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Near-bottom particle flux in the abyssal northeast Atlantic

Near-bottom particle flux in the abyssal northeast Atlantic
Near-bottom particle flux in the abyssal northeast Atlantic
During a 17-month study at a site on the Porcupine Abyssal Plain of the northeast Atlantic (approx. 48°N 20°W), the downward flux of particulate material within and above the benthic nepheloid layer (BNL) was measured using sediment traps 1455 m above bottom (mab) (3100 m depth) and 90 mab (4465 m depth). Flux at 90 mab is usually higher than the primary flux at 3100 m depth, and this enhancement is especially pronounced during the winter. The additional material found in the near-bottom trap comprises recently deposited resuspended material (rebound flux), but with an admixture of refractory sediment. It is unlikely that scavenging of either BNL particles or dissolved material contributes greatly to the near-bottom flux. Fluxes of metal tracers (232Th and Al) and cyanobacteria into traps were used to examine the process of resuspension. The ratio of tracer flux at 90 mab to that at 3100 m depth was taken as a measure of the strength of the resuspension process (the resuspension factor RF) and reflects clearly the enhanced resuspension in winter. This seasonal variation appears to be related to both the magnitude of near-bottom currents and to the wave height at the surface 40 days before. It is also possible that recently deposited material forms a partly cohesive blanket on the sediment surface that restricts resuspension to the benthic boundary layer.
PARTICULATE FLUX, ABYSSAL ZONES, PORCUPINE ABYSSAL PLAIN, SEDIMENT TRAPS, BENTHIC BOUNDARY LAYER
0967-0645
2051-2071
Lampitt, R.S.
dfc3785c-fc7d-41fa-89ee-d0c6e27503ad
Newton, P.P.
dd983c9d-73b0-4c4f-ad34-55f3e538b695
Jickells, T.D.
d85be7a3-239c-402f-83a6-8014b78cc4cc
Thomson, J.
3395054f-e507-4841-9758-a06ed37f7d6b
King, P.
18cb0014-ae2b-4ece-8039-f4f05a03e629
Lampitt, R.S.
dfc3785c-fc7d-41fa-89ee-d0c6e27503ad
Newton, P.P.
dd983c9d-73b0-4c4f-ad34-55f3e538b695
Jickells, T.D.
d85be7a3-239c-402f-83a6-8014b78cc4cc
Thomson, J.
3395054f-e507-4841-9758-a06ed37f7d6b
King, P.
18cb0014-ae2b-4ece-8039-f4f05a03e629

Lampitt, R.S., Newton, P.P., Jickells, T.D., Thomson, J. and King, P. (2000) Near-bottom particle flux in the abyssal northeast Atlantic. Deep Sea Research Part II: Topical Studies in Oceanography, 47 (9-11), 2051-2071. (doi:10.1016/S0967-0645(00)00016-3).

Record type: Article

Abstract

During a 17-month study at a site on the Porcupine Abyssal Plain of the northeast Atlantic (approx. 48°N 20°W), the downward flux of particulate material within and above the benthic nepheloid layer (BNL) was measured using sediment traps 1455 m above bottom (mab) (3100 m depth) and 90 mab (4465 m depth). Flux at 90 mab is usually higher than the primary flux at 3100 m depth, and this enhancement is especially pronounced during the winter. The additional material found in the near-bottom trap comprises recently deposited resuspended material (rebound flux), but with an admixture of refractory sediment. It is unlikely that scavenging of either BNL particles or dissolved material contributes greatly to the near-bottom flux. Fluxes of metal tracers (232Th and Al) and cyanobacteria into traps were used to examine the process of resuspension. The ratio of tracer flux at 90 mab to that at 3100 m depth was taken as a measure of the strength of the resuspension process (the resuspension factor RF) and reflects clearly the enhanced resuspension in winter. This seasonal variation appears to be related to both the magnitude of near-bottom currents and to the wave height at the surface 40 days before. It is also possible that recently deposited material forms a partly cohesive blanket on the sediment surface that restricts resuspension to the benthic boundary layer.

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More information

Published date: 2000
Keywords: PARTICULATE FLUX, ABYSSAL ZONES, PORCUPINE ABYSSAL PLAIN, SEDIMENT TRAPS, BENTHIC BOUNDARY LAYER

Identifiers

Local EPrints ID: 8862
URI: http://eprints.soton.ac.uk/id/eprint/8862
ISSN: 0967-0645
PURE UUID: 17c75871-f752-4f98-850c-7ed9b9794d10

Catalogue record

Date deposited: 13 Sep 2004
Last modified: 15 Mar 2024 04:53

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Contributors

Author: R.S. Lampitt
Author: P.P. Newton
Author: T.D. Jickells
Author: J. Thomson
Author: P. King

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