PROYECTO

NOMBRE:Fuentes geogénicas y mecanismos de movilización de arsénico, fluoruro y uranio a sistemas de flujo de agua subterránea en la Sierra Madre Occidental
RESPONSABLE:Antonio Cardona Benavides
FINANCIADO POR:CONACYT
MONTO:1400000
VIGENCIA:12/2020
LÍNEA DE INVESTIGACIÓN:
DESCRIPCIÓN:In at least 15 of the 32 states of the Mexican Republic, groundwater concentrations of arsenic (As) and fluoride (F) above Mexican drinking water standards have been detected; uranium (U) concentrations partly exceed international standards although there is no regulation in Mexico yet. Elevated concentrations have mostly been associated with natural geogenic sources and basin fill sediments. However, the specific processes releasing these toxic elements into groundwater have only been determined in a few areas. This information is needed to understand the mechanisms of water-rock interaction that allow in some cases and limit in others the mobility of these elements in groundwater; it is of crucial importance for sustainable water management, especially in (semi-) arid regions like Mexico. It is believed that the concentrations of As, F and U in groundwater flow systems of the Sierra Madre Occidental depend on the degree of alteration of the glassy matrix in the volcanic rocks and on the characteristics and types of crystalline and amorphous mineral phases. Nevertheless, there is a lack of specific studies focusing on this hypothesis. For these reasons, it is crucial to characterize the presence, occurrence, hosting mechanisms and potential mobility of As, F and U in the mineralogical and amorphous assemblage of the volcanic rocks and basin fill sediments of the Sierra Madre Occidental – both on a macro - and microscale – as a key to understand the controls on mobilization to groundwater, by far the most important source of drinking water in the region. In a multi-method approach, this research aims at finding the relationship between the degree of devitrification of the glassy matrix and the concentrations of As, F and U in the volcanic rocks and basin fill sediments of the Sierra Madre Occidental and effects on their concentrations in partly thermal groundwater flow systems as a function of their interaction with the different solid phases in aquifers. The solid fractionation and potential mobility of the trace elements as well as dominant mobilization processes during water-rock-interaction will be characterized, and results transferred to other volcano-sedimentary regions worldwide. According to previous results, three sediments rich in Iron, like clays and/or sands, will be selected in order to be tested in natural groundwater samples from deep wells with the highest arsenic concentrations. Kinetic and Isotherm sorption batch tests will be developed. Adsorption capacity, temperature, optimum pH, contaminant concentration (mg/L), % of removal and particle diameter of the adsorbent material (?m) As removed will be reported. Also, a pilot scale test using a household filter will be installed in order to remove arsenic and complain with Mexican regulatory norm (MCL: 25 ?g/L). Co-ocurrence of As, U and F in groundwater is feasible. In the same test, the change in the concentration of F and U from groundwater will be evaluated. To check the effectiveness of water treatment, the filter material will be characterized to find within itself As, F and U minerals, some of them immobilized, via precipitation or adsorption processes, from groundwater.
PARTICIPANTES UASLP:
PARTICIPANTES EXTERNOS: