Assinatura geoquímica e suas implicações para o meio ambiente: Bacia do Rio São Francisco, região entre os municípios de Abaeté e Belo Horizonte.

Multi-elementary geochemical surveys and the definition of background concentration values of the chemical elements in sediments, soils, rocks and water by advanced techniques of data processing and statistical analyses are important tools for the comprehension of the dispersion and behavior of these elements. Such procedures are crucial for environmental studies linked to sustainable territorial management. The definition of these concentration values allows the confrontation with those values pointed out by laws and regulations, highlighting the potentially toxic elements (PTE), which often do not take into account the complexity and the heterogeneity a given region. The aim of this research is to describe the geochemical signature of chemical elements in stream sediments in the region between the Abaeté and Belo Horizonte municipalities, identifying the influence of the geological domains and anthropogenic activities in the behavior of these elements. The geochemical data used were obtained from Geological Survey of Brazil (SGB/CPRM) stream sediments geochemical surveys and submitted to the robust statistical analysis, characterized by univariate and bivariate statistics. As results, geospatial information was generated (chemical elements distribution maps and environmental indexes maps), which presented strong evidences of the geological influence in the sediment samples as well as some punctual evidences of anthropogenic influences (farming, industries and urbanization influences). The determination of the background values and the geochemical compartments revealed strong similarity with the geological domains, showing control of the geology upon the chemical elements’ behavior. Therefore, the definition of background concentration values is crucial consider the geological units as the base of those calculations (samples inside the geological unit), reinforcing that using only one background concentration value (i.e., the median value of the samples for the entire study region) for a given element is inappropriate. The obtained background concentration values for the study region allow the monitoring and the controlling of the anomalous concentration of the PTE, mainly in the using of the environmental indexes, assisting the environmental policies and environmental and social impacts studies.