DIAGNOSIS OF EMERGING CONTAMINANTS AND HEAVY METALS IN THE WATER AND SEDIMENTS OF THE RIVER SANTA CATARINA IN THE METROPOLITAN AREA OF MONTERREY TO DETERMINE THE IMPACT ON ITS QUALITY AND ITS SUSTAINABLE USE

Shale gas is at present being explored in northern Nuevo Leon state in the Burgos basin. Recent exploration indicates two prospective shale targets for unconventional shale gas development: i) Cretaceous (mainly Turonian) Eagle Ford Shale play and ii) Jurassic La Casita and Pimienta formations. The former has a direct correlation with a productive Texas counterpart. Such a development has produced concern about the potential environmental impacts by hydraulic fracturing on regional water resources. Monterrey metropolitan area with a population of ~4.3 million of inhabitants is a fast growing region with serious water supply limitations. Main water sources are local groundwater (30% approximately) and surface water (local and imported 70% approximately). Any additional water user should not compete with the same source, in this semiarid environment (600 Mm/year precipitation) wastewater is actually a potential additional source for future developments.

The objective is to evaluate water quality and presence of emerging contaminants, heavy metals and radioactive elements in the surface water, groundwater, and sediments of the Santa Catarina River to improve the water use. This study considered the hydrological, geological, hydrogeological and hydrogeochemical components to evaluate the environmental impact in water, subsoil, and "El Cuchillo" dam a significant water drinking source for Monterrey.

Twelve sampling sites were selected, results confirm the presence of metals (Zn, Al, Cu and Fe) in sediments, with values above the natural geochemical which correlate with water sampling results at the same points. Radioactive analysis alpha and beta emitters revealed below 0.56 and 1.85 Bq.L-1, respectively which constitute the limit for human consumption. The presence of emerging contaminants is confirmed, such as cocaine, amphetamines, Bisphenol A and bis-2-ethylhexyl phthalate. The last two compounds were the most commonly found across all points studied because they are normally used as raw materials in the manufacture of plastics.