Sara Jutterström

Out-gassing of CO2 from Siberian Shelf seas by terrestrial organic matter decomposition

the transport to the deep central Arctic Ocean as well as the atmospheric exchange. However the substantial input of both dissolved and particulate organic matter to the shelf seas [Macdonald et al., 2008], especially during the ice free summer season, hampers light penetration and results in moderate marine primary production outside the river mouths of the great Siberian rivers. Hence, terrestrial organic matter dominates over marine produced organic matter as a source of CO2 to the atmosphere in this area. [4] Here we show that significant microbial decay of terrestrial organic matter occurs in the Siberian Shelf Seas, which results in a substantial flux of CO2 to the atmosphere. Our findings suggest that the release of CO2 from decaying terrestrial organic matter within the Siberian Shelf Seas could be an important and so far underestimated source of CO2 to the atmosphere. This source of CO2 will likely increase, as predicted results of future warming include increased permafrost thawing, river discharge and coastal erosion.

Ventilation of the Arctic Ocean : Mean ages and inventories of anthropogenic CO2 and CFC-11

The Arctic Ocean constitutes a large body of water that is still relatively poorly surveyed because of logistical difficulties, although the importance of the Arctic Ocean for global circulation and climate is widely recognized. For instance, the concentration and inventory of anthropogenic CO2 (C ant) in the Arctic Ocean are not properly known despite its relatively large volume of well-ventilated waters. In this work, we have synthesized available transient tracer measurements (e.g., CFCs and SF6) made during more than two decades by the authors. The tracer data are used to estimate the ventilation of the Arctic Ocean, to infer deep-water pathways, and to estimate the Arctic Ocean inventory of C ant. For these calculations, we used the transit time distribution (TTD) concept that makes tracer measurements collected over several decades comparable with each other. The bottom water in the Arctic Ocean has CFC values close to the detection limit, with somewhat higher values in the Eurasian Basin. The ventilation time for the intermediate water column is shorter in the Eurasian Basin (∼200 years) than in the Canadian Basin (∼300 years). We calculate the Arctic Ocean C ant inventory range to be 2.5 to 3.3 Pg-C, normalized to 2005, i.e., ∼2% of the global ocean C ant inventory despite being composed of only ∼1% of the global ocean volume. In a similar fashion, we use the TTD field to calculate the Arctic Ocean inventory of CFC-11 to be 26.2 ± 2.6 × 106 moles for year 1994, which is ∼5% of the global ocean CFC-11 inventory