Nitrification, Denitrification and Nitrogen Fixation in Bottom Sediments of Lagoons of the Seychelles Islands by M. v. Propp, v. S. Odintsov, L. N. Propp Issued by National Museum of Natural History Smithsonian Institution
نویسندگان
چکیده
Major processes of the nitrogen cycle (i.e., nitrogen fixation, denitrification, ammonia mineralization and nitrification) were investigated in coastal sediments of several Seychelles Islands. Sediments were represented by carbonate sands, except in Victoria Harbor where they were carbonate silt. Nitrogen fixation was measured by acetylene reduction assay, other processes were studied by an experimental flow-through system with regulated nitrogen and oxygen concentrations. In anoxic conditions, nitrate reduction to nitrite and denitrification were determined in all sediment samples. The rates of these processes are rather low, the constants of Michaelis-Menten's equation are adduced; Vshows values ranging from 0.2-1 p ~ a n " h ~ , Km = 15-30 pM. -3. -1 Nitrification did not occur in sandy sediments, and showed low rates (V= 0.1 pMcm h , Km = 12-15 pM) in silty sediments. Denitrification and nitrification rates were dependent on oxygen tension in silty sediments. Overall, the rates of nitrogen transformation in benthic coastal sediments of the Seychelles Islands are considerably lower than in temperate regions. It is probable that the nitrogen cycle in these coastal waters is mainly controlled by processes in very deep vs. shallow waters.
منابع مشابه
Mauke, Mitiaro and Atiu: Geomorphology of Makatea Islands in the Southern Cooks by D. R. Stoddart, C. D. Woodroffe and T. Spencer Issued by National Museum of Natural History Smithsonian Institution
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