Free Ammonia Inhibition of Nitrification in River Sediments Leading to Nitrite Accumulation
1997; Wiley; Volume: 26; Issue: 4 Linguagem: Inglês
10.2134/jeq1997.00472425002600040016x
ISSN1537-2537
AutoresR.V. Smith, L.C. Burns, Rebecca M. Doyle, S. D. Lennox, Beverley H. L. Kelso, R. H. Foy, Robert Stevens,
Tópico(s)Fish Ecology and Management Studies
ResumoPrevious studies have reporled that only 40% of nitrite (NO−2) in major rivers in Northern Ireland originates from land drainage. The remainder appears to originale from N transformations at the interface between sediment and water within river systems. Streams in two major river catchments in Northern Ireland were monitored for the presence of NO−2. Mean NO2 concentrations (which all exceeded 3.0 µg N L−1 which is the European Community (EC) guide values for supporting salmonid fish) ranged from 3.8 to 84.5 µg N L−1 in 14 streams in the Upper Bann and 10.7 to 60.0 µg N L−1 in 14 streams in the Colebrooke river system. Evidence from multiple regression analysis suggested that NO2 accumulation in these streams was associated with the presence of free NH3. Incubation and differential 15N labeling of sediment extracts with ammonium nitrale (NH4NO3) provided support for this hypothesis that showed that the mechanistic process involved in NO−2 accumulation is nitrification inhibition rather than denitrification. Free NH3 partially inhibils NO−2 oxidation by Nitrobacter, but does not inhibit the oxidation of ammonium (NH+4) by Nitrosomonas. Most of the NH+4 in streams originates from pollution by agricultural effluents and must be curtailed to prevent NO−2 accumulation.
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