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

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

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.

abyssal community, carbon budget, carbon flux
0027-8424
12235-12240
Smith, Kenneth L.
c282f721-59cf-4caa-a344-f4a26f6b534c
Ruhl, Henry A.
177608ef-7793-4911-86cf-cd9960ff22b6
Huffard, Christine L.
888a9c43-4643-4865-9c70-0b324f42d54b
Messié, Monique
af861ec4-d67c-406a-ad95-7fc2193ef173
Kahru, Mati
15e387a7-4eee-43ab-9b05-00e117f6164f
Smith, Kenneth L.
c282f721-59cf-4caa-a344-f4a26f6b534c
Ruhl, Henry A.
177608ef-7793-4911-86cf-cd9960ff22b6
Huffard, Christine L.
888a9c43-4643-4865-9c70-0b324f42d54b
Messié, Monique
af861ec4-d67c-406a-ad95-7fc2193ef173
Kahru, Mati
15e387a7-4eee-43ab-9b05-00e117f6164f

Smith, Kenneth L., Ruhl, Henry A., Huffard, Christine L., Messié, Monique and 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. (doi:10.1073/pnas.1814559115).

Record type: Article

Abstract

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.

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e-pub ahead of print date: 14 November 2018
Published date: 27 November 2018
Keywords: abyssal community, carbon budget, carbon flux

Identifiers

Local EPrints ID: 426764
URI: http://eprints.soton.ac.uk/id/eprint/426764
ISSN: 0027-8424
PURE UUID: 98459d5c-f33f-4d7f-b7c1-59a496ad0809

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Date deposited: 12 Dec 2018 17:30
Last modified: 16 Dec 2019 17:49

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Contributors

Author: Kenneth L. Smith
Author: Henry A. Ruhl
Author: Christine L. Huffard
Author: Monique Messié
Author: Mati Kahru

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