title: The use of a Weight-of-Evidence approach to address sediment quality in the Odiel River basin (SW, Spain).
abstract: The fluvial systems of the Iberian Pyrite Belt (SW Iberian Peninsula) are affected by acid mine drainage (a lixiviate residue product of mining activities derived from sulfide oxidation). The high acidity and high concentrations of sulfates and metal(loid)s are the main causes of the environmental degradation of the Odiel River basin. The use of weight of evidence approach in areas of the Odiel River basin implies the integration of different lines of evidence (chemistry, toxicity and bioaccumulation) using the freshwater clam Corbicula fluminea as target species. The integration of the results from the application of the different lines of evidence showed that the index of pollution was higher downvalley (Ptriad=12,312), moderate after mining effluent discharges (Ptriad=13.9) and very low where the Odiel River sources (Ptriad=6.31). The multivariate analysis indicated that variables and chemicals were associated with geochemical matrix and background levels (% of fines and toxic metal(loid) concentrations), toxic effects, and metal(loid) bioaccumulation reflecting the geographical distribution of the contamination towards the estuary. Metal(loid) thresholds were calculated for the study area as site-specific values of interim freshwater sediment quality values: As≥171; Cd≥0.48; Co≥8.82; Cr≥38.4; Cu≥451; Ni≥18.4; Pb≥377; Sb≥17.7; Zn≥221mg/kg of freshwater fluvial dry sediment. These results revealed the possibility of using the TEL values proposed by the USEPA and the NOAA for sediments from this site, and proposed lower PEL values for the Iberian Pyrite Belt as result of toxicity effects found in the Asian clam due to the combination of extreme acidity and high metal(loid) concentrations.
authors.affiliation: UNESCO UNITWIN/WiCop. Department of Physical-Chemistry, Faculty of Marine and Environmental Sciences, University of Cádiz, Campus Río San Pedro, Puerto Real, 11510 Cádiz, Spain. Electronic address: estefania.bonnail@uca.es.
authors.forename: Estefanía
authors.initials: E
authors.lastname: Bonnail
authors.affiliation: Department of Geodynamics and Palaeontology, Faculty of Experimental Sciences, University of Huelva, Campus 'El Carmen', 21071 Huelva, Spain. Electronic address: aguasanta.miguel@dgeo.uhu.es.
authors.forename: Aguasanta M
authors.initials: AM
authors.lastname: Sarmiento
authors.affiliation: UNESCO UNITWIN/WiCop. Department of Physical-Chemistry, Faculty of Marine and Environmental Sciences, University of Cádiz, Campus Río San Pedro, Puerto Real, 11510 Cádiz, Spain. Electronic address: angel.valls@uca.es.
authors.forename: T Ángel
authors.initials: TÁ
authors.lastname: DelValls
mesh_terms: D000143:Acids; D000818:Animals; D001835:Body Weight; D049874:Corbicula; D004784:Environmental Monitoring / Q000379:methods*; D063366:Estuaries; D005618:Fresh Water; D019015:Geologic Sediments / Q000737:chemistry*; D007501:Iron; D008906:Mining; D045483:Rivers / Q000737:chemistry; D013030:Spain; D013440:Sulfides; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D000143:Acids; D013440:Sulfides; D014874:Water Pollutants, Chemical; C011342:pyrite; D007501:Iron
keywords: Corbicula fluminea; Freshwater Sediment Quality values; Iberian Pyrite Belt; Weight of Evidence