Spatial distribution of soil δ13C in the central Brazilian savanna.

Stable carbon isotope ratios (δ13C) of soil record information regarding C3 and C4 plants at the landscape scale that can be used to document vegetation distribution patterns. The Central Brazilian savanna (locally called the Cerrado) has a substantial potential to develop studies of patterns of dynamics and distribution of soil δ13C, due to its environmental diversity. The purpose of this work was to develop a spatial model of soil δ13C (soil δ13C isoscape) to the Cerrado, based on multiple linear regression analysis, and compare the results with the existing model to obtain greater detail of the soil δ13C distribution. The model used 219 soil samples (0-20 cm depth) and a set of climatic, pedological, topographic, and vegetation correlations. The soil δ13C isoscape model presented amplitude between -29‰ and -13‰, with the highest estimated values in the southern and the lowest values in the northern of the Cerrado. Results indicate that soil δ13C, by reflecting the relative contribution of C3 and C4 species to plant community productivity, served as a proxy indicator of the vegetation history at the landscape scale for the Central Brazilian savanna. Despite the large sampling effort, there are still regions with some gaps that the model could not estimate. However, the soil δ13C isoscape model filled most the existing gaps and provided greater detail of some unique local aspects of the Cerrado.

Environmental and social effects on the incidence of tuberculosis in three Brazilian municipalities and in Federal District.

INTRODUCTION: The territorial characteristics, heterogeneities of landscapes, and the regional profiles of Brazil show great disparities in the spatial distribution of tuberculosis burden. Objective of this study is to analyze the effects of environmental and social factors on tuberculosis incidence in three Brazilian municipalities and in the Federal District of Brazil. METHODOLOGY: We performed an ecological study carried out with 131,576 new cases of tuberculosis registered in the Brazilian national disease notification system. For our research we used climatic data, topographic data and socioeconomic data. RESULTS: Wind speed and vapor pressure increased the risk of tuberculosis infection between 4.6 and 5.8 times in the 3 municipalities, in comparison with the Federal District. In Recife socioeconomic aspects showed a greater association with tuberculosis. Lack of garbage collection, poor basic sanitation, and access to drinking water, respectively, increased 49, 33, and 28 times the risk of infection. In the multiple regression analysis, Rio de Janeiro showed several environmental characteristics - such as precipitation (p = 0.002), radiation (p = 0.020) and water vapor (p = 0.055) - and social characteristics associated with tuberculosis - such as the lack of sewage treatment, which revealed a 13.5-fold higher risk of infection (p < 0.001). CONCLUSIONS: Incidence in the areas studied was influenced by environmental and social conditions at different levels depending on the territory where the problem was identified. The results make it possible to guide an urban and social policy to reach the targets set out in the WHO End tuberculosis Strategy in large Brazilian urban agglomerations.