title: The microbial impact on the sorption behaviour of selenite in an acidic, nutrient-poor boreal bog.
abstract: (79)Se is among the most important long lived radionuclides in spent nuclear fuel and selenite, SeO3(2-), is its typical form in intermediate redox potential. The sorption behaviour of selenite and the bacterial impact on the selenite sorption in a 7-m-deep profile of a nutrient-poor boreal bog was studied using batch sorption experiments. The batch distribution coefficient (Kd) values of selenite decreased as a function of sampling depth and highest Kd values, 6600 L/kg dry weight (DW), were observed in the surface moss and the lowest in the bottom clay at 1700 L/kg DW. The overall maximum sorption was observed at pH between 3 and 4 and the Kd values were significantly higher in unsterilized compared to sterilized samples. The removal of selenite from solution by Pseudomonas sp., Burkholderia sp., Rhodococcus sp. and Paenibacillus sp. strains isolated from the bog was affected by incubation temperature and time. In addition, the incubation of sterilized surface moss, subsurface peat and gyttja samples with added bacteria effectively removed selenite from the solution and on average 65% of selenite was removed when Pseudomonas sp. or Burkholderia sp. strains were used. Our results demonstrate the important role of bacteria for the removal of selenite from the solution phase in the bog environment, having a high organic matter content and a low pH.
authors.affiliation: Laboratory of Radiochemistry, Department of Chemistry, P.O. Box 55, 00014 University of Helsinki, Finland. Electronic address: merja.lusa@helsinki.fi.
authors.forename: M
authors.initials: M
authors.lastname: Lusa
authors.affiliation: VTT Technical Research Centre of Finland, P.O. Box 1000, 02044 VTT, Finland.
authors.forename: M
authors.initials: M
authors.lastname: Bomberg
authors.affiliation: Laboratory of Radiochemistry, Department of Chemistry, P.O. Box 55, 00014 University of Helsinki, Finland.
authors.forename: H
authors.initials: H
authors.lastname: Aromaa
authors.affiliation: Laboratory of Radiochemistry, Department of Chemistry, P.O. Box 55, 00014 University of Helsinki, Finland.
authors.forename: J
authors.initials: J
authors.lastname: Knuutinen
authors.affiliation: Laboratory of Radiochemistry, Department of Chemistry, P.O. Box 55, 00014 University of Helsinki, Finland.
authors.forename: J
authors.initials: J
authors.lastname: Lehto
mesh_terms: D000327:Adsorption; D000332:Aerobiosis; D000693:Anaerobiosis; D001419:Bacteria / Q000378:metabolism*; D005387:Finland; D020887:Selenious Acid / Q000378:metabolism*; D012644:Selenium Radioisotopes / Q000378:metabolism*; D012990:Soil Pollutants, Radioactive / Q000378:metabolism*; D014875:Water Pollutants, Radioactive / Q000378:metabolism*; D053833:Wetlands
chemical_list: D012644:Selenium Radioisotopes; D012990:Soil Pollutants, Radioactive; D014875:Water Pollutants, Radioactive; D020887:Selenious Acid
keywords: Bacteria; Biosorption; Nuclear waste; Peat; Selenite; Sorption