Geochemical evolution and the problems arising from the use of water from the Arroyo Marín aquifer (Archidona-Málaga)

El estudio de las facies químicas del Arroyo Marín, afl uente más importante del río Guadalhorce, se justifi ca por elcarácter selenitoso de las aguas aportadas por los numerosos manantiales existentes en la margen izquierda del arroyoy que modifi can notablemente las características organolépticas del río Guadalhorce que nutre de agua a la provinciade Málaga. Además, desde el punto de vista sanitario se aprecian altas concentraciones de magnesio y nitratos, quedesaconsejan su consumo humano, hecho importante por ser una zona de tránsito para excursionistas.El acuífero analizado está marcado a su vez por la actividad del imponente karst de yesos de Archidona, cuya cuencade recepción tiene numerosas dolinas y las aguas drenan por conexiones subterráneas laberínticas, poco conocidas,que consolidan las facies hidroquímicas del suelo.The chemical facies from the stream Arroyo Marin, the largest tributary to the river Guadalhorce, is consideredto be worthy of study, due to the high selenium content in the waters emanating from the numerous springsfound to the left margin of the stream. These waters considerably modify the organoleptic characteristics of theriver Guadalhorce, which serves as an important source of water for the province of Malaga. Furthermore, froma health safety point of view, these waters present high concentrations of magnesium and nitrate, rendering themunsuitable for human consumption. This is an important consideration, given that the areas is popular as acountry treking destination.The aquifer under analysis is also characterised by the imposing activity of the Archidona gypsum karst, whoserainfall cachment area has numerous sinkholes. The water is subsequently drained into the ground through a littleknown laberynth of subterranean conections, which help determine the hydrochemical facies of the terrain