Predicting effects of cations on copper toxicity to lettuce (Lactuca sativa) by the biotic ligand model
✍ Scribed by T.T. Yen Le; Willie J.G.M. Peijnenburg; A. Jan Hendriks; Martina G. Vijver
- Publisher
- John Wiley and Sons
- Year
- 2011
- Tongue
- English
- Weight
- 97 KB
- Volume
- 31
- Category
- Article
- ISSN
- 0730-7268
- DOI
- 10.1002/etc.736
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✦ Synopsis
Abstract
A biotic ligand model (BLM) was developed to estimate Cu toxicity to lettuce (Lactuca sativa) in terms of root elongation after 4 d of exposure. Effects of Na^+^, K^+^, Ca^2+^, and Mg^2+^ on Cu toxicity were examined. The addition of these cations resulted in a 50‐fold difference in the copper median effective activity (${\rm EC}50_{{\rm cu}^{2 + } } $). However, these variations could not be interpreted entirely as a function of the concentrations of these cations alone. In particular, only the relationship between ${\rm EC}50_{{\rm cu}^{2 + } } $ and the activity of protons was found to be significant in the whole range of pH examined from 5.0 to 7.0. The addition of K^+^, Na^+^, Ca^2+^, and Mg^2+^ at concentrations up to 20 mM resulted in a 16‐fold difference in ${\rm EC}50_{{\rm cu}^{2 + } } $ values. This difference was significant, as indicated by non‐overlapping standard deviations of the negative logarithm of ${\rm EC}50_{{\rm cu}^{2 + } } $ (${\rm pEC}50_{{\rm cu}^{2 + } } $) obtained with (7.37 ± 0.22) and without (6.76 ± 0.22) additions of K^+^, Na^+^, Ca^2+^, and Mg^2+^. The variations were not statistically significantly related to concentrations of these cations; therefore, only protons can be integrated in the BLM predicting Cu toxicity to lettuce L. sativa with the important parameters: log K~HBL~= 6.27, log K~CuBL~= 7.40, and $f_{{\rm CuBL}}^{{\rm 50}%} $ = 0.36 at pH = 7. The lack of significant relationships between ${\rm EC}50_{{\rm cu}^{2 + } } $ and concentrations of the cations was not in line with the main assumption of the BLM about the competition between cations for binding sites. Environ. Toxicol. Chem. 2012;31:355–359. © 2011 SETAC