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Benthic-pelagic coupling in the Barents Sea: an integrated data-model framework.

https://arctichealth.org/en/permalink/ahliterature304883
Source
Philos Trans A Math Phys Eng Sci. 2020 Oct 02; 378(2181):20190359
Publication Type
Journal Article
Date
Oct-02-2020
Author
Felipe S Freitas
Katharine R Hendry
Sian F Henley
Johan C Faust
Allyson C Tessin
Mark A Stevenson
Geoffrey D Abbott
Christian März
Sandra Arndt
Author Affiliation
School of Earth Sciences, University of Bristol, Wills Memorial Building, Queen's Road, Bristol BS8 1RJ, UK.
Source
Philos Trans A Math Phys Eng Sci. 2020 Oct 02; 378(2181):20190359
Date
Oct-02-2020
Language
English
Publication Type
Journal Article
Abstract
The Barents Sea is experiencing long-term climate-driven changes, e.g. modification in oceanographic conditions and extensive sea ice loss, which can lead to large, yet unquantified disruptions to ecosystem functioning. This key region hosts a large fraction of Arctic primary productivity. However, processes governing benthic and pelagic coupling are not mechanistically understood, limiting our ability to predict the impacts of future perturbations. We combine field observations with a reaction-transport model approach to quantify organic matter (OM) processing and disentangle its drivers. Sedimentary OM reactivity patterns show no gradients relative to sea ice extent, being mostly driven by seafloor spatial heterogeneity. Burial of high reactivity, marine-derived OM is evident at sites influenced by Atlantic Water (AW), whereas low reactivity material is linked to terrestrial inputs on the central shelf. Degradation rates are mainly driven by aerobic respiration (40-75%), being greater at sites where highly reactive material is buried. Similarly, ammonium and phosphate fluxes are greater at those sites. The present-day AW-dominated shelf might represent the future scenario for the entire Barents Sea. Our results represent a baseline systematic understanding of seafloor geochemistry, allowing us to anticipate changes that could be imposed on the pan-Arctic in the future if climate-driven perturbations persist. This article is part of the theme issue 'The changing Arctic Ocean: consequences for biological communities, biogeochemical processes and ecosystem functioning'.
PubMed ID
32862804 View in PubMed
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Does Arctic warming reduce preservation of organic matter in Barents Sea sediments?

https://arctichealth.org/en/permalink/ahliterature304877
Source
Philos Trans A Math Phys Eng Sci. 2020 Oct 02; 378(2181):20190364
Publication Type
Journal Article
Date
Oct-02-2020
Author
Johan C Faust
Mark A Stevenson
Geoffrey D Abbott
Jochen Knies
Allyson Tessin
Isobel Mannion
Ailbe Ford
Robert Hilton
Jeffrey Peakall
Christian März
Author Affiliation
School of Earth and Environment, The University of Leeds, Leeds, UK.
Source
Philos Trans A Math Phys Eng Sci. 2020 Oct 02; 378(2181):20190364
Date
Oct-02-2020
Language
English
Publication Type
Journal Article
Abstract
Over the last few decades, the Barents Sea experienced substantial warming, an expansion of relatively warm Atlantic water and a reduction in sea ice cover. This environmental change forces the entire Barents Sea ecosystem to adapt and restructure and therefore changes in pelagic-benthic coupling, organic matter sedimentation and long-term carbon sequestration are expected. Here we combine new and existing organic and inorganic geochemical surface sediment data from the western Barents Sea and show a clear link between the modern ecosystem structure, sea ice cover and the organic carbon and CaCO3 contents in Barents Sea surface sediments. Furthermore, we discuss the sources of total and reactive iron phases and evaluate the spatial distribution of organic carbon bound to reactive iron. Consistent with a recent global estimate we find that on average 21.0?±?8.3 per cent of the total organic carbon is associated to reactive iron (fOC-FeR) in Barents Sea surface sediments. The spatial distribution of fOC-FeR, however, seems to be unrelated to sea ice cover, Atlantic water inflow or proximity to land. Future Arctic warming might, therefore, neither increase nor decrease the burial rates of iron-associated organic carbon. However, our results also imply that ongoing sea ice reduction and the associated alteration of vertical carbon fluxes might cause accompanied shifts in the Barents Sea surface sedimentary organic carbon content, which might result in overall reduced carbon sequestration in the future. This article is part of the theme issue 'The changing Arctic Ocean: consequences for biological communities, biogeochemical processes and ecosystem functioning'.
PubMed ID
32862811 View in PubMed
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Transformation of organic matter in a Barents Sea sediment profile: coupled geochemical and microbiological processes.

https://arctichealth.org/en/permalink/ahliterature304875
Source
Philos Trans A Math Phys Eng Sci. 2020 Oct 02; 378(2181):20200223
Publication Type
Journal Article
Date
Oct-02-2020
Author
Mark A Stevenson
Johan C Faust
Luiza L Andrade
Felipe S Freitas
Neil D Gray
Karen Tait
Katharine R Hendry
Robert G Hilton
Sian F Henley
Allyson Tessin
Peter Leary
Sonia Papadaki
Ailbe Ford
Christian März
Geoffrey D Abbott
Author Affiliation
School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK.
Source
Philos Trans A Math Phys Eng Sci. 2020 Oct 02; 378(2181):20200223
Date
Oct-02-2020
Language
English
Publication Type
Journal Article
Abstract
Process-based, mechanistic investigations of organic matter transformation and diagenesis directly beneath the sediment-water interface (SWI) in Arctic continental shelves are vital as these regions are at greatest risk of future change. This is in part due to disruptions in benthic-pelagic coupling associated with ocean current change and sea ice retreat. Here, we focus on a high-resolution, multi-disciplinary set of measurements that illustrate how microbial processes involved in the degradation of organic matter are directly coupled with inorganic and organic geochemical sediment properties (measured and modelled) as well as the extent/depth of bioturbation. We find direct links between aerobic processes, reactive organic carbon and highest abundances of bacteria and archaea in the uppermost layer (0-4.5?cm depth) followed by dominance of microbes involved in nitrate/nitrite and iron/manganese reduction across the oxic-anoxic redox boundary (approx. 4.5-10.5?cm depth). Sulfate reducers dominate in the deeper (approx. 10.5-33?cm) anoxic sediments which is consistent with the modelled reactive transport framework. Importantly, organic matter reactivity as tracked by organic geochemical parameters (n-alkanes, n-alkanoic acids, n-alkanols and sterols) changes most dramatically at and directly below the SWI together with sedimentology and biological activity but remained relatively unchanged across deeper changes in sedimentology. This article is part of the theme issue 'The changing Arctic Ocean: consequences for biological communities, biogeochemical processes and ecosystem functioning'.
PubMed ID
32862813 View in PubMed
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