EGU2020-22442, updated on 14 Oct 2021
https://doi.org/10.5194/egusphere-egu2020-22442
EGU General Assembly 2020
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Long time-series of export fluxes in the western Ross Sea (Antarctica)

Patrizia Giordano1, Federico Giglio1, Mariangela Ravaioli2, Marco Capello3, Laura Cutroneo3, Robert B. Dunbar4, David A. Mucciarone4, Walker O. Smith5, Clara Manno6, and Leonardo Langone1
Patrizia Giordano et al.
  • 1CNR, Institute of Polar Sciences, Bologna, Italy
  • 2CNR, Institute of Marine Sciences, Bologna, Italy
  • 3University of Genoa, DISTAV, Genoa, Italy
  • 4Stanford University, Stanford, USA
  • 5Virginia Institute of Marine Science, Gloucester Point, USA
  • 6BAS, British Antarctic Survey, Cambridge, UK

The export of particulate organic carbon (POC) from the sea surface is an essential part of the biological pump. Export fluxes are the result of what is produced in surface water and how much is consumed during particle sinking in the water column. In the Ross Sea, fluxes of POC and total mass are well correlated implying that particle fluxes are dominated by biogenic debris.

Here, we report new and reference data of vertical particle fluxes to below the productive layer obtained on decadal time scales (1990-2017) by automatic sediment traps tethered to moorings in the western Ross Sea (Antarctica). Compilation of all data available in the Ross Sea (23 sites, >1000 samples) shows that annual POC fluxes to below 200 m average 4.4±3.3 g C m-2  y-1. Particle fluxes are relatively low when primary production is high (spring-summer) followed by enhanced sedimentation in late summer-fall. The high degree of decoupling between production and sedimentation is unusual compared to records of Antarctic Peninsula and may represent low grazing rates. Furthermore, data exhibit a large interannual variability and a decreasing trend over time, with a clear shift after 2000. Do the reduced export fluxes depend on lower biological production, enhanced OM consumption, or other processes (e.g., lateral transfer of biogenic particles outside the study area)?

Satellite observations allow us to reconstruct the seasonal and interannual change of chlorophyll biomass, and sea ice extent and duration. Water temperature recorded at mid-depth is used to monitor the different intrusion over time of CDW, the main driver of temporal variability of Fe supply for the Ross Sea. Time series of particle fluxes, chlorophyll, sea ice cover and mid-depth temperature will be compared in order to test if the recent reduction of downward particle fluxes depend on primary production changes.

How to cite: Giordano, P., Giglio, F., Ravaioli, M., Capello, M., Cutroneo, L., Dunbar, R. B., Mucciarone, D. A., Smith, W. O., Manno, C., and Langone, L.: Long time-series of export fluxes in the western Ross Sea (Antarctica), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22442, https://doi.org/10.5194/egusphere-egu2020-22442, 2020.

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