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The flux of bio- and lithogenic material associated with sinking particles in the mesopelagic 'twilight zone' of the northwest and North Central Pacific Ocean
Citation
Lamborg, CH and Buesseler, KO and Valdes, J and Bertrand, CH and Bidigare, R and Manganini, S and Pike, S and Steinberg, D and Trull, T and Wilson, S, The flux of bio- and lithogenic material associated with sinking particles in the mesopelagic 'twilight zone' of the northwest and North Central Pacific Ocean, Deep Sea Research Part II: Topical Studies in Oceanography, 55, (1-15) pp. 1540-1563. ISSN 0967-0645 (2008) [Refereed Article]
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DOI: doi:10.1016/j.dsr2.2008.04.011
Abstract
As part of the VERTIGO program, we collected and analyzed sinking particles using tethered and
neutrally buoyant sediment traps at three depths in the oceanic mesopelagic zone and at two
biogeochemically contrasting sites (N. Central Pacific at ALOHA; N. Pacific Western Subarctic Gyre at
K2). This effort represented the first large-scale use of neutrally buoyant traps and represents a
significant step forward in the study of the marine biological pump. In this paper, we present the results
of mass, macronutrient, biominerals and phytoplankton pigment determinations made on these
samples.
The impact of a variety of potential collection biases were examined, including those from in-trap
particle degradation, zooplankton swimmers and poisons. Though these factors have been observed to
affect results in other programs, we found them to have relatively little impact on measured fluxes in
this study. There was evidence, however, that the neutrally buoyant traps performed better than the
tethered traps in terms of flux accuracy during one deployment, possibly because of improved large
particle collection efficiency.
Fluxes of material exhibited three different patterns through the mesopelagic: increasing, decreasing
and constant with depth. Decreasing fluxes with depth were observed for all biogenic material formed
in the euphotic zone. The attenuation of flux with depth was not the same for all components, however,
with phytoplankton pigments exhibiting the greatest degradation with depth and particulate inorganic
carbon the least. Organic carbon and nitrogen showed a very high correlation in these samples, with
little evidence of different attenuation length scales. Increasing fluxes with depth were observed for
particulate Ba at both sites and Al at K2. The increases in Ba are attributed to the formation of barite in
degrading particles, while increasing Al at K2 was the result of lateral inputs from a continental shelf/
slope. Constant fluxes with depth were observed for Al at ALOHA, where fluxes appeared to be in steady
state with atmospheric dust deposition.
The mesopelagic zone at K2 was observed to attenuate particle flux less than at ALOHA, and with a
higher POC/PIC (rain) ratio. These two factors combine to imply that the Subarctic province had a
much more efficient biological pump than had the subtropical gyre during our occupations. This could
be the result of either faster sinking particles, generated from grazing by large zooplankton, or
inherently slower particle degradation rates.
Item Details
Item Type: | Refereed Article |
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Keywords: | Mesopelagic zone, Sediment traps, Sinking particles, Organic carbon, Nutrients, Biominerals |
Research Division: | Earth Sciences |
Research Group: | Oceanography |
Research Field: | Chemical oceanography |
Objective Division: | Environmental Management |
Objective Group: | Coastal and estuarine systems and management |
Objective Field: | Measurement and assessment of estuarine water quality |
UTAS Author: | Trull, T (Professor Thomas Trull) |
ID Code: | 54598 |
Year Published: | 2008 |
Web of Science® Times Cited: | 69 |
Deposited By: | IASOS |
Deposited On: | 2009-02-25 |
Last Modified: | 2009-06-03 |
Downloads: | 0 |
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