Enhanced carbon export to the abyssal depths driven by atmosphere dynamics

Abstract

Long‐term biogeochemical observations are critical to understand the natural ability of the oceans to fix CO2 into organic carbon and export it to the deep as sinking particles. Here we present results from a 3 year (2010–2013) sediment trap deployment that allowed detecting interannual variations of carbon fluxes beyond 4000 m depth in the Eastern Mediterranean Sea. Anomalous atmospheric conditions triggering strong heat losses in winter–spring 2012 resulted in convective mixing, nutrient uplifting, and a diatom‐dominated bloom southeast of Crete. Phytoplankton growth, reinforced by the arrival of nutrients from airborne Etna volcano ash, was the highest in the last decade (satellite‐derived Chl a concentrations up to 1.9 mg m−3). This situation caused carbon export to increase by 2 orders of magnitude (12.2 mg m−2 d−1) with respect to typical values, which demonstrates how pulses of sinking fresh phytodetritus linked to rare atmospheric processes can episodically impact one of the most oligotrophic environments in the world ocean.

Hurricanes Enhance Labile Carbon Export to the Deep Ocean

“…The magnitude of the increases in total lipid and phytoplankton‐derived lipid fluxes following Nicole is of the same magnitude as the increases in labile lipid fluxes that have been observed at 3,200 m depth at the Bermuda Time Series Site following mesoscale physical forcing of a transient bloom (Conte et al, , ; Table S1). Previous studies have demonstrated that mesoscale ocean features can stimulate production and carbon export to the deep ocean (Conte et al, ; Pedrosa‐Pàmies et al, ; Shih et al, ; Stukel et al, ), but the only prior documented evidence of storm‐induced export of POC to depth is the study of Chen et al () in the oligotrophic northwest Pacific Ocean, where an increase in flux of POC at 125 m depth was observed following an extreme weather event.…”

Atmospheric and Oceanographic Forcing Impact Particle Flux Composition and Carbon Sequestration in the Eastern Mediterranean Sea: A Three-Year Time-Series Study in the Deep Ierapetra Basin

“…Frontiers in Earth Science | www.frontiersin.org February 2021 | Volume 9 | Article 591948 bloom on March 2012 ( Figure 2B). As emphasized by Pedrosa-Pàmies et al (2016), the exceptional phytoplankton bloom was most probably stimulated by the arrival of Si and Fe from airborne Etna volcano ash during March-April 2012. Volcanic eruptions have the potential to cause regional or even global-scale nutrient (mainly Fe)-fertilization (Olgun et al, 2013;Browning et al, 2015;Weinbauer et al, 2017).…”

“…In spring 2012, TMF and POC fluxes were one and two orders of magnitude, respectively, higher than in other spring periods over the study period ( Figure 3C). As highlighted by Pedrosa-Pàmies et al (2016), winter and spring of 2012 were characterized by exceptional atmospheric conditions. During winter 2011-12, particularly strong cold and dry northerly winds triggered intense convection not only in the EMS but also in the NW Mediterranean Sea (Durrieu de Madron et al, 2013;Palanques and Puig, 2018), and in the Adriatic Sea (Bensi et al, 2013;Janeković et al, 2014).…”

“…), and coccolithophores (F) as well as ash microspherules (G-L). Mag: Magnification (see more details in Pedrosa-Pàmies et al, 2016).…”

“…Carbon vertical flux was found to be differentiated along a north-south oligotrophy gradient and "hot spots" for CO 2 sequestration to the ocean interior on long time scales were detected in the less oligotrophic area (Siokou-Frangou et al, 2002;Gogou et al, 2014;Pedrosa-Pàmies et al, 2016;Pavlidou et al, 2020). The weak seasonality of the phytoplankton biomass and production drives NPP rates below 200 mg C m −2 d −1 (Psarra et al, 2000;Moutin and Raimbault, 2002;Bosc, 2004), while very low amounts of POC (<0.5% of NPP) reach the deep sea floor (Warnken, 2003;Koppelmann et al, 2004;Stavrakakis et al, 2013;Gogou et al, 2014;Pedrosa-Pàmies et al, 2016;Karageorgis et al, 2018).…”