Intercalibration of benthic flux chambers II. Hydrodynamic characterization and flux comparisons of 14 different designs
|Author(s)||Tengberg Anders, Hall P, Andersson U, Linden B, Styrenius O, Boland G, De Bovee F, Carlsson B, Ceradini S, Devol A, Duineveld G, Friemann J, Glud R, Khripounoff Alexis, Leather J, Linke P, Lund Hansen L, Rowe G, Santschi P, De Wilde P, Witte U|
|Affiliation(s)||Univ Gothenburg, Dept Chem, SE-41296 Gothenburg, Sweden.
US Dept Interior, Minerals Management Serv, New Orleans, LA USA.
CNRS, URA 117, Observ Oceanol Banyuls, Lab Arago, F-66650 Banyuls sur Mer, France.
Chalmers Univ Technol, Dept Hydraul, S-41296 Gothenburg, Sweden.
CISE SpA, I-20090 Segrate, MI, Italy.
Univ Washington, Sch Oceanog, Seattle, WA 98195 USA.
Netherlands Inst Sea Res, NL-1790 AB Den Burg, Netherlands.
Univ Copenhagen, Biol Marine Lab, DK-3000 Helsingor, Denmark.
IFREMER, Ctr Brest, F-29263 Plouzane, France.
USN, Nacal Command, Control & Ocean Surveillance Ctr, RDTE Div, San Diego, CA 92152 USA.
GEOMAR, Forschungszentrum Marine Geowissensch, D-24148 Kiel, Germany.
Aarhus Univ, DK-8200 Aarhus, Denmark.
Texas A&M Univ, Dept Oceanog, Galveston, TX 77553 USA.
Max Planck Inst Marine Microbiol, D-28359 Bremen, Germany.
|Source||Marine Chemistry (0304-4203) (Elsevier), 2005-03 , Vol. 94 , N. 1-4 , P. 147-173|
|WOS© Times Cited||27|
|Keyword(s)||Comparative flux incubations, Hydrodynamic properties, Calibration, Benthic chambers|
|Abstract||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.|