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Organic Matter Sources in North Atlantic Fjord Sediments

To better constrain the global carbon cycle fundamental knowledge of the role of carbon cycling on continental margins is crucial. Fjords are particularly important shelf areas for carbon burial due to relatively high sedimentation rates and high organic matter fluxes. As terrigenous organic matter...

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Published in:Geochemistry, geophysics, geosystems : G3 geophysics, geosystems : G3, 2019-06, Vol.20 (6), p.2872-2885
Main Authors: Faust, J.C., Knies, J.
Format: Article
Language:English
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Summary:To better constrain the global carbon cycle fundamental knowledge of the role of carbon cycling on continental margins is crucial. Fjords are particularly important shelf areas for carbon burial due to relatively high sedimentation rates and high organic matter fluxes. As terrigenous organic matter is more resistant to remineralization than marine organic matter, a comprehensive knowledge of the carbon source is critical to better constrain the efficiency of organic carbon burial in fjord sediments. Here we investigated highly productive fjords in northern Norway and compare our results with both existing and new organic carbon to organic nitrogen ratios and carbon stable isotope compositions from fjords in mid‐Norway, west Svalbard, and east Greenland. The marine organic carbon contribution varies significantly between these fjords, and the contribution of marine organic carbon in Norwegian fjords is much larger than previously suggested for fjords in NW Europe and also globally. Additionally, northern Norwegian fjords show very high marine carbon burial rates (73.6 gC · m‐2 · year‐1) suggesting that these fjords are probably very distinct carbon burial hotspots. We argue that the North Atlantic Current inflow sustains these high burial rates and changes in the current strength due to ongoing climate change are likely to have a pronounced effect on carbon burial in North Atlantic fjords. Key Points Organic matter sources in North Atlantic fjords are much more heterogeneous than previously estimated Ongoing climate change is likely to have a pronounced effect on carbon burial in North Atlantic fjords
ISSN:1525-2027
1525-2027
DOI:10.1029/2019GC008382