METAL CONCENTRATIONS OF DUST IN RURAL AREAS FROM ARID REGIONS OF THE SONORAN DESERT

One of the main arid regions of Mexico is located within the Sonoran Desert, in the northwestern of Mexico, which includes the states of Sonora, Arizona, and California. Despite its arid climatic conditions, Sonora contains some of the main agricultural fields such as La Costa de Hermosillo, Mayo Valley, Yaqui Valley, Caborca, among others. The misuse of the hydrological resources along the La Costa de Hermosillo caused a problem of saltwater intrusion, resulting in the abandonment of some agricultural fields. The El Poblado Miguel Aleman village is surrounded by agricultural fields of La Costa de Hermosillo, and is characterized by high dust concentrations. The arid conditions, saltwater intrusion, and desertification processes, suggest that these fields are important sources of dust, affecting both rural and urban areas. The present investigation carried out a geochemical characterization and evaluation of contamination of both rural dust and agricultural topsoil. Dust samples were collected on roads, courtyards, schoolyards of the village and surrounding agricultural surface soils, both abandoned and active. The concentrations of metals (Ba, Cd, V, Hg, Cu, Zn, Ni, Ag, Pb and Se) were measured from <44 and <20 µm size particle fractions, using a Portable X-ray Fluorescence (PXRF). Additionally Enrichment Factor (EF) indexes were calculated. Among all elements analyzed in all matrices, V in all samples is exceeding (78 ppm) the Mexican regulation (NOM-147). Mostly all elements showed EF values less than 1.5. However, moderate enrichment was found in all samples for Sr, Zn and Pb.