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41.
Raquel G. Loreto Adam G. Hart Thairine M. Pereira Mayara L. R. Freitas David P. Hughes Simon L. Elliot 《Die Naturwissenschaften》2013,100(10):957-963
Trail-making ants lay pheromones on the substrate to define paths between foraging areas and the nest. Combined with the chemistry of these pheromone trails and the physics of evaporation, trail-laying and trail-following behaviours provide ant colonies with the quickest routes to food. In relatively uniform environments, such as that provided in many laboratory studies of trail-making ants, the quickest route is also often the shortest route. Here, we show that carpenter ants (Camponotus rufipes), in natural conditions, are able to make use of apparent obstacles in their environment to assist in finding the fastest routes to food. These ants make extensive use of fallen branches, twigs and lianas as bridges to build their trails. These bridges make trails significantly longer than their straight line equivalents across the forest floor, but we estimate that ants spend less than half the time to reach the same point, due to increased carriage speed across the bridges. We also found that these trails, mainly composed of bridges, are maintained for months, so they can be characterized as trunk trails. We suggest that pheromone-based foraging trail networks in field conditions are likely to be structured by a range of potentially complex factors but that even then, speed remains the most important consideration. 相似文献
42.
Fernando Ferraz do Nascimento Dani Gamerman Hedibert Freitas Lopes 《Environmental and Ecological Statistics》2011,18(3):495-512
Many situations in practice require appropriate specification of operating characteristics under extreme conditions. Typical
examples include environmental sciences where studies include extreme temperature, rainfall and river flow to name a few.
In these cases, the effect of geographic and climatological inputs are likely to play a relevant role. This paper is concerned
with the study of extreme data in the presence of relevant auxiliary information. The underlying model involves a mixture
distribution: a generalized Pareto distribution is assumed for the exceedances beyond a high threshold and a non-parametric
approach is assumed for the data below the threshold. Thus, the full likelihood including data below and above the threshold
is considered in the estimation. The main novelty is the introduction of a regression structure to explain the variation of
the exceedances through all tail parameters. Estimation is performed under the Bayesian paradigm and includes model choice.
This allows for determination of higher quantiles under each covariate configuration and upper bounds for the data, where
appropriate. Simulation results show that the models are appropriate and identifiable. The models are applied to the study
of two temperature datasets: maxima in the U.S.A. and minima in Brazil, and compared to other related models. 相似文献
43.
Accumulation of (137)Cs in Brazilian soils and its transfer to plants under different climatic conditions 总被引:1,自引:0,他引:1
Handl J Sachse R Jakob D Michel R Evangelista H Gonçalves AC de Freitas AC 《Journal of environmental radioactivity》2008,99(2):271-287
The spatial distribution and behaviour of the global fallout (137)Cs in the tropical, subtropical and equatorial soil-plant systems were investigated at several upland sites in Brazil selected according to their climate characteristics, and to the agricultural importance. To determine the (137)Cs deposition density, undisturbed soil profiles were taken from 23 environments situated between the latitudes of 02 degrees N and 30 degrees S. Sampling sites located along to the equator exhibited (137)Cs deposition densities with an average value of 219Bqm(-2). Extremely low deposition densities of 1.3Bqm(-2) were found in the Amazon region. In contrast, the southern part of Brazil, located between latitudes of 20 degrees S and 34 degrees S, exhibited considerably higher deposition densities ranging from 140Bqm(-2) to 1620Bqm(-2). To examine the (137)Cs soil-to-plant transfer in the Brazilian agricultural products, 29 mainly tropical plant species, and corresponding soil samples were collected at 43 sampling locations in nine federal states of Brazil. Values of the (137)Cs concentration factor plant/soil exhibited a large range from 0.020 (beans) to 6.2 (cassava). Samples of some plant species originated from different collecting areas showed different concentration factors. The (137)Cs content of some plants collected was not measurable due to a very low (137)Cs concentration level found in the upper layers of the incremental soils. Globally, the soil-to-plant transfer of (137)Cs can be described by a logarithmic normal distribution with a geometric mean of 0.3 and a geometric standard deviation of 3.9. 相似文献
44.
Mariana Egler Claudio Antonio Gonçalves Egler Barbara Franz Maria Silvia Muylaert de Araujo Marcos Aurélio Vasconcelos de Freitas 《Regional Environmental Change》2013,13(2):263-271
In recent years, Amazonian deforestation has become a question of global concern. Deforestation in Amazon is a complex phenomenon in nature and has been related to traditional agriculture expansion. In this work, land use, socioeconomic and conservation indicators, combined with statistical analysis, were used to understand forces associated with patterns of deforestation. This approach was applied in Southern Brazilian Pre-Amazon in Mato Grosso State, which represents an extensive rain forest-savanna ecotone, located in the south border of Amazon biome. Based on data from the last two agricultural censuses (1995/1996–2006), we compared agricultural expansion in this area and Mato Grosso state. Results have shown that 85 % of state deforestation was concentrated in Southern Pre-Amazon and was closely related to increase in number of cattle and pasture area. PCA results pointed that population (92 %), number of cattle (86.5 %), pastures (84.2 %) and tractors (78.4 %) were variables with highest positive correlation to deforestation. It showed that GDP contributes to an individual axis and has a low correlation to deforestation (37.8 %). Conservation units and indigenous reserves also contribute to a single axis and were negatively correlated to temporary crops area. Results revealed a significant reduction in production and commercialization of extractive products in the region, revealing that the main, almost only conservation policy in Mato Grosso remains the creation of Special Areas. We suggest that further studies are necessary to screen development alternatives to simple cutting trees down. It is important to diversify strategies for deforestation control, and development aspects must be more seriously considered to reach a sustainable deforestation control policy. 相似文献
45.
Sophie Quérouil Jeremy Kiszka Ana Rita Cordeiro Irma Cascão Luís Freitas Ana Dinis Filipe Alves Ricardo Serrão Santos Narcisa M. Bandarra 《Marine Biology》2013,160(6):1325-1337
Short-beaked common dolphins (Delphinus delphis) and Atlantic spotted dolphins (Stenella frontalis) are the two most abundant cetacean species in the oceanic waters of Madeira and the Azores. They are of similar size, occur in similar habitats and are regularly observed in mixed-species groups to forage together. Genetic analyses suggested that, within each species, dolphins ranging around both archipelagos belong to the same panmictic population. We tested the hypotheses that (1) within each species, individuals from the two archipelagos belong to a single ecological stock; (2) between species, common and spotted dolphins have distinct trophic niches; using fatty acid (FA) and stable isotope (SI) analyses. Fatty acids and stable isotopes were analysed from 86 blubber and 150 skin samples of free-ranging dolphins, respectively. Sex-related differences were not significant, except for common dolphin FA profiles. In S. frontalis, FA and SI differences between archipelagos suggested that individuals belonged to different ecological stocks, despite the existence of gene flow between the two archipelagos. In D. delphis, differences were more pronounced, but it was not possible to distinguish between stock structure and a seasonal effect, due to differential sampling periods in the Azores and Madeira. Inter-specific comparisons were restricted to the Azores where all samples were collected during summer. Differences in FA proportions, noticeably for FA of dietary origin, as well as in nitrogen SI profiles, confirmed that both species feed on distinct resources. This study emphasizes the need for an integrated approach including both genetic and biochemical analyses for stock assessment, especially in wide-ranging marine top predators. 相似文献
46.
Marina M. S. Cabral Pinto A. Paula Marinho-Reis Agostinho Almeida Carlos M. Ordens Maria M. V. G. Silva Sandra Freitas Mário R. Simões Paula I. Moreira Pedro A. Dinis M. Luísa Diniz Eduardo A. Ferreira da Silva M. Teresa Condesso de Melo 《Environmental geochemistry and health》2018,40(5):1767-1784
New lines of evidence suggest that less than 10% of neurodegenerative diseases have a strict genetic aetiology and other factors may be prevalent. Environmental exposures to potentially toxic elements appear to be a risk factor for Parkinson’s, Alzheimer’s and sclerosis diseases. This study proposes a multidisciplinary approach combining neurosciences, psychology and environmental sciences while integrating socio-economic, neuropsychological, environmental and health data. We present the preliminary results of a neuropsychological assessment carried out in elderly residents of the industrial city of Estarreja. A battery of cognitive tests and a personal questionnaire were administered to the participants. Multivariate analysis and multiple linear regression analysis were used to identify potential relationships between the cognitive status of the participants and environmental exposure to potentially toxic elements. The results suggest a relationship between urinary PTEs levels and the incidence of cognitive disorders. They also point towards water consumption habits and profession as relevant factors of exposure. Linear regression models show that aluminium (R 2 = 38%), cadmium (R 2 = 11%) and zinc (R 2 = 6%) are good predictors of the scores of the Mini-Mental State Examination cognitive test. Median contents (µg/l) in groundwater are above admissible levels for drinking water for aluminium (371), iron (860), manganese (250), and zinc (305). While the World Health Organization does not provide health-based reference values for aluminium, results obtained from this study suggest that it may have an important role in the cognitive status of the elderly. Urine proved to be a suitable biomarker of exposure both to elements with low and high excretion rates. 相似文献
47.
Carlos Alberto de Albuquerque Carlos Henrique Pereira Mello Jos Henrique de Freitas Gomes Valquíria Claret dos Santos Julia Vidigal Zara 《环境质量管理》2020,29(3):63-72
Environmental issues have been at the center of society's concerns for a long time. Recently, this kind of concern is growing even more due to the damage caused to the environment by electrical and electronic product waste. Based on this same concern, this work aimed to analyze, through a literature review, the production and treatment of electronic waste in today's world, with an emphasis on Brazil and China. The articles reviewed point to an increase in the production of this type of waste, in both Brazil and China, and reveal that the current processes of treatment of electronic waste mostly aim to obtain profit through the recovery of precious metals such as copper. This paper concluded that although Brazil is one of the major producers of e‐waste, more than 90% of its e‐waste has not had a proper final destination. This deficiency in e‐waste treatment in Brazil is mainly due to financial factors and the lack of a robust educational policy focused on the environment. Thus, this work suggests the implementation of an effective educational policy aimed at environmental conservation, as well as investments in research on recycling methods in Brazil, especially on the use of e‐waste as an aggregate in the manufacture of concrete. 相似文献
48.
C.A. Alves C. Gonçalves C.A. Pio F. Mirante A. Caseiro L. Tarelho M.C. Freitas D.X. Viegas 《Atmospheric environment (Oxford, England : 1994)》2010,44(25):3024-3033
Gaseous and particulate samples from the smoke from prescribed burnings of a shrub-dominated forest with some pine trees in Lousã Mountain, Portugal, in May 2008, have been collected. From the gas phase Fourier transform infrared (FTIR) measurements, an average modified combustion efficiency of 0.99 was obtained, suggesting a very strong predominance of flaming combustion. Gaseous compounds whose emissions are promoted in fresh plumes and during the flaming burning phase, such as CO2, acetylene and propene, produced emission factors higher than those proposed for savannah and tropical forest fires. Emission factors of species that are favoured by the smouldering phase (e.g. CO and CH4) were below the values reported in the literature for biomass burning in other ecosystems. The chemical composition of fine (PM2.5) and coarse (PM2.5–10) particles was achieved using ion chromatography (water-soluble ions), instrumental neutron activation analysis (trace elements) and a thermal–optical transmission technique (organic carbon and elemental carbon). Approximately 50% of the particulate mass was carbonaceous in nature with a clear dominance of organic carbon. The organic carbon-to-elemental carbon ratios up to 300, or even higher, measured in the present study largely exceeded those reported for fires in savannah and tropical forests. More than 30 trace elements and ions have been determined in smoke aerosols, representing in total an average contribution of about 7% to the PM10 mass. 相似文献
49.
50.
Teresa Rocha-Santos Filipe Ferreira Lurdes Silva Ana Cristina Freitas Ruth Pereira Mário Diniz Luísa Castro Isabel Peres Armando Costa Duarte 《Environmental science and pollution research international》2010,17(4):866-874