title: Aseptic hydroponics to assess rhamnolipid-Cd and rhamnolipid-Zn bioavailability for sunflower (Helianthus annuus): a phytoextraction mechanism study.
abstract: The availability of cadmium (Cd) and zinc (Zn) to sunflower (Helianthus annuus) was investigated in rhamnolipid- and ethylenediaminetetraacetic acid (EDTA)-buffered solutions in order to evaluate the influence of aqueous speciation of the metals on their uptake by the plant, in relation to predictions of uptake by the free ion activity model (FIAM). Free metal ion activity was estimated using the chemical equilibrium program MINTEQ or measured by Donnan dialysis. The uptake of Cd followed the FIAM for the EDTA-buffered solution at EDTA concentrations below 0.4 μM; for the rhamnolipid-buffered solution, the uptake of both metals in roots was not markedly affected by increasing rhamnolipid concentrations in solution. This suggests rhamnolipid enhanced metal accumulation in plant roots (per unit free metal in solution) possibly through formation and uptake of lipophilic complexes. The addition of normal Ca concentrations (low millimetre range) to the rhamnolipid uptake solutions reduced Cd accumulation in shoots by inhibiting Cd translocation, whereas it significantly increased Zn accumulation in shoots. This study confirms that although rhamnolipid could enhance accumulation of Cd in plants roots at low Ca supply, it is not suitable for Cd phytoextraction in contaminated soil environments where Ca concentrations in soil solution are orders of magnitude greater than those of Cd.
authors: Soil Science, School of Agriculture, Food and Wine, The University of Adelaide, PMB 1, Glen Osmond, SA, 5064, Australia. jwen@hnu.edu.cn.|College of Environmental Science and Engineering, Hunan University, Changsha, 410082, People's Republic of China. jwen@hnu.edu.cn.
authors: Jia
authors: J
authors: Wen
authors: Soil Science, School of Agriculture, Food and Wine, The University of Adelaide, PMB 1, Glen Osmond, SA, 5064, Australia.|CSIRO Land and Water, Agricultural Sustainable Flagship, Environmental Biogeochemistry Program, Waite Campus, Urrbrae, SA, 5064, Australia.
authors: Mike J
authors: MJ
authors: McLaughlin
authors: Soil Science, School of Agriculture, Food and Wine, The University of Adelaide, PMB 1, Glen Osmond, SA, 5064, Australia.|Everris Australia Pty Ltd, Baulkham Hills, Bella Vista, NSW, Australia.
authors: Samuel P
authors: SP
authors: Stacey
authors: CSIRO Land and Water, Agricultural Sustainable Flagship, Environmental Biogeochemistry Program, Waite Campus, Urrbrae, SA, 5064, Australia.
authors: Jason K
authors: JK
authors: Kirby
mesh_terms: D001673:Biodegradation, Environmental; D001682:Biological Availability; D002104:Cadmium / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism*; D004492:Edetic Acid / Q000737:chemistry; D006017:Glycolipids / Q000737:chemistry*; D006368:Helianthus / Q000254:growth & development / Q000378:metabolism*; D018527:Hydroponics; D018517:Plant Roots / Q000378:metabolism; D012987:Soil / Q000737:chemistry; D012989:Soil Pollutants / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D015032:Zinc / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism*
chemical_list: D006017:Glycolipids; D012987:Soil; D012989:Soil Pollutants; C418382:rhamnolipid; D002104:Cadmium; D004492:Edetic Acid; D015032:Zinc
keywords: Free ion activity model; Metals; Phytoremediation; Rhamnolipid