scholarly journals Laminarin is a major molecule in the marine carbon cycle

2020 ◽  
Vol 117 (12) ◽  
pp. 6599-6607 ◽  
Author(s):  
Stefan Becker ◽  
Jan Tebben ◽  
Sarah Coffinet ◽  
Karen Wiltshire ◽  
Morten Hvitfeldt Iversen ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Atmospheric Carbon Dioxide ◽  
Carbon Sink ◽  
Light Availability ◽  
Structural Type ◽  
Trophic Levels ◽  
The Arctic ◽  
Terrestrial Plants ◽  
Carbon Export ◽  
The North

Marine microalgae sequester as much CO2into carbohydrates as terrestrial plants. Polymeric carbohydrates (i.e., glycans) provide carbon for heterotrophic organisms and constitute a carbon sink in the global oceans. The quantitative contributions of different algal glycans to cycling and sequestration of carbon remain unknown, partly because of the analytical challenge to quantify glycans in complex biological matrices. Here, we quantified a glycan structural type using a recently developed biocatalytic strategy, which involves laminarinase enzymes that specifically cleave the algal glycan laminarin into readily analyzable fragments. We measured laminarin along transects in the Arctic, Atlantic, and Pacific oceans and during three time series in the North Sea. These data revealed a median of 26 ± 17% laminarin within the particulate organic carbon pool. The observed correlation between chlorophyll and laminarin suggests an annual production of algal laminarin of 12 ± 8 gigatons: that is, approximately three times the annual atmospheric carbon dioxide increase by fossil fuel burning. Moreover, our data revealed that laminarin accounted for up to 50% of organic carbon in sinking diatom-containing particles, thus substantially contributing to carbon export from surface waters. Spatially and temporally variable laminarin concentrations in the sunlit ocean are driven by light availability. Collectively, these observations highlight the prominent ecological role and biogeochemical function of laminarin in oceanic carbon export and energy flow to higher trophic levels.

scholarly journals Permafrost-Affected Soils of the Russian Arctic and their Carbon Pools

2014 ◽  
Vol 6 (1) ◽  
pp. 619-655
Author(s):  
S. Zubrzycki ◽  
L. Kutzbach ◽  
E.-M. Pfeiffer
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Carbon Sink ◽  
Global Climate ◽  
Fundamental Property ◽  
Climate System ◽  
The Arctic ◽  
Quaternary Period ◽  
Permafrost Regions

Abstract. Permafrost-affected soils have accumulated enormous pools of organic matter during the Quaternary Period. The area occupied by these soils amounts to more than 8.6 million km2, which is about 27% of all land areas north of 50° N. Therefore, permafrost-affected soils are considered to be one of the most important cryosphere elements within the climate system. Due to the cryopedogenic processes that form these particular soils and the overlying vegetation that is adapted to the arctic climate, organic matter has accumulated to the present extent of up to 1024 Pg (1 Pg = 1015 g = 1 Gt) of soil organic carbon stored within the uppermost three meters of ground. Considering the observed progressive climate change and the projected polar amplification, permafrost-affected soils will undergo fundamental property changes. Higher turnover and mineralization rates of the organic matter are consequences of these changes, which are expected to result in an increased release of climate-relevant trace gases into the atmosphere. As a result, permafrost regions with their distinctive soils are likely to trigger an important tipping point within the global climate system, with additional political and social implications. The controversy of whether permafrost regions continue accumulating carbon or already function as a carbon source remains open until today. An increased focus on this subject matter, especially in underrepresented Siberian regions, could contribute to a more robust estimation of the soil organic carbon pool of permafrost regions and at the same time improve the understanding of the carbon sink and source functions of permafrost-affected soils.

scholarly journals Greenland Ice Sheet exports labile organic carbon to the Arctic oceans

2013 ◽  
Vol 10 (12) ◽  
pp. 19311-19345 ◽  
Author(s):  
E. C. Lawson ◽  
J. L. Wadham ◽  
M. Tranter ◽  
M. Stibal ◽  
G. P. Lis ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
River System ◽  
The Arctic ◽  
Marine Microorganisms ◽  
The North ◽  
Glacial Runoff ◽  
Order Of Magnitude ◽  
Free Carbohydrates

Abstract. Runoff from small glacier systems contains dissolved organic carbon (DOC), rich in protein-like, low molecular weight (LMW) compounds, designating glaciers as an important source of bioavailable carbon for downstream heterotrophic activity. Fluxes of DOC and particulate organic carbon (POC) exported from large Greenland catchments, however, remain unquantified, despite the Greenland Ice Sheet (GrIS) being the largest source of global glacial runoff (ca. 400 km3 yr−1). We report high and episodic fluxes of POC and DOC from a large (1200 km2) GrIS catchment during contrasting melt seasons. POC dominates organic carbon (OC) export (70–89% on average), is sourced from the ice sheet bed and contains a significant bioreactive component (9% carbohydrates). A major source for the "bioavailable" (free carbohydrates) LMW-DOC fraction is microbial activity on the ice sheet surface, with some further addition of LMW-DOC to meltwaters by biogeochemical processes at the ice sheet bed. The bioavailability of the exported DOC (30–58%) to downstream marine microorganisms is similar to that reported from other glacial watersheds. Annual fluxes of DOC and free carbohydrates during two melt seasons were similar, despite the ~ 2 fold difference in runoff fluxes, suggesting production-limited DOC sources. POC fluxes were also insensitive to an increase in seasonal runoff volumes, indicating supply-limitation of suspended sediment in runoff. Scaled to the GrIS, the combined DOC and POC fluxes (0.13–0.17 Tg C yr−1 DOC, 0.36–1.52 Tg C yr−1 mean POC) are of a similar order of magnitude to a large Arctic river system, and hence represent an important OC source to the North Atlantic, Greenland and Labrador Seas.

scholarly journals Permafrost-affected soils and their carbon pools with a focus on the Russian Arctic

Solid Earth ◽  
2014 ◽  
Vol 5 (2) ◽  
pp. 595-609 ◽  
Author(s):  
S. Zubrzycki ◽  
L. Kutzbach ◽  
E.-M. Pfeiffer
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Carbon Sink ◽  
Fundamental Property ◽  
The Arctic ◽  
Quaternary Period ◽  
Organic Carbon Pool ◽  
Property Changes ◽  
Permafrost Regions

Abstract. Permafrost-affected soils have accumulated enormous pools of organic matter during the Quaternary period. The area occupied by these soils amounts to more than 8.6 million km2, which is about 27% of all land areas north of 50° N. Therefore, permafrost-affected soils are considered to be one of the important cryosphere elements within the climate system. Due to the cryopedogenic processes that form these particular soils and the overlying vegetation that is adapted to the arctic climate, organic matter has accumulated to the present extent of up to 1024 Pg (1 Pg = 1015 g = 1 Gt) of soil organic carbon stored within the uppermost 3 m of ground. Considering the observed progressive climate change and the projected polar amplification, permafrost-affected soils will undergo fundamental property changes. Higher turnover and mineralisation rates of the organic matter are consequences of these changes, which are expected to result in an increased release of climate-relevant trace gases into the atmosphere. The controversy of whether permafrost regions continue accumulating carbon or already function as a carbon source remains open until today. An increased focus on this subject matter, especially in underrepresented Siberian regions, could contribute to a more robust estimation of the soil organic carbon pool of permafrost regions and at the same time improve the understanding of the carbon sink and source functions of permafrost-affected soils.

7. The Arctic carbon vault

2021 ◽  
pp. 125-136
Author(s):  
Klaus Dodds ◽  
Jamie Woodward
Keyword(s):  
Organic Carbon ◽  
Carbon Sink ◽  
Ice Age ◽  
The Arctic ◽  
Yamal Peninsula ◽  
Frozen Ground ◽  
Global Soil ◽  
Shelf Sea ◽  
Thawing Permafrost ◽  
Bodies Of Water

‘The Arctic carbon vault’ describes the large share of Earth's organic carbon sequestered in the frozen ground and within the shelf sea sediments of the Arctic Ocean. The organic carbon stock of the permafrost is roughly equivalent to half of total global soil carbon. A cold Arctic with extensive permafrost is an effective long-term carbon sink as carbon is safely locked away as long as permafrost is maintained. Giant craters appeared on the Yamal peninsula. The thawing permafrost leads to the formation of thermokarst lakes, which are frozen bodies of water held in subsidence depressions created by the thawing of ground ice. Well-preserved carcasses of extinct ice age beasts, including woolly mammoths and cave bears, have been recovered from the thawing permafrost.

Dissolved organic carbon export and subsequent remineralization in the mesopelagic and bathypelagic realms of the North Atlantic basin

2010 ◽  
Vol 57 (16) ◽  
pp. 1433-1445 ◽  
Author(s):  
Craig A. Carlson ◽  
Dennis A. Hansell ◽  
Norman B. Nelson ◽  
David A. Siegel ◽  
William M. Smethie ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
North Atlantic ◽  
Carbon Export ◽  
Atlantic Basin ◽  
North Atlantic Basin ◽  
The North ◽  
The North Atlantic

scholarly journals Projected increase of Arctic coastal erosion and its sensitivity to warming in the 21st Century

2021 ◽  
Author(s):  
David Nielsen ◽  
Patrick Pieper ◽  
Armineh Barkhordarian ◽  
Paul Overduin ◽  
Tatiana Ilyina ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Coastal Erosion ◽  
Erosion Rate ◽  
Carbon Sink ◽  
The Arctic ◽  
Coastal Conservation ◽  
Organic Carbon Flux ◽  
High Emission ◽  
Future Work ◽  
The Impact

Abstract Arctic coastal erosion damages infrastructure, threatens coastal communities, and releases organic carbon from permafrost. However, the magnitude, timing and sensitivity of coastal erosion increase to global warming remain unknown. Here, we project the Arctic-mean erosion rate to roughly double by 2100 and very likely exceed its historical range of variability by mid-21st century. The sensitivity of erosion to warming also doubles, reaching 0.4-0.5 m year-1 oC-1 and 2.3-2.8 TgC year-1 oC-1 by the end of the century under moderate and high-emission scenarios. Our first 21st-century pan-Arctic coastal erosion rate projections should inform policy makers on coastal conservation and socioeconomic planning. Our organic carbon flux projections also lay out the path for future work to investigate the impact of Arctic coastal erosion on the changing Arctic Ocean, on its role as a global carbon sink, and on the permafrost-carbon feedback.

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