Sediment Nitrification, Denitrification, and Nitrous Oxide Production in a Deep Arctic Lake †

AUTOR(ES)

Klingensmith, K. M.

RESUMO

We used a combination of 15N tracer methods and a C2H2 blockage technique to determine the role of sediment nitrification and denitrification in a deep oligotrophic arctic lake. Inorganic nitrogen concentrations ranged between 40 and 600 nmol · cm−3, increasing with depth below the sediment-water interface. Nitrate concentrations were at least 10 times lower, and nitrate was only detectable within the top 0 to 6 cm of sediment. Eh and pH profiles showed an oxidized surface zone underlain by more reduced conditions. The lake water never became anoxic. Sediment Eh values ranged from −7 to 484 mV, decreasing with depth, whereas pH ranged from 6.0 to 7.3, usually increasing with depth. The average nitrification rate (49 ng of N · cm−3 · day−1) was similar to the average denitrification rate (44 ng of N · cm−3 · day−1). In situ N2O production from nitrification and denitrification ranged from 0 to 25 ng of N · cm−3 · day−1. Denitrification appears to depend on the supply of nitrate by nitrification, such that the two processes are coupled functionally in this sediment system. However, the low rates result in only a small nitrogen loss.

Documentos Relacionados

• Denitrification, Acetylene Reduction, and Methane Metabolism in Lake Sediment Exposed to Acetylene
• Effects of Methane Metabolism on Nitrification and Nitrous Oxide Production in Polluted Freshwater Sediment
• Biosensor Determination of the Microscale Distribution of Nitrate, Nitrate Assimilation, Nitrification, and Denitrification in a Diatom-Inhabited Freshwater Sediment
• Denitrification, Dissimilatory Reduction of Nitrate to Ammonium, and Nitrification in a Bioturbated Estuarine Sediment as Measured with 15N and Microsensor Techniques
• Kinetic Explanation for Accumulation of Nitrite, Nitric Oxide, and Nitrous Oxide During Bacterial Denitrification †