Nitrous Oxide Production by Bacterioneuston
Abstract
Covering 70% of the Earth, the interface between the ocean and atmosphere, the sea surface microlayer, plays a key role in controlling the exchange of natural and anthropogenic materials. Knowledge of the specific role of the sea surface microlayer and its bacterial population, the bacterioneuston is currently limited. Denitrification is an important route of nitrogen loss from the marine environment. It is also both a sink and source of the greenhouse gas nitrous oxide. Here we investigated the role of denitrifying organisms in the sea-surface microlayer and their potential to lower net emissions of N2O by reducing to N2. Bacterioneuston was sampled from two sites in the Ythan Estuary and in Moray Firth at Cromarty during phytoplankton blooms in Autumn 2007 and Spring 2008 and obtained enrichment cultures from these. Incubation experiments were carried out over a 72 hour period, testing bacterioneuston cultures for N2O production using gas chromatography and nitrate, nitrite and ammonium concentrations. All of the enrichment cultures analysed produced significant quantities of N2O. Results of nitrate, nitrite and ammonium analysis were mixed. Some cultures showed a decrease in nitrate concentration possibly due to nitrate reduction by the bacterioneuston. However, an increase in the nitrate concentration measured with other cultures indicates that N2O production could be due to other nitrogen cycle processes other than denitrification, most likely ammonia oxidation. The results indicate that further research is necessary to establish which nitrogen cycle processes are being carried out the bacterioneuston cultures. Keywords: Denitrification; Bacterioneuston; Sea surface microlayer; Gas Chromatography (GC); Nitrous oxide
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2008
- Bibcode:
- 2008AGUFM.B31B0295M
- Keywords:
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- 0442 Estuarine and nearshore processes (4235);
- 0460 Marine systems (4800);
- 0469 Nitrogen cycling;
- 0470 Nutrients and nutrient cycling (4845;
- 4850);
- 0471 Oxidation/reduction reactions (4851)