Resumen Los enclaves húmedos que aparecen en las cimas de montañas y mesetas son de suma importancia para la región semiárida, ya que son considerados refugios de especies de flora y fauna, así como fuentes de humedad para diversas actividades humanas, ya que tienen un ambiente más fresco y húmedo. clima resultante de los efectos de la altitud. En este contexto, el objetivo principal de esta investigación fue realizar un levantamiento de los aspectos geográficos de la Serra de Santana, con énfasis en las características climáticas, edafológicas, hídricas y de cobertura vegetal. También se consideró los usos del suelo y la reflexión sobre las posibilidades de prácticas sustentables para la conservación de esta importante unidad del paisaje que, a pesar de tener condiciones geográficas privilegiadas en la región semiárida, como un clima “templado” en cuanto a temperatura condiciones, tipo de suelo desarrollado y condiciones hidrográficas de aprovechamiento, el proceso de uso y ocupación del suelo resultó en pérdidas significativas de vegetación nativa.

Resumo Enclaves úmidos que aparecem nos topos das montanhas e chapadas são de extrema importância para o semiárido, visto que são considerados refúgios para espécies da flora e fauna, além de fontes de umidade para diversas atividades humanas uma vez que apresentam clima mais fresco e úmido decorrente dos efeitos da altitude. Nesse contexto, o objetivo principal dessa pesquisa foi realizar um levantamento dos aspectos geográficos da Serra de Santana, com ênfase nas caraterísticas climáticas, pedológicas, hídricas e de cobertura vegetal. Considerou-se também os usos da terra e a reflexão acerca das possibilidades de práticas sustentáveis para a conservação desta importante unidade da paisagem que, apesar de possuir condições geográficas privilegiadas a nível de região semiárida, como clima “ameno” em se tratando das condições térmicas, tipo de solo desenvolvido e condições hidrográficas de vantagem, o processo de uso e ocupação do solo acarretou em perdas significativas da vegetação nativa.

Abstract Wet enclaves that appear on the tops of mountains and plateaus are extremely important for the semiarid region, as they are considered refuges for species of flora and fauna, as well as sources of water moisture for various human activities, since they have a cooler and wetter climate resulting from of the effects of altitude. In this context, the main objective of this research was to carry out a survey of the geographic aspects of Serra de Santana, with emphasis on climatic, pedological (i. e. soil), water and vegetation cover characteristics. It was also considered the uses of the land and the reflection on the possibilities of sustainable practices for the conservation of this important unit of the landscape that, despite having privileged geographical conditions in the semiarid region, as a “mild” climate in terms of thermal conditions , type of soil developed and hydrographic conditions of advantage, the process of use and occupation of the soil resulted in significant losses of native vegetation.

ABSTRACT: Evaluating soil geochemical diversity in the Amazon Basin has been a challenge largely because most study sites have been at the edge of the basin and it is difficult to get samples in such a region. Here we show that even among the most weathered soils, physicochemical soil properties express lithology. Our results are based on topsoil samples collected from different locations in minimally disturbed areas in the state of Amazonas, Brazil. Soil properties were measured using methods which are suitable for highly developed soils. The Chemical Index Alteration and Weathering Index of Parker was calculated based on the content of metal(loid)s in soils determined by X-ray fluorescence. Descriptive statistics, Pearson correlation, and Principal Component Analysis (PCA) were performed on data. In general, Amazon rainforest soils are more deeply weathered than soils in other Brazilian biomes and tropical rainforests in Asia and Africa. The high coefficient of variation of metal(loid) contents express pedogenesis and parent material diversity. Correlation analysis indicated that the tri-pentavalent elements are strongly associated with Al and Fe contents in the topsoil. In contrast, mono-divalent elements are correlated with sand and silt fractions. According to PCA, five soil groups with defined geochemical compositions and degrees of weathering could be identified: i) acidic sandy podzolized soils; ii) acidic loamy ferralitic soils with the highest content of tri-pentavalent ions; iii) acidic clayey kaolinitic soils with low metal(loid) contents; iv) acidic loamy kaolinitic soils with low metal(loid) contents; and v) silty neutral 2:1 clay soils. This study is the first effort to analyze the geochemical diversity in Amazon rainforest soils. These data are extremely valuable in determining the geochemical background for these soil types and this region. Geochemical variability can be predicted to some extent by lithology and pedogenesis, which can be applied to define the sampling required in future studies.

ABSTRACT: The great geological and soil variation in the state of Minas Gerais, Brazil, indicates the need for regional studies to understand the geochemical background of soils. The Rio Doce Basin became a priority area for geochemical background determination after the rupture of the tailings dam of Fundão in 2015. In this context, the objectives of this study were to propose Reference Values of Soil Quality in the Rio Doce Basin, to define variables that can predict metal(loid) concentrations in the soil, and to examine the correlation between metal(loid) concentrations determined by X-ray fluorescence and by the traditional method. One hundred and seven samples were collected from minimally disturbed areas, representing the main soils and source materials. Metal(loid)s were determined by acid digestion and X-ray fluorescence. Descriptive statistics of the data, as well as the calculation of the Randomized Dependence Coefficient (RDC) and Principal Component Analysis (PCA) were carried out. The soils were found to be acidic, dystrophic with low Mehlich-1 extracted P contents, and have a variable texture. The coefficient of determination ranged from 0.4 to 0.9, suggesting X-ray fluorescence as a promising technique for determining metal(loid) concentrations in soils. The absence of correlation between clay and organic matter contents with metal(loid) concentrations suggests that the latter were inherited exclusively from the parent material, with little influence of pedogenesis. Metal mineralization in the highlands that constitute the topographic drainage divide of the basin increase the reference values of soil quality to higher values than established for the State of Minas Gerais.