Change search
ReferencesLink to record
Permanent link

Direct link
Recent sediment dynamics in hadal trenches: Evidence for the influence of higher-frequency (tidal, near-inertial) fluid dynamics
Stockholm University, Faculty of Science, Department of Meteorology .
Show others and affiliations
2014 (English)In: Deep Sea Research Part I: Oceanographic Research Papers, ISSN 0967-0637, Vol. 90, 125-138 p.Article in journal (Refereed) Published
Abstract [en]

In addition to high hydrostatic pressure, scarcity of food is viewed as a factor that limits the abundance and activity of heterotrophic organisms at great ocean depths, including hadal trenches. Supply of nutritious food largely relies on the flux of organic-rich particulate matter from the surface ocean. It has been speculated that the shape of hadal trenches helps to 'funnel' particulate matter into the deeper parts of the trench, leading to sediment 'focussing' and improved benthic food supply. Here we investigate for five Northwest Pacific trenches the efficiency of sediment focussing by evaluating ratios of measured (sediment-derived) and expected (water-column-derived) sedimentary inventories of the naturally occurring and radioactive particulate-matter tracer Pb-210(xs). The sites comprise a broad range of surface-ocean productivity and physical-oceanographic regimes. Across the five trench-axis settings the inventory ratio varies between 0.5 and 4.1, with four trench-axis settings having ratios > 1 (sediment focussing) and one trench-axis setting a ratio < 1 (sediment winnowing). Although the fluid- and sediment-dynamical forcing behind sediment focussing remains unclear, this study finds evidence for another mechanism that is superimposed on, and counteracts, the focussing mechanism. This superimposed mechanism is related to higher-frequency (tidal, near-inertial) fluid dynamics. In particular, there is evidence for a strong and negative relation between the intensity of propagating internal tides and the extent of sediment focussing in the trench-axis. The relation can be approximated by a power function and the most intense drop in sediment focussing already occurs at moderate internal-tide intensities. This suggests that propagating internal tides may have a subtle but significant influence on particulate-matter dynamics and food supply in hadal trenches in particular, but possibly also in the deep seas in general. A mechanism for the influence of internal tides on sediment dynamics is proposed.

Place, publisher, year, edition, pages
2014. Vol. 90, 125-138 p.
Keyword [en]
Hadal trench, Benthos, Sediment, Inertial oscillation, Internal tide, Lead-210 (Pb-210)
National Category
Earth and Related Environmental Sciences
URN: urn:nbn:se:su:diva-106740DOI: 10.1016/j.dsr.2014.05.005ISI: 000338978400012OAI: diva2:739131


Available from: 2014-08-20 Created: 2014-08-19 Last updated: 2014-08-20Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text

Search in DiVA

By author/editor
Falahat, Saeed
By organisation
Department of Meteorology
In the same journal
Deep Sea Research Part I: Oceanographic Research Papers
Earth and Related Environmental Sciences

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 65 hits
ReferencesLink to record
Permanent link

Direct link