Intercalibration of benthic flux chambers II. Hydrodynamic characterization and flux comparisons of 14 different designs
Artikel i vetenskaplig tidskrift, 2005

We have compared 14 different sediment incubation chambers, most of them were used on bottom landers. Measurements of mixing time, pressure gradients at the bottom and Diffusive Boundary Layer thickness (DBL) were used to describe the hydrodynamic properties of the chambers and sediment-water solute fluxes of silicate (34 replicates) and oxygen (23 replicates) during three subsequently repeated incubation experiments on a homogenized, macrofauna-free sediment. The silicate fluxes ranged from 0.24 to 1.01 mmol m(-2) day(-1) and the oxygen fluxes from 9.3 to 22.6 mmol m(-2) day(-1). There was no statistically significant correlation between measured fluxes and the chamber design or between measured fluxes and hydrodynamic settings suggesting that type of chamber was not important in these flux measurements. For verification of sediment homogeneity, 61 samples of meiofauna were taken and identified to major taxa. In addition. 13 sediment cores were collected. sectioned into 5-10-mm slices and separated into pore water and solid phase. The pore water profiles of disolved silicale were used to calculate diffusive fluxes of silicate. These fluxes ranged from 0.63 to 0.87 mmol m(-2) day(-1). All of the collected sediment parameters indicated that the sediment homogenization process had been satisfactorily accomplished, hydrodynamic variations inside and between chambers are a reflection of the chamber design and the stirring device, In general. pump stirrers with diffusers give a more even distribution of bottom currents and DBL thicknesses than paddle wheel-type stirrers, Most chambers display no or low static differential pressures when the water is mixed at rates of normal Use, Consequently. there is a low risk of creating stirrer induced pressure effects on the measured fluxes. Centrally placed stirrers are preferable to off-center placed stirrers which are more difficult to map and do not seem to give any hydrodynamic advantages, A vertically rotating stirrer gives about five times lower static differential pressures at the same stirring, speed as the same stirrer mounted horizontally If the aim is to simulate or mimic resuspension at high flow velocities, it cannot be satisfactorily done in a chamber using it horizontal (standing) rotating impeller (as is the case for most chambers in use) due to the creation of unnatural conditions. i,e. large static differential pressures and pre-mature resuspension at certain locations in the chamber. (c) 2004 Elsevier B.V. All rights reserved.

SOLUTE TRANSPORT

INSITU

calibration

DIFFUSIVE BOUNDARY-LAYERS

comparative

EXCHANGE

benthic chambers

IN-SITU

hydrodynamic properties

DEEP-SEA

OXYGEN-UPTAKE

flux incubations

FLOOR

SEDIMENT-WATER INTERFACE

PORE-WATER

Författare

Anders Tengberg

Göteborgs universitet

Per Hall

Göteborgs universitet

U Andersson

Göteborgs universitet

Bengt Lindén

Göteborgs universitet

O Styrenius

Göteborgs universitet

G Boland

Minerals Management Service

F de Bovee

CNRS Centre National de la Recherche Scientifique

B. Carlsson

Chalmers University of Technology

S Ceradini

CISE S.p.A.

A Devol

University of Washington

G. Duineveld

Royal Netherlands Institute for Sea Research - NIOZ

Jens-Uwe Friemann

Chalmers, Bygg- och miljöteknik, Vatten Miljö Teknik

R. N. Glud

Köbenhavns Universitet

A. Khripounoff

IFREMER Centre de Brest

J. Leather

NCCOSC RDTE Division

P. Linke

GEOMAR - Helmholtz Zentrum für Ozeanforschung Kiel

L. Lund-Hansen

Aarhus Universitet

G. Rowe

Texas A&M University

P. Santschi

Texas A&M University

P. de Wilde

Royal Netherlands Institute for Sea Research - NIOZ

U. Witte

Max Planck-institutet

Marine Chemistry

0304-4203 (ISSN)

Vol. 94 147-173

Ämneskategorier

Kemi

DOI

10.1016/j.marchem.2004.07.014