title: The effect of calcium and pH on nickel accumulation in and rhizotoxicity to pea (Pisum sativum L.) root-empirical relationships and modeling.
abstract: The accumulation and rhizotoxicity of Ni to pea were investigated. Calcium, H, and Ni competed for root-binding sites with high pH and low Ca favoring more Ni accumulation. At low pH, Ca accumulation is the key factor determining root growth, while at medium to high pH, root elongation is more sensitive to Ni concentration. The tissue concentration of Ni and Ca ([Ni]t or [Ca]t, micromol g(-1) dry root) can be predicted from total dissolved Ni ([Ni](T), microM), pH, and total dissolved Ca ([Ca](T), mM) by two approaches. Approach 1 is the empirical equations [Ni]t = (0.361 pH-0.695[Ca](T))*[Ni](T) and [Ca]t = 8.29 pH + 10.8 [Ca](T). The second approach involves a two-step model. The surface-bound Ni and Ca are estimated from a surface adsorption model with binding constants derived from independent ion adsorption experiments. Then transfer functions are used to predict internal root Ni and Ca accumulation.
authors.affiliation: Department of Natural Resource Sciences, McGill University, 21,111 Lakeshore Road, Ste-Anne-de-Bellevue, Quebec H9X 3V9, Canada. yonghong.wu@mail.mcgill.ca
authors.forename: Yonghong
authors.initials: Y
authors.lastname: Wu
authors.forename: William H
authors.initials: WH
authors.lastname: Hendershot
mesh_terms: D002118:Calcium / Q000737:chemistry / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008954:Models, Biological; D009532:Nickel / Q000737:chemistry / Q000378:metabolism / Q000633:toxicity*; D018532:Pisum sativum / Q000737:chemistry / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D018517:Plant Roots / Q000737:chemistry / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism
chemical_list: D009532:Nickel; D002118:Calcium