Th-234 and Po-210 as POC flux proxies during the ARK-XXVII/3 expedition (August-October 2012) ...

• Main Authors: Roca-Martí, Montserrat, Puigcorbé, Viena, Stimac, Ingrid, Rutgers van der Loeff, Michiel M, Masqué, Pere
• Format: Article in Journal/Newspaper
• Language: English
• Published: PANGAEA 2016
• Subjects: Arctic Ocean; Phytoplankton; Sea ice; Zooplankton
• Online Access: https://dx.doi.org/10.1594/pangaea.858790; https://doi.pangaea.de/10.1594/PANGAEA.858790

The Arctic sea-ice extent reached a record minimum in September 2012. Sea-ice decline increases the absorption of solar energy in the Arctic Ocean, affecting primary production and the plankton community. How this will modulate the sinking of particulate organic carbon (POC) from the ocean surface remains a key question. We use the 234Th/238U and 210Po/210Pb radionuclide pairs to estimate the magnitude of the POC export fluxes in the upper ocean of the central Arctic in summer 2012, covering time scales from weeks to months. The 234Th/238U proxy reveals that POC fluxes at the base of the euphotic zone were very low (2 ± 2 mmol C/m**2/d) in late summer. Relationships obtained between the 234Th export fluxes and the phytoplankton community suggest that prasinophytes contributed significantly to the downward fluxes, likely via incorporation into sea-ice algal aggregates and zooplankton-derived material. The magnitude of the depletion of 210Po in the upper water column over the entire study area indicates that ... : Supplement to: Roca-Martí, Montserrat; Puigcorbé, Viena; Rutgers van der Loeff, Michiel M; Katlein, Christian; Fernández-Méndez, Mar; Peeken, Ilka; Masqué, Pere (2016): Carbon export fluxes and export efficiency in the central Arctic during the record sea-ice minimum in 2012: A joint 234Th/238U and 210Po/210Pb study. Journal of Geophysical Research: Oceans, 121(7), 5030-5049 ...