title: Speciation and ecological risk of toxic elements in estuarine sediments affected by multiple anthropogenic contributions (Guadiana saltmarshes, SW Iberian Peninsula): I. Surficial sediments.
abstract: Recent studies have demonstrated that the Guadiana Estuary contains metal concentrations in excess of background values. Therefore, this work aims to document the potential environmental hazards associated with the availability of these metals in this environment of high ecological value. Mineralogical analysis shows that the sediments are composed mainly of quartz, albite, and clay minerals (illite, smectite, kaolinite, and vermiculite) along with several small, reactive compounds (including soluble sulphated salts, Fe-Mn oxyhydroxides, organic matter, and pyrite) capable of retaining metals, which can be subsequently released, causing environmental degradation. BCR sequential extraction shows that As, Cd, Cu, Mn, Pb, and Zn present mobile fractions with respect to the total metal content (41, 100, 57, 53, 70, and 69%, respectively) in any of the described reactive phases (F1+F2+F3).Calculated environmental risk indices demonstrate moderate to considerable ecological risk for almost the entire estuary, associated mainly with acid mine drainage from the nearby Iberian Pyrite Belt. In addition, the indices highlight several zones of extremely high risk, which are related to industrial and urban dumps in the vicinity of the estuary and to heavy traffic on the international bridge.
authors: Dpto. Geología, Facultad de Ciencias Experimentales, Universidad de Huelva, Av. 3 de Marzo, S/N, 21071 Huelva, Spain. joaquin.delgado@dgeo.uhu.es
authors: Joaquín
authors: J
authors: Delgado
authors: Cinta
authors: C
authors: Barba-Brioso
authors: José Miguel
authors: JM
authors: Nieto
authors: Tomasz
authors: T
authors: Boski
mesh_terms: D004784:Environmental Monitoring; D019015:Geologic Sediments / Q000737:chemistry*; D011174:Portugal; D018570:Risk Assessment; D013030:Spain; D014873:Water Pollutants / Q000032:analysis* / Q000737:chemistry
chemical_list: D014873:Water Pollutants