Evaluating the heavy metal contamination in sediments from the guadalquivir estuary after the Aznalcóllar mining spill (SW Spain): a multivariate analysis approach.

The Doñana National Park is one of the most important Natural Reserves in west Europe. The park and the Guadalquivir estuary were impacted by the release of 5 million cubic meters of acid waste from the processing of pyrite ore. Here are presented a multivariate analysis approach to evaluate the extension and the magnitude of the accidental spill on the estuarine sediments. Sediments were used to analyze 6 different metals (Fe, Mn, Zn, Cd, Pb, Cu). Also the concentration of the metals in the different geochemical sediment fractions were determined as a means of assessing the potential impact of the acid water from the mine. The analysis of the results obtained permits to establish that the impact of the accident was acute on the ecosystem due to the set up of a treatment plan in June 1998 and to the high hydrodynamic of the estuary that absorb the early impact. Chronic contamination by Cu was also detected during the monitoring of the impact of the accident in the estuary but this did not appear to be related to the accidental spill. Because the likelihood of long term adverse effects from the heavy metal contamination of estuarine sediments, further ecotoxicological evaluations should be carried out for the estuary and the park using an integrated approach.