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341.
Land cover mapping of the tropical savanna region in Brazil 总被引:1,自引:0,他引:1
Edson E. Sano Roberto Rosa Jorge L. S. Brito Laerte G. Ferreira 《Environmental monitoring and assessment》2010,166(1-4):113-124
The Brazilian tropical savanna (Cerrado), encompassing more than 204 million hectares in the central part of the country, is the second richest biome in Brazil in terms of biodiversity and presents high land use pressure. The objective of this study was to map the land cover of the Cerrado biome based on the segmentation and visual interpretation of 170 Landsat Enhanced Thematic Mapper Plus satellite scenes acquired in 2002. The following land cover classes were discriminated: grasslands, shrublands, forestlands, croplands, pasturelands, reforestations, urban areas, and mining areas. The results showed that the remnant natural vegetation is still covering about 61% of the biome, however, on a highly asymmetrical basis. While natural physiognomies comprise 90% of the northern part of the biome, only 15% are left in its southern portions. Shrublands were the dominant natural land cover class, while pasturelands were the dominant land use class in the Cerrado biome. The final Cerrado’s land cover map confirmed the intensive land use pressure in this unique biome. This paper also showed that Landsat-like sensors can provide feasible land cover maps of Cerrado, although ancillary data are required to help image interpretation. 相似文献
342.
343.
Josef CF Adriano LR De França EJ Arantes de Carvalho GG Ferreira JR 《Environmental pollution (Barking, Essex : 1987)》2008,152(3):592-596
An analytical procedure for the determination of Hg in otter (Lontra longicaudis) feces was developed, to separate fish scales for the identification of the animal diet. Samples were washed with ultra-pure water and the suspension was sampled and transferred for digestion. The solubilization was performed with nitric-perchloric acid mixture, and detection carried out by the atomic fluorescence spectrometry (AFS). The quality of the analytical procedure was assessed by analyzing in-house standard solutions and certified reference materials. Total Hg concentrations were in the range of 7.6-156 ng g(-1) (July 2004), 25.6-277 ng g(-1) (January 2005) and 14.6-744 ng g(-1) (May 2005) that is approximately the same order of magnitude for all samples collected in two reservoirs at the Tiete River, Brazil. Although Hg concentrations varied with sampling periods and diet, high levels were correlated to the percentage of carnivorous fish scales present in the otter feces. 相似文献
344.
PCDD/Fs in ambient air in north-east Italy: The role of a MSWI inside an industrial area 总被引:1,自引:0,他引:1
Andrea Colombo Emilio Benfenati Giulio Mariani Marco Lodi Roberto Marras Giuseppe Rotella Vincenzo Senese Elena Fattore Roberto Fanelli 《Chemosphere》2009,77(9):1224-1229
The stack gases of a municipal solid waste incinerator (MSWI), and ambient air were sampled in four locations around the plant for the analysis of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDDs/Fs). The sampling area was close to an industrial area near Trieste, in north-east Italy. The purpose of the study was to estimate the impact of the MSWI emissions and to distinguish the contribution of these emissions from other potential emission sources in the industrial area.PCDD/F atmospheric concentrations were similar to those generally detected in urban–rural areas with one location about 2–3 times more contaminated than the others. Since the most contaminated location was inside the industrial area but upwind of the MSWI, principal component analysis (PCA) was used to establish whether other sources were the cause. This analysis clearly showed that a local steel plant’s emission was the main source of PCDDs/Fs in ambient air. This study highlights the usefulness of multivariate data analysis such as PCA to identify, among different potential emission sources, the one really responsible for the contamination. 相似文献
345.
Gerosa G Marzuoli R Rossini M Panigada C Meroni M Colombo R Faoro F Iriti M 《Environmental pollution (Barking, Essex : 1987)》2009,157(5):1727-1736
Stomatal ozone uptake, determined with the Jarvis' approach, was related to photosynthetic efficiency assessed by chlorophyll fluorescence and reflectance measurements in open-top chamber experiments on Phaseolus vulgaris. The effects of O3 exposure were also evaluated in terms of visible and microscopical leaf injury and plant productivity. Results showed that microscopical leaf symptoms, assessed as cell death and H2O2 accumulation, preceded by 3-4 days the appearance of visible symptoms. An effective dose of ozone stomatal flux for visible leaf damages was found around 1.33 mmol O3 m−2. Significant linear dose-response relationships were obtained between accumulated fluxes and optical indices (PRI, NDI, ΔF/Fm′). The negative effects on photosynthesis reduced plant productivity, affecting the number of pods and seeds, but not seed weight. These results, besides contributing to the development of a flux-based ozone risk assessment for crops in Europe, highlight the potentiality of reflectance measurements for the early detection of ozone stress. 相似文献
346.
Cíntia Melazo Dias Everaldo C. Telles Roberto Ventura Santos Kristina Stenström Iêda Gomes Nícoli Rosangela da Silveira Corrêa Göran Skog 《Journal of environmental radioactivity》2009
Nuclear power plants release 14C during routine operation mainly as airborne gaseous effluents. Because of the long half-life (5730 years) and biological importance of this radionuclide (it is incorporated in plant tissue by photosynthesis), several countries have monitoring programs in order to quantify and control these emissions. This paper compares the activity of 14C in soils taken within 1 km from a Brazilian nuclear power plant with soils taken within a reference area located 50 km away from the reactor site. Analyses of total carbon, δ13C and 137Cs were also performed in order to understand the local soil dynamics. Except for one of the profiles, the isotopic composition of soil organic carbon reflected the actual forest vegetation present in both areas. The 137Cs data show that the soils from the base of hills are probably allocthonous. 相似文献
347.
Mike F. Quartacci Barbara Irtelli Roberto Gabbrielli 《Environmental pollution (Barking, Essex : 1987)》2009,157(10):2697-2703
Due to relatively high chelant dosages and potential environmental risks it is necessary to explore different approaches in the remediation of metal-contaminated soils. The present study focussed on the removal of metals (As, Cd, Cu, Pb and Zn) from a multiple metal-contaminated soil by growing Brassica carinata plants in succession to spontaneous metallicolous populations of Pinus pinaster, Plantago lanceolata and Silene paradoxa. The results showed that the growth of the metallicolous populations increased the extractable metal levels in the soil, which resulted in a higher accumulation of metals in the above-ground parts of B. carinata. Root exudates of the three metallicolous species were analysed to elucidate their possible role in the enhanced metal availability. The presence of metals stimulated the exudation of organic and phenolic acids as well as flavonoids. It was suggested that root exudates played an important role in solubilising metals in soil and in favouring their uptake by roots. 相似文献
348.
Persistent toxic substances in soils and waters along an altitudinal gradient in the Laja River Basin, Central Southern Chile 总被引:5,自引:0,他引:5
In this study the levels and distribution of some persistent toxic substances (PTS) were investigated in soils, superficial water, and snow along an altitudinal gradient in the Laja River Basin (South Central Chile). The principal objective was to establish the basin's contamination status. The working hypothesis was that PTS levels and distribution in the basin are dependent on the degree of anthropogenic intervention. Fifteen PAHs, seven PCBs congeners, and three organochlorine pesticides were studied in superficial soil and water samples obtained along the altitudinal gradient and from a coastal reference station (Lleu-Lleu River). Soil samples were extracted using accelerated solvent extraction with acetone/cyclohexane (1:1) for PAHs and organochlorine compounds. Contaminants were extracted from water and snow samples by liquid-liquid extraction (LLE). PAH and organochlorine compound quantification was carried out by HPLC with fluorescence detection and GC-MS, respectively. PCBs in soils presented four different profiles in the altitudinal gradient, mainly determined by their chlorination degree; these profiles were not observed for the chlorinated pesticides. In general, the detected levels for the analyzed compounds were low for soils when compared with soil data from other remote areas of the world. Higher summation operator PAHs levels in soils were found in the station located at 227 masl (4243 ng g-1 TOC), in a forestry area and near a timber industry, where detected levels were up to eight times higher than the other sampling sites. In general, PAH levels and distribution seems to be dependent on local conditions. No pesticides were detected in surface waters. However, congeners of PCBs were detected in almost all sampling stations with the highest levels being found in Laja Lake waters, where 1.1 ng/l were observed. This concentration is two times higher than values reported for polluted lakes in the Northern Hemisphere. The presence of organochlorine compound in snow sampled at the highest elevation point of the basin is indicative of the transport and atmospheric deposition phenomena of alpha-HCH, gamma-HCH and PCB 52, with values being similar to the levels reported in Canadian snow samples. We conclude that environmental PTS substance levels are in general relatively low, although PAHs may be of concern in some areas of the basin. 相似文献
349.
In summer 1997, gelatinous aggregates appeared in the Adriatic Sea, covering large areas of the northern basin. This study deals with the comparison between the biochemical composition of the sedimentary organic matter in summer, 1996 (when no aggregates appeared), and in summer, 1997 (during the appearance of aggregates). the biochemical composition of organic matter in surface sediments (determined in terms of proteins, carbohydrates, lipids, phytopigments and nucleic acids) has been investigated in two areas along the coast of the NW-Adriatic Sea in order to characterize benthic processes during aggregate deposition on the sea floor. During mucilage accumulation, a significant increase of biochemical compounds was observed, and chlorophyll-a and carbohydrate concentrations doubled their concentrations. in contrast, protein concentrations decreased, so that overall biopolymeric carbon content (expressed as the sum of lipid, protein and carbohydrate carbon equivalents) did not display significant differences between sampling periods (1579.3 in June, 1996 1678.8 μgCg-1 and June, 1997). the protein to carbohydrate ratio decreased from 4.9 in June, 1996 to 1.8 in June, 1997. Mucilage production in June, 1997, modified significantly the biochemical composition of the sedimentary OM, thus affecting the potential availability of OM to benthic consumers. We hypothesise that the production of highly refractory composition of the sedimentary OM during mucilage accumulation might have an important biogeochemical implications. 相似文献
350.
Juliana Ferreira Floriano Natan Roberto de Barros José Luiz Ferreira Cinman Rosangela Gonçalves da Silva Augusto Villela Loffredo Felipe Azevedo Borges Ana Maria Queiros Norberto Ana Laura Destro Chagas Bruna Cambraia Garms Carlos Frederico de Oliveira Graeff Rondinelli Donizetti Herculano 《Journal of Polymers and the Environment》2018,26(6):2281-2289
Ketoprofen is an analgesic with potent anti-inflammatory activity against acute inflammation, subacute inflammation, for the acute and long-term treatment of various inflammatory pathologies, as rheumatoid arthritis and colonic adenocarcinoma. In order to minimize the incidence of systemic events related to ketoprofen, the transdermal drug delivery system development has been most important. The advantages of using natural rubber latex membranes include not only the reduction of adverse systemic events, but also the suitability of the low cost of the material together with its physicochemical properties such as flexibility, mechanical stability, surface porosity and water vapor permeability, and besides being a biocompatible material also presents biological activity to stimulate the angiogenesis, being able to be used in tissue repair. This study demonstrated that ketoprofen was successfully incorporated into natural latex membranes for drug delivery. FTIR indicated that the drug did not interact chemically with the membrane. Moreover, the natural latex membranes released 60% of the ketoprofen incorporated in 50 h. SEM images indicated that a portion of the drug was present on the membrane surface, being this portion responsible for the burst release. The tensile tests showed that the addition of the drug into the natural latex membrane did not influence on the polymer mechanical behavior. In addition, drug-natural latex membranes presented no red blood cell damaging effects. Our data shows that the ketoprofen loaded natural latex membranes is a promising system for sustained drug delivery which can be used to minimize the adverse side effects of high dose systemic drug delivery. 相似文献