Acute toxicity of inorganic chloramines to Daphnia magna in two types of dilution water

The effects of small amounts of fluoride and bromide ions on the LT sub(50) and LC sub(50) values of inorganic chloramines to Daphnia magna were investigated. Two types of dilution water were used: a reconstituted water containing no Br super(-) and F super(-), and a natural well water containing small amounts of both ions. The well water had a greater alkalinity and conductivity than the reconstituted water. Inorganic chloramines in reconstituted water appeared to be slightly more toxic to D. magna than in well water, except for the trend of LT sub(50) for the two highest test concentrations. The 48-h LC sub(50) values of inorganic chloramines to D. magna in reconstituted and natural well water were 0.010 and 0.016 mg/l, respectively.