| Among contamination episodes caused by heavy metals in Spain, the toxic spill of the Aznalcollar Mine (Seville, April 25, 1998) is stood out, being one of the worst environmental pollution accidents recorded in Andalusia history. The international significance of this event was the possible effects on the National Park of Donana, a nature reserve of bird species in Europe and declared Reserve of the Biosphere (Unesco).; In this thesis, trends of the total levels and the chemical speciation of heavy metals in the water of Brazo de la Torre Tributary and the Guadalquivir Estuary affected by the mine spill were studied. The objective was the evaluation of the Aznalcollar disaster impact on the levels of particulate and dissolved metal (Cu, Cd, Pb and Zn) in waters after two years of the accident, in order to study the toxicity and bioavailability of these metals. The speciation analysis was carried out classifying metals in several fractions: particulate, ionic forms, labile forms and strongly forms, associated with organic or inorganic matter. The results could allow assessing the differential behaviour of each metal and illustrating the potential value of the spill-induced pollution in the area. In spite of the Spanish authorities reduced the potential impact of the mud with cleaning and remedial activities, the spilled metal reached the sediment where metals were accumulated. So, the influence of disaster on this environment will be a slow process, whose consequences we still don't know. Also, outstanding metallic pollution in the estuary was found from Guadalquivir River, principally of free and toxic forms of Cd and Pb.; In addition to these studies, two methods of heavy metals analysis were developed. They was based on the use of a bulk liquid membrane (BLM) containing 2-acetylpyridine benzoylhydrazone as mobile carrier dissolved in toluene and applied successfully to the preconcentration of Cu and Cd in natural water prior to determination by flame atomic absorption spectrophotometry, allowing the precise and accurate analysis of these metals at ppb level. The methods offer important advantages such as simplicity and economy and enables eliminating matrix interferences, being applied to seawater with important complex matrix. |
