title: Fate of ZnO nanoparticles in soils and cowpea (Vigna unguiculata).
abstract: The increasing use of zinc oxide nanoparticles (ZnO-NPs) in various commercial products is prompting detailed investigation regarding the fate of these materials in the environment. There is, however, a lack of information comparing the transformation of ZnO-NPs with soluble Zn(2+) in both soils and plants. Synchrotron-based techniques were used to examine the uptake and transformation of Zn in various tissues of cowpea ( Vigna unguiculata (L.) Walp.) exposed to ZnO-NPs or ZnCl2 following growth in either solution or soil culture. In solution culture, soluble Zn (ZnCl2) was more toxic than the ZnO-NPs, although there was substantial accumulation of ZnO-NPs on the root surface. When grown in soil, however, there was no significant difference in plant growth and accumulation or speciation of Zn between soluble Zn and ZnO-NP treatments, indicating that the added ZnO-NPs underwent rapid dissolution following their entry into the soil. This was confirmed by an incubation experiment with two soils, in which ZnO-NPs could not be detected after incubation for 1 h. The speciation of Zn was similar in shoot tissues for both soluble Zn and ZnO-NPs treatments and no upward translocation of ZnO-NPs from roots to shoots was observed in either solution or soil culture. Under the current experimental conditions, the similarity in uptake and toxicity of Zn from ZnO-NPs and soluble Zn in soils indicates that the ZnO-NPs used in this study did not constitute nanospecific risks.
authors.affiliation: School of Agriculture and Food Sciences, The University of Queensland , St. Lucia, Queensland 4072, Australia.
authors.forename: Peng
authors.initials: P
authors.lastname: Wang
authors.forename: Neal W
authors.initials: NW
authors.lastname: Menzies
authors.forename: Enzo
authors.initials: E
authors.lastname: Lombi
authors.forename: Brigid A
authors.initials: BA
authors.lastname: McKenna
authors.forename: Bernt
authors.initials: B
authors.lastname: Johannessen
authors.forename: Chris J
authors.initials: CJ
authors.lastname: Glover
authors.forename: Peter
authors.initials: P
authors.lastname: Kappen
authors.forename: Peter M
authors.initials: PM
authors.lastname: Kopittke
mesh_terms: D007887:Fabaceae / Q000737:chemistry*; D053758:Nanoparticles / Q000032:analysis*; D009928:Organ Specificity; D018517:Plant Roots / Q000378:metabolism; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis*; D014018:Tissue Distribution; D056928:X-Ray Absorption Spectroscopy; D015032:Zinc / Q000378:metabolism; D015034:Zinc Oxide / Q000032:analysis*
chemical_list: D012987:Soil; D012989:Soil Pollutants; D015032:Zinc; D015034:Zinc Oxide