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https://hdl.handle.net/2440/57340
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Type: | Journal article |
Title: | Identification of hydroxyl copper toxicity to barley (Hordeum vulgare) root elongation in solution culture |
Author: | Wang, X. Ma, Y. Hua, L. McLaughlin, M. |
Citation: | Environmental Toxicology and Chemistry, 2009; 28(3):662-667 |
Publisher: | Setac |
Issue Date: | 2009 |
ISSN: | 0730-7268 1552-8618 |
Statement of Responsibility: | Xuedong Wang, Yibing Ma, Luo Hua, and Mike J. McLaughlin |
Abstract: | The effect of pH on the acute toxicity of Cu to barley (Hordeum vulgare) root elongation was investigated in solution culture. The results showed that the median effective concentrations (EC50s; i.e., the concentration that reduced root elongation by 50% based on free Cu²⁺ activity) were not significantly different in the low-pH range from 4.5 to 6.5, but in the high-pH range from 7.0 to 8.0, a significant effect of pH on EC50s was found. The nonlinear relationship between EC50 and H⁺ activity in the present study indicated that the increased toxicity with increasing pH in solution may not be caused by decreasing H⁺ competition. When we take account of CuOH⁺ activities, a good linear relationship (r²> 0.97) between the ratio of CuOH⁺ activity to free Cu²⁺ activity and acute Cu toxicity to barley root elongation was achieved, which indicated that the observed toxicity in the highpH range may be caused by CuOH⁺ plus free Cu²⁺ in solution. Linear-regression analysis suggested CuOH⁺ had a greater binding affinity than Cu²⁺ at the biotic ligand sites. The logistic dose–response curve showed that expressing the Cu dose as Cu²⁺ +2.92 ·CuOH⁺ improved the data fit significantly compared to consideration of the free Cu²⁺ activity only. Thus, our results suggest CuOH⁺ was highly toxic to barley root elongation. The enhanced toxicity of CuOH⁺ therefore needs to be considered when modeling the effect of pH on Cu toxicity to barley for exposures having pH greater than 6.5. |
Keywords: | Copper Hydroxyl copper pH Biotic ligand model |
DOI: | 10.1897/07-641.1 |
Published version: | http://dx.doi.org/10.1897/07-641.1 |
Appears in Collections: | Aurora harvest 5 Earth and Environmental Sciences publications Environment Institute publications |
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