Abstract

The objective of the study was to evaluate soil quality in population centers near gold mining areas. The concentration of heavy metals and metalloids (As, Cd, Cu, Cr, Ni, Pb, and Zn) was analyzed in soil samples collected in public areas, yards, gardens, and cultivation areas. As a result, it was identified that the concentration of Ni and Cr exceeded the maximum permissible limit (MPL) established in the Unified Text of Secondary Environmental Legislation of Ecuador (TULSMA) in 100 % of the samples analyzed, while the concentration of Cu and Zn was higher than the MPL in 90 % of the sites sampled. Cd exceeded the MPL in 64 % of the samples, and As and Pb exceeded the MPL in 26 % and 21 % of the samples, respectively. Cd, As and Pb are elements of special concern due to their high toxicity and significant presence in the study area. Regarding pH analysis, values between 3.31 and 8.21 were obtained, indicating acidic conditions in 60 % of the soil samples, possibly as a result of anthropogenic activity in the area. Strong positive correlations were detected between As-Cd, Cr-Ni, Cu-Ni, and moderate correlations between Cr-Cu and Pb-Zn, which is related to the mineralization of the area. Cluster analysis indicated that cluster C1, characterized by a high content of potentially toxic elements, is mostly located south of the study area. These preliminary results can serve as a baseline for future research in the area, highlighting the importance of soil quality assessment in mining areas.

Abstract

Six structural domains were defined using data from acoustic televiewers and oriented boreholes as part of the reopening of the old Aznalcóllar mining site in Sevilla, southern Spain, by Minera Los Frailes (MLF). Additionally, geotechnical subdomains were defined within each structural domain, classifying the subdomains based on geotechnical parameters obtained from the geotechnical logging of boreholes and through correlations. The methodology used to define the domains allows mine design and planning to be done with enough accuracy to determine the underground excavation needs and the systematic methodology. The main source of this new structural information was acoustic borehole image televiewers (ABI) and, on a much minor scale and as a complement for ABI data, oriented boreholes. This paper describes the methodology used for this definition, some of the challenges encountered during the investigation, the main results obtained and the utility of these defined structural domains in the development of the MLF mining site reopening. Additionally, a preliminary approach to an updated methodology in the definition of structural domains with the combination of televiewer data, both acoustic and optical, with data obtained from other downhole probes is also included.