کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
9758413 | 1496748 | 2005 | 27 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Intercalibration of benthic flux chambers
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
شیمی
شیمی (عمومی)
پیش نمایش صفحه اول مقاله
![عکس صفحه اول مقاله: Intercalibration of benthic flux chambers Intercalibration of benthic flux chambers](/preview/png/9758413.png)
چکیده انگلیسی
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 mâ2 dayâ1 and the oxygen fluxes from 9.3 to 22.6 mmol mâ2 dayâ1. 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 dissolved silicate were used to calculate diffusive fluxes of silicate. These fluxes ranged from 0.63 to 0.87 mmol mâ2 dayâ1. 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 a 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.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Marine Chemistry - Volume 94, Issues 1â4, 1 March 2005, Pages 147-173
Journal: Marine Chemistry - Volume 94, Issues 1â4, 1 March 2005, Pages 147-173
نویسندگان
A. Tengberg, P.O.J. Hall, U. Andersson, B. Lindén, O. Styrenius, G. Boland, F. de Bovee, B. Carlsson, S. Ceradini, A. Devol, G. Duineveld, J.-U. Friemann, R.N. Glud, A. Khripounoff, J. Leather, P. Linke, L. Lund-Hansen, G. Rowe, U. Witte,