RESUMO
The underlying causes of late-Holocene climate variability in the tropics are incompletely understood. Here we report a 1,500-year reconstruction of climate history and glaciation in the Venezuelan Andes using lake sediments. Four glacial advances occurred between anno Domini (A.D.) 1250 and 1810, coincident with solar-activity minima. Temperature declines of -3.2 +/- 1.4 degrees C and precipitation increases of approximately 20% are required to produce the observed glacial responses. These results highlight the sensitivity of high-altitude tropical regions to relatively small changes in radiative forcing, implying even greater probable responses to future anthropogenic forcing.
Assuntos
Clima , Luz Solar , Temperatura , Clima Tropical , Sedimentos Geológicos , Camada de Gelo , Modelos Teóricos , VenezuelaRESUMO
In order to determine the sequential prevalence of pollen grains and fungi spores in the city of Caracas by the volumetric method of collection and its effect on the population at risk, the first multidisciplinary team of aerobiological research was structured through a protocol designed for five experimental stages namely: a) Determination of the climatological parameters: temperature, relative humidity, speed and wind direction, precipitation and atmospheric stability, through simultaneous records of meteorological status located in the metropolitan area of Caracas; b) Collection, identification, classification and determination of the local distribution of the most important pollen grains existing in the zone under study; c) Collection, identification and classification of the most important fungi spores in the area; d) Preparation of the first pollinic calendar of Caracas and e) Evaluation of possible implication of the environment and the response through the IgE antibody in the selected patients in the area under study. Our results show: 1) The climatic conditions existing during the sampling period coincide with the analysis of the last 20 years in the Valley of Caracas. 2) The Venezuelan Central University (UCV) station was elected as the most representative point for permanent sampling. 3) An ideal statistical method is obtained in order to determine the spatial arrangement in the sampler rod of a dense type of fungi spores typical of the area under study. 4) The first pollinic calendar of Caracas was structured and 5) A seasonal tendency of the IgE response is shown. These results suggest an evident interrelation between the suggested concept of polyseasonality and antigenic polysensitization, and between individual seasonality with a specific reactivity and, finally, between tropical mixed seasonality with the expression of combined respiratory pathologies in our environment.
Assuntos
Microbiologia do Ar , Ar/análise , Pólen , Esporos Fúngicos/isolamento & purificação , Especificidade de Anticorpos , Asma/epidemiologia , Asma/etiologia , Asma/imunologia , Humanos , Imunoglobulina E/imunologia , Conceitos Meteorológicos , Prevalência , Rinite Alérgica Perene/epidemiologia , Rinite Alérgica Perene/etiologia , Rinite Alérgica Perene/imunologia , Rinite Alérgica Sazonal/epidemiologia , Rinite Alérgica Sazonal/etiologia , Rinite Alérgica Sazonal/imunologia , Estações do Ano , População Urbana , Venezuela/epidemiologiaRESUMO
In order to search an uniform criteria for sampling aerobiological particles, three sites were selected along the valley of Caracas. The distribution of vegetation, topographical and meteorological parameters were monitored. Pollen and spores were collected at each site during 24 hr at 6 min-intervals with a Rotorod sampler. Pollen counts were similar in all sites and much less abundant than spores. Cladosporium was the most abundant spore and grass pollen represented more than 50% of the pollen grains. Results showed that the three sites could be selected as suitable sampling area for airborne pollen and spores. Nevertheless, we recommend the selection of the most accessible and central site for a long-term sampling.
Assuntos
Ar/análise , Pólen/análise , Esporos , Geografia , VenezuelaRESUMO
Aunque existen algunos estudios aerobiológicos de la ciudad de Caracas y áreas cercanas, no se dispone en los momentos de una orientación cronológica de los tipos de polen presentes en el aire y sus abundancias absolutas o relativas. Con el objeto de determinar dicha sucesión polínica y estudiar su influencia así como la de esporas de hongos sobre las enfermedades de tipo alérgico, el Cnric/Cecoic estructuró el primer equipo multidisciplinario en aerobiología. Después del primer año de muestreo del aire se presenta un calendario provisional, basado en los resultados obtenidos entre diciembre 84 y noviembre de 85