Geochemical and mineralogical characterization of stream sediments impacted by mine wastes containing arsenic, cadmium and lead in North-Central Mexico Article uri icon

abstract

  • This study aimed to evaluate the chemical distribution and natural attenuation of relevant potentially toxic elements (As, Cd, and Pb) contained in stream sediments that were partly generated by the weathering of waste dumps from mining operations. Sequential extraction procedure was used to evaluate the heavy metals and metalloid fractionation related to the primary and secondary mineral phases, showing that there is still a significant amount of As (12–75%25), Cd (8–29%25) and Pb (1–32%25) present in the form of sulfides, representing a potential release of As, Cd and Pb associated with the weathering of the mine wastes. Furthermore, significant amounts of As, Cd and Pb are associated with the most available fractions of mine wastes and stream sediments. Based on these results, the main mechanisms that control the release of As, Cd and Pb are the progressive oxidation of sulfides, the acidic dissolution of carbonates, the reductive dissolution of Fe oxides and arsenate mineral phases, and the processes of ionic exchange. Although background values for As, Cd, and Pb have been documented in stream sediments in this mineralized zone, the high concentration and spatial distribution of these elements suggests that mine wastes are their main source in the studied area. The results show that the hydric dispersion of fine particles from both waste dumps and stream sediments represent environmental risks since these particles could undergo different chemical release mechanisms for As, Pb and Cd. © 2020 Elsevier B.V.

publication date

  • 2021-01-01