title: Cadmium accumulation is enhanced by ammonium compared to nitrate in two hyperaccumulators, without affecting speciation.
abstract: Nitrogen fertilization could improve the efficiency of Cd phytoextraction in contaminated soil and thus shorten the remediation time. However, limited information is available on the effect of N form on Cd phytoextraction and associated mechanisms in plants. This study examined the effect of N form on Cd accumulation, translocation, and speciation in Carpobrotus rossii and Solanum nigrum Plants were grown in nutrient solution with 5-15 μM Cd in the presence of 1000 µM NH4 (+) or NO3 (-) Plant growth and Cd uptake were measured, and Cd speciation was analyzed using synchrotron-based X-ray absorption spectroscopy. Shoot Cd accumulation was 30% greater with NH4 (+) than NO3 (-) supply. Carpobrotus rossii accumulated three times more Cd than S. nigrum. However, Cd speciation in the plants was not influenced by N form, but it did vary with species and tissues. In C. rossii, up to 91% of Cd was bound to S-containing ligands in all tissues except the xylem sap where 87-95% were Cd-OH complexes. Furthermore, the proportion of Cd-S in shoots was substantially lower in S. nigrum (44-69%) than in C. rossii (60-91%). It is concluded that the application of NH4 (+) (instead of NO3 (-)) increased shoot Cd accumulation by increasing uptake and translocation, rather than changing Cd speciation, and is potentially an effective approach for increasing Cd phytoextraction.
authors.affiliation: Department of Animal, Plant and Soil Sciences, Centre for AgriBioscience, La Trobe University, Victoria 3086, Australia.
authors.forename: Miaomiao
authors.initials: M
authors.lastname: Cheng
authors.affiliation: School of Agriculture and Food Sciences, The University of Queensland, Queensland 4072, Australia.
authors.forename: Peng
authors.initials: P
authors.lastname: Wang
authors.affiliation: School of Agriculture and Food Sciences, The University of Queensland, Queensland 4072, Australia.
authors.forename: Peter M
authors.initials: PM
authors.lastname: Kopittke
authors.affiliation: Department of Animal, Plant and Soil Sciences, Centre for AgriBioscience, La Trobe University, Victoria 3086, Australia.
authors.forename: Anan
authors.initials: A
authors.lastname: Wang
authors.affiliation: Department of Animal, Plant and Soil Sciences, Centre for AgriBioscience, La Trobe University, Victoria 3086, Australia.
authors.forename: Peter W G
authors.initials: PW
authors.lastname: Sale
authors.affiliation: Department of Animal, Plant and Soil Sciences, Centre for AgriBioscience, La Trobe University, Victoria 3086, Australia C.Tang@latrobe.edu.au.
authors.forename: Caixian
authors.initials: C
authors.lastname: Tang
mesh_terms: D015502:Absorptiometry, Photon; D035722:Aizoaceae / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D064751:Ammonium Compounds / Q000494:pharmacology*; D002104:Cadmium / Q000032:analysis / Q000378:metabolism*; D052918:Environmental Restoration and Remediation / Q000379:methods; D010078:Oxazines / Q000494:pharmacology*; D018520:Plant Shoots / Q000737:chemistry; D032324:Solanum nigrum / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*
chemical_list: D064751:Ammonium Compounds; D010078:Oxazines; D002104:Cadmium; C038619:punky blue
keywords: Carpobrotus rossii; Cd speciation; Cd translocation; Solanum nigrum; XANES.; halophytes; nitrogen form; phytoremediation; synchrotron