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Predicting acute zinc toxicity for Daphnia magna as a function of key water chemistry characteristics: Development and validation of a biotic ligand model
Author(s) -
Heijerick Dagobert G.,
De Schamphelaere Karel A. C.,
Janssen Colin R.
Publication year - 2002
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1002/etc.5620210628
Subject(s) - daphnia magna , zinc , toxicity , chemistry , ec50 , biotic ligand model , acute toxicity , zinc toxicity , environmental chemistry , nuclear chemistry , biochemistry , in vitro , organic chemistry
Abstract The individual effect of different major cations(Ca 2+ , Mg 2+ , Na + , K + , and H + ) on the acute toxicity of zinc to the waterflea Daphnia magna was investigated. The 48‐h median effective concentration (EC50) in the baseline test medium (i.e., a standard medium with very low ion concentrations) was about 6 μM (Zn 2+ ). An increase of Ca 2+ (from 0.25 mM to 3 mM), Mg 2+ (from 0.25 mM to 2 mM), and Na + activity (from 0.077 mM to 13 mM) reduced zinc toxicity by a factor of 6.3, 2.1, and 3.1, respectively. No further toxicity reduction was observed when Ca 2+ and Mg 2+ activities exceeded 3.0 and 2.0 mM, respectively. Both K + and H + did not significantly alter zinc toxicity (expressed as Zn 2+ activity). From these data, conditional stability constants for Ca 2+ (log K = 3.24), Mg 2+ (log K = 2.97), Na 2+ (log K = 2.16), and Zn 2+ (log K = 5.31) were derived and incorporated into a biotic ligand model (BLM) predicting acute zinc toxicity to D. magna in surface waters with different water quality characteristics. Validation of the developed BLM using 17 media with different pH, hardness, and dissolved organic carbon (DOC) content resulted in a significant correlation coefficient ( R 2 = 0.76) between predicted and observed 48‐h EC50. Eighty‐eight percent of the predictions were within a factor of 1.3 of the observed 48‐h EC50.