RESUMO Croton zehntneri Pax et Hoffm. (canela de cunhã) é nativa do nordeste do

The Itataia uranium-phosphate deposit is the largest uranium reserve in Brazil. Rare earth elements (REEs) are commonly associated with phosphate deposits; however, there are no studies on the concentrations of REEs in soils of the Itataia deposit region. Thus, the objective of the research was to evaluate the concentration and spatial variability of REEs in topsoils of Itataia phosphate deposit region. In addition, the influence of soil properties on the geochemistry of REEs was investigated. Results showed that relatively high mean concentrations (mg kg) of heavy REEs (Gd 6.01; Tb 1.25; Ho 1.15; Er 4.05; Tm 0.64; Yb 4.61; Lu 0.65) were found in surface soils samples. Soil properties showed weak influence on the geochemical behavior of REEs in soils, except for the clay content. On the other hand, parent material characteristics, such as P and U, had strong influence on REEs concentrations. Spatial distribution patterns of REEs in soils are clearly associated with P and U contents. Therefore, geochemical surveys aiming at the delineation of ore-bearing zones in the region can benefit from our data. The results of this work reinforce the perspective for co-mining of P, U and REEs in this important P-U reserve.

Anthropic activities, combined with the natural ones, may trigger soil degradation, which has increased day by day and contributed to accentuating the desertification processes, resulting in losses of biodiversity and fertility of the soils. Because of that, the utilization of tools that indicate the stages of such degradation and recovery becomes necessary, in order to make viable and adequate management of these areas. Thus, the study on arbuscular mycorrhizal fungi (AMF), as a perspective to facilitate the recovery of degraded areas has increased, especially for the production of glomalin-related soil protein, which is of great importance for aggregate stability, besides showing a great potential of utilization as soil quality indicator. Therefore, the present study aimed to evaluate the contents of glomalin-related soil protein, correlating with chemical, physical and biological attributes in areas of the municipality of Irauçuba-CE: area degraded by overgrazing, area under process of natural revegetation managed with the exclusion of domestic animals and area of native forest, characterized by tree-shrub Caatinga vegetation. Disturbed soil samples were collected in the layer of 0-10 cm in each area and evaluated for AMF attributes, soil chemical attributes and physical attributes. The results obtained with the tests of means prove that, among the three areas, only the native forest showed significant differences with respect to both fractions of the protein. However, in regard to spore density and aggregate stability, the areas of native forest and exclusion showed the best mean values. The content glomalin-related soil protein (GRPS), associated with other edaphic attributes, contributes to discriminating the quality and to the monitoring of areas with different levels of soil degradation. The highest correlation values were observed among the contents of calcium, nitrogen and organic carbon and both GRSP fractions (easily extractable: GRSPEE,which represents the recently deposited frsction that has not yet suffered biochemical alterations in the soil; total: GRSPT, which is strongly adhered to the clays), indicating that the protein directly influences the contents of these elements in the soil.

RESUMO O trabalho teve como objetivo verificar a relação entre atributos químicos relacionados com a salinidade (CTC, pH, PST e CE) e concentrações de metais pesados (Fe, Al, Si, Ti, Mn, Zn, Cr, V, Ni, Cu, Co, B, Pb, Se, Cd, Mo, Zr) e suas inter-relações em solos afetados por sais relativo a quatro perímetros irrigados no Ceará. Foram coletadas amostras de solo, de diferentes texturas, nas profundidades de 0–10 e 10-20 cm em 10 pontos dentro de cada perímetro, totalizando oitenta (80) amostras. Foram utilizadas a análise de correlação canônica (ACC) e a análise fatorial com extração dos fatores em componentes principais (AF) para verificar as possíveis relações entre os dois conjuntos de variáveis. Os atributos do solo relacionadas com a salinidade contribuíram para explicar as concentrações de metais pesados nos solos dos quatro perímetros irrigados, quando analisados em conjunto; todavia, não foram capazes de explicar quando analisados de forma individual; seguindo a ordem de importância: CTC > pH > PST > CE. Foram verificadas correlações entre os elementos metálicos analisados neste estudo (B, Mo, Si, Zr, Cr, Ni, Pb, Ti, Zn, Cd, Co, Se e Cu) com o Fe, Mn, Al, Ti e V, ou, ainda, afinidades geoquímicas entre os elementos.

No abstract