A multi-elemental study to establish the natural background and geochemical anomalies in rocks from the Sonora river upper basin, NW Mexico

Abstract

Growing industrialization, including mining activity, dramatically increases environmental pollution. Exploitation of natural resources triggers landscape alteration, inputs of potentially toxic chemical elements to the environment and health diseases. In the case of mining activity, the measure of any associated environmental disturbance requires a geochemical background as a reference frame. Since in Mexico, there is a lack of this type of references in mining districts, the present study took a recent mining spill as an opportunity to establish the geochemical background of the upper Sonora river basin, which includes active and historical mining areas. The weighted average of elemental values was calculated using GIS tools. The data show that rocks have a similar geochemical behavior, which is characterized by pristine enrichment of Mn, Ca, P, Ba, Zn, As, Ag, Sb, W, Pb and Bi relative to the upper continental crust. Coefficients of variation values reveal that Sc, Y, Zr, Ce, Yb, Fe, Ti and Al display a conservative behavior and, therefore, they are recommended to be used as reference elements in environmental studies in the basin. The findings of this work highlight the need of determining the geochemical background in mining regions to reach more realistic environmental assessments.Key words: geochemical background; conservative reference elements; Sonora river upper basin; mining district, Mexico. RESUMEN La creciente industrialización, incluyendo la actividad minera, in-

Incorporating Remote Sensing Techniques To The DRASTIC Index To Assess Groundwater Vulnerability In The Mining Area of the Rio Sonora Aquifer in Northwestern Mexico

“…The study area has a long history of mining activity. Thus, mine tailings, abandoned mines, active mines, as well as natural mineralization (Calmus et al, 2018;Del Rio-Salas et al, 2019;Guzmán et al, 2019) occurs in the region. The main mining operations correspond, from north to south, to the El Gachi mine (Pb-Zn) located east of Arizpe, the Santa Elena mine (Au) localized east of Banámichi, the San Felipe mine (Cu, Pb, Zn and Au), as well as, El Jaralito (W) and the Washington mine (Cu, W and Mo) situated west and east of Baviácora, respectively (Calmus et al, 2018).…”

“…Thus, mine tailings, abandoned mines, active mines, as well as natural mineralization (Calmus et al, 2018;Del Rio-Salas et al, 2019;Guzmán et al, 2019) occurs in the region. The main mining operations correspond, from north to south, to the El Gachi mine (Pb-Zn) located east of Arizpe, the Santa Elena mine (Au) localized east of Banámichi, the San Felipe mine (Cu, Pb, Zn and Au), as well as, El Jaralito (W) and the Washington mine (Cu, W and Mo) situated west and east of Baviácora, respectively (Calmus et al, 2018). The El Gachi mine is currently inactive and corresponds to a distal replacement deposit related to a porphyry copper-like environment, lodged in sediments that correspond to the Early Cretaceous (Zuñiga-Hernández, 2010).…”

“…The El Gachi mine is currently inactive and corresponds to a distal replacement deposit related to a porphyry copper-like environment, lodged in sediments that correspond to the Early Cretaceous (Zuñiga-Hernández, 2010). The Santa Elena mine is the largest active mining site within the study area; it is considered of hydrothermal origin, the elements with the highest abundance are Au, Ag, Zn and Pb (Calmus et al, 2018). The San Felipe mining area is currently abandoned; it has several mineral deposits in the form of hydrothermal veins.…”

Identification of Mining Residual Pollutants in the Sonora River Basin (Northwestern Mexico) Using Thermomagnetic Measurements

“…According to Calmus et al (2018), rocks from the area have a high content of heavy metals and, in consequence, river sediments in the area have inherited a high amount of heavy metal content from the rocks.…”

“…Afterwards, some geochemical studies have been performed trying to assess the presence of residual pollutants that may represent a risk for flora, fauna and human health in the area. Nevertheless, those studies did not get conclusive results, due to the geochemistry of the area that naturally presents high contents of heavy metals (Calmus et al 2018). Some studies have used geophysical indirect indicators as electrical conductivity and magnetic susceptibility (Ramos 2017), but it was also observed that the natural presence of some minerals with high values of these properties makes difficult to distinguish the contribution of pollutants.…”