Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

The Suquía river basin (area ~6300 km2) is a medium-sized hydrological system located in the province of Córdoba, in the central region of Argentine. The Suquía river derives from the San Roque lake. This river flows through mountainous areas, crosses a densely populated city (Córdoba: 1.5 million inhabitants) and continues its course through the Chaco-Pampean plain, where agriculture and livestock farming are typical anthropic activities. The Suquía river receives along its course diverse polluting contributions. The degree of contamination of this natural system was evaluated through geochemical and magnetic analyses. For this purpose, sediment samples were collected from the river bed. The environmental magnetism methods (magnetic susceptibility and anhysteretic remanent magnetization) were carried out in order to determine and quantify the magnetic minerals. Major oxides and trace elements were determined in the < 62.5 mm fraction. The sediments show a low degree of mineralogical maturity and are equivalent to shales and Fe-shales. Diverse contamination indices showed the highest values in the mountainous area where the most elevated measurements of magnetic susceptibility were also registered. This is interpreted as consequence of natural factors enhanced by quarries exploitation. The lowest levels of pollution were recorded in the urban area, while in the rural area, a moderate to high degree of pollution associated with agricultural activities was determined. Thus, the processes that originate the geochemical and magnetic characteristics of these sediments are spatially differentiated throughout the basin and are due to the effect of both natural and anthropogenic factors. In addition, metal concentrations have increased in the last decade throughout the basin. A significant correlation between geochemical variables and magnetic parameters was determined, proving the potential of combined studies as a methodology for environmental monitoring in hydrological systems.

The main purpose of this work was to study and understand the interaction that occurred between an acid solution spilled from Buenavista del Cobre Mine and the soils located in the Bacanuchi River area. The question put forward in this work was: if the soils of the area were able to cushion the impact of the acid solution?. Two soil profiles were examined: Profile 8A, was located on the riverbank and was affected by the spill, whilst Profile 8B, located on the first terrace of the river valley, remained intact . Both soils profiles were chemically characterized. An additional three surface samples (0-30 cm) were taken for geoavailability tests (RBI, SB2, belonging to Profile 8B, and SB3, belonging to Profile 8A). Two further samples, representing typical unaltered soils of profiles 8A and 8B, were taken for their micromorphological study. The results showed a difference between the two profiles, with profile 8A having more acidic pH, greater electrical conductivity, and higher concentrations of Fe, Pb, Cu and As than profile 8B. The geoavailability test showed that the elements enriched in SB3 were stable and not available to the aqueous phase. The soils of Bacanuchi River contain carbonates, which interacted with the acid solution and stabilized the potentially toxic elements presents in the spilled acid solution.  This interaction with carbonates promoted a new minerals formation such as gypsum and copiapite. So, the release of contaminants from soil to surface and ground waters is improbable, unless the redox conditions change or a new spill occurs releasing the potentially toxic elements (PTE) to the environment. In this work we show the importance of pedogenic carbonates in soils of arid and semi-arid environments; these carbonates represent a natural geochemical barrier, that can prevent the migration of PTEs in mining areas.

An almost complete cranium of a gomphoterium found in Tepeticpac, Tlaxcala, was analyzed with X-ray diffraction (XRD), Petrography and Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM-EDS) to stablish the transformations of the bone during its burial. The analyses assessed that the bone mineral (bioapatite) had suffered modifications in mineral composition, “crystallinity index”, cell parameters and CO2 content. However, the paleohistological structure of the bone was not significantly affected, although evidence of microbial attack was found in the bone surfaces. The filling minerals of bone macro and micro porosity were also analyzed; its main filling minerals are calcite (micrite and sparite), clays, and minerals of volcanic origin.

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