MEPS 206:59-71 (2000)  -  doi:10.3354/meps206059

Benthic carbon mineralization in a high-Arctic sound (Young Sound, NE Greenland)

Ronnie Nøhr Glud1,*, Nils Risgaard-Petersen2, Bo Thamdrup3, Henrik Fossing2, Søren Rysgaard2

1Marine Biological Laboratory, Copenhagen University, Strandpromenaden 5, 3000 Helsingør, Denmark
2National Environmental Research Institution, Department of Lake and Estuarine Ecology, Vejlsøvej 25, 8600 Silkeborg, Denmark
3Danish Center for Earth System Science, Institute of Biology, Odense University, Campusvej 55, 5230 Odense M, Denmark

ABSTRACT: Benthic carbon mineralization was investigated along a depth transect across a sound in the high Arctic. Aerobic mineralization accounted for approximately 30% of the total degradation. Anaerobic degradation, responsible for the remaining 70%, was dominated by sulfate- and iron respiration, while denitrification and manganese respiration were of marginal importance. The total benthic degradation rate exhibited a rapidly attenuating exponential decline with increasing water depth. Permanent carbon burial accounted for approximately 50% of the total degradation rate, and was comparable to estimates from similar settings at lower latitudes. At the shallow stations, benthic infauna stimulated the benthic oxygen exchange by a factor of 1.5 to 3 relative to molecular diffusion. However, the estimated metabolic activity of the fauna itself accounted for <10% of total benthic degradation. From the rates of benthic degradation, permanent burial, pelagic primary production, and sedimentation of organic carbon, a budget for the pelagic-benthic coupling for outer Young Sound was established. Pelagic production accounted for only a minor fraction of the carbon required by the benthic community, and δ13C values suggested that terrestric carbon inputs were significant. However, the budget also indicated that additional sources of labile organic carbon (ice-algae, benthic microphytes and oceanic inputs) were important. During July, the time of the summer bloom, 36% of the sedimenting organic material was either degraded or buried. The remainder fueled the community respiration during the long, non-productive, winter.

KEY WORDS: Sediment · Benthic exchange · Fluxes · Oxygen · Carbon · Burial

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