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91.
Land surface temperature is one of the most important parameters related to global warming. It depends mainly on soil type, discontinuous vegetation cover, or lack of precipitation. The main purpose of this paper is to investigate the relationship between high LST, synoptic conditions and air masses trajectories, vegetation cover, and soil type in one of the driest region in Romania. In order to calculate the land surface temperature and normalized difference vegetation index, five satellite images of LANDSAT missions 5 and 7, covering a period of 26 years (1986–2011), were selected, all of them collected in the month of June. The areas with low vegetation density were derived from normalized difference vegetation index, while soil types have been extracted from Corine Land Cover database. HYSPLIT application was employed to identify the air masses origin based on their backward trajectories for each of the five study cases. Pearson, logarithmic, and quadratic correlations were used to detect the relationships between land surface temperature and observed ground temperatures, as well as between land surface temperature and normalized difference vegetation index. The most important findings are: strong correlation between land surface temperature derived from satellite images and maximum ground temperature recorded in a weather station located in the area, as well as between areas with land surface temperature equal to or higher than 40.0 °C and those with lack of vegetation; the sandy soils are the most prone to high land surface temperature and lack of vegetation, followed by the chernozems and brown soils; extremely severe drought events may occur in the region.  相似文献   
92.
With the ubiquity of advanced web technologies and location-sensing hand held devices, citizens regardless of their knowledge or expertise, are able to produce spatial information. This phenomenon is known as volunteered geographic information (VGI). During the past decade VGI has been used as a data source supporting a wide range of services, such as environmental monitoring, events reporting, human movement analysis, disaster management, etc. However, these volunteer-contributed data also come with varying quality. Reasons for this are: data is produced by heterogeneous contributors, using various technologies and tools, having different level of details and precision, serving heterogeneous purposes, and a lack of gatekeepers. Crowd-sourcing, social, and geographic approaches have been proposed and later followed to develop appropriate methods to assess the quality measures and indicators of VGI. In this article, we review various quality measures and indicators for selected types of VGI and existing quality assessment methods. As an outcome, the article presents a classification of VGI with current methods utilized to assess the quality of selected types of VGI. Through these findings, we introduce data mining as an additional approach for quality handling in VGI.  相似文献   
93.
Eclogite lenses in the Agualada Unit (western Ordenes Complex, Spain) contain the peak mineral assemblage garnet (prograde rim: Alm = 48 mol%, Prp = 30 mol%), omphacite (Jd max = 36 mol%), quartz, rutile and rare zoisite, which equilibrated at T = 700 °C and P > 12–14 kbar. Garnet shows discontinuous growth zoning, with a pyrope-poor intermediate zone (Alm = 51 mol%, Prp = 10 mol%) between a core zone where pyrope is slightly higher (Alm = 46 mol%, Prp = 16 mol%) and areas just inward from the rims where the maximum pyrope contents (Alm = 48 mol%, Prp = 30 mol%) are recorded. In atoll interiors, garnet contains inclusions of a first generation of omphacite (Jd max = 40 mol%). This omphacite is replaced in the matrix by a second generation (Jd max = 36 mol%) with higher Fe/Fe + Mg ratio. The compositions of garnet and omphacite suggest a complex syneclogitic tectonothermal evolution for the Agualada Unit, characterized by: (1) eclogite-facies metamorphism (T = 585 °C, P > 12–13 kbar), followed by (2) cooling during a slight decompression (T = 500 °C, P > 11–12 kbar), and (3) a final increase in P and T to form the garnet rim-matrix omphacite mineral assemblage. The Agualada Unit is part of a subduction complex which affected the Gondwana margin at the beginning of the Variscan cycle. The P-T evolution of the Agualada eclogites is closely related to the structural evolution of the accretionary complex and the whole orogenic wedge. The cooling event recorded by the Agualada eclogites may have resulted from the accretion of a new colder crustal slice under the unit, whereas the final progradation reflects the emplacement of the Agualada Unit directly under the mantle wedge. This evolution fits well with previously presented the retical models, both for the tectonothermal evolution of accretionary complexes and for the dynamic evolution of orogenic wedges. P-T paths such as the one for the Agualada Unit eclogites, probably reflect a prolonged structural evolution. Although evidently rarely preserved, such paths are probably the rule rather than the exception during plate convergence.  相似文献   
94.
Igneous formations associated with massive sulphide deposits in the Iberian Pyrite Belt (IPB) are essentially composed of basic lavas and dolerites, and dacitic to rhyolitic volcanites; intermediate lavas are subordinate. The basic rocks show variable geochemical characteristics: lavas and dolerites comparable to recent within-plate alkaline basalts seem restricted to the western and southern parts of the IPB, whereas basic rocks comparable to continental tholeiites or arc-related basalts occur across the whole belt. The felsic rocks are classified as calc-alkaline and belong to the “low-Al2O3 and high-Yb type”. At given SiO2, Al2O3 and TiO2 contents, they show variable Zr, Nb, and HREE contents. Heavy-rare-earth element fractionation decreases from the dacites to the rhyolites ([Gd/Yb]N ∼ 1), whereas the negative Eu-anomaly becomes more pronounced. The characteristics of the rhyolites are typical of sulphide-fertile volcanic packages. Trace-element modelling suggests that the felsic rocks evolved from a dacitic parent magma through fractional crystallization of hornblende and plagioclase. Partial melting of an amphibolite protolith, which appears as the most probable model for the origin of this dacitic magma, requires a high T/P gradient in the crust. The occurrence of alkaline basalts and continental tholeiites is consistent with formation of the IPB in a tensional tectonic setting. However, the associated island-arc tholeiites suggest a location in a domain of plate convergence. Emplacement in a fore-arc basin over a recently accreted crustal segment is envisaged as a possible hypothesis to account for the geological and petrological constraints. A high geothermal gradient and eruption in a submarine tensional basin could have been two key ingredients for the development of massive sulphide deposits within the IPB.
Resumen (translated by E. Pascual) Las formaciones ígneas asociadas con los depósitos de sulfuros masivos de la Faja Pirítica Ibérica (IPB) se componen esencialmente de doleritas y lavas básicas y de rocas volcánicas dacíticas a riolíticas; las lavas intermedias son poco abundantes. Las rocas básicas muestran caracteres geoquímicos variables: lavas y doleritas comparables a basaltos alcalinos intraplaca recientes parecen hasta ahora restringidos a las partes W y S de la IPB, mientras que rocas básicas de caracteres comparables a las de toleítas continentales o basaltos relacionados con arcos aparecen en toda la zona. Las rocas ácidas se clasifican como calcoalcalinas del tipo “low-Al2O3, high-Yb”. Para un contenido dado en SiO2, Al2O3 y TiO2, muestran contenidos variables en Zr, Nb y REE. El contenido en tierras raras pesadas decrece de dacitas a riolitas ([Gd/Yb]N ∼ 1), al tiempo que la anomalía de Eu se hace más pronunciada. La modelización de elementos trazas sugiere que las rocas evolucionaron a partir de un magma parental dacítico mediante cristalización fraccionada de hornblenda y plagioclasa. La fusión parcial de un protolito anfibolítico, que parece el modelo más plausible para el origen del magma dacítico, requiere un elevado gradiente T/P en la corteza. La existencia de basaltos alcalinos y de toleítas continentales es congruente con la formación de la IPB en un entorno tectónico distensivo. El emplazamiento en una cuenca “fore-arc”, en un segmento cortical de reciente acreción, se contempla como una hipótesis posible para explicar los caracteres geológicos y petrológicos. Un alto gradiente térmico, junto con la erupción en una cuenca submarina extensional, pueden haber sido los dos ingredientes clave en el desarrollo de los depósitos de sulfuros masivos en la IPB.


Received: 3 March 1996 / Accepted: 7 April 1997  相似文献   
95.
96.
Various studies have revealed high concentrations of contaminants such as organochlorines (OCs) and heavy metals in Mediterranean cetaceans. A geographical trend of contamination (PCBs and DDTs) has been found for striped dolphin (Stenella coeruleoalba). In this study we used a non-lethal approach (skin biopsy) to investigate bioaccumulation of OCs, including polychlorobiphenyls (PCBs), DDTs, polychlorodibenzo-p-dioxins (PCDDs), polychlorodibenzofurans (PCDFs), trace elements (Hg, Cd, Pb) and CYP1A activity (BPMO) in nine striped dolphins sampled in the Aeolian area (Sicily – Italy) in summer 2002. The arithmetic mean value of BPMO activity in this group was 43.46 AUF/g tissue/h. This value is approximately 3 times and 5 times lower, respectively, than the value found in the Ionian and in the Ligurian groups. Skin biopsies of striped dolphins emerged as a suitable material for assessing the toxicological status of the various Mediterranean groups.  相似文献   
97.
Coastal water bodies are a heterogeneous resource typified by high spatial and temporal variability and threatened by anthropogenic impacts. This includes saline lagoons, which support a specialist biota and are a priority habitat for nature conservation. This paper describes the biotic variation in coastal water bodies in Sussex, England, in order to characterise the distinctiveness of the saline lagoon community and elucidate environmental factors that determine its distribution. Twenty-eight coastal water bodies were surveyed for their aquatic flora and invertebrate fauna and a suite of exploratory environmental variables compiled. Ordination and cluster analyses were used to examine patterns in community composition and relate these to environmental parameters. Biotic variation in the coastal water body resource was high. Salinity was the main environmental parameter explaining the regional distribution of taxa; freshwater and saline assemblages were evident and related to sea water ingress. Freshwater sites were indicated by the plant Myriophyllum spicatum and gastropod mollusc Lymnaea peregra, while more saline communities supported marine and brackish water taxa, notably a range of chlorophytic algae and the bivalve mollusc Cerastoderma glaucum. Site community differences were also related to bank slope and parameters describing habitat heterogeneity. A saline lagoon community was discerned within the matrix of biotic variation consisting of specialist lagoonal species with associated typically euryhaline taxa. For fauna, the latter were the molluscs Abra tenuis and Hydrobia ulvae, and the crustaceans Corophium volutator and Palaemonetes varians, and for flora they were the algae Ulva lactuca, Chaetomorpha mediterranea, Cladophora spp. and Enteromorpha intestinalis. One non-native polychaete species, Ficopomatus enigmaticus, also strongly influenced community structure within the lagoonal resource. The community was not well defined as specialist and associated taxa were distributed throughout the spectrum of sites surveyed. Implications for the identification and conservation of saline lagoons are discussed.  相似文献   
98.
99.
100.
In this project we investigated the ecotoxicological effects of endocrine disrupters in a four-year survey of the Mediterranean population of swordfish (Xiphias gladius). In the Mediterranean environment, top predators, such as swordfish, accumulate high concentrations of polyhalogenated aromatic hydrocarbons (PHAHs) and toxic metals, potentially incurring high toxicological risk. The effects of organochlorines and trace elements (Hg, Cd and Pb) in 192 swordfish specimens, caught in the Strait of Messina, Sicily, Italy, were investigated using vitellogenin (Vtg), zona radiata proteins (Zrp) and CYP1A (BPMO, EROD) activities. Vtg and Zrp were found to be dramatically induced in some adult male specimens, suggesting that this species is highly exposed to estrogens in the Mediterranean Sea. A role of organochlorines in this induction phenomenon is suggested by the statistically significant correlations between Zrp in plasma and PCB concentrations in muscle (p<0.032) and Vtg in plasma and PCB concentrations in liver (p<0.034) of male specimens. Levels of trace elements in liver were in the following ranges: Hg 1-22, Cd 1-28 and Pb 0-1.6 ppm d.w. These data indicate potential reproductive alterations in large pelagic fish and suggest the need for continuous monitoring to avoid reductions in the population of this fish species of high commercial and ecological interest.  相似文献   
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