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Episodic organic carbon fluxes from surface ocean to abyssal depths during long-term monitoring in NE Pacific

Smith, Kenneth L.; Ruhl, Henry A.; Huffard, Christine L.; Messié, Monique; Kahru, Mati. 2018 Episodic organic carbon fluxes from surface ocean to abyssal depths during long-term monitoring in NE Pacific. Proceedings of the National Academy of Sciences, 115 (48). 12235-12240. https://doi.org/10.1073/pnas.1814559115

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Abstract/Summary

Growing evidence suggests substantial quantities of particulate organic carbon (POC) produced in surface waters reach abyssal depths within days during episodic flux events. A 29-year record of in situ observations was used to examine episodic peaks in POC fluxes and sediment community oxygen consumption (SCOC) at Station M (NE Pacific, 4,000-m depth). From 1989 to 2017, 19% of POC flux at 3,400 m arrived during high-magnitude episodic events (≥mean + 2 σ), and 43% from 2011 to 2017. From 2011 to 2017, when high-resolution SCOC data were available, time lags between changes in satellite-estimated export flux (EF), POC flux, and SCOC on the sea floor varied between six flux events from 0 to 70 days, suggesting variable remineralization rates and/or particle sinking speeds. Half of POC flux pulse events correlated with prior increases in EF and/or subsequent SCOC increases. Peaks in EF overlying Station M frequently translated to changes in POC flux at abyssal depths. A power-law model (Martin curve) was used to estimate abyssal fluxes from EF and midwater temperature variation. While the background POC flux at 3,400-m depth was described well by the model, the episodic events were significantly underestimated by ∼80% and total flux by almost 50%. Quantifying episodic pulses of organic carbon into the deep sea is critical in modeling the depth and intensity of POC sequestration and understanding the global carbon cycle.

Item Type: Publication - Article
Digital Object Identifier (DOI): https://doi.org/10.1073/pnas.1814559115
ISSN: 0027-8424
Date made live: 08 Jan 2019 15:28 +0 (UTC)
URI: http://nora.nerc.ac.uk/id/eprint/521990

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