Concentración de arsénico en sedimentos de ríos contaminados por la actividad minera en el cantón Santa Rosa, 2023

Abstract

The central objective of this study focuses on the quantification of the concentration of arsenic present in the sediments of rivers that have been impacted by mining activity in the Bella María parish, in the Santa Rosa Canton, where the Chico and Birón rivers were specifically selected. as study sites during the months of July and August 2023. Subsequently, an exhaustive comparison of the results obtained was carried out with international reference standards, such as those established by the United States Environmental Protection Agency (US EPA). and the Canadian Council of Ministers of the Environment (CCME). The sampling points were strategically located in four different places along the Birón River bed; While the fifth point was located in the upper part of the Chico River, this last point was taken as a reference because it is estimated that it has a low degree of mining contamination due to the limitations in its accessibility. It is important to mention that for each sampling point, three sediment subsamples were collected with a distance of 50 m between them and a depth of 30 cm, with the purpose of generating a composite sample that is representative of each place. Subsequently, the samples were subjected to a pretreatment process and stored until further analysis. During the experimentation, the following physicochemical parameters were analyzed: pH, electrical conductivity and organic matter, obtaining results that highlight the complexity of the interactions between physicochemical factors and the concentration of arsenic in sediments, underlining the need to address arsenic contamination in the Birón River to protect the health of the aquatic ecosystems and the local population of the Caluguro site. Atomic absorption spectrophotometry was used as an analytical technique to determine the presence and concentration of arsenic in the sediment samples; The results obtained reveal that all the samples analyzed exceed the maximum permissible limits established by international regulations of 5,9 mg/Kg in relation to arsenic. At point 1 located at the Piriguiña site, an average arsenic concentration of 21.45 mg/Kg was detected in the Birón River; which contrasts with point 5 of the Chico River where its average concentration was 6.8 mg/Kg. From the above, it can be concluded that the quality of the sediments of the Birón River, and to a lesser extent the Chico River (reference point), represent a risk for aquatic ecosystems and humans.