The Organic Carbon Budget of a Shallow Arctic Tundra Lake on the Tuktoyaktuk Peninsula, N.W.T., Canada: Arctic Lake Carbon Budget

• Published in: Biogeochemistry 1994-01, Vol.24 (3), p.145-172
• Main Authors: Ramlal, P. S., Hesslein, R. H., Hecky, R. E., Fee, E. J., Rudd, J. W. M., Guildford, S. J.
• Format: Article
• Language: English
• Subjects: Carbon dioxide; Freshwater; Freshwater fishes; Global carbon budget; Ice; Lakes; Macrophytes; Photosynthesis; Respiration; Sediments; Surface water
• ISSN: 0168-2563; 1573-515X
• DOI: 10.1007/BF00003270

The organic carbon cycle of a shallow, tundra lake (mean depth 1.45 m) was followed for 5 weeks of the open water period by examining CO2 fluxes through benthic respiration and anaerobic decomposition, photosynthesis of benthic and phytoplankton communities and gas exchange at the air-water interface. Total photosynthesis (as consumption of carbon dioxide) was 37.5 mmole C m-2 d-1, 83% of which was benthic and macrophytic. By direct measurement benthic respiration exceeded benthic photosynthesis by 6.6 mmole C m-2 d-1. The lake lost 1.4× 106 moles C in two weeks after ice melted by degassing CO2, and 6.8 mmole C m-2 d-1(1.5× 106 moles) during the remainder of the open water period; 2.2 mmole C m-2 d-1 of this was release of CO2 stored in the sediments by cryoconcentration the previous winter. Anaerobic microbial decomposition was only 4% of the benthic aerobic respiration rate of 38 mmole C m-2 d-1. An annual budget estimate for the lake indicated that 50% of the carbon was produced by the benthic community, 20% by phytoplankton, and 30% was allochthonous material. The relative contribution of allochthonous input was in accordance with measurement of the δ 15N of sedimented organic matter.