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761.
Madruga MJ Brogueira A Alberto G Cardoso F 《Journal of environmental radioactivity》2001,54(1):175-188
Large amounts of solid wastes (tailings) resulting from the exploitation and treatment of uranium ore at the Urgeiri?a mine (north of Portugal) have been accumulated in dams (tailing ponds). To reduce the dispersion of natural radionuclides into the environment, some dams were revegetated with eucalyptus (Eucalyptus globolus) and pines (Pinus pinea). Besides these plants, some shrubs (Cytisus spp.) are growing in some of the dams. The objective of this study is to determine the 226Ra bioavailability from uranium mill tailings by quantifying the total and available fraction of radium in the tailings and to estimate its transfer to plants growing on the tailing piles. Plant and tailing samples were randomly collected and the activity concentration of 226Ra in plants (aerial part and roots) and tailings was measured by gamma-spectrometry. The exchangeable fraction of radium in tailings was quantified using one single step extraction with 1 mol dm-3 ammonium acetate (pH = 7) or 1 mol dm-3 calcium chloride solutions. The results obtained for 226Ra uptake by plants show that 226Ra concentration ratios for eucalyptus and pines decrease at low 226Ra concentrations in the tailings and appear relatively constant at higher radium concentrations. For shrubs, the concentration ratios increase at higher 226Ra solid waste concentrations approaching a saturation value. Percentage values of 16.0 +/- 8.3 and 12.9 +/- 8.9, for the fraction of radium extracted from the tailings, using 1 mol dm-3 ammonium acetate or calcium chloride solutions, respectively, were obtained. The 226Ra concentration ratios determined on the basis of exchangeable radium are one order of magnitude higher than those based on total radium. It can be concluded that, at a 95% confidence level, more consistent 226Ra concentration ratios were obtained when calculated on the basis of available radium than when total radium was considered, for all the dams. 相似文献
762.
Derval dos Santos Rosa Maria Regina Calil Cristina das Graças Fassina Guedes Carlos Eduardo O. Santos 《Journal of Polymers and the Environment》2001,9(3):109-113
The biodegradability of poly--hydroxybutyrate and poly--caprolactone in soil compostage before and after irradiation of the polymers for 192, 425, and 600 h in a Weather-Ometer was examined. The biodegradability tests were done in soil compostage at pH 7.0, 9.0, and 11.0 to assess the influence of this parameter on degradation. The rate of degradation was directly proportional to the soil alkalinity. Poly--hydroxybutyrate showed the greatest weight loss and aging in a Weather-Ometer did not significantly increase the biodegradation, except when the polymer was aged for 425 h and buried in soil compostage of pH 11.0. 相似文献
763.
Let us consider i = 1, 2,...n alternative forest plans to be evaluated according to j = 1, 2,...m indicators of sustainability. An expert or panel of experts suggests a set of targets or desirable levels of achievement for the m indicators of sustainability considered. Within this context, an important problem is to determine the system with a higher level of achievement with respect to the targets attached by the expert to the m indicators. A natural extension of this problem involves determining a ranking of the n systems considered. A general procedure based on discrete goal programming is proposed to address these problems. The methodology is applied in a case study of a Spanish forest. 相似文献
764.
Sources, distribution and behaviour of methyl tert-butyl ether (MTBE) in the Tamar Estuary, UK 总被引:1,自引:0,他引:1
Negligible information is currently available concerning levels of the fuel additive methyl tert-butyl ether (MTBE) in European estuaries or coastal environments. MTBE was measured at selected potentially contaminated harbours and marinas, and throughout an axial transect of the Tamar Estuary, UK. Headspace solid-phase microextraction was used in combination with GC-MS for its determination. MTBE was detected in water samples from all stations at concentrations ranging from a few ng/l to a maximum of 194 ng/l (in a semi-enclosed harbour). Elevated levels were generally associated with motor vehicle and boating activities. The Tamar road and rail bridges provided a major input to the lower estuary, downstream of which conservative mixing appeared depressed, probably through volatilisation and possibly through salting-out. The selected analytical system (using a Carboxen/PDMS fiber) proved both rapid and highly sensitive (with a detection limit of 6 ng/l). During method development, salinity was shown to have a major influence in controlling the extraction efficiency and it was found necessary to adjust salinity in all samples (to 75% saturation) prior to extraction. From these tests, we (for the first time) estimated the Setschenow ("salting-out") constant of MTBE to be 0.11 l/mol. 相似文献
765.
Alves E Velini ED Trindade ML Cataneo AC Marino CL Mori ES Guerrini IA Furtado EL Wilcken CF 《Journal of environmental science and health. Part. B》2005,40(1):151-157
Oxidative stress generating active oxygen species has been proved to be one of the underlying agents causing tissue injury after the exposure of Eucalyptus (Eucalyptus spp.) plants to a wide variety of stress conditions. The objective of this study was to perform data mining to identify favorable genes and alleles associated with the enzyme systems superoxide dismutase, catalase, peroxidases, and glutathione S-transferase that are related to tolerance for environmental stresses and damage caused by pests, diseases, herbicides, and by weeds themselves. This was undertaken by using the eucalyptus expressed-sequence database (https//forests.esalq.usp.br). The alignment results between amino acid and nucleotide sequences indicated that the studied enzymes were adequately represented in the ESTs database of the FORESTs project. 相似文献
766.
Leonardo?Alberto?Rios?OsorioEmail author Manuel?Ortiz?Lobato Xavier?álvarez?Del?Castillo 《Environment, Development and Sustainability》2005,7(4):501-518
The paper analyzes the concept of sustainable development in the light of the different interpretations existing on the issue
since its appearance and establishment as an ideal to lead humanity’s line of progress. Within these interpretations, a characteristic
generation of diverse debates can be appreciated, arising from different perspectives, academic as well as ideological, aiming
at describing, clarifying and determining their conceptual reach.
Based on these facts a model of categorization for these debates has developed, a model in which interpretations generated
on the concept of sustainable development were catalogued into four realms: conceptual, contextual, academic and geopolitical.
The configuration of these four areas of debate, as well as the recognition of the diversity of interpretations existing on
sustainable development, is a reflection of the intrinsic complexity of the phenomena, which affect the natural and social
world, both at the local and global level. The analysis of this complexity is based on the subjectivity, which is inherent
to the interpretation of these phenomena, with permanent reference to the cultural context from which the diverse discourses
were structured.
This global perspective on the state-of-the-art controversy concerning the idea of sustainable development as an articulatory
axis reveals the necessity of building epistemological models, which can give a new direction to scientific research. From
these new models, based on the analysis of the holistic character of reality, the subjective and the objective must be integrated
in the generation of knowledge, which contributes usefully to the unceasing reconstruction of our world-(view).
Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue. 相似文献
767.
768.
For decades, industry has been the main source of pollution in China. Determined to make changes, the mainland Chinese authorities have decided to promote mechanisms that incorporate environmental concerns into the internal management of enterprises. This is manifested in the rapid adoption of the ISO14000 standards, including a significant increase in ISO14001 registrations in China. Thus, this study examined the environmental policy statements of 106 certified facilities in mainland China against a strict interpretation of the mandatory requirements of the ISO 14001:1996 standard and the nonmandatory ISO14004 requirements in order to shed some light on the implementation of environmental management systems in an emerging economic giant. It was decided to analyze the environmental policy statement because such a statement is a core element in the ISO system of environmental management of each facility and there are relatively clear and specific requirements on what an environmental policy statement shall include. An analysis of the contents of the environmental policy statements shows that conformance to the relevant requirements of both the mandatory ISO14001 standard and the nonmandatory ISO14004 standard is far from impressive and that the facilities in our sample seldom went beyond the minimum requirements. By using ISO14001 and ISO14004 conformance scores as the dependent variables, we found that conformity to ISO14001 and overall conformance to ISO14000 series can be explained to some extent by the degree of top management commitment, the experience with informal environmental management systems, and the form of ownership of the facilities. 相似文献
769.
Seasonal variation of above ground and belowground biomass of Spartina maritima and Halimione portulacoides, decomposition rates of belowground detritus in litterbags, and carbon partitioning in plant components and sediments were determined in two Tagus estuary marshes with different environmentalconditions. Total biomass was higher in the saltier marsh from 7,190 to 6,593 g m-2 dw and belowground component contributed to more than 90%. Litterbag experiment showed that 30 to 50% of carbonis decomposed within a month (decomposition rate from 0.024 to 0.060 d-1). Slower decomposition in subsequent periods agrees with accumulation of carbon concentration in sediment. Atmospheric carbon annually transferred to the plant belowground biomass is stored more efficiently in sediments of Corroios than Pancas. 相似文献
770.
Silveira AJ 《Traffic injury prevention》2003,4(2):173-175
Can a nongovernmental organization influence or determine seat belt use in a nation? The problems that implementing such a simple, yet effective, measure for traffic safety may trigger in a developing country are impossible to imagine. Just having the right laws is not enough: A great effort is necessary to create awareness and inform the population, but the governmental authorities in Argentina are not doing this, nor do they show any interest in it. In most of the developing countries, the situation is similar. Starting from a diagnosis of seat belt use by means of systematic observations, a program of awareness and massive education was developed for national radio and TV about the advantages of seat belt use. The first stage of this program was launched at the end of 1991, and it continues to this day. Articles in newspapers and communications and requests on the same subject sent to public officials also have helped mobilize public opinion on seat belt use. After 10 years of systematic and continued work by a nongovernmental organization, seat belt use is now part of the government's agenda and there is a high rate of "almost voluntary" seat belt use. The voluntary seat belt use in the city of Buenos Aires has reached 26.9%, and in national highways 58.9%. The roads that have been traveled in Argentina (documented with follow-up statistics) may be useful as guidelines for other countries that are starting this process, and may help to shorten times, avoid pitfalls, and save lives since it is estimated that 1,100 more lives could be saved every year in Argentina when seat belts become the norm. 相似文献