Sediment Nitrification, Denitrification, and Nitrous Oxide Production in a Deep Arctic Lake †
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 in...
| Main Authors: | , |
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| Format: | Text |
| Language: | English |
| Published: |
1983
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| Subjects: | |
| Online Access: | http://www.ncbi.nlm.nih.gov/pmc/articles/PMC239523 http://www.ncbi.nlm.nih.gov/pubmed/16346416 |
| Summary: | 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. |
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