Contaminación actual del acuífero aluvial de los ríos Agrio y Guadiamar (Aznalcollar, España)

Abstract

In April 1998 the breakage of the pyritic tailings dam of Aznacóllar mines occurred and approximately 2 hm3 of sludges and 4 hm3 of acidic waters spilled to the Agrio and Guadiamar rivesr. The environmental disaster was enormous, approximately 4600 ha were flooded by toxic sludges and the acidic waters reached the limit of the Doñana National Park. The remediation measures undertaken, together with the ending of the mining, have produced the water quality recovery of the Guadiamar river. A sampling of groundwaters along the Agrio and Guadiamar alluvial aquifer was carried out in the summer of 2009. Results show that, eleven year after the spill, this aquifer is still contaminated, with low pH values an high concentrations of sulphates and toxic metals. While the aquifer contamination exists, groundwater flow will continue affecting the water quality of the Agrio and Guadimar rivers. Nevertheless, the contamination levels ofgroundwaters have decreased and are much lesser now than those existing after the spill