Resumen del producto

The mining zone at El Triunfo, Baja California Sur, Mexico was exploited for the gold extraction for 200 years. This area has more than 100 abandoned mining sites with tailings highly contaminated with Potential Toxic Elements (PTE), such as As, Pb, Zn, and other associated elements. These wasteshave been contaminating the sediment of adjacent fluvial systems over time. Our aim was to assess the vertical variations of the PTE from the abandoned mining zone and in the discharge of the main arroyo into a small lagoon at the Pacific Ocean. The sediments were collected at the mining zone close to thetailings in the arroyo basin at i) an Old Alluvial Terrace (OAT) and a Test Pit (TP), and ii) Two cores at the discharge of the arroyo in an hypersaline small lagoon. Samples were analyzed by ICP-MS, ICP-OES, and INAA and methods were validated. The OAT was the most contaminated, with topcontents for As, Pb, and Zn of 8690, 84700, and 42600 mg kg-1 respectively, decreasing with depth. The TP also had elevated contents (694, 5001, and 4170 mg kg-1 respectively). Sediment cores were less contaminated, but their contents are higher than that of the Earth´s crust. The Normalized Enrichment Factors (NEF) calculated from the background levels of the system had an extremely severe enrichment of As, Pb, and Zn (NEF>50) at the OAT. The TP had a severe to very severe enrichment of As, Pb, and Zn (NEF = 10-50). The sediment cores had a severe enrichment of As, Pb, and Zn (NEF = 10-25). The vertical profiles show the anthropogenic influence in the historic sediment deposition at the OAT, TP, and sediment cores, with the concentrations of As, Pb, and Zn in the sediment cores related to the deposition of fine sediment and organic carbon.

Palabras clave:

Para obtener una copia del documento contacta la personal de la biblioteca a través del correo bibliocicimar{a}ipn.mx