Monitoring the impact of the Aznalcollar mining spill on recent sediments from the Guadalquivir estuary, Southwest Spain.

摘要

Composite sediment samples collected from different stations: GL2 and GL6 stations during May 1998 and GL2, GL4 and GL6 in the Guadalquivir river and GR2, GR4 and GR6 in the Guadiamar river in September 1998, which cover the influences of the contamination from the Aznalcollar accident in southwest Spain, to assess both the concentration and chemical forms of Fe, Mn, Zn, Cd, Pb and Cu in the sediments and the potential environmental risk associated with the heavy metals. The concentrations of all the metals including the heavy metals were higher in the Guadiamar river sediments than in Guadalquivir. Highest surface enrichment value of the heavy metals Zn and Cd was found in the confluence of both rivers (GR2). Positive values of environmental riskfactors (ERF) indicate the potential adverse biological effect associated with the metal. Only the ERF values associated with Zn present positive values in some of the stations located near the confluence of both rivers. Fe, Pb and Cu were mainly associated to the lithogenic fraction, Mn to carbonate fraction, and Zn and Cd to the more biologically available fractions. Zn showed higher association with the reactive fractions in the Guadalquivir estuary compared to other ecosystems.