23 Aug 2022
23 Aug 2022
Status: this preprint is open for discussion.

Drivers of Particle Sinking Velocities in the Peruvian Upwelling System

Moritz Baumann1, Allanah Joy Paul1, Jan Taucher1, Lennart Thomas Bach2, Silvan Goldenberg1, Paul Stange1, Fabrizio Minutolo3, and Ulf Riebesell1 Moritz Baumann et al.
  • 1Biological Oceanography, GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
  • 2Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, Australia
  • 3Helmholtz Centre Hereon, Institute of Carbon Cycles, Geesthacht, Germany

Abstract. As one of Earth’s most productive marine ecosystems, the Peruvian Upwelling System transports large amounts of biogenic matter from the surface to the deep ocean. Whilst particle sinking velocity is a key factor controlling the biological pump, thereby affecting carbon sequestration and O2-depletion, it has not yet been measured in this system. During a 50-day mesocosm experiment in the surface waters off the coast of Peru, we measured particle sinking velocities and their biogeochemical and physical drivers. We further characterized the general properties of exported particles under different phytoplankton communities and nutritional states. Average sinking velocities varied between size classes and ranged from 12.8 ± 0.7 m d-1 (particles 40–100 µm), to 19.4 ± 0.7 m d-1 (particles 100–250 µm), and 34.2 ± 1.5 m d-1 (particles 250–1000 µm) (±95% CI). Surprisingly, no relationship between opal ballast and sinking velocity could be identified, despite the presence of diatoms, questioning the importance of opal ballast in freshly produced material sinking from the surface. In contrast, we found higher sinking velocities with increasing particle size, compactness and roundness. Size had by far the strongest influence among these physical particle properties. Our study provides a detailed analysis of the drivers of particle sinking velocity in the Peruvian Upwelling System, which allows modelers to optimize local particle flux parameterization. This will help to better project oxygen concentrations and carbon sequestration in a region that is subject to substantial climate-driven changes.

Moritz Baumann et al.

Status: open (until 04 Oct 2022)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2022-814', Emmanuel C. Laurenceau-Cornec, 27 Sep 2022 reply
  • RC2: 'Comment on egusphere-2022-814', Emma Cavan, 29 Sep 2022 reply

Moritz Baumann et al.

Moritz Baumann et al.


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Short summary
The sinking velocity of marine particles affects how much atmospheric CO2 is stored inside our oceans. We measured particle sinking velocities in the Peruvian Upwelling System and assessed their physical and biochemical drivers. We found that sinking velocity was mainly influenced by particle size and compactness, while ballasting minerals played only a minor role. Our findings help to better understand the particle sinking dynamics in this highly productive marine system.