부산대학교 도서관

1. Introduction Large quantities of mineral residues that are rich in Ag and other associated elements, such as Cu and Ni, are produced when artisanal mining techniques are used to [...]
The dispersal of Ag, Cu, and Ni in mine wastes (tailings and ash) was studied from the source of an abandoned gold mine at El Triunfo (Baja California Sur, Mexico) to the adjacent coast of the Pacific Ocean. The highest contamination levels of the studied elements were measured in one sample of the tailings (Ag: 247 mg [kg.sup.-1]; Cu: 1660 mg [kg.sup.-1]; Ni: 111 mg [kg.sup.-1)]. Horizontal and vertical distributions of these elements were obtained from the analysis of surface sediments, tailings, a test pit, a sediment core, and dunes. The background levels of these elements were estimated from independent methods. Then, these regional background level calculations were used to determine the normalised enrichment factors (NEFs). Relatively high NEF values (averages of Ag, Cu, and Ni were 24.0, 3.0, and 1.4, respectively) indicated that the area close to the mine waste zone (up to about 18 km from the source area) was moderately to severely polluted. Moderate to null pollution (average NEFs of Ag, Cu, and Ni were 7, 2 and 1, respectively) was interpreted for the area at about 18-49 km from the mine waste zone. Vertical distributions of the elements in sediments of the overbank, the test pit in the mine zone, and the sediment core (at the discharge of the main arroyo Hondo-Las Gallinas- El Carrizal), also revealed enrichment of Ag, Cu, and Ni relative to the surface sediments. This study indicated that historic and contemporary contamination continues to impact the fluvial environment. Keywords: silver, copper, metals, contamination, tailings, arroyo Se estudio la dispersion de Ag, Cu, y Ni, en desechos mineros (jales y cenizas) desde su origen en la mina de oro abandonada de El Triunfo (Baja California Sur, Mexico) hasta su desembocadura en la costa adyacente al Oceano Pacifico. Los mayores niveles de la contaminacion de los elementos estudiados se presentan en los jales (Ag: 247 mg [kg.sup.-1]; Cu: 1660 mg [kg.sup.-1]; Ni: 111 mg [kg.sup.-1]). Se obtuvieron distribuciones horizontales y verticales de estos elementos a partir de los analisis de sedimentos superficiales, de un jale, de un pozo de ensayo, de un testigo y en las dunas adyacentes a la desembocadura del arroyo. Los niveles de fondo fueron calculados considerando varios metodos independientes. Luego, con estos calculos de niveles de fondo se determinaron los Factores de Enriquecimiento Normalizados (NEFs). Los valores relativamente altos de NEF (promedios de Ag, Cu and Ni de 24.0, 3.0 y 1.4, respectivamente) indicaron que el area situada cerca de la zona minera (aproximadamente 18 km de los desechos mineros abandonados) se encuentra de moderada a severamente contaminada. Una contaminacion moderada a nula (NEFs promedio de Ag, Cu y Ni: 7, 2 y 1, respectivamente) fue determinada en el area comprendida entre los 18 y los 49 km medidos desde el distrito minero. Las distribuciones verticales de los elementos en los sedimentos de los jales y el pozo de ensayo en la zona minera, asi como en el testigo analizado en la desembocadura del arroyo principal (Arroyo Hondo-- Las Gallinas--El Carrizal), muestran mayor enriquecimiento de Ag, Cu y Ni, que los sedimentos superficiales adyacentes. Este estudio indica que la contaminacion historica y contemporanea esta impactando el ambiente fluvial. Palabras clave: plata, cobre, metales, contaminacion, jales, arroyo