Borgmann U, Borgmann A I
National Water Research Institute, Environment Canada, Burlington, Ontario, L7R 4A6, Canada.
Environ Pollut. 1997;95(3):325-31. doi: 10.1016/s0269-7491(96)00138-8.
The toxicity of ammonia to Hyalella azteca at constant pH in artificial media was controlled by sodium and potassium, and not by calcium, magnesium, or anions. Small increases in the LC50 for total ammonia (from 0.15 to 0.5 mM) occurred as sodium was increased from 0.1 to 1 mM and above, but major increases in the LC50 (to over 10 mM total ammonia) required the addition of potassium. Potassium was, however, more effective at reducing ammonia toxicity at high (1 mM) sodium than at low (0.1 mM) sodium. Ammonia toxicity was independent of pH at low sodium and potassium concentrations, when ammonia toxicity appeared to be associated primarily with aqueous ammonium ion concentrations. At high sodium and potassium concentrations, the toxicity of ammonia was reduced to the point where un-ionized ammonia concentrations also affected toxicity, and the LC50 became pH dependent. A mathematical model was produced for predicting ammonia toxicity from sodium and potassium concentrations and pH.
在人工培养基中，恒定pH条件下氨对阿氏摇蚊的毒性受钠和钾的控制，而不受钙、镁或阴离子的控制。随着钠浓度从0.1 mM增加到1 mM及以上，总氨的半数致死浓度（LC50）略有增加（从0.15 mM增至0.5 mM），但要使LC50大幅增加（至总氨超过10 mM）则需要添加钾。然而，在高钠（1 mM）条件下，钾在降低氨毒性方面比在低钠（0.1 mM）条件下更有效。在低钠和钾浓度时，氨毒性与pH无关，此时氨毒性似乎主要与水合铵离子浓度有关。在高钠和钾浓度时，氨的毒性降低到未电离氨浓度也影响毒性的程度，且LC50变得依赖于pH。建立了一个数学模型，用于根据钠、钾浓度和pH预测氨毒性。
