Skip to main content

Free Content A sediment trap experiment in the Vema Channel to evaluate the effect of horizontal particle fluxes on measured vertical fluxes

Download Article:
 Download
(PDF 2333.296875 kb)
 

Abstract:

Sediment traps are used to measure fluxes and collect samples for studies in biology, chemistry and geology, yet we have much to learn about factors that influence particle collection rates. Toward this end, we deployed cylindrical sediment traps on five current meter moorings across the Vema Channel to field-test the effect of different horizontal particle fluxes on the collection rate of the traps— instruments intended for the collection of vertically settling particles. The asymmetric flow of Antarctic Bottom Water through the Vema Channel created an excellent natural flume environment in which there were vertical and lateral gradients in the distribution of both horizontal velocity and particle concentration and, therefore, the resulting horizontal flux. Horizontal effects were examined by comparing quantities of collected material (apparent vertical fluxes) with the horizontal fluxes of particles past each trap. We also looked for evidence of hydrodynamic biases by comparing and contrasting the composition of trap material based on particle size and the concentration of Al, Si, Ca, Mg, Mn, Corg and CaCO3. Experimental inverted traps and traps with only side openings were deployed to test a hypothesis of how particles are collected in traps.

The vertical flux of surface-water particles should have been relatively uniform over the 45 km region of the mooring locations, so if horizontal transport contributed significantly to collection rates in traps, the calculated trap fluxes should be correlated positively with the horizontal flux. If the horizontal flow caused undertrapping, there should be a negative correlation with velocity or Reynolds number. The gross horizontal flux past different traps varied by a factor of 37, yet the quantity collected by the traps differed by only a factor of 1.4. The calculated horizontal fluxes were 2–4 orders of magnitude larger than the measured apparent vertical fluxes. Mean velocities past the traps ranged from 1–22 cm s−1 (Reynolds numbers of 3,500–43,000 for these traps with a diameter of 30.5 cm and an aspect ratio of ≈3) and showed no statistically significant relationship to the apparent vertical flux. We conclude that at current speeds measured in a very large portion of the world's oceans, vertical fluxes measured with moored, cylindrical traps should exhibit little effect from horizontal currents.

Document Type: Research Article

DOI: https://doi.org/10.1357/0022240973224139

Publication date: 1997-09-01

More about this publication?
  • The Journal of Marine Research publishes peer-reviewed research articles covering a broad array of topics in physical, biological and chemical oceanography. Articles that deal with processes, as well as those that report significant observations, are welcome. In the area of biology, studies involving coupling between ecological and physical processes are preferred over those that report systematics. Authors benefit from thorough reviews of their manuscripts, where an attempt is made to maximize clarity. The time between submission and publication is kept to a minimum; there is no page charge.
  • Editorial Board
  • Information for Authors
  • Subscribe to this Title
  • Ingenta Connect is not responsible for the content or availability of external websites
  • Access Key
  • Free content
  • Partial Free content
  • New content
  • Open access content
  • Partial Open access content
  • Subscribed content
  • Partial Subscribed content
  • Free trial content
Cookie Policy
X
Cookie Policy
Ingenta Connect website makes use of cookies so as to keep track of data that you have filled in. I am Happy with this Find out more