Studies On Acute Toxicity Of Ammoniacal Nitrogen,Nitrite And Nitrate In Pseudorasbora Parva

In this paper, Pseudorasbora parva was selected as experimental animal to detect the acute toxicity of ammoniacal nitrogen, nitrite and nitrate respectively. A96h half static water aquatic organism acute toxicity test and the aquarium with3.5L volume contained10tail P. parva of each were used in the experiment (body length3.2±0.2cm, weight0.47±0.09g). The water for the experiment was the tap water which had been aerating at least three days. Water temperature was kept at12.7±1℃with dissolved oxygen9.86±0.01mg/L, pH7.95-8.05. The ammoniacal nitrogen (NH4CI), nitrite (NaNO2), and nitrate (NaNO3) in experiment are pure analysis. A preliminary test in the toxicity of ammoniacal nitrogen, nitrite, and nitrate were conducted to determine24h-LC100and96h-LC0. According to the results of the preliminary test, seven concentration groups with equal logarithm interval between24h-LC100and96h-LC0of each compound were set up. All treatments were performed in triplicate and each replicate contained10tails. Among them, different concentrations of ammoniacal nitrogen were:14.8,21.9,32.4,47.9,70.8,104.7,154.9mg/L, respectively. Different concentrations of nitrite were:45.7,79.4,138.0,239.9,416.9,724.4,1258.9mg/L, respectively. Different concentrations of nitrate were:1.000,1.175,1.380,1.622,1.905,2.239,2.630g/L, respectively. Each test and control medium was changed each day and removed the dead one timely for the duration of the experiment. Meanwhile, the fluctuation of the oxygen was kept at5.60-9.87mg/L. The results were showed as follows:1. The24h-LC50,48h-LC50,72h-LC50and96h-LC50(95%confidence interval) after exposure non-ionic ammonia to P.parva were0.435mg/L (0.407～0.466mg/L),0.384mg/L (0.356～0.417mg/L),0.371mg/L (0.344～0.402mg/L),0.346mg/L (0.316～0.383mg/L), respectively. The safe concentration of non-ionic ammonia to P. parva was0.0346mg/L.2. The24h-LC50,48h-LC50,72h-LC50and96h-LC50(95%confidence interval) after exposure nitrite to P. parva were422.862mg/L (365.741～490.035mg/L),327.746 mg/L (276.875～394.054mg/L),266.291mg/L (228.302～310.877mg/L),236.907mg/L (200.488～281.108mg/L), separately. The safe concentration of nitrite to P. parva was23.6907mg/L.3. The24h-LC50,48h-LC50,72h-LC50and96h-LC50(95%confidence interval)after exposure nitrate to P. parva were2.155g/L (2.074-2.242g/L),1.929g/L (1.864～1.999g/L),1.769g/L (1.701～1.842g/L),1.663g/L (1.577～1.780g/L), respectively. The safe concentration of nitrate to P. parva was0.1663g/L.4. All in all, in three kinds of compound, the toxicity of non-ionic ammonia to P. parva was maximum, nitrite was the second smallest, and the toxicity of nitrate to P. parva was minimum.