Carbon cycling and burial in the glacially influenced polar North Atlantic

Abstract

We have collated published records of carbon storage (wt % calcium carbonate and organic carbon) in polar North Atlantic sediments in order to assess the role that the glacial history of Greenland and Fennoscandia may have had on carbon cycling in this oceanographically important region. The proportion of carbonate in sediment varies between 0 and ∼50%, while that of organic carbon varies between 0 and ∼2.0%. The spatial variation of the concentration and accumulation of both constituents is markedly different. Bulk accumulation shows a strong relationship with depth, distance offshore, and the location of major glacial outlets on neighboring landmasses. Therefore, ice sheet dynamics and erosion influence carbon (especially organic carbon) storage strongly during the late Weichselian (27-12 14C ka) via their impact on sedimentation rates and constituents. In contrast, water mass characteristics are important in determining the pattern of carbon storage during the Holocene. Carbonate fluxes to the polar North Atlantic sediment column fall by ∼50% during glacials to ∼1.1 × 1013 kg kyr-1, but organic carbon storage is maintained at or greater than interglacial levels (∼4.6 × 1011 kg kyr-1). This represents a 100% change in the ratio of preserved inorganic to organic carbon. When combined with reduced deep water ventilation, respiration of this relatively greater organic carbon flux in both the water and sediment columns provides a good explanation for the observed periodic enhanced dissolution of carbonate in polar North Atlantic late Weichselian sections, perhaps enhancing CO2 storage in deep waters.