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Distribution and export of particulate organic carbon in East Antarctic coastal polynyas

Citation

Ratnarajah, L and Puigcorbe, V and Moreau, S and Roca-Marti, M and Janssens, J and Corkill, M and Duprat, L and Genovese, C and Lieser, J and Masque, P and Lannuzel, D, Distribution and export of particulate organic carbon in East Antarctic coastal polynyas, Deep-Sea Research. Part 1, 190 Article 103899. ISSN 0967-0637 (2022) [Refereed Article]

Copyright Statement

2022 Published by Elsevier Ltd.

DOI: doi:10.1016/j.dsr.2022.103899

Abstract

Polynyas represent regions of enhanced primary production because of the low, or absent, sea-ice cover coupled with the proximity of nutrient sources. However, studies throughout the Southern Ocean suggest elevated primary production does not necessarily result in increased carbon export. Three coastal polynyas in East Antarctica and an off-shelf region were visited during the austral summer from December 2016 to January 2017 to examine the vertical distribution and concentration of particulate organic carbon (POC). Carbon export was also examined using thorium-234 (234Th) as a proxy at two of the polynyas. Our results show that concentrations and integrated POC stocks were higher within the polynyas compared to the off-shelf sites. Within the polynyas, vertical POC concentrations were higher in the Mertz and Ninnis polynyas compared to the Dalton polynya. Similarly, higher carbon export was measured in the diatom-dominated Mertz polynya, where large particles (>53 μm) represented a significant fraction of the particulate 234Th and POC (average 50% and 39%, respectively), compared to the small flagellate-dominated Dalton polynya, where almost all the particulate 234Th and POC were found in the smaller size fraction (153 μm). The POC to Chlorophyll-a ratios suggest that organic matter below the mixed layer in the polynyas consisted largely of fresh phytoplankton at this time of the year. In combination with a parallel study on phytoplankton production at these sites, we find that increased primary production at these polynyas does lead to greater concentrations and export of POC and a higher POC export efficiency.

Item Details

Item Type:Refereed Article
Keywords:particulate organic carbon, POC export, 234Th, polynya, Southern Ocean, East Antarctica
Research Division:Biological Sciences
Research Group:Ecology
Research Field:Ecology not elsewhere classified
Objective Division:Environmental Management
Objective Group:Management of Antarctic and Southern Ocean environments
Objective Field:Biodiversity in Antarctic and Southern Ocean environments
UTAS Author:Ratnarajah, L (Dr Lavenia Ratnarajah)
UTAS Author:Moreau, S (Dr Sebastien Moreau)
UTAS Author:Janssens, J (Miss Julie Janssens)
UTAS Author:Corkill, M (Mr Matthew Corkill)
UTAS Author:Duprat, L (Mr Duprat)
UTAS Author:Genovese, C (Miss Cristina Genovese)
UTAS Author:Lieser, J (Dr Jan Lieser)
UTAS Author:Lannuzel, D (Associate Professor Delphine Lannuzel)
ID Code:154055
Year Published:2022
Deposited By:Directorate
Deposited On:2022-10-26
Last Modified:2022-11-30
Downloads:0

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