Abstract

HERNANDEZ-CRUZ, Berenice; DE LUNA-CRUZ, Faustino; SANCHEZ-CRUZ, José A.  and  MARTIN ROMERO, Francisco. Hydric Dispersion of Arsenic in the San Antonio-El Triunfo Mining District, Baja California Sur, Mexico. Tecnol. cienc. agua [online]. 2015, vol.6, n.5, pp.113-122. ISSN 2007-2422.

The granulometric characteristics of the San Antonio-El Triunfo mining district, Baja California Sur, Mexico were studied in order to determine the relationship between the distribution of arsenic (As) and the size of particles containing As that are transported by runoff. The characteristics of rainfall at five weather stations were analyzed. Effective rainfall was obtained and used to simulate runoff. The simulation resulted in the determination of runoff velocity in m³/s, a value related to the Hjulstrom diagram, to identify the size of particles that were transported or deposited. The results show velocities over 3.0 m/s which transported particles between 0.001 and 100 mm, and velocities under 2.0 m/s which did not transport particles. Materials are deposited from this alternation between velocities. Deposits of materials over 2.0 mm in diameter are associated with high concentrations of As (500 - 1 000 mg/kg) measured in the study area, which were interpolated with a geographic information system. Given the configuration of the distribution of As in surface soil, it can be concluded that water is the primary cause of the movement of As. In addition, diameters of 2.0 mm contain the highest amount of As. Although few studies have performed a physical characterization such as the one herein, their scientific contributions are crucial, especially for environmental issues. By combining the physical characterization with geochemical data and remediation studies, a comprehensive perspective can be obtained for the management of sites affected by mining waste.

Keywords : Distribution of Arsenic; dispersion of Arsenic; runoff speeds; sizes of particles; riverbed.