title: Biotic interactions modify the transfer of cesium-137 in a soil-earthworm-plant-snail food web.
abstract: The present study investigated the possible influence of the earthworm Aporrectodea tuberculata on the transfer of cesium-137 ((137)Cs) from a contaminated (130 Bq/kg) deciduous forest soil to the lettuce Lactuca sativa and to the snail Cantareus aspersus (formerly Helix aspersa) in two laboratory experiments. In the first experiment, the International Organization for Standardization 15952 test was used to expose snails for five weeks to contaminated soil with or without earthworms. In these conditions, the presence of earthworms caused a two- to threefold increase in (137)Cs concentrations in snails. Transfer was low in earthworms as well as in snails, with transfer factors (TFs) lower than 3.7 x 10(-2). Activity concentrations were higher in earthworms (2.8- 4.8 Bq/kg dry mass) than in snails (<1.5 Bq/kg). In the second experiment, microcosms were used to determine the contribution of soil and lettuce in the accumulation of (137)Cs in snails. Results suggest that the contribution of lettuce and soil is 80 and 20%, respectively. Microcosms also were used to study the influence of earthworms on (137)Cs accumulation in snail tissues in the most ecologically relevant treatment (soil-earthworm-plant-snail food web). In this case, soil-to-plant transfer was high, with a TF of 0.8, and was not significantly modified by earthworms. Conversely, soil-to-snail transfer was lower (TF, approximately 0.1) but was significantly increased in presence of earthworms. Dose rates were determined in the microcosm study with the EDEN (elementary dose evaluation for natural environment) model. Dose rates were lower than 5.5 x 10(-4) mGy/d, far from values considered to have effects on terrestrial organisms (1 mGy/d).
authors.affiliation: Department of Chrono-Environment, University of Franche-Comté, Place Leclerc, F-25030 Besançon Cedex, France.
authors.forename: Clémentine
authors.initials: C
authors.lastname: Fritsch
authors.forename: Renaud
authors.initials: R
authors.lastname: Scheifler
authors.forename: Karine
authors.initials: K
authors.lastname: Beaugelin-Seiller
authors.forename: Philippe
authors.initials: P
authors.lastname: Hubert
authors.forename: Michaël
authors.initials: M
authors.lastname: Coeurdassier
authors.forename: Annette
authors.initials: A
authors.lastname: de Vaufleury
authors.forename: Pierre-Marie
authors.initials: PM
authors.lastname: Badot
mesh_terms: D000818:Animals; D002588:Cesium Radioisotopes / Q000494:pharmacology*; D004463:Ecology; D017753:Ecosystem; D004784:Environmental Monitoring / Q000379:methods; D020387:Food Chain; D015233:Models, Statistical; D009835:Oligochaeta / Q000187:drug effects*; D011874:Radiometry; D012908:Snails / Q000187:drug effects*; D012987:Soil; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: D002588:Cesium Radioisotopes; D012987:Soil; D014867:Water