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PARTICULATE ORGANIC CARBON FLUX CALCULATED FROM
234TH MEASUREMENTS AND SEDIMENT TRAPS IN THE EASTERN
TROPICAL SOUTH PACIFIC
by
William Ziegler Haskell II
___________________________________________________________
A Thesis Presented to the
FACULTY OF THE USC GRADUATE SCHOOL
UNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillment of the
Requirements for the Degree
MASTER OF SCIENCE
(OCEAN SCIENCES)
August 2011
Copyright 2011 William Ziegler Haskell II
Object Description
| Title | Particulate organic carbon flux calculated from ²³⁴Th measurements and sediment traps in the eastern tropical south Pacific |
| Author | Haskell, William Ziegler, II |
| Author email | whaskell@usc.edu;wzhaskell@gmail.com |
| Degree | Master of Science |
| Document type | Thesis |
| Degree program | Ocean Sciences |
| School | College of Letters, Arts And Sciences |
| Date defended/completed | 2011-07-22 |
| Date submitted | 2011-07-22 |
| Date approved | 2011-07-22 |
| Restricted until | 2011-07-22 |
| Date published | 2011-07-22 |
| Advisor (committee chair) | Hammond, Douglas E. |
| Advisor (committee member) |
Berelson, William M. Moffett, James |
| Abstract | The disequilibrium between the particle-reactive ²³⁴Th (t1/2= 24.1 days) and its soluble parent ²³⁸U (t1/2= 4.5 by) is used to quantify removal rates of ²³⁴Th on sinking particles. During February-March 2010, seven ²³⁴Th profiles were measured from the surface to 300m in the Eastern Tropical South Pacific (ETSP), in a region bounded by 10°S – 20°S and 80°W – 100°W. Horizontal transport of ²³⁴Th in surface waters, determined using geostrophic current vectors was found to be negligible, thus only vertical transport or 1-dimensional processes should be significant. Depth-integrated Thorium deficiencies (DITD) and measured ratios of particulate organic carbon (POC) to ²³⁴Th obtained from sediment trap samples were used in a steady state, one-dimensional model to determine POC export from the upper ocean. ²³⁴Th flux from the DITD method ranged from 800 to 3120 dpm/m²-d, and the ²³⁴Th-based calculated POC export flux at 200m ranged from 2.3 to 12.9 mmolC/m²-d. At each location, drifting sediment traps were deployed for 23-65 hours at 200m to measure ²³⁴Th and POC flux directly. The flux of ²³⁴Th into the traps ranged from 48 to 747 dpm/m²-d, which was very low compared to the flux calculated using the Thorium deficiency (DITD). However, at two stations, the trap:DITD flux ratio was 0.47 (station #7) and 0.76 (station #1). At other sites, this ratio was <0.15, and as low as 0.02 at station #5. The trap-measured flux of POC was also lower than the ²³⁴Th-predicted POC flux, ranging between 0.19 and 2.2 mmolC/m²-d. Although the ²³⁴Th deficiency in the water column and fluxes of ²³⁴Th into the traps do not agree, the DITD-based ²³⁴Th flux and POC flux results are consistent with those of previous studies in the central Equatorial Pacific. Each estimate of POC export may suffer biases and artifacts, and certainly a 24-hour trap deployment may not be representative of export integrated over the time-scale of the ²³⁴Th tracer (~2-5 weeks). Non-steady state conditions, the failure of the traps to collect efficiently, the grazing of zooplankton swimmers on trap material, remineralization of POC and ²³⁴Th above the trap depth, and vertical transport of ²³⁴Th by swimmers are believed to contribute to the disagreement between the two techniques. |
| Keyword | 234Th; carbon flux; eastern tropical south Pacific; particulate organic carbon; sediment traps |
| Language | English |
| Part of collection | University of Southern California dissertations and theses |
| Publisher (of the original version) | University of Southern California |
| Place of publication (of the original version) | Los Angeles, California |
| Publisher (of the digital version) | University of Southern California. Libraries |
| Provenance | Electronically uploaded by the author |
| Type | texts |
| Legacy record ID | usctheses-m |
| Contributing entity | University of Southern California |
| Rights | Haskell, William Ziegler, II |
| Physical access | The author retains rights to his/her dissertation, thesis or other graduate work according to U.S. copyright law. Electronic access is being provided by the USC Libraries in agreement with the author, as the original true and official version of the work, but does not grant the reader permission to use the work if the desired use is covered by copyright. It is the author, as rights holder, who must provide use permission if such use is covered by copyright. The original signature page accompanying the original submission of the work to the USC Libraries is retained by the USC Libraries and a copy of it may be obtained by authorized requesters contacting the repository e-mail address given. |
| Repository name | University of Southern California Digital Library |
| Repository address | USC Digital Library, University of Southern California, University Park Campus MC 7002, 106 University Village, Los Angeles, California 90089-7002, USA |
| Repository email | cisadmin@dots.usc.edu |
| Archival file | uscthesesreloadpub_Volume71/etd-HaskellWil-158-0.pdf |
Description
| Title | Page 1 |
| Contributing entity | University of Southern California |
| Repository email | cisadmin@dots.usc.edu |
| Full text | PARTICULATE ORGANIC CARBON FLUX CALCULATED FROM 234TH MEASUREMENTS AND SEDIMENT TRAPS IN THE EASTERN TROPICAL SOUTH PACIFIC by William Ziegler Haskell II ___________________________________________________________ A Thesis Presented to the FACULTY OF THE USC GRADUATE SCHOOL UNIVERSITY OF SOUTHERN CALIFORNIA In Partial Fulfillment of the Requirements for the Degree MASTER OF SCIENCE (OCEAN SCIENCES) August 2011 Copyright 2011 William Ziegler Haskell II |
