title: Fixation of metals in soil constituents and potential remobilization by hyperaccumulating and non-hyperaccumulating plants: results from an isotopic dilution study.
abstract: In this study isotopic dilution methods were used to investigate the hypothesis that access to metals associated with specific chemical components in the soil that are not available to non-accumulator species could be involved in hyperaccumulation. The hyperaccumulator Thlaspi caerulescens and a non-accumulator species, Brassica napus, were grown in Cd and Zn enriched soil components calcite, goethite, charcoal and cryptomelane. The metal enriched components were aged to allow transformation of a proportion of added metals to non-labile forms. Results from the isotopic dilution L value method showed that despite taking up more metals, T. caerulescens accessed the same pool of metals as B. napus. Hence differential access to different solid-phase pools of metals appears to be an unlikely mechanism underlying metal hyperaccumulation. For all components except charcoal, L values for Cd and Zn were greater than the corresponding E values suggesting that E values may tend to underestimate the bioavailable fraction of metals in soils.
authors.affiliation: Swiss Federal Institute of Technology, ENAC-ISTE-Laboratory of Soil Science, GR B1 423, Station no. 2, Ecublens, 1015 Lausanne, Switzerland.
authors.forename: Daniel
authors.initials: D
authors.lastname: Hammer
authors.forename: Catherine
authors.initials: C
authors.lastname: Keller
authors.forename: Michael J
authors.initials: MJ
authors.lastname: McLaughlin
authors.forename: Rebecca E
authors.initials: RE
authors.lastname: Hamon
mesh_terms: D001682:Biological Availability; D029688:Brassica napus / Q000378:metabolism*; D002104:Cadmium / Q000493:pharmacokinetics*; D006801:Humans; D019216:Metals, Heavy / Q000493:pharmacokinetics*; D018517:Plant Roots / Q000378:metabolism; D012989:Soil Pollutants / Q000493:pharmacokinetics*; D031227:Thlaspi / Q000378:metabolism*; D014018:Tissue Distribution; D018505:Waste Management; D015032:Zinc / Q000493:pharmacokinetics*
chemical_list: D019216:Metals, Heavy; D012989:Soil Pollutants; D002104:Cadmium; D015032:Zinc