Qingdao Engineering Research Center for Rural Environment, College of Resource and Environment, Qingdao Agricultural University, Qingdao, Shandong, 266109, PR China; National Soil Fertility and Fertilizer Effects Long-term Monitoring Network, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, 100081, PR China.
National Soil Fertility and Fertilizer Effects Long-term Monitoring Network, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, 100081, PR China; School of Resources and Environment, University of Jinan, Jinan, Shandong, 250022, PR China.
Chemosphere. 2017 Mar;171:537-543. doi: 10.1016/j.chemosphere.2016.12.050. Epub 2016 Dec 10.
The influence of pH on the toxicity of Cr(VI) to barley root elongation was studied in solution culture to better understand the toxicity of different species of Cr(VI). Results showed that the values of EC50{CrO} (the free CrO that results in50% of barley root elongation with respect to the control) increased when the pH increased from 4.5 to 6.5; however, it was not significantly different in the high-pH range from 7.0 to 8.5. The nonlinear relationship between EC50{CrO} and OH activity indicated that OH competition with Cr(VI) on cell membrane ligands was not strong. There was a good linear relationship (R = 0.99) between the ratio of HCrO activity to CrO activity and Cr(VI) toxicity to barley root elongation when the toxicity of HCrO were considered, indicating that the observed toxicity of Cr(VI) in the high pH range may be caused by HCrO and CrO in solution. It was found that HCrO had a greater binding affinity than CrO on the biotic ligand sites. The logistic dose-response curves showed that consideration of Cr(VI) dose as HCrO and CrO significantly improved the data fit compared to consideration of the activity of HCrO or CrO only. The present study suggested that HCrO was highly toxic to the root of barely, and both HCrO and CrO species needed to be considered when predicting the toxicity of Cr(VI) under different pH conditions.
研究了溶液培养中 pH 值对 Cr(VI) 对大麦根伸长毒性的影响，以更好地理解不同种类的 Cr(VI) 的毒性。结果表明，当 pH 值从 4.5 增加到 6.5 时，EC50{CrO}（相对于对照使大麦根伸长 50%的游离 CrO）的值增加；然而，在 pH 值为 7.0 到 8.5 的高 pH 值范围内，它没有显著差异。EC50{CrO}与 OH 活性之间的非线性关系表明，OH 与细胞膜配体上的 Cr(VI) 竞争并不强烈。当考虑 HCrO 的毒性时，HCrO 活性与 CrO 活性的比值与 Cr(VI) 对大麦根伸长的毒性之间存在良好的线性关系（R = 0.99），表明在高 pH 值范围内观察到的 Cr(VI)的毒性可能是由溶液中的 HCrO 和 CrO 引起的。研究发现，HCrO 在生物配体位点上与 CrO 相比具有更大的结合亲和力。逻辑剂量-反应曲线表明，与仅考虑 HCrO 或 CrO 的活性相比，将 Cr(VI) 剂量视为 HCrO 和 CrO 考虑时，数据拟合得到显著改善。本研究表明，HCrO 对大麦根具有高毒性，在预测不同 pH 条件下 Cr(VI) 的毒性时，需要同时考虑 HCrO 和 CrO 物种。
