Arsenic contamination of the Salamanca aquifer system in Mexico:: a risk analysis

Solutes coming from different pollution sources are affecting the Salamanca aquifer system. The solid wastes of different chemical industries were disposed in dumps located around the urban area. Arsenic, lead and benzene are some of the reported pollutants in the local groundwater. Most of the urban wells reported As contents over the national standard for drinking water. Groundwater is the only water source for the Salamanca inhabitants. An aquifer vulnerability assessment was done using the DRASTIC method. A vulnerability zoning, a potential pollution sources inventory and a population survey permitted a risk analysis. The most critical areas are related to a subsidence fault that is acting as a preferential channel for pollutants, particularly for hydrocarbon residuals. The fault permits the hydraulic communication between an unexploited shallow aquifer and the exploited unit. Evidences of health affectation were not found. Three urban wells located near of the fault were closed.