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261.
Carotenoid pigments cannot be synthesized by vertebrates but must be ingested through the diet. As they seem to be a limited
resource, carotenoid-based ornaments are particularly interesting as possible honest signals of individual quality, in particular
of foraging efficiency and nutritional status. Some studies have demonstrated the condition dependence of carotenoid-based
plumage in birds. However, many other carotenoid-pigmented bare parts (i.e. skin, caruncles, bills, cere, and tarsi) are present
in birds but, in comparison with plumage, little is known about these traits as indicators of individual quality. Here, we
show that the eye ring pigmentation and bill redness of the red-legged partridge (Alectoris rufa) are positively associated to body condition and recent changes in body mass. Also, we found a negative relationship between
these two traits and heterophil-to-lymphocyte ratio, an indicator of physiological stress (the relationship with bill redness
being significant only for males). In an experiment, we found that after a period of reduction in food intake (with the consequent
loss of body mass), food-restricted birds showed lower eye ring pigmentation than ad-libitum-fed birds. Therefore, different
ornaments seem to reflect changes in body condition but at different speeds or intensities (eye ring, a fleshy ornament, appears
to respond more rapidly to changes in the nutritional status than a keratinized structure as the bill). These results indicate
that carotenoid-based ornaments are condition-dependent traits in the red-legged partridge, being therefore susceptible to
be employed as honest signals of quality in sexual selection. 相似文献
262.
Cañaveras JC Cuezva S Sanchez-Moral S Lario J Laiz L Gonzalez JM Saiz-Jimenez C 《Die Naturwissenschaften》2006,93(1):27-32
In this study, we show that moonmilk subaerial speleothems in Altamira Cave (Spain) consist of a network of fiber calcite
crystals and active microbial structures. In Altamira moonmilks, the study of the typology and distribution of fiber crystals,
extracellular polymeric substances, and microorganisms allowed us to define the initial stages of fiber crystal formation
in recent samples as well as the variations in the microstructural arrangement in more evolved stages. Thus, we have been
able to show the existence of a relationship among the different types of fiber crystals and their origins. This allowed us
to outline a model that illustrates the different stages of formation of the moonmilk, developed on different substrata, concluding
that microbes influence physicochemical precipitation, resulting in a variety of fiber crystal morphologies and sizes. 相似文献
263.
In situ stabilization of toxic elements in contaminated soils by the addition of amendments is being considered as an effective technique for remediation. In this paper, we performed both kinetics and equilibrium-based sorption experiments of three toxic elements (As, Cd and Tl) in soils amended with two by-products (phosphogypsum and sugar foam, rich in gypsum and calcium carbonate, respectively) to ascertain the feasibility of their application for improving the sorption capacity of As, Cd and Tl from the soil at 25, 35 and 50 °C. Kinetic studies indicated that the sorption follows a pseudo-second-order (PSO) kinetics and the sorption is a two-step diffusion process where both film and intraparticle diffusion played important roles in the sorption mechanisms of the elements. The Langmuir isotherms applied for sorption studies showed that the estimated maximum sorption capacity of the elements in control and amended soils decreased in the order of Cd > As > Tl. Using the thermodynamic equilibrium parameters obtained at different temperatures, the thermodynamic constants of sorption (ΔG, ΔH and ΔS) were also evaluated, indicating spontaneous and endothermic nature of the process, except Tl which was exothermic. An optimal scaling procedure was undertaken to determine the relationships between the kinetic and equilibrium sorption parameters. By means of statistical analysis it was seen that these inter-parametric relationships are dependent on the element nature. 相似文献
264.
This study qualifies and quantifies the immobilization of Cd, Zn and Co, (used as models of bivalent metal ions due to their relevant toxicity) in filters of synthetic hydroxyapatite (HAP) [Ca5(PO4)3OH]. They were flushed with solutions containing Cd (1 x 10(-5)M), Zn and Co (1 x 10(-4)M) at constant pH (8.6) and ionic strength (0.01 M). The concentration of these metal ions in the outlet was measured by ICP-OEM spectroscopy. The software PHREEQC (version 2.4.2) was used to model sorption process and the potential effect of salinity (KCl), pH, alkalinity (NaHCO3) and hardness (CaCl2) over the efficiency of the treatment. Results showed an excellent retention capacity of HAP for Cd, Zn and Co. Sorption data were successfully described considering a mix model of surface complexation onto phosphate surface groups, ionic exchange in surface calcium sites and the precipitation of ZnO. Co exchange and surface complexation constants (Kex and Kc) were taken from previous experiments, while KexCd=0.32 and KcCd=0.63 were estimated from our modeling results. Predictive values of metal ion sorption show that: (a) an increase in hardness does not play a significant role in the retention capacity of these metals on HAP; (b) an increase in alkalinity promotes the precipitation of MeCO3 which could alter the hydrodynamic of the column; (c) a decrease in pH and an increase in salinity inhibit ZnO precipitation enhancing Zn and Cd adsorption and decreasing Co retention on HAP. 相似文献
265.
Sibling aggression, hatching asynchrony, and nestling mortality in the black kite (Milvus migrans) 总被引:3,自引:0,他引:3
Javier Viñuela 《Behavioral ecology and sociobiology》1999,45(1):33-45
In siblicidal species, hatching asynchrony could act to reduce sibling rivalry or promote the death of last-hatched chicks.
The pattern of hatching asynchrony was experimentally altered in the black kite Milvus migrans. Hatching asynchrony in control broods was intermediate between those of experimentally synchronised and asynchronised broods.
Sibling aggression and wounds on the chicks were more commonly observed early in the nestling period and in synchronous nests.
Serious injuries were observed on last-hatched chicks in asynchronous nests, as were observations of intimidated or crushed
chicks. Sibling aggression was related to food abundance, but some chicks died at an early age in nests with abundant food
(cainism). Cainism was more commonly found in asynchronous nests. For species with facultative siblicide, moderate hatching
asynchrony could be a compromise between reducing sibling rivalry and avoiding large size differences between sibs that would
result in cainism. Female black kites preferentially fed the smallest chicks and exhibited behaviours to reduce sibling aggression,
contrary to observations in other siblicidal species. In a highly opportunistic forager such as the black kite, a strategy
may exist to protract the life of all the chicks in the brood, waiting for unpredictable situations of food overabundance.
This would induce the appearance of a parent-offspring conflict over brood reduction, reflected in the existence of a possible
anticipated response by some of the chicks (cainism) and in the appearance of special behaviours by the parents to selectively
feed smaller chicks or reduce sibling aggression. In this facultatively siblicidal species, cainism does not seem to be the
final stage of an evolutionary trend favouring the raising of high-quality chicks, but a manifestation of a parent-offspring
conflict over brood size.
Received: 9 March 1998 / Accepted after revision: 8 August 1998 相似文献
266.
Manuel Alvarez-Guerra Javier R. Viguri Nikolaos Voulvoulis 《Environment international》2009,35(6):920-930
Decision-making for sediment management is a complex task that incorporates the selections of areas for remediation and the assessment of options for any mitigation required. The application of Multicriteria Analysis (MCA) to rank different areas, according to their need for sediment management, provides a great opportunity for prioritisation, a first step in an integrated methodology that finally aims to assess and select suitable alternatives for managing the identified priority sites. This paper develops a methodology that starts with the delimitation of management units within areas of study, followed by the application of MCA methods that allows ranking of these management units, according to their need for remediation. This proposed process considers not only scientific evidence on sediment quality, but also other relevant aspects such as social and economic criteria associated with such decisions. This methodology is illustrated with its application to the case study area of the Bay of Santander, in northern Spain, highlighting some of the implications of utilising different MCA methods in the process. It also uses site-specific data to assess the subjectivity in the decision-making process, mainly reflected through the assignment of the criteria weights and uncertainties in the criteria scores. Analysis of the sensitivity of the results to these factors is used as a way to assess the stability and robustness of the ranking as a first step of the sediment management decision-making process. 相似文献
267.
Teresa Moreno Javier Lavín Xavier Querol Andrés Alastuey Mar Viana Wes Gibbons 《Atmospheric environment (Oxford, England : 1994)》2009,43(27):4178-4186
Average 21st century concentrations of urban air pollutants linked to cardiorespiratory disease are not declining, and commonly exceed legal limits. Even below such limits, health effects are being observed and may be related to transient daytime peaks in pollutant concentrations. With this in mind, we analyse >52,000 hourly urban background readings of PM10 and pollutant gases throughout 2007 at a European town with legal annual average concentrations of common pollutants, but with a documented air pollution-related cardiorespiratory health problem, and demonstrate the hourly variations in PM10, SO2, NOx, CO and O3. Back-trajectory analysis was applied to track the arrival of exotic PM10 intrusions, the main controls on air pollutants were identified, and the typical hourly pattern on ambient concentrations during 2007 was profiled. Emphasis was placed on “worst case” data (>90th percentile), when health effects are likely to be greatest. The data show marked daytime variations in pollutants result from rush-hour traffic-related pollution spikes, midday industrial SO2 maxima, and afternoon O3 peaks. African dust intrusions enhance PM10 levels at whatever hour, whereas European PM incursions produce pronounced evening peaks due to their transport direction (across an industrial traffic corridor). Transient peak profiling moves us closer to the reality of personal outdoor exposure to inhalable pollutants in a given urban area. We argue that such an approach to monitoring data potentially offers more to air pollution health effect studies than using only 24 h or annual averages. 相似文献
268.
ngel Rodriguez Juan M. Manso ngel Aragn Javier J. Gonzalez 《Resources, Conservation and Recycling》2009,53(11):645-651
Ladle furnace basic slag (LFS) is a by-product of the steelmaking process. It has rarely been recovered in the past and is usually disposed of in landfill sites. Despite containing stable chemical substances of great quality, some of which are potentially hydraulic, its practical applications have been limited. This paper discusses the attractive option of using LFS in the manufacture of masonry mortars for use in the construction industry, which requires an analysis of the principal characteristics of such mortars, i.e. workability and mechanical strength. It reports on a comparative study, using standard commercial admixtures, between conventional masonry mortars and mortars manufactured with LFS as a partial replacement for sand and cement, the results of which imply considerable economic savings in sand and cement, improvements in the properties of the mortars and in overall sustainability, by avoiding disposal and conserving natural resources. 相似文献
269.
Contaminant mass‐balance assessments are useful tools to help quantify various mass transport and removal mechanisms that may be active in a remedial system setting. This article presents the basics of performing a mass balance and illustrates the utility of using the information derived to support project management decisions. It is important to understand the partitioning of contaminant mass into various environmental media and physical forms, as well as the relationships among the partitions. Contaminant partitioning tends toward an equilibrium state, so natural or engineered mass transfer into or out of one partition will affect the others. Mass balances are exercises that quantify, to the extent possible, the contaminant mass in the various environmental partitions and the transfer and transformation processes that affect contaminant distribution. Understanding mass partitioning and transfer mechanisms helps remediation practitioners to engineer and optimize those mechanisms that contribute to risk reduction at a contaminated site. Such knowledge can inform risk managers when natural mechanisms may dominate engineered approaches and help identify uncertainties in contaminant fate and transport. © 2009 Wiley Periodicals, Inc. 相似文献
270.
Gera A Alcoverro T Mascaró O Pérez M Romero J 《Environmental monitoring and assessment》2012,184(6):3675-3686
The European Water Framework Directive commits partner countries to evolve uniform protocols for monitoring the environmental
condition of natural water bodies, crucially integrating biological and ecological criteria from the associated ecosystems.
This has encouraged considerable research on the development of bioindicator-based systems of water quality monitoring. A
critical step towards this end is providing evidence that the proposed bioindicator system adequately reflects the human pressures
to which a specific water body is submitted. Here we investigate the utility of pulse-amplitude-modulated (PAM) fluorometry,
a fast, non-destructive and increasingly popular bioindicator-based method, in assessing water quality based on the widespread
Mediterranean seagrass Posidonia oceanica, an important constituent of submersed benthic vegetation. Specifically, we evaluated the ability of PAM to discriminate
between sites along a pre-established gradient of anthropogenic pressures and the consistency and reliability of PAM parameters
across spatial scales. Our results show that the maximum quantum yield (Fv/Fm), representing the structural photosynthetic
efficiency of the plant, responds significantly to the degree of site-level anthropogenic pressure. However, Fv/Fm values
in our study increased with increasing pressure, in striking contrast with other studies that report declines in Fv/Fm values
with increasing stress. A potential explanation for this discrepancy is that our study sites were influenced by multiple diffuse
stressors (characteristic of most coastal waters) that could potentially interact with each other to influence Fv/Fm values
in often unpredictable ways. The photosynthetic variables calculated from rapid light curves (ETRmax, maximum electron transport rate; α, initial slope of the curve; I
k, saturating irradiance), which represent an instant picture of the photosynthetic activity of the plant, were unable to clearly
discriminate between sites subject to different anthropogenic pressures due to considerable small-scale variability. Taken
together, these results suggest that even though PAM fluorometry may be a good candidate tool for monitoring water bodies
in terms of costs and applicability, considerably more needs to be understood about how its parameters respond to real-world
stressors, particularly when they act in concert with each other. With our present understanding of seagrass photosynthetic
responses to anthropogenic stress, it would be ill advised to employ PAM as anything but a complementary tool to validate
environmental stress derived with other, more robust methodologies. 相似文献