The control of ammonia toxicity to Hyalella azteca by sodium, potassium, and pH / by Uwe Borgmann & Anne I. Borgmann. : En13-5/96-88E-PDF

"The toxicity of ammonia to Hyalella azteca at constant pH in artificial media is 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) occur as sodium is increased from 0.1 to M1 mM(and above, but major increases in the LC50 (to over 10 m_M total ammonia) require the addition of potassium. Potassium is, however, more effective at reducing ammonia toxicity at high (1 mM) sodium than at low (0.1 mM)‘ sodium. Ammonia toxicity is independent of pH at low sodium and potassium concentrations, when ammonia toxicity appears to be due primarily to the ammonium ion. At high sodium and potassium, the toxicity of the ammonium ion is reduced to the point where un-ionized ammonia also contributes to toxicity, and the LC50 becomes pH dependent. A mathematical model was produced for predicting ammonia toxicity from sodium and potassium concentrations and pH"--Abstract.

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