Schuytema, Gerald S., and Alan V. Nebeker. 1999. Comparative toxicity of ammonium and nitrate compounds to Pacific treefrog and African clawed frog tadpoles. Environmental Contamination and Toxicology 18(10):2251-2257.
The effects of ammonium nitrate, ammonium chloride, ammonium sulfate, and sodium nitrate on survival and growth of Pacific Treefrog (Psuedacris regilla [Baird and Girard] and African clawed frog (Xenopus laevis [Daudin]) tadpoles were determined in static-renewal tests. The 10-d ammonium nitrate and ammonium sulfate SC50s for P regilla were 55.2 and 89.7 mg/L NH4 respectively. The 10-d LC50s for X. laevis for the three ammonium compounds ranged from 45 to 64 mg/L NH4-N. The 10-d sodium nitrate LC50s were 266.2 mg/L NO3-N for P. regilla and 1,236.2 mg/L NO3-N for X. laevis. The lowest observed adverse effect level (LOAEL) of ammonium compound based on reduced length or weight was 24.6 mg/L NH4 -N for P. regilla and 99.5 mg/L NH4-N for X. laevis. The lowest sodium nitrate LOAELs based on reduced length or width were 30.1 NH4 -N concentration. Potential harm to amphibians could occur if sensitive life stages were impacted by NH4-N and NO3 in agricultural runoff or drainage for a sufficiently long period.