El papel de la geología en la determinación de los niveles de referencia para la evaluación de la contaminación del suelo

Abstract

Due to the intense industrial activity in certain areas, many soils have suffered large accumulations of polluting compounds, as is the case of heavy metals. However, the genesis and natural chemical composition of the soils is intimately related to the underlying lithology, in such a way that the soils contain a natural concentration of heavy metals (geochemical baseline) varying according to the geology of the place. An analysis of these natural concentrations is necessary to determine, from them, a maximum admissible concentration level (reference level) that establishes the limit from which a soil can be considered as contaminated. This study analyzes the natural concentration of arsenic, chromium, copper, nickel and zinc in representative soils of the province of Salamanca and establishes its background and reference standards. Finally, through statistical treatment of data, the fundamental role of lithology in the chemical characterization of soils is demonstrated, which suggests the determination of standards or levels by differentiating different values for each metal according to the existing lithologies, to the detriment of a generic estimate that does not contemplate the role of geology.