Luo Xiao-San, Li Lian-Zhen, Zhou Dong-Mei
State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China; Graduate School of Chinese Academy of Sciences, Beijing 100049, China.
Chemosphere. 2008 Sep;73(3):401-6. doi: 10.1016/j.chemosphere.2008.05.031. Epub 2008 Jun 27.
The extent to which calcium, magnesium, sodium, potassium and hydrogen ions independently mitigate Cu rhizotoxicity to wheat (Triticumaestivum) in nutrient solutions was examined. Increasing activities of Ca2+ and Mg2+ but not Na+, K+ and H+ linearly increased the 2 d EC50 (as Cu2+ activity), supporting the concept that some cations can compete with Cu2+ for binding the active sites at the terrestrial organism-solution interface (i.e., the biotic ligand, BL). According to the biotic ligand model (BLM) concept, the conditional stability constants for the binding of Cu2+, Ca2+ and Mg2+ to the BL were derived from the toxicity data. They were 6.28, 2.43 and 3.34 for logK(CuBL), logK(CaBL) and logK(MgBL), respectively. It was calculated that on average 43.6% of BL sites need to be occupied by Cu2+ to induce 50% root growth inhibition. Using the estimated parameters, a BLM was successfully developed to predict Cu toxicity for wheat as a function of solution characteristics.
研究了在营养液中钙、镁、钠、钾和氢离子对铜毒害小麦（普通小麦）的独立缓解程度。增加Ca2+和Mg2+的活性，但不增加Na+、K+和H+的活性，会使2 d EC50（以Cu2+活性计）呈线性增加，这支持了一些阳离子可以与Cu2+竞争在陆地生物 - 溶液界面（即生物配体，BL）上的结合活性位点的概念。根据生物配体模型（BLM）概念，从毒性数据中得出了Cu2+、Ca2+和Mg2+与BL结合的条件稳定常数。logK(CuBL)、logK(CaBL)和logK(MgBL)分别为6.28、2.43和3.34。经计算，平均43.6%的BL位点被Cu2+占据时会导致50%的根生长抑制。利用估算参数，成功建立了一个BLM来预测小麦铜毒性与溶液特性的函数关系。
