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101.
Oxidation of trichloroethene over metal oxide catalysts: kinetic studies and correlation with adsorption properties 总被引:3,自引:0,他引:3
The performance of bulk chromium oxide is compared with that of a Mn commercial catalyst for the deep oxidation of trichloroethene (1000-2500ppmv, 55h(-1) space velocity) in air, in dry and wet (20000ppm of H(2)O) conditions, in terms of activity, selectivity and stability. Chromium oxide was found to be more active (on a catalyst weight basis), however its activity decreases continuously with time on stream. The presence of water increases its stability, the Mn catalyst showing the opposite behaviour. The effect of water on the Cr catalyst can be explained according to the Deacon equilibrium, as the presence of water tends to decrease the Cl(2) concentration, assumed to be responsible of the catalyst deactivation. Regarding to the selectivity, the Mn catalyst yields C(2)Cl(4), CCl(4) and CHCl(3) as organochlorinated by-products, whereas chromium oxide produces only trace amounts of CCl(4). Simple power-law kinetics expressions (first-order for Mn and zero-order for Cr) provide fairly good fits for the evolution of the conversion with the temperature. Furthermore, the kinetic behaviour of chromium oxide can be represented with a Langmuir-Hinshelwood model taking into account the chlorine inhibitory effect. 相似文献
102.
Sánchez-Chardi A López-Fuster MJ Nadal J 《Environmental pollution (Barking, Essex : 1987)》2007,145(1):7-14
We quantified bioaccumulation of lead, mercury, and cadmium in bones from 105 greater white-toothed shrews (Crocidura russula) collected at the Ebro Delta, a polluted area, and the Medas Islands, a control site. Lead and mercury levels varied with site, age, and sex, although statistical significances depended on each factor. Globally, shrews from the polluted area exhibited significantly higher concentrations of Pb and Hg. Increment of Pb with age was particularly remarkable in wetland animals and was interpreted in relation to human activities, namely hunting. Unlike males, females from the Ebro Delta maintained low Hg levels, which were associated with gestation and lactation. Cadmium levels did not differ between sites, sexes, or ages. This study provides the first data on heavy metals in mammals from this wetland and suggests that C. russula is a good bioindicator of metal pollution. We concluded that sex and age may represent an important source of variation in the bioaccumulation of these metals in wild populations. 相似文献
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Policy documents are commonly identified as key outcomes that guide initiatives directed by senior university leaders towards sustainability through plans and policies. Many studies have called for a more integration of sustainability into universities. Nevertheless, the interest in sustainability issues has been more recent in the specific case of Spain. This study analyses the strategic plans developed by Spanish universities in the last decade with two different aims: first, we examine the extent to which Spanish universities are incorporating strategies on sustainability. The second goal evaluates whether the presence of strategies on sustainability in Spanish universities could be associated with coercive and mimetic pressures. Findings indicate the low presence of strategies on sustainability in Spanish universities. Moreover, the results seem to suggest that the presence of strategies on sustainability in Spanish universities could be linked with coercive and mimetic pressures emanating from the State performance funding for universities. The results indicate that universities usually incorporate practices and strategies on sustainability as a response of the pressure exerted by institutional forces, such as the funding systems of higher education institutions. 相似文献
105.
Larissa Stieven Montagna Thaís Larissa do Amaral Montanheiro Fábio Roberto Passador Ana Paula Lemes Mirabel Cerqueira Rezende 《Journal of Polymers and the Environment》2018,26(4):1511-1519
The potential use of poly(3-hydroxybutyrate-co-3-hydroxyvalerate)/graphite nanosheets (GNS) as a biodegradable nanocomposite has been explored. PHBV/GNS nanocomposites films were prepared by solution casting at various concentrations of GNS—0.25, 0.50 and 1.00 wt% GNS. The films were exposed to artificial ultraviolet radiation (UV) during 52 h. The effect of GNS on PHBV photodegradation was investigated and compared to neat PHBV film. The artificial photodegradation induced changes in physical (weight loss), chemical carbonyl index by Fourier transform infrared spectroscopy, thermal degree of crystallinity and melting temperature by differential scanning calorimetry and morphological scanning electron microscopy characteristics. Based on the results obtained from aforementioned analyzes it was verified that GNS inhibits the oxidative degradation of PHBV matrix. 相似文献
106.
Recent Changes in Stream Flashiness and Flooding,and Effects of Flood Management in North Carolina and Virginia 下载免费PDF全文
Beatriz Mogollón Emmanuel A. Frimpong Andrew B. Hoegh Paul L. Angermeier 《Journal of the American Water Resources Association》2016,52(3):561-577
The southeastern United States has undergone anthropogenic changes in landscape structure, with the potential to increase (e.g., urbanization) and decrease (e.g., reservoir construction) stream flashiness and flooding. Assessment of the outcome of such change can provide insight into the efficacy of current strategies and policies to manage water resources. We (1) examined trends in precipitation, floods, and stream flashiness and (2) assessed the relative influence of land cover and flow‐regulating features (e.g., best management practices and artificial water bodies) on stream flashiness from 1991 to 2013. We found mean annual precipitation decreased, which coincided with decreasing trends in floods. In contrast, stream flashiness, overall, showed an increasing trend during the period of study. However, upon closer examination, 20 watersheds showed stable stream flashiness, whereas 5 increased and 6 decreased in flashiness. Urban watersheds were among those that increased or decreased in flashiness. Watersheds that increased in stream flashiness gained more urban cover, lost more forested cover and had fewer best management practices installed than urban watersheds that decreased in stream flashiness. We found best management practices are more effective than artificial water bodies in regulating flashy floods. Flashiness index is a valuable and straightforward metric to characterize changes in streamflow and help to assess the efficacy of management interventions. 相似文献
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109.
Mercedes Sánchez Natalia López-Mosquera 《Journal of Environmental Policy & Planning》2016,18(1):47-66
Over the last 30 years, Spain has witnessed great economic growth. Nevertheless, in spite of an increasing degree of environmental concern, environmentally friendly attitudes and behaviours are still clearly below the European average. In this context, this paper analyses the impact of personal control and attitudes, and of certain socio-demographic, economic and political variables in the development of two environmentally friendly behaviours in Spain: consumption and purchase. The data were provided by a survey carried out in 2007 by the Centro de Investigaciones Sociológicas (Centre for Sociological Research) in Spain. The results show the importance of personal control, level of environmental information, political ideology, age and educational level variables to explaining the development of pro-environmental-related consumption behaviours. Personal attitudes, work situation, female gender and level of environmental information influence pro-environmental purchase behaviour in a positive way. Taking into account that personal attitudes are more determining of pro-environmental purchase than consumption behaviour, policy measures such as informal education, tax measures, social and individual norms and interpersonal and institutional trust are discussed to increase the development of pro-environmental behaviours in Spain. 相似文献
110.
Ester Heath Marjeta Česen Noelia Negreira Miren Lopez de Alda Laura Ferrando-Climent Lucie Blahova Tung Viet Nguyen Mohamed Adahchour Achim Ruebel Neville Llewellyn Janez Ščančar Srdjan Novaković Vesna Mislej Marjeta Stražar Damià Barceló Tina Kosjek 《Environmental science and pollution research international》2016,23(15):14692-14704
The results of an inter-laboratory comparison exercise to determine cytostatic anticancer drug residues in surface water, hospital wastewater and wastewater treatment plant effluent are reported. To obtain a critical number of participants, an invitation was sent out to potential laboratories identified to have the necessary knowledge and instrumentation. Nine laboratories worldwide confirmed their participation in the exercise. The compounds selected (based on the extent of use and laboratories capabilities) included cyclophosphamide, ifosfamide, 5-fluorouracil, gemcitabine, etoposide, methotrexate and cisplatinum. Samples of spiked waste (hospital and wastewater treatment plant effluent) and surface water, and additional non-spiked hospital wastewater, were prepared by the organising laboratory (Jo?ef Stefan Institute) and sent out to each participant partner for analysis. All analytical methods included solid phase extraction (SPE) and the use of surrogate/internal standards for quantification. Chemical analysis was performed using either liquid or gas chromatography mass (MS) or tandem mass (MS/MS) spectrometry. Cisplatinum was determined using inductively coupled plasma mass spectrometry (ICP-MS). A required minimum contribution of five laboratories meant that only cyclophosphamide, ifosfamide, methotrexate and etoposide could be included in the statistical evaluation. z-score and Q test revealed 3 and 4 outliers using classical and robust approach, respectively. The smallest absolute differences between the spiked values and the measured values were observed in the surface water matrix. The highest within-laboratory repeatability was observed for methotrexate in all three matrices (CV?≤?12 %). Overall, inter-laboratory reproducibility was poor for all compounds and matrices (CV 27–143 %) with the only exception being methotrexate measured in the spiked hospital wastewater (CV?=?8 %). Random and total errors were identified by means of Youden plots. 相似文献