Influence of organic ammonium derivatives on the equilibria between NH4+, NO2− and NO3− ions in the Nistru River water

Abstract

The toxic effects of ammonium derivatives in the river water depend dramatically on their natural or synthetic origins and on their chemical structures. It has been proved that 1-naphtylamine (1-NA) and diphenylamine (DPA) breaking impact on the ammonium oxidation and especially on nitrite ions oxidation processes in natural waters is associated with its toxicity. The NH4+ oxidation process slows down for about five days and ten days in river water samples with 0.5 mg/L DPA and corresponding 0.5 mg/L 1-NA. The NO2− oxidation delay in model samples of river water with 0.025 and 0.05 mg/L 1-NA, is four days and 35 days in the one with 0.5 mg/L 1-NA. For the sample with 0.05 mg/L DPA the delay of the NO2− oxidation is approximately of six days and 25 days for sample with 0.5 mg/L, DPA. The laboratory simulations have revealed: (1) absorption–desorption, the micro biotic reaction to the instantaneous increase of the concentration of ammonium ion in the river water (so-called shock/stress effect) and (2) the NH4+ increase stimulated by a certain (0.05 mg/L) concentration of 1-NA.The diethylamine (DEA) decomposition leads to increasing with approximately 3.8 mg/L NH4+ in river water samples of 20.0 mg/L DEA.