Radio tracking of 142 males captured at 44 leks in Spain showed that partial migration of great bustard males in summer is
a widespread behaviour in many Iberian populations, in contrast to their previously assumed sedentariness. A variable number
of males migrated immediately after mating to summering areas with lower temperatures and human population densities and more
trees and rainfall levels than the breeding sites. Birds selected there fields with trees and sunflower crops which provided
shade during the hottest midday hours and protective cover against predators. Males breeding in areas with higher July temperatures
had a higher tendency to migrate, and males from hotter, southern regions migrated longer distances than those from milder,
northern regions and showed a preferred northward direction. These results confirmed various predictions from the weather
sensitivity hypothesis, suggesting that summer migration of great bustard males represents primarily an adaptation to escape
the summer heat of most breeding areas in central and southern Iberia. The hypothesis that males migrated to benefit from
higher food availability at the summering areas could not be rejected by our results. Finally, migrating males also gained
more tranquillity during the post-breeding moult due to the lower human population density at the summering areas. Summer
migration of Iberian great bustard males may thus be interpreted as a form of behavioural thermoregulation which has not been
described for other Palaearctic populations of this species or for other bird species breeding in temperate latitudes. 相似文献
Modelling ozone (O3) deposition for impact risk assessment is still poorly developed for herbaceous vegetation, particularly for Mediterranean annual pastures. High inter-annual climatic variability in the Mediterranean area makes it difficult to develop models characterizing gas exchange behaviour and air pollutant absorption suitable for risk assessment. This paper presents a new model to estimate stomatal conductance (gs) of Trifolium subterraneum, a characteristic species of dehesa pastures. The MEDPAS (MEDiterranean PAStures) model couples 3 modules estimating soil water content (SWC), vegetation growth and gs. The gs module is a reparameterized version of the stomatal component of the EMEP DO3SE O3 deposition model. The MEDPAS model was applied to two contrasting years representing typical dry and humid springs respectively and with different O3 exposures. The MEDPAS model reproduced realistically the gs seasonal and inter-annual variations observed in the field. SWC was identified as the major driver of differences across years. Despite the higher O3 exposure in the dry year, meteorological conditions favoured 2.1 times higher gs and 56 day longer growing season in the humid year compared to the dry year. This resulted in higher ozone fluxes absorbed by T. subterraneum in the humid year. High inter-family variability was found in gas exchange rates, therefore limiting the relevance of single species O3 deposition flux modelling for dehesa pastures. Stomatal conductance dynamics at the canopy level need to be considered for more accurate O3 flux modelling for present and future climate scenarios in the Mediterranean area. 相似文献
Since the damage suffered by buildings as a consequence of explosions usually affect the people inside them, it is important to take it into account when performing consequence analysis. The aim of this paper is to provide a methodology to estimate consequences to buildings from pressure waves produced by spherical vessel burst. This is done by combining characteristic overpressure–impulse–distance curves [González Ferradás, E., Diaz Alonso, F., Sanchez Perez, J.F., Miñana Aznar, A., Ruiz Gimeno, J. and Martinez Alonso, J., 2006, Characteristic overpressure–impulse–distance curves for vessel burst, Process Safety Progress, 25(3): 250–254] with PROBIT equations. The main advantage of this methodology is that it allows an overview of all the magnitudes involved, as damage is shown in the same graph as the overpressure, impulse and distance. In this paper diagrams and equations are presented to determine minor damage to buildings (broken windows, displacement of doors and window frames, tile displacement, etc.), major structural damage (cracks in walls, collapse of some walls) and collapse (the damage is so extensive that the building is partially or totally demolished). 相似文献
The transport of chromium by the emulsion pertraction technology (EPERT) using Hostarex A327 (tertiary amine) as a carrier has been investigated. The permeation of the metal is studied as a function of various experimental variables: hydrodynamic conditions, concentration of Cr(VI) and HCl in the source phase, carrier concentration and diluent in the organic phase, strippant concentration in the stripping phase and support characteristics of the membrane. The mass transfer coefficient and the thickness of the aqueous source boundary layer were estimated from the experimental data. Furthermore, the selectivity of the Hostarex A327-bases EPERT towards different metal ions and the behaviour of the system against other carriers are presented. 相似文献
The ormer, Haliotis tuberculata Linnaeus, 1758, is able to accumulate paralytic shellfish toxins (PST) in the foot side skin. Epidermal and secretory cells are described
separately for the pedal side and sole epithelia, as notable differences have been observed. Melanin and photosynthetic pigment
granules in the epidermal cells of the foot side epithelium give this skin its appearance and characteristic color. This epidermis
also has abundant secretory cells containing at least three kinds of secretory granules. Conversely, the epidermal cells of
foot sole epithelium do not have pigment granules, and the secretory cells are mostly subepithelial. Immunohistochemical reaction
against PST (saxitoxin and its derivatives) showed that the toxins are located in specific cells of the foot side epithelium,
which are distinct from the epidermal cells. Immunofluorescence also reveals toxins throughout many areas of the mucilage
covering the epithelium, suggesting the secretory nature of the cells containing the toxins. These results do not show any
apparent relationship between melanin or photosynthetic pigment granules and PST content. PST were not detected in the foot
sole epithelium either immunohistochemically or by HPLC. Considering the toxic characteristics of ormers described in previous
studies and the results presented here, the authors discuss the role of toxins retained or produced by the foot side epithelium
Received: 25 July 2000 / Accepted: 7 November 2000 相似文献
A new Aeromonas bioassay is described to assess the potential harmful effects of the glyphosate-based herbicide, Roundup®, in the Albufera lake, a protected area near Valencia. Viability markers as membrane integrity, culturability and β-galactosidase production of Aeromonas caviae were studied to determine the influence of the herbicide in the bacterial cells. Data from the multifactor analysis of variance test showed no significant differences (P > 0.05) between A. caviae counts of viability markers at the studied concentrations (0, 50 and 100 mg l−1 of glyphosate).
The effects of Roundup® on microbial biota present in the lake were assessed by measuring the number of indigenous mesophilic Aeromonas in presence of different amounts of the herbicide at 0, 50 and 100 mg l−1 of glyphosate. In samples containing 50 and 100 mg l−1 of glyphosate a significant (P < 0.05) increase in Aeromonas spp. counts and accompanying flora was observed.
The acute toxicity of Roundup® and of Roundup® diluted with Albufera lake water to Microtox® luminescent bacterium (Vibrio fischeri) also was determined. The EC50 values obtained were 36.4 mg l−1 and 64.0 mg l−1 of glyphosate respectively. The acidity (pH 4.5) of the herbicide formulation was the responsible of the observed toxicity. 相似文献
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
A novel concept for capturing CO2 from biomass combustion using CaO as an active solid sorbent of CO2 is discussed and experimentally tested. According to the CaO/CaCO3 equilibrium, if a fuel could be burned at a sufficiently low temperature (below 700 °C) it would be possible to capture CO2 “in situ” with the CaO particles at atmospheric pressure. A subsequent step involving the regeneration of CaCO3 in a calciner operating at typical conditions of oxyfired-circulating fluidized combustion would deliver the CO2 ready for purification, compression and permanent geological storage. Several series of experiments to prove this concept have been conducted in a 30 kW interconnected fluidized bed test facility at INCAR-CSIC, made up of two interconnected circulating fluidized bed reactors, one acting as biomass combustor-carbonator and the other as air-fired calciner (which is considered to yield similar sorbent properties than those of an oxyfired calciner). CO2 capture efficiencies in dynamic tests in the combustor-carbonator reactor were measured over a wide range of operating conditions, including different superficial gas velocities, solids circulation rates, excess air above stoichiometric, and biomass type (olive pits, saw dust and pellets). Biomass combustion in air is effective at temperatures even below the 700 °C, necessary for the effective capture of CO2 by carbonation of CaO. Overall CO2 capture efficiencies in the combustor-carbonator higher than 70% can be achieved with sufficiently high solids circulation rates of CaO and solids inventories. The application of a simple reactor model for the combined combustion and CO2 capture reactions allows an efficiency factor to be obtained from the dynamic experimental test that could be valuable for scaling up purposes. 相似文献