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Importance of calcium in modifying the acute toxicity of sodium sulphate to Hyalella azteca and Daphnia magna
Author(s) -
Davies Trevor D.,
Hall Ken J.
Publication year - 2007
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 - 10.1897/06-510r.1
Subject(s) - hyalella azteca , daphnia magna , toxicity , calcium , acute toxicity , sodium , environmental chemistry , toxicology , biology , zoology , chemistry , amphipoda , crustacean , organic chemistry
Modification of the acute toxicity of sodium sulphate to Hyalella azteca and Daphnia magna was investigated using exposure water with different levels of water hardness (expressed as CaCO 3 equivalents) and calcium–magnesium molar (Ca:Mg) ratios. The influence of Ca:Mg ratios on the toxicity of sodium and potassium chloride to D. magna also was investigated. For both species, the mean lethal concentrations that resulted in mortality of 50% of the sample population (LC50s), expressed as mg SO 4 2– /L, were increased significantly in harder water and in water with higher Ca:Mg ratios. The LC50s for H. azteca increased from 569 to 5,259 mg/L with a change in water hardness from 25 to 250 mg/L. Furthermore, modifying the Ca:Mg ratio from 0.7 to 7.0 at a constant hardness of 100 mg/L significantly increased LC50s from 2,101 to 2,725 mg/L. The LC50s for D. magna were also significantly higher in harder water with LC50s increasing from 1,194 to 3,203 mg/L with a change in water hardness from 25 to 100 mg/L. In addition, modifying the Ca:Mg ratio from 0.7 to 7.0 significantly increased LC50s from 1,194 to 1,985 at a constant hardness of 25 mg/L, and from 3,203 to 4,395 mg/L at a constant hardness of 100 mg/L. No significant change in the toxicity of potassium or sodium chloride to D. magna was observed in waters with higher Ca:Mg ratios.