Fluxes, dynamics and chemistry of particulates in the ocean
type: CreativeWork
description: Sediment traps designed to yield quantitative data of particulate fluxes have been deployed and successfully recovered on four moorings in the deep sea. The traps were designed after extensive calibration of different shapes of containers. Further intercalibration of trap design was made in field experiments over a range of current velocities. Experiments with Niskin bottles showed that concentrations of suspended particulate matter obtained with standard filtration methods were low and had to be increased by an average factor of 1.5 to correct for particles settling below the sampling spigot. The trap arrays were designed to sample the particulate fluxes both immediately above and within the nepheloid layer. The data derived from the traps have been used to estimate vertical fluxes of particles including, for the first time, an attempt to distinguish between the flux of material settling from the upper water column (the "primary flux") and material which has been resuspended from some region of the sea floor (resuspension flux). From these data and measurements of the net nepheloid standing crop of particles one can also estimate a residence time for particles resuspended in the nepheloid layer. This residence time appears to be on the order of days to weeks in the bottom 15 m of the water column and weeks to months in the bottom 100 m. Between 80% and 90% of the particles collected in the six traps where particle size was measured were less than 63 μm. The mean size of particles collected in the nepheloid layer was about 20 μm, and above the nepheloid layer the mean was 11 μm. Less than 3% of the organic carbon produced in the photic zone at the trap sites was collected as primary flux 500 m above the sea floor. The primary flux measured at two sites was enough to supply 75% on the upper Rise and 160% on the mid Rise of the organic carbon needed for respiration and for burial in the accumulating sediments. From an intercomparison of the composition of particles fa…
abstract: Sediment traps designed to yield quantitative data of particulate fluxes have been deployed and successfully recovered on four moorings in the deep sea. The traps were designed after extensive calibration of different shapes of containers. Further intercalibration of trap design was made in field experiments over a range of current velocities. Experiments with Niskin bottles showed that concentrations of suspended particulate matter obtained with standard filtration methods were low and had to be increased by an average factor of 1.5 to correct for particles settling below the sampling spigot. The trap arrays were designed to sample the particulate fluxes both immediately above and within the nepheloid layer. The data derived from the traps have been used to estimate vertical fluxes of particles including, for the first time, an attempt to distinguish between the flux of material settling from the upper water column (the "primary flux") and material which has been resuspended from some region of the sea floor (resuspension flux). From these data and measurements of the net nepheloid standing crop of particles one can also estimate a residence time for particles resuspended in the nepheloid layer. This residence time appears to be on the order of days to weeks in the bottom 15 m of the water column and weeks to months in the bottom 100 m. Between 80% and 90% of the particles collected in the six traps where particle size was measured were less than 63 μm. The mean size of particles collected in the nepheloid layer was about 20 μm, and above the nepheloid layer the mean was 11 μm. Less than 3% of the organic carbon produced in the photic zone at the trap sites was collected as primary flux 500 m above the sea floor. The primary flux measured at two sites was enough to supply 75% on the upper Rise and 160% on the mid Rise of the organic carbon needed for respiration and for burial in the accumulating sediments. From an intercomparison of the composition of particles fa…
author: Gardner, Wilford D.
language: en_US
keywords: Marine sediments, Sediment transport, Particles, Particle size determination, Oceanus (Ship : 1975-) Cruise OC6, Knorr (Ship : 1970-) Cruise KN58
date published: 1977-10
date modified: 2026-07-27T22:05:08Z
provider: Woods Hole Oceanographic Institute
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Massachusetts Institute of Technology and Woods Hole Oceanographic Institution

PropertyValue
property ID: Handle
value: https://hdl.handle.net/1912/1546

PropertyValue
property ID: DOI
value: 10.1575/1912/1546