A Terrestrial Biotic Ligand Model. 1. Development and Application to Cu and Ni Toxicities to Barley Root Elongation in Soils

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• 作者：Sagar Thakali ; Herbert E. Allen ; Dominic M. Di Toro ; Alexander A. Ponizovsky ; Corinne P. Rooney ; Fang-Jie Zhao ; Stephen P. McGrath
• 刊名：Environmental Science & Technology
• 出版年：2006
• 出版时间：November 15, 2006
• 年：2006
• 卷：40
• 期：22
• 页码：7085 - 7093
• 全文大小：314K
• 年卷期：v.40,no.22(November 15, 2006)
• ISSN：1520-5851

文摘

A Terrestrial Biotic Ligand Model (TBLM) was developedusing noncalcareous soils from Europe based on Cu and Nispeciation and barley (Hordeum vulgare cv. Regina) rootelongation bioassays. Free metal ion (M²⁺) activity wascomputed by the WHAM VI model using inputs of soil metal,soil organic matter, and alkali and alkaline earth metalsconcentrations, and pH in soil solution. The TBLM assumesthat metal in soil and in the solution are in equilibrium.Metal ions react with the biotic ligand, the receptor site,and inhibit root elongation. Other ions, principally H⁺, Ca²⁺and Mg²⁺, compete with M²⁺ and, therefore, affect itstoxicity. Toxicity is correlated only to the fraction of thetotal biotic ligand sites occupied by M²⁺. Compared to othermodels using either the soil metal concentration or M²⁺activity as the toxic dose, the TBLM provides a more consistentmethod to normalize and compare Cu and Ni toxicitiesto root elongation among different soils. The TBLM wasable to predict the EC50 soil Cu and Ni concentrations generallywithin a factor of 2 of the observed values, a level ofprecision similar to that for the aquatic Biotic Ligand Model,indicating its potential utility in metals risk assessmentin soils.