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231.
232.
Silvia Bolado-Rodríguez David García-Sinovas Javier Álvarez-Benedí 《Journal of environmental management》2010,91(12):2594-2598
The effect of physical–chemical slurry treatment on the mobility and transformation of nitrogen and organic matter from pig slurry after soil application is evaluated. Two different pig slurries (one treated by stripping with air at pH = 9 and another non-treated) were applied at the top of a soil column, containing approximately 100 kg of soil. Effluents were monitored measuring concentration values of ammonia, nitrites, nitrates and total organic carbon (TOC). The breakthrough curves were modelled using STANMOD and HYDRUS 1D codes. Low concentrations of ammonia were detected in the effluent recovered at the bottom of the soil profile for both types of slurry. Nitrate concentration in effluent was lower and more homogenous over time when applying stripping treated pig slurry. In N modelling, adsorption of ammonia by soil proved an important process, nitrite and nitrate adsorption being less significant, although not negligible. Transformation from ammonia to nitrite controls the kinetics of the nitrification process. Total organic carbon in the column effluent was higher in the experiment using treated pig slurry, which can be attributed to organic matter solubilisation in the stripping treatment process. 相似文献
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234.
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
235.
Manuel B. Morales Fabián Casas Eladio García de la Morena Anna Ponjoan Gustau Calabuig Jesús Martínez-Padilla Jesús T. García Santi Mañosa Javier Viñuela Gerard Bota 《Behavioral ecology and sociobiology》2014,68(9):1493-1504
We evaluated the effect of conspecific abundance and habitat quality of leks on the territorial behaviour of males in an exploded lekking species, the Little Bustard (Tetrax tetrax). The hypothesis that males more intensely defend territories with higher conspecific abundance and better habitat quality was evaluated experimentally analysing the agonistic response of experimental males to male decoys placed on their displaying areas. Decoy experiments showed that the intensity of display territory defence by little bustard males is density dependent. The time experimental males took to return to their display sites after decoy placement decreased with abundance of both males and females. The strength of their final response was positively associated to local male and female abundance in the vicinity of their display sites. Habitat quality also influenced males’ display territory defence since the intensity of male response increased with the degree of natural vegetation cover. Habitat quality was particularly relevant in explaining variation of experimental males’ snort call rate, which decreased with the degree in plough cover and increased with the number of fields in the lekking area. Snort call rate decreased with the level of male aggregation and was lowest in males exhibiting the strongest aggressive response to decoys. These results add new evidence for the density dependence of species’ breeding territorial behaviour, supporting density-dependent models of lek formation and reinforcing the role of resources defence in exploded lek mating systems. 相似文献
236.
Andrea S. Grunst Javier Salgado-Ortiz John T. Rotenberry Melissa L. Grunst 《Behavioral ecology and sociobiology》2014,68(4):669-680
Carotenoid- and phaeomelanin-based sexual pigmentation may signal a capacity to maintain oxidative balance and viability. However, diverse empirical results leave the association between pigmentation and oxidative stress (OS) unclear. We assessed the hypothesis that population-specific levels of oxidative challenge, or strategies for managing OS, affect relationships between sexual pigmentation and OS. Specifically, intense oxidative challenge in migratory, temperate breeding birds might enhance correlations between pigmentation and OS relative to allied tropical breeders, since quality-based differences in OS may arise only under intense oxidative challenge. Alternatively, in temperate breeders with intense within-season reproductive effort, high-quality birds may invest in reproduction over oxidative balance, dampening negative correlations between pigmentation and OS. To assess these alternatives, we compared prenesting relationships between pigmentation and OS in a migratory, Californian population of yellow warblers (Setophaga petechia brewsteri) and in a resident, Mexican population (Setophaga petechia bryanti, “mangrove warblers”). Yellow warblers displayed higher OS than mangrove warblers. However, year of capture and sex had bigger influences on correlations between pigmentation and OS than population. Males with more intense melanin pigmentation had lower OS among mangrove warblers and yellow warblers captured in 2011, but not among yellow warblers captured in 2012. In females only, lower OS levels were associated with more colorful carotenoid pigmentation. Results suggest that both phaeomelanin- and carotenoid-based pigmentation have the potential to correlate with OS levels, but that the signaling potential of pigmentation may shift with inter-annual variation in environmental conditions and display sex-specific dynamics. 相似文献
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238.
Organized tours to watch wildlife are popular recreational and educational activities, in which the visitor expectative (to observe as many and as diverse animals as possible) runs parallel to conservation purposes. However, the presence of visitors may cause negative impacts on wildlife, which makes recreation difficult to manage. Thus, restricting visitor's load to minimize impacts on fauna may be advisable, but too much restriction may end up disappointing the public. We analysed how visitors' group size influences the number and variety of birds observed during an educational activity directed to scholars, in a forested area where public access is otherwise restricted. We observed fewer birds, but not fewer species, as the size of scholars' groups increased. Such effect was apparently mediated by a few species demonstrating reduced tolerance to increased group size. Our results support the idea that reducing the size of visitors' groups not only helps to minimize the negative impacts on wildlife derived from leisure activities, but also allows visitors to watch more wildlife. Therefore, organizing visitors in small numbers is recommended in the design of activities directed to groups of people visiting natural areas. 相似文献
239.
Patricia Prado Catherine J. Collier Javier Romero Teresa Alcoverro 《Marine Biology》2011,158(7):1473-1482
Herbivory is now recognized as an important structuring agent in seagrass meadows but the attack pattern and tissue damage
of consumers are highly variable. Nutritional preferences of herbivores and/or easy access to resources may cause differences
in biomass loss among tissues that damage the plant in functionally distinctive ways. The two main Mediterranean herbivores,
the fish Sarpa salpa (L.) and the sea urchin Paracentrotus lividus (Lmk.), remove higher amounts of intermediate and external shoot leaves, respectively. To test whether this selective feeding
can have different consequences on the allocation patterns of nutrient within plants, we simulated the effect of both herbivores
by clipping external and intermediate leaves (plus unclipped controls) of Posidonia oceanica (L.) and we measured plant tolerance in terms of shoot growth and leaf nutrient supply to new tissue using isotopic markers.
As expected, control treatments displayed high carbon and nutrient supply from external leaves (83% of the total 15N and 84% of the total 13C incorporated by the shoot). When subjected to clipping, the remaining leaves enhanced carbon and nitrogen supply compared
with the control by 16% of N and 36% of C—in the intermediate clipping—and by over 100% of N and 200% of C—in the external
clipping—to compensate for the nutrient lost. However, only in the case of fish herbivory (intermediate clipping), enhanced
supply alone was able to fully compensate for the nutrient losses. In contrast, this mechanism is not completely effective
when external leaves are clipped (urchin herbivory). Yet, the consequences of this nutrient loss under sea urchin herbivory
are not apparent from the nutrient content of the new tissue, suggesting that there are other sources of nitrogen income (uptake
or reallocation from rhizomes). Our study does not only confirm the tolerance of P. oceanica to herbivory, but also constitutes the first evidence of leaf-specific, compensatory nutrient supply in seagrasses. 相似文献
240.
Varea M Galindo N Gil-Moltó J Pastor C Crespo J 《Journal of environmental monitoring : JEM》2011,13(9):2471-2476
Particle-bound PAHs were measured at three sites in southeastern Spain (an urban background location, a suburban-industrial site in the vicinity of two cement plants and a rural area) in order to investigate the influence of the type of location on PAH concentrations. A clear influence of cement production on particulate PAH levels could not be established since for the urban background and suburban-industrial sites the average concentrations of total PAHs in the PM2.5 fraction were very similar (1.085 and 1.151 ng m(-3), respectively), with benzo[b+k]fluoranthene and chrysene as the predominant compounds. Diagnostic ratios, used to identify PAH emission sources, pointed to traffic as the main source of particulate PAH at both locations. As expected, PAH levels at the rural site were significantly lower (0.408 ng m(-3) in the PM10 fraction) due to increasing distance from the emission sources. PAH seasonal variations at the urban background and suburban-industrial sites were the same as reported in many previous studies. Average winter to summer ratios for total PAHs were 4.4 and 4.9 for the urban background and industrial sites, in that order. This seasonal cycle could be partially explained by the higher temperature and solar radiation during summer enhancing PAH evaporation from the particulate phase and PAH photochemical degradation, respectively. The study of PAH distribution between the fine and coarse fraction at the urban site revealed that on average around 80% of total PAHs were associated with fine particles. 相似文献