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ABSTRACT:The semiarid region of northeastern Brazil has a large area occupied by Planosols, where in the State of Pernambuco these soils are mainly used for livestock farming and subsistence crops. The knowledge on these soils is limited, which compromises the understanding on their behavior, potentialities and limitations.This study aimed to analyze morphological, chemical, physical and mineralogical attributes of Planosols developed under different geoenvironmental conditions. Morphological descriptions and chemical, physical and mineralogical analyses were performed in four profiles of Planosols along a rainfall gradient. An increase in rainfall allowed for an increase in the clay content in the Bt horizon and a reduction in ESP, EC, Na + , CEC, S, pH (water and KCl) and soil density. Horizons A and E were thicker in Planosols in more humid environments. The increase in ESP associated with the presence of expansive minerals (smectite and vermiculite) allowed the development of a prismatic structure in Haplic Planosols and a columnar structure in Natric Planosols. The mineralogical assembly is indicative of poorly weathered soils. The mineralogical assemblies of the silt and clay fractions were similar in the different geoenvironments, while higher contents of easily alterable minerals were observed in the composition of the sand fraction in environments with a drier climate.

Fernando de Noronha is a small volcanic archipelago in the Southern Atlantic, some 350 km NE of the city of Natal in NE Brazil. These remote volcanic islands represent a largely pristine environment, distant from sources of anthropogenic contamination. This study was carried out to determine the natural concentrations of Ag, Ba, Cd, Co, Cr, Cu, Mo, Ni, Pb, Sb, V and Zn in the A and B horizons of soils of Fernando de Noronha. The aims of the study were twofold: determine whether there is a relationship between the bedrock geology and soils and to establish quality reference values for soils from Fernando de Noronha. Soil samples were subjected to acid digestion by the USEPA method 3051A, and metals were determined by inductively coupled plasma emission spectrophotometry. The results showed that the trace element distribution largely reflects the geochemistry of the underlying volcanic rocks of the Remedios and Quixaba Formations. The results demonstrate that the concentrations of Ba, Cr, Zn, Ni and Cu from the soils of the volcanic Fernando de Noronha archipelago are higher than those found in soils from continental Brazil. However, concentrations of Ni, Cu and Co are lower in soils of the archipelago as compared to other volcanic islands throughout the world. The elevated trace element concentrations of the volcanic parent material of Fernando de Noronha soils seem to be the main factor governing the relatively high natural concentrations of trace elements.

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A partir do conhecimento morfométrico de uma bacia pode-se planejar melhor os diferentes usos das terras. O objetivo do presente trabalho é a caracterização morfométrica da bacia hidrográfica do rio Natuba-PE, visando identificar atributos auxiliares para a tomada de decisão no manejo da referida bacia. Foram analisados os parâmetros morfométricos de padrão e forma de bacia hidrográfica. Os resultados apresentam os canais classificados até a quarta ordem. As densidades de drenagem e hidrográfica evidenciam a influência do forte controle estrutural e do relevo movimento. A bacia apresente histórico de cheias no período chuvoso. Porém, os dados de coeficiente de compacidade e índice de circularidade não corroboraram os dados históricos de cheias. Esta contradição pode estar associada à combinação da forma alongada da bacia e por está inserida numa zona de cisalhamento. Os parâmetros morfométricos apontam para o controle geológico-estrutural em que a bacia está inserida. Palavras chave: diagnóstico de enchentes; hierarquia fluvial; declividade; análise de formas.