PT13 Aquatic Ecotoxicology I
Exhibit Hall
8:00 AM - Tuesday
(PT173) Acute Toxicity of Nitrite to Ceriodaphnia dubia and Pimephales promelas.
Baummer, J1, McCulloch, W1, Hammer, J2, Meyer, J2, Goodfellow, W1, 1 EA Enginnering Science and Technology, Sparks, MD, USA2 Tyson Fresh Meats, Dakota City, NE
ABSTRACT- Nitrite is the most toxic of all the nitrogen species in freshwater aquatic systems. Nitrite rarely poses acute toxicity issues in properly treated effluents from wastewater treatment plants with biological nutrient reduction. However, if the treatment plant biomass is inhibited, nitrite can be found at detectable concentrations that could pose potential acute toxicity issues. The objective of this study was to determine the acute toxicity of nitrite as sodium nitrite to the freshwater invertebrate Ceriodaphnia dubia and the freshwater vertebrate Pimephales promelas in two matrices, moderately hard synthetic freshwater and a synthetic effluent with moderate concentrations of dissolved ions. Daily renewal acute toxicity tests were completed following US EPA guidance for acute toxicity tests. Synthetic effluent was selected as a test matrix because the acute toxicity of nitrite can be counteracted by a number of ions (chloride, bicarbonate alkalinity and pH). Test results showed that nitrite was highly toxic to C. dubia in moderately hard synthetic freshwater. The mean measured 48-hour LC50 for nitrite was 0.5 mg/L NO2. For P. promelas the measured mean 96-hour LC50 for nitrite in moderately hard synthetic freshwater was 16.2 mg/L NO2. In synthetic effluent, nitrite was far less toxic. For C. dubia, the mean measured 48-hour LC50 was 6.7 mg/L NO2 in synthetic effluent while the mean measured 96-hour LC50 for P. promelas was 488 mg/L NO2.
Key words: Pimephales promelas, Ceriodaphnia dubia, acute toxicity