Determinación del contenido de metales pesados en suelos colindantes a un drenaje ácido de mina en el municipio de California, Santander, Colombia

Abstract

Mining is one of the main economic activities in Colombia, since it entails important opportunities in generating employment and sustainability. However, this activity is also responsible for serious pollution problems, among which the formation of acid mine drainage (AMD) is more relevant, which, in addition to a low pH, have high levels of sulfates and heavy metals and, consequently, they are toxic in varying degrees to humans, flora and fauna. Thus, mining in the municipality of California (Santander) has caused an interest in conducting environmental impact studies, to evaluate the quality of the soils that are affected by the AMD that are generated there and that cause heavy metals be leached quickly. The experimental work of this research consisted of implementing the methodologies established in the Colombian Technical Standards 3656 and 3934. Five sampling points were taken from the soils affected by the AMD, at the "El Tigre" mine entrance of the municipality of California (Santander) and the quantification of Copper, Lead and Zinc in soils was carried out in the research laboratory of the Santo Tomas University of Bucaramanga, with the Atomic Absorption team. In addition, the analysis of Copper, Lead and Zinc for the AMD was carried out in the Chemical Laboratory of Industrial Consultations. The results obtained in the soil samples were compared with Annex 2 of book VI of the Unified text of secondary legislation of the Ministry of Environment of Ecuadorian, amended by ministerial agreement N°. 061 of 2015: norm of environmental quality of the soil resource and with the remediation criteria for contaminated soils of that same country, since there is no national norm in this regard. For its part, the results of the AMD sample were compared with Resolution 0631 of March 17, 2015 of the Ministry of Environment and Sustainable Development and Decree 1594 of 1984. As a corollary to the above, the concentration of Copper in all the soil sampling points exceeded the maximum value (30mg/Kg) allowed by the Ecuadorian norm; in the Lead concentration, only one point exceeding the permissible value (25mg/Kg) was obtained, and about the Zinc concentration, four of the five samples exceeded the permissible value (60mg/Kg). Likewise, of the three metals analyzed in the AMD, Copper was the metal that surpassed the value (1,0mg/L) admitted by Resolution 0631 of 2015, in the Lead concentration did not point exceeding the permissible value (0,20mg/L), and although the Zinc concentration did not exceed the permitted value (3,0mg/L), it did obtain a value very close to the maximum allowed.