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The Partition Intervalometer: A Programmable Underwater Timer for Marking Accumulated Sediment Profiles Collected in Anderson Sediment Traps: Development, Operation, Testing Procedures, and Field Results

Open-File Report 2009-1101

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Abstract

This manual illustrates the development of a programmable instrument designed to deploy a series of wafer-shaped discs (partitions) into the collection tube of a sediment trap in various aquatic environments. These hydrodynamically shaped discs are deployed at discrete time intervals from the Intervalometer and provide markers that delineate time intervals within the sediments that accumulate in the collection tube. The timer and mechanical system are lodged in an air-filled, water-tight pressure housing that is vertically hung within the confines of a cone-shaped sediment trap. The instrumentation has been operationally pressure tested to an equivalent water depth of approximately 1 km. Flaws discovered during extensive laboratory and pressure testing resulted in the implementation of several mechanical modifications (such as a redesign of the rotor and the discs) that improved the operation of the rotor assembly as well as the release of discs through the end cap. These results also identified a preferred azimuth placement of the rotor disc relative to the drop hole of the end cap. In the initial field trial, five sediment traps and coupled Intervalometers were attached to moored arrays and deployed at two sites off the coast of Southern California for approximately 8 months. Each of the instruments released 18 discs at the programmed 10 day intervals, except one unit, which experienced a malfunction after approximately 4 months. Most of the discs oriented in a near-horizontal position upon the surface of the sediment in the collection tubes. Sampling of the sediments for geochemical analyses was improved by these clearly defined markers, which indicated the changes in the flux and nature of sediments accumulated during the deployment period of each sediment trap.

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Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
The Partition Intervalometer: A Programmable Underwater Timer for Marking Accumulated Sediment Profiles Collected in Anderson Sediment Traps: Development, Operation, Testing Procedures, and Field Results
Series title:
Open-File Report
Series number:
2009-1101
Edition:
-
Year Published:
2009
Language:
ENGLISH
Publisher:
U.S. Geological Survey
Contributing office(s):
U.S. Geological Survey
Description:
Available online only
Online Only (Y/N):
Y
Additional Online Files(Y/N):
Y