Qingdao Engineering Research Center for Rural Environment, School of Resources and Environment, Qingdao Agricultural University, Qingdao, 266109, PR China.
Qingdao Engineering Research Center for Rural Environment, School of Resources and Environment, Qingdao Agricultural University, Qingdao, 266109, PR China.
Environ Pollut. 2021 Mar 1;272:115935. doi: 10.1016/j.envpol.2020.115935. Epub 2020 Nov 6.
It has not been well understood that the binding affinity and potential toxicity of different chemical forms of selenite (Se(IV)), which are predominant forms of selenium with plant availability. The influences of pH and major anions on Se(IV) toxicity to wheat root elongation were determined in solutions and modeled based on the biotic ligand model (BLM) and free ion activity model (FIAM) concepts. Results showed that EC50[Se(IV)] values increased from 164 to 273 μM as the pH raised from 4.5 to 8.0, indicating the increase of pH induced weakened Se(IV) toxicity. The EC50{SeO} values increased from 0.019 to 71.3 μM while the EC50{HSeO} values sharply decreased from 2.08 μM to 0.760 nM with the pH increasing from 4.5 to 8.0. The effect of pH on Se(IV) toxicity could be explained by the changes of Se(IV) species in different pH solutions as HSeO, HSeO and SeO were differently toxic to wheat root elongation. The toxicity of Se(IV) decreased with increasing HPO activity but not for SO, NO and Cl activities, indicating that only HPO had a competitive effect with Se(IV) on the binding sites. A site-specific BLM was developed to count in effects of pH and HPO, and stability constants of HSeO, HSeO, SeO and HPO to the binding sites were obtained: log [Formula: see text] = 4.96, log [Formula: see text] = 3.47, log [Formula: see text] = 2.56 and log [Formula: see text] = 2.00. Results implied that BLM performed much better than FIAM in the wheat root elongation prediction when coupling toxic species HSeO, HSeO, SeO, and the competitions of HPO for the binding sites while developing the Se(IV)-BLM.
尚未充分理解亚硒酸盐（Se(IV)）的不同化学形式的结合亲和力和潜在毒性，这些形式是硒的主要存在形式，具有植物可用性。在溶液中确定了 pH 值和主要阴离子对硒（IV）对小麦根伸长毒性的影响，并基于生物配体模型（BLM）和游离离子活度模型（FIAM）概念对其进行了建模。结果表明，随着 pH 值从 4.5 升高到 8.0，EC50[Se(IV)]值从 164 增加到 273 μM，表明 pH 值升高导致 Se(IV)毒性减弱。随着 pH 值从 4.5 升高到 8.0，EC50{SeO}值从 0.019 增加到 71.3 μM，而 EC50{HSeO}值从 2.08 μM急剧下降到 0.760 nM。pH 值对 Se(IV)毒性的影响可以通过不同 pH 溶液中 Se(IV)物种的变化来解释，因为 HSeO、HSeO 和 SeO 对小麦根伸长的毒性不同。随着 HPO 活性的增加，Se(IV)的毒性降低，但 SO、NO 和 Cl 活性则没有，表明只有 HPO 对与 Se(IV)结合位点具有竞争作用。开发了一个特定于位点的 BLM，以考虑 pH 值和 HPO 的影响，并获得了 HSeO、HSeO、SeO 和 HPO 与结合位点的稳定性常数：log [Formula: see text] = 4.96，log [Formula: see text] = 3.47，log [Formula: see text] = 2.56 和 log [Formula: see text] = 2.00。结果表明，当结合毒性物种 HSeO、HSeO、SeO 和 HPO 对结合位点的竞争时，BLM 在预测小麦根伸长方面比 FIAM 表现得更好，同时开发了 Se(IV)-BLM。
