ARCTIC SEDIMENTS (SVALBARD) - CONSUMPTION AND MICRODISTRIBUTION OF OXYGEN

Total sediment oxygen consumption rates (TSOC or J(tot)), measured dur ing sediment-water incubations, and sediment oxygen microdistributions were studied at 16 stations in the Arctic Ocean (Svalbard area). The oxygen consumption rates ranged between 1.85 and 11.2 mmol m-2 d-1, an d oxygen penetrated from 5.0 to greater-than-or-equal-to 59 mm into th e investigated sediments. Measured TSOC exceeded the calculated diffus ive oxygen fluxes (J(diff)) by 1.1-4.8 times. Diffusive fluxes across the sediment-water interface were calculated using the whole measured microprofiles, rather than the linear oxygen gradient in the top sedim ent layer. The lack of a significant correlation between found abundan ces of bioirrigating meiofauna and high J(tot)/J(diff) ratios as well as minor discrepancies in measured TSOC between replicate sediment cor es, suggest molecular diffusion, not bioirrigation, to be the most imp ortant transport mechanism for oxygen across the sediment-water interf ace and within these sediments. The high ratios of J(tot)/J(diff) obta ined for some stations were therefore suggested to be caused by topogr aphic factors, i.e. underestimation of the actual sediment surface are a when one-dimensional diffusive fluxes were calculated, or sampling a rtifacts during core recovery from great water depths. Measured TSOC c orrelated to water depth raised to the -0.4 to -0.5 power (TSOC = wate r depth-0.4 to -0.5) for all investigated stations, but they could be divided into two groups representing different geographical areas with different sediment oxygen consumption characteristics. The difference s in TSOC between the two areas were suggested to reflect hydrographic factors (such as ice coverage and import/production of reactive parti culate organic material) related to the dominating water mass (Atlanti c or polar) in each of the two areas. The good correlation between TSO C and water depth-0.4 to -0.5 rules out any of the stations investigat ed to be topographic depressions with pronounced enhanced sediment oxy gen consumption.