摘要
Several aquifers located in North-Central Mexico have natural arsenic(As)concentrations higher than those allowed by national and international regulations;these aquifers are usually located in fractured volcanic environments that interact with sedimentary basins and have a carbonate basement.In this study,an evaluation of As in volcanic and sedimentary rocks collected at 13 sampling sites along the Sierra de Codornices(Guanajuato State,Central Mexico)was carried out.These geologic materials are representative of the dominant hydrogeologic environment.The As content is disseminated in volcanic rocks and the highest contents were obtained in felsic rocks;this information served to identify the hydrogeochemical processes related to the mobilization and transport of arsenic in the aquifer.The mobilization of As is a product of the dissolution of volcanic glass,a process involved in the alkaline desorption that occurs on As-containing mineral surfaces and possibly by the dissolution/desorption of Fe minerals and some clays,all these processes may be accelerated by the geothermal characteristics of the groundwater in the study area.
基金
financed partially by PAPIIT-DGAPA(Contribution IN-105023)。
