsum are approximately 7 × 10² g Sr, 1.1 × 10² g Fe, 55 g Y, 30 g Ce, 12 g Cr, 11 g Ti, 5 g Zn, 4 g each of Cu and Pb, 3 g each of V and Cd, 2 g each of As and Ni and 1 g U. Multiplying these amounts by 100 Mt and 20–25 t/ha, it is possible to calculate risk assessments of phosphogypsum for both estuarine zones, e.g. in a hypothetical stack collapse and waste spilling, and agricultural soils, respectively.  相似文献   

Strong earthquakes associated with high amplitude daily geomagnetic variations   总被引：1，自引：0，他引：1  

Taha Rabeh  Miguel Miranda  Milan Hvozdara 《Natural Hazards》2010,53(3):561-574

In this work, we attempt to quantify forces that result from the interaction between the induced Sq-variation currents in the Earth’s lithosphere and the regional Earth’s magnetic field, in order to assess its influence on the tectonic stress field and on seismic activity. The study area is the Sinai Peninsula, a seismically active region where both seismic and magnetic data are available. We show that both short-term and long-term magnetic changes correlate with the seismic activity extending to this area in other previous studies. We also analyze a set of large earthquakes and magnetic data from observatories around the world to deduce a relationship between earthquake magnitude and maximum distance up to which precursory variations of the magnetic field are observed.  相似文献   

Late pleistocene/early holocene environments and climates,fauna, and human occupation in the argentine altiplano     

Jorge Fernndez  Vera Markgraf  Hctor O. Panarello  Miguel Albero  Fernando E. Angiolini  Susana Valencio  Mirta Arriaga 《Geoarchaeology》1991,6(3):251-272

The Barro Negro site (23°S lat., 65°37′W long.) in the Altiplano (Puna) of northwestern Argentina contains a well stratified sequence of remains of Hippidion, the American extinct horse, camelids, and archaeological materials, which is the focus of this study. In addition to establishing a reliable chronology, paleoenvironmental information was obtained based on analyses of pollen and stable isotopes (oxygen and carbon) from bone and marl. The data indicate that Hippidion was present at the site between 12,000 and 10,000 yr B. P., at a time when Altoandean grasslands had expanded to lower elevations. By 10,000 yr B.P., when modern semi-arid sub-puna scrub had replaced the Altoandean grasslands, only camelids (Lama or Vicugna) were present, simultaneous with the first evidence of local human occupation. This suggests that a climatic shift from cool and moist (winter rain regime) to warm and dry (summer rain regime) conditions took place simultaneously with the disappearance of the American horse and the appearance of camelids and man.  相似文献