Significance of Low-Oxygen Zone for Nitrogen Cycling in a Freshwater Lake : Production of N2O by Simultaneous Denitrification and Nitrification

• Published in: Japanese Journal of Limnology (Rikusuigaku Zasshi) Vol. 51; no. 3; pp. 163 - 171
• Main Authors: YOH, Muneoki, YAGI, Akihiko, TERAI, Hisayoshi
• Format: Journal Article
• Language: English; Japanese
• Published: The Japanese Society of Limnology 1990
• Subjects: denitrification; low-oxygen zone; N2O; nitrification
• ISSN: 0021-5104; 1882-4897
• DOI: 10.3739/rikusui.51.163

Denitrifying and nitrifying activities were determined to elucidate the mechanism of N2O accumulation in the oxygen depleted zone of Lake Kizaki. Both activities were detected without any substrate enrichments in a zone of low-oxygen content (0.03-0.14 ml·-1), where N2O and NO2-were accumulated. The determined nitrifying activity approximately coincided with the NH4+ utilization estimated from the NH4+ budget in this zone during the observation interval. On the basis of these activities and the change in N2O concentation, it was suggested that the observed N2O accumulation had dual origins of nitrification and denitirification and that these productions were in a dynamic equilibrium with further reduction of N2O to N2. The low-oxygen zone was found to be an active site for nitrogen cycling and was characterized by the presence of dissolved Mn and the absences of dissolved Fe and sulfide.