title: Toxicity risk assessment of mercury, DDT and arsenic legacy pollution in sediments: A triad approach under low concentration conditions.
abstract: The determination of sediment toxicity is challenging due to site-specific factors affecting pollutants distribution and bioavailability, especially when contamination levels are close to expected non-effect concentrations. Different lines of evidence and sensitive tools are necessary for a proper toxicity risk assessment. We examined the case study of the Toce River (Northern Italy), where past industrial activities determined Hg, DDT and As enrichment in sediments. A triad approach comprising chemical, ecotoxicological and ecological analyses (benthic invertebrates) was carried out for risk assessment of residual contamination in river sediments. A "blank" site upstream from the industrial site was selected to compare the other sites downstream. Sediment, water and benthic invertebrate samplings were carried out following standard protocols. Results emphasized that despite the emissions of the industrial site ceased about 20years ago, sediments in the downstream section of the river remain contaminated by Hg, DDT and As with concentrations exceeding Threshold Effect Concentrations. A chronic whole-sediment test with Chironomus riparius showed decreased development rate and a lower number of eggs per mass in the contaminated sediments. Benthic community was analyzed with the calculation of integrated (STAR_ICMi) and stressor-specific metrics (SPEARpesticideand mean sensitivity to Hg), but no significant differences were found between upstream and downstream sites. On the other hand, multivariate analysis (partial Redundancy Analysis and variation partitioning) emphasized a slight impact on invertebrate community, accounting for 5% variation in taxa composition. Results show that legacy contaminants in sediments, even at low concentrations, may be bioavailable and possibly toxic for benthic invertebrates. At low concentration levels, sensitive and site-specific tools need to be developed for a proper risk analysis.
authors.affiliation: Water Research Institute - National Research Council (IRSA-CNR), Via del Mulino 19, 20861 Brugherio, MB, Italy. Electronic address: marziali@irsa.cnr.it.
authors.forename: L
authors.initials: L
authors.lastname: Marziali
authors.affiliation: Water Research Institute - National Research Council (IRSA-CNR), Via del Mulino 19, 20861 Brugherio, MB, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Rosignoli
authors.affiliation: Water Research Institute - National Research Council (IRSA-CNR), Via del Mulino 19, 20861 Brugherio, MB, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Drago
authors.affiliation: Water Research Institute - National Research Council (IRSA-CNR), Via del Mulino 19, 20861 Brugherio, MB, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Pascariello
authors.affiliation: Water Research Institute - National Research Council (IRSA-CNR), Via del Mulino 19, 20861 Brugherio, MB, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Valsecchi
authors.affiliation: University of Milan, Department of Food, Environmental and Nutritional Sciences (DeFENS), Via Celoria 2, 20133 Milan, Italy.
authors.forename: B
authors.initials: B
authors.lastname: Rossaro
authors.affiliation: Water Research Institute - National Research Council (IRSA-CNR), Via del Mulino 19, 20861 Brugherio, MB, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Guzzella
mesh_terms: D000818:Animals; D001151:Arsenic / Q000633:toxicity*; D002683:Chironomidae; D003634:DDT / Q000633:toxicity*; D054750:Ecotoxicology; D004784:Environmental Monitoring; D019015:Geologic Sediments / Q000737:chemistry*; D007448:Invertebrates; D007558:Italy; D008628:Mercury / Q000633:toxicity*; D018570:Risk Assessment; D045483:Rivers / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D014874:Water Pollutants, Chemical; D003634:DDT; D008628:Mercury; D001151:Arsenic
keywords: Benthic invertebrate community; C. riparius chronic test; Era; Pesticides; Sediment toxicity; Trace elements