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IDENTIFICATION OF HYDROXYL COPPER TOXICITY TO BARLEY (HORDEUM VULGARE) ROOT ELONGATION IN SOLUTION CULTURE.
- Source :
- Environmental Toxicology & Chemistry; Mar2009, Vol. 28 Issue 3, p662-667, 6p, 1 Chart, 6 Graphs
- Publication Year :
- 2009
-
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 Cu<superscript>2+</superscript> 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<superscript>+</superscript> activity in the present study indicated that the increased toxicity with increasing pH in solution may not be caused by decreasing H<superscript>+</superscript> competition. When we take account of CuOH<superscript>+</superscript> activities, a good linear relationship (r² > 0.97) between the ratio of CuOH<superscript>+</superscript> activity to free Cu<superscript>2+</superscript> 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<superscript>+</superscript> plus free Cu<superscript>2+</superscript> in solution. Linear-regression analysis suggested CuOH<superscript>+</superscript> had a greater binding affinity than Cu<superscript>2+</superscript> at the biotic ligand sites. The logistic dose-response curve showed that expressing the Cu dose as Cu<superscript>2+</superscript> + 2.92 ∙ CuOH<superscript>+</superscript> improved the data fit significantly compared to consideration of the free Cu<superscript>2+</superscript> activity only. Thus, our results suggest CuOH<superscript>+</superscript> was highly toxic to barley root elongation. The enhanced toxicity of CuOH<superscript>+</superscript> therefore needs to be considered when modeling the effect of pH on Cu toxicity to barley for exposures having pH greater than 6.5. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 07307268
- Volume :
- 28
- Issue :
- 3
- Database :
- Complementary Index
- Journal :
- Environmental Toxicology & Chemistry
- Publication Type :
- Academic Journal
- Accession number :
- 36776783
- Full Text :
- https://doi.org/10.1897/07-641.1