PARENT SESSION
PT1 - Aquatic Toxicology
Tuesday, 19 November 2002
8:00 AM to 6:30 PM
Exhibit Hall
(P478) Anion effects on reproduction of Ceriodaphnia dubia.
Lasier, Peter*,1, Winger, Parley1, 1 USGS Patuxent Wildlife Research Center, The University of Georgia, Athens, GA, USA
ABSTRACT- Industrial effluents produced from textile dyeing and finishing often contain substantial concentrations of chloride, sulfate and bicarbonate due to processes utilizing sodium and the need to neutralize alkaline solutions. Information describing the toxicity of these anions could be used to reduce or mitigate the ecological effects of textile effluents. Toxicity was assessed using Ceriodaphnia dubia in 7-day, 3-brood reproduction tests. Anions were added to solutions as sodium salts. Chloride and sulfate concentrations were determined analytically and bicarbonate was determined by measuring alkalinity. Conductivity and total dissolved solids (TDS) were determined for each test solution and all solutions were prepared at 40 mg/L hardness. Chloride and sulfate solutions had alkalinities around 120 mg/L (as CaCO3) and alkalinity in the bicarbonate test ranged from 45 to 725 mg/L. Mixtures of chloride and sulfate were assessed in ratios (Cl:SO4) of 1:10, 1:5, 1:1, 5:1, and 10:1. Bicarbonate was the most toxic of the anions with an IC50 of 635 mg/L and a TDS IC50 of 1587 mg/L. IC50 values for chloride and sulfate were similar at 1031 mg/L and 1001 mg/L, with TDS IC50s of 1760 mg/L and 1758 mg/L, respectively. Mixtures of chloride and sulfate were more toxic than the individual ions, and mixture toxicity increased as chloride content increased. A strong relationship exists between conductivity and total dissolved solids, but it is dependent on solution constituents. Inhibition concentrations based on conductivity and milli-equivalents/L varied significantly among the three anions due to differences in electrical conductance and neutralizing capacity. These differences may be useful in the development of manufacturing procedures that reduce the toxicity of textile effluents.
Key words: anions, toxicity, Ceriodaphnia dubia, mixtures