title: Subcellular partitioning of metals in Aporrectodea caliginosa along a gradient of metal exposure in 31 field-contaminated soils.
abstract: Subcellular fractionation of metals in organisms was proposed as a better way to characterize metal bioaccumulation. Here we report the impact of a laboratory exposure to a wide range of field-metal contaminated soils on the subcellular partitioning of metals in the earthworm Aporrectodea caliginosa. Soils moderately contaminated were chosen to create a gradient of soil metal availability; covering ranges of both soil metal contents and of several soil parameters. Following exposure, Cd, Pb and Zn concentrations were determined both in total earthworm body and in three subcellular compartments: cytosolic, granular and debris fractions. Three distinct proxies of soil metal availability were investigated: CaCl2-extractable content dissolved content predicted by a semi-mechanistic model and free ion concentration predicted by a geochemical speciation model. Subcellular partitionings of Cd and Pb were modified along the gradient of metal exposure, while stable Zn partitioning reflected regulation processes. Cd subcellular distribution responded more strongly to increasing soil Cd concentration than the total internal content, when Pb subcellular distribution and total internal content were similarly affected. Free ion concentrations were better descriptors of Cd and Pb subcellular distribution than CaCl2 extractable and dissolved metal concentrations. However, free ion concentrations and soil total metal contents were equivalent descriptors of the subcellular partitioning of Cd and Pb because they were highly correlated. Considering lowly contaminated soils, our results raise the question of the added value of three proxies of metal availability compared to soil total metal content in the assessment of metal bioavailability to earthworm.
authors: INRA, UR 251 PESSAC, 78026 Versailles Cedex, France.
authors: Léa
authors: L
authors: Beaumelle
authors: Laboratoire Chrono-Environnement, UMR 6249 University of Franche-Comté/CNRS Usc INRA, 16 route de Gray, 25030 Besançon Cedex, France.
authors: Frédéric
authors: F
authors: Gimbert
authors: INRA, UR 251 PESSAC, 78026 Versailles Cedex, France.
authors: Mickaël
authors: M
authors: Hedde
authors: INRA, US 0010 LAS Laboratoire d'analyses des sols, 273 rue de Cambrai, 62000 Arras, France.
authors: Annie
authors: A
authors: Guérin
authors: INRA, UR 251 PESSAC, 78026 Versailles Cedex, France. Electronic address: lamy@versailles.inra.fr.
authors: Isabelle
authors: I
authors: Lamy
mesh_terms: D000818:Animals; D008670:Metals / Q000378:metabolism*; D009835:Oligochaeta / Q000378:metabolism*; D012987:Soil / Q000737:chemistry; D012989:Soil Pollutants / Q000378:metabolism*
chemical_list: D008670:Metals; D012987:Soil; D012989:Soil Pollutants
keywords: Bioavailability; Earthworm; Field-contaminated soils; Geochemical modeling; Subcellular fractionation