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Seasonal and interannual changes in particulate organic carbon export and deposition in the Chukchi Sea

Seasonal and interannual changes in particulate organic carbon export and deposition in the Chukchi Sea
Seasonal and interannual changes in particulate organic carbon export and deposition in the Chukchi Sea
Particulate organic carbon (POC) export fluxes were estimated in the shelf-slope region of the Chukchi Sea using measurements of 234Th?238U disequilibria and the POC/234Th ratio in large (>53-?m) particles. These export fluxes were used in conjunction with rates of primary productivity and benthic carbon respiration to construct a POC budget for this shelf-slope region. Samples were collected along a series of shelf-basin transects in the spring (May–June) and summer (July–August) of 2004. These stations were previously occupied during the ice covered (spring) and open water (summer) seasons of 2002, allowing for an interannual comparison of export flux. In contrast to 2002, when open water POC fluxes were significantly higher than in the ice-covered period, POC export fluxes in 2004 were similar during the spring (average = 19.7 ± 24.8 mmol C m?2 d?1) and summer (average = 20.0 ± 14.5 mmol C m?2 d?1). The high POC fluxes measured during the spring are attributed to a plankton bloom, as evidenced by exceptionally high rates of primary productivity (average = 124.4 ± 88.1 mmol C m?2 d?1). The shelf-slope budget of particulate organic carbon indicates that 10–20% of primary productivity was exported below 50 m but was not consumed during benthic carbon respiration or burial and oxidation in underlying sediments. Furthermore, a water column?sediment budget of 234Th indicates that particulate material is retained in shelf sediments on a seasonal basis.
thorium-234, carbon, arctic
2169-9275
C10024
Lepore, K.
cac7d1b6-16ac-4d5d-8680-3ef36823565e
Moran, S.B.
d51ee82a-f1da-42f9-8f1f-2b37fa42e1ac
Grebmeier, J.M.
291b0646-7872-47a4-88ac-2d523b14865f
Cooper, L.W.
ef1a64b1-2402-49f3-a9e7-9f29669afaca
Lalande, C.
b8ee2411-169c-4ca6-9f71-abbaebe210a2
Maslowski, W.
3d4f2e71-281e-42e3-b7c3-ab1c161c6e4d
Hill, V.
18192132-d8a8-459c-baa9-42fddf01a2ca
Bates, N.R.
954a83d6-8424-49e9-8acd-e606221c9c57
Hansell, D.A.
53f10e53-25f5-4608-a9b0-58a9f8a05686
Mathis, J.T.
ea2fbcc0-d00e-44d4-98a8-0f97e7e3274b
Kelly, R.P.
837aa6c5-6019-460e-943d-8bb49b9c49c0
Lepore, K.
cac7d1b6-16ac-4d5d-8680-3ef36823565e
Moran, S.B.
d51ee82a-f1da-42f9-8f1f-2b37fa42e1ac
Grebmeier, J.M.
291b0646-7872-47a4-88ac-2d523b14865f
Cooper, L.W.
ef1a64b1-2402-49f3-a9e7-9f29669afaca
Lalande, C.
b8ee2411-169c-4ca6-9f71-abbaebe210a2
Maslowski, W.
3d4f2e71-281e-42e3-b7c3-ab1c161c6e4d
Hill, V.
18192132-d8a8-459c-baa9-42fddf01a2ca
Bates, N.R.
954a83d6-8424-49e9-8acd-e606221c9c57
Hansell, D.A.
53f10e53-25f5-4608-a9b0-58a9f8a05686
Mathis, J.T.
ea2fbcc0-d00e-44d4-98a8-0f97e7e3274b
Kelly, R.P.
837aa6c5-6019-460e-943d-8bb49b9c49c0

Lepore, K., Moran, S.B., Grebmeier, J.M., Cooper, L.W., Lalande, C., Maslowski, W., Hill, V., Bates, N.R., Hansell, D.A., Mathis, J.T. and Kelly, R.P. (2007) Seasonal and interannual changes in particulate organic carbon export and deposition in the Chukchi Sea Journal of Geophysical Research: Oceans, 112, (C10), C10024. (doi:10.1029/2006JC003555).

Record type: Article

Abstract

Particulate organic carbon (POC) export fluxes were estimated in the shelf-slope region of the Chukchi Sea using measurements of 234Th?238U disequilibria and the POC/234Th ratio in large (>53-?m) particles. These export fluxes were used in conjunction with rates of primary productivity and benthic carbon respiration to construct a POC budget for this shelf-slope region. Samples were collected along a series of shelf-basin transects in the spring (May–June) and summer (July–August) of 2004. These stations were previously occupied during the ice covered (spring) and open water (summer) seasons of 2002, allowing for an interannual comparison of export flux. In contrast to 2002, when open water POC fluxes were significantly higher than in the ice-covered period, POC export fluxes in 2004 were similar during the spring (average = 19.7 ± 24.8 mmol C m?2 d?1) and summer (average = 20.0 ± 14.5 mmol C m?2 d?1). The high POC fluxes measured during the spring are attributed to a plankton bloom, as evidenced by exceptionally high rates of primary productivity (average = 124.4 ± 88.1 mmol C m?2 d?1). The shelf-slope budget of particulate organic carbon indicates that 10–20% of primary productivity was exported below 50 m but was not consumed during benthic carbon respiration or burial and oxidation in underlying sediments. Furthermore, a water column?sediment budget of 234Th indicates that particulate material is retained in shelf sediments on a seasonal basis.

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Published date: October 2007
Keywords: thorium-234, carbon, arctic
Organisations: Ocean Biochemistry & Ecosystems

Identifiers

Local EPrints ID: 357432
URI: http://eprints.soton.ac.uk/id/eprint/357432
ISSN: 2169-9275
PURE UUID: 680bf19e-d960-405f-8043-dde279ca3ad6

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Date deposited: 25 Sep 2013 12:20
Last modified: 18 Jul 2017 03:32

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Contributors

Author: K. Lepore
Author: S.B. Moran
Author: J.M. Grebmeier
Author: L.W. Cooper
Author: C. Lalande
Author: W. Maslowski
Author: V. Hill
Author: N.R. Bates
Author: D.A. Hansell
Author: J.T. Mathis
Author: R.P. Kelly

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