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

Benthic carbon mineralization was investigated along a depth transect acros s a sound in the high Arctic. Aerobic mineralization accounted for approxim ately 30% of the total degradation. Anaerobic degradation, responsible for the remaining 70%, was dominated by sulfate- and iron respiration, while de nitrification and manganese respiration were of marginal importance. The to tal benthic degradation rate exhibited a rapidly attenuating exponential de cline with increasing water depth. Permanent carbon burial accounted for ap proximately 50% of the total degradation rate, and was comparable to estima tes from similar settings at lower latitudes. At the shallow stations, bent hic 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 t he rates of benthic degradation, permanent burial, pelagic primary producti on, and sedimentation of organic carbon, a budget for the pelagic-benthic c oupling for outer Young Sound was established. Pelagic production accounted for only a minor fraction of the carbon required by the benthic community, and <delta>C-13 values suggested that terrestric carbon inputs were signif icant. However, the budget also indicated that additional sources of labile organic carbon (ice-algae, benthic microphytes and oceanic inputs) were im portant. During July, the time of the summer bloom, 36% of the sedimenting organic material was either degraded or buried. The remainder fueled the co mmunity respiration during the long, non-productive, winter.