title: Sediment properties influencing the bioavailability of uranium to Chironomus dilutus larvae in spiked field sediments.
abstract: The partitioning of metals between dissolved and solid phases directly affects metal bioavailability to benthic invertebrates and is influenced by metal-binding properties of sediment phases. Little research has been done examining the effects of sediment properties on the bioavailability of uranium (U) to freshwater benthic invertebrates. In the present study, 18 field sediments with a wide range of properties (total organic carbon, fine fraction, cation exchange capacity, and iron content) were amended with the same concentrations of U to characterize the effects of these sediment properties on U bioavailability to freshwater midge, Chironomus dilutus. Bioaccumulation of U by C. dilutus larvae varied by over an order of magnitude when exposed to sediments spiked with 50 mg U kg(-1) d.w. (5-69 mg U kg(-1) d.w.) and 500 mg U kg(-1) d.w. (20-452 mg U kg(-1) d.w.), depending on the type of sediment. Variance in U bioaccumulation was best explained by differences in the cation exchange capacity, fine fraction (≤50 μm particle size), and Fe content of U-spiked sediment, with generated regression equations predicting observed bioaccumulation within a factor of two. The presented regression equations offer an easy-to-apply method for accounting for the influence of sediment properties on U bioavailability in freshwater sediment, with fine fraction being the single most practical variable. This research strongly supports that risk assessments and guidelines for U-contaminated sediments should not ignore the influence of sediment properties that can result in substantial differences in the bioaccumulation of U in benthic invertebrates.
authors.affiliation: Toxicology Centre, University of Saskatchewan, 44 Campus Drive, Saskatoon, SK S7N 5B3, Canada. Electronic address: Sarah.Crawford@usask.ca.
authors.forename: Sarah E
authors.initials: SE
authors.lastname: Crawford
authors.affiliation: Toxicology Centre, University of Saskatchewan, 44 Campus Drive, Saskatoon, SK S7N 5B3, Canada; School of Environment and Sustainability, University of Saskatchewan, 117 Science Place, Saskatoon, SK S7N 5C8, Canada; Institute of Loess Plateau, Shanxi University, 92 Wucheng Road, Taiyuan, Shanxi 030006, PR China. Electronic address: Karsten.Liber@usask.ca.
authors.forename: Karsten
authors.initials: K
authors.lastname: Liber
mesh_terms: D000818:Animals; D001682:Biological Availability; D055598:Chemical Phenomena; D002683:Chironomidae / Q000187:drug effects* / Q000378:metabolism; D005618:Fresh Water / Q000737:chemistry; D019015:Geologic Sediments / Q000737:chemistry*; D007814:Larva / Q000187:drug effects / Q000378:metabolism; D008962:Models, Theoretical; D014501:Uranium / Q000032:analysis* / Q000378:metabolism; D014875:Water Pollutants, Radioactive / Q000032:analysis* / Q000378:metabolism
chemical_list: D014875:Water Pollutants, Radioactive; D014501:Uranium
keywords: Bioavailability; Cation exchange capacity; Field sediments; Fine fraction; Iron content; Uranium