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51.
Moreno-Tost R Oliveira ML Eliche-Quesada D Jiménez-Jiménez J Jiménez-López A Rodríguez-Castellón E 《Chemosphere》2008,72(4):608-615
Copper based catalysts supported on mesoporous materials, which were in turn based on a surfactant expanded zirconium phosphate for the formation of silica galleries in the interlayer space, were prepared by the impregnation method. They were then characterised and tested in the selective catalytic reduction of NO with ammonia as active catalysts for the control of the NOx emissions from heavy duty vehicles. Copper catalysts displayed a high catalytic performance, even in the presence of 14% (v/v) of H2O and 100 ppm of SO2. They also displayed improved catalytic behaviour when compared to a CuZSM5 catalyst. 相似文献
52.
Recent research has identified that the major fraction of chemical oxygen demand in domestic wastewaters is in particulate form. The research presented herein develops the kinetics of particle removal as a response to bioflocculation at the surface of aerobic biofilms. This study focuses on the removal of particles that are maintained in aqueous suspension after 30 minutes of gravity settling. It is helpful to consider the particulate organics removal process in biofilms as the sum of four steps, namely (1) external transport of the particles to the biofilm surface, (2) bioflocculation, (3) organic particulate hydrolysis, and (4) diffusion and reaction of the solubilized organics by the bacterial cells comprising the biofilm. Organic (native corn starch) and inorganic particle (Min-U-Sil 10 [U.S. Silica Company, Berkeley Springs, West Virginia]) suspensions, with micronutrients, were continuously fed to a rotating disc biofilm reactor to verify a first-order kinetic expression that has been used to describe bioflocculation and to demonstrate that bioflocculation is the primary particle removal mechanism. Extracellular polymeric substances were extracted and quantified to describe the role they play in the bioflocculation process. 相似文献
53.
Fernando Díaz Alonso Enrique Gonzlez Ferrads Juan Francisco Snchez Prez Agustín Miana Aznar Jos Ruiz Gimeno Jesús Martínez Alonso 《Journal of Loss Prevention in the Process Industries》2006,19(6):724-728
A number of models have been proposed to calculate overpressure and impulse from accidental industrial explosions. When the blast is produced by explosives, pyrotechnics or unstable substances, the TNT equivalent model is widely used. From the curves given by this model, data are fitted to obtain equations showing the relationship between overpressure, impulse and distance. These equations, referred to here as characteristic curves, can be fitted by means of power equations, which depend on the TNT equivalent mass. Characteristic curves allow determination of overpressure and impulse at each distance. 相似文献
54.
Matías Feijoo Enrique P. Lessa Rocío Loizaga de Castro Enrique A. Crespo 《Marine Biology》2011,158(8):1857-1867
Several major breeding areas have been defined for the South American sea lion (Otaria flavescens) along the Atlantic Ocean including the Uruguayan and Patagonian coasts. Together with a documented and severe reduction
in population sizes caused by commercial hunting in the last century, these areas show opposite population trends. While Patagonian
populations are recovering since hunting ceased, Uruguayan populations are declining. In this context, population genetic
structure and genetic diversity were studied for the first time with both nuclear (microsatellites) and mitochondrial (control
region) markers together. Alternative scenarios were found for both markers. While mitochondrial marker showed geographically
structured populations, the nuclear loci showed a lack of geographical structure. These opposite patterns in genetic structure
could be explained by female phylopatry and high male dispersion. The reduction in population size caused by commercial hunting
did not leave a detectable footprint of bottleneck at the genetic level. 相似文献
55.
Santacatalina M Carratalá A Mantilla E 《Journal of environmental monitoring : JEM》2011,13(6):1634-1645
This work presents the results of a 4-year study on sulfur dioxide (SO(2)) ground-level concentrations in an area of southeastern Spain, the L'Alacantí region, where the cement industry is important and coke use extends to other industries as well. The main source of SO(2) emissions in the area was found to be a the Lepold cement plant (one of the two cement plants in the area). The high levels of SO(2) probably extend back to 1920 when this plant began operations. Both local and Mediterranean-scale meteorological processes influence the SO(2) ground-level concentration and together explain the dispersion dynamics of this pollutant. The location and topography of the study zone result in NW Atlantic advections and E-SE sea breezes being the dominant atmospheric circulation patterns in the area. Under stable meteorological conditions, minor local circulations are also relevant to the SO(2) concentration levels. The high frequency of local circulations determines a concentration pattern that changes during the day, with impacts occurring preferentially in a W-NW direction from the source at midday (sea breeze and strong thermal mixture), and in a SE direction at night. This causes the SO(2) concentrations to present well-defined diurnal cycles with well-differentiated shapes depending on the location of the sampling station relative to the source. The dependence of SO(2) 10 min levels on the wind origin and speed throughout the day has been evaluated by studying statistical parameters including P95, P50 and arithmetic mean. Exceedances occur under specific dispersion conditions at distances less than 1 km from the source. However, the source is traceable at larger distances and the levels are higher than typical urban ones. P95 was used as an estimator of the occurrence of larger levels or impacts. Leeward of NW winds and the source, at night and in early morning, P95 levels are comprised between 30 and 55 μg m(-3). In contrast, with SE winds and at midday, P95 levels stay at 17 μg m(-3). The same P95 was obtained for winds lower than 5 m s(-1), which represent 89% of the winds in the area. However, stronger winds can have P95 levels above 125 μg m(-3). 相似文献
56.
Enrique Morán-Tejeda Sixto Herrera J. Ignacio López-Moreno Jesús Revuelto Anthony Lehmann Martin Beniston 《Regional Environmental Change》2013,13(4):873-885
Snow cover in Spanish mountains is crucial for ensuring water availability in spring and summer months, for the success of winter tourism or for the maintenance of biodiversity in mountain ecosystems. A changing climate may affect the volume of snow cover even in high mountains, where weather conditions are usually favorable for snow accumulation. In this paper, we aim to investigate the evolution (1970–2007) of combined precipitation–temperature modes in the Spanish mountains, and the sensitivity of the snowpack to their occurrence. The climatic database “Spain02” and snow thickness data for Spanish mountains were used for this purpose. Results showed that the frequency of dry-warm and wet-warm days has increased over time in all mountain ranges, while the frequency of the “cold” modes has decreased. The thickness of the snowpack in the Pyrenees has also decreased and its evolution is negatively correlated with the frequency of dry-warm days, and positively correlated with the frequency of dry-cold and wet-cold days. This work constitutes the first approach that relates the evolution of climatic conditions favorable or unfavorable for snow accumulation and the evolution of the snowpack in Spanish mountains. 相似文献
57.
58.
Míguez DM Huertas R Carrara MV Carnikián A Bouvier ME Martínez MJ Keel K Pioda C Darré E Pérez R Viera S Massa E 《Environmental geochemistry and health》2012,34(2):199-205
Bioassays of two sites along the Rio Negro in Uruguay indicate ecotoxicity, which could be attributable to trace concentrations of lead in river sediments. Monthly samples at two sites at Baygorria and Bonete locations were analyzed for both particle size and lead. Lead was determined by atomic spectrometry in river water and sediment and particle size by sieving and sedimentation. Data showed that Baygorria's sediments have greater percentage of clay than Bonete's (20.4 and 5.8%, respectively). Lead was measurable in Baygorria's sediments, meanwhile in Bonete's, it was always below the detection limit. In water samples, lead was below detection limit at both sites. Bioassays using sub-lethal growth and survival test with Hyalella curvispina amphipod, screening with bioluminescent bacteria Photobacterium leiognathi, and acute toxicity bioassay with Pimephales promelas fish indicated toxicity at Baygorria, with much less effect at Bonete. Even though no lethal effects could be demonstrated, higher sub-lethal toxicity was found in samples from Baygorria site, showing a possible concentration of the contaminant in the clay fraction. 相似文献
59.
The effect of bottom-water dissolved oxygen on the structure of demersal fish communities off south Namibia was analized. Collections were made during two cruises of the zone in winter 1987 and summer 1988, i.e., before and after the intensive upwelling season. Multivariate analysis revealed four distinct associations, separated by latitude (ca 27°S) and depth (ca 300 m isobath), indicating that dissolved oxygen is an important factor affecting the distribution of demersal fish communities in the zone. Faunal diversity decreased in areas of low oxygen levels. The seasonal variation in upwelling reflected the extent of fish association, their composition, and the seasonal geographical displacement of their boundaries. 相似文献
60.
Miguel F. Varela Annalise S. Hooper Enrique Rivadulla Jesús L. Romalde 《Food and environmental virology》2016,8(3):187-193
The prevalence and genetical diversity of human Sapovirus were studied during an 18-month study in Ría do Burgo, an estuary nearby the city of A Coruña in Galicia (NW Spain). Sapovirus was detected using RT-qPCR procedure in 30 out of 80 mussel samples (37.5 %). Quantifications ranged from 2.2 × 103 to 2.1 × 105 RNA copies per gram of digestive tissue. Detection occurred mainly during the cold and rainy seasons of the period studied. Sequences obtained could be distributed into 5 genotypes being the most abundant GI.1 and GI.3. Results obtained indicate that the hydrodynamic characteristics of the harvesting area and the proximity of population density clearly influence the presence of the virus in shellfish. 相似文献