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THE ACCURACY OF CORE INCUBATIONS TO DETERMINE BENTHIC FLUXES OF 222-RADON, 224-RADIUM AND 228-RADIUM
by
Christa Iris Wolfe
________________________________________________________________________
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
(GEOLOGICAL SCIENCES)
May 2011
Copyright 2011 Christa Iris Wolfe
Object Description
| Title | The accuracy of core incubations to determine benthic fluxes of 222-radon, 224-radium and 228-radium |
| Author | Wolfe, Christa Iris |
| Author email | cwolfe@usc.edu; wolfechrista@gmail.com |
| Degree | Master of Science |
| Document type | Thesis |
| Degree program | Geological Sciences |
| School | College of Letters, Arts and Sciences |
| Date defended/completed | 2011-03-30 |
| Date submitted | 2011 |
| Restricted until | Unrestricted |
| Date published | 2011-05-03 |
| Advisor (committee chair) | Hammond, Douglas E. |
| Advisor (committee member) |
Berelson, William M. Sanudo-Wilhelmy, Sergio |
| Abstract | This study presents a new method to determine the accuracy of estimating benthic fluxes of isotopes by incubating sediment cores from San Pedro Basin and measuring the changes in concentrations of 222Rn, 224Ra and 228Ra in the overlying water, over a four to six day incubation period. These results have been compared to fluxes from standing crop measurements, benthic flux chambers and by applying diffusion-reaction models to the sediment column, based on measuring isotope emanation from sediments, adsorption coefficients, and profiles of the parent isotopes in sediments. The core incubation method is considered accurate for estimating 222Rn flux given that the average flux is within one standard deviation of the sediment diffusive and standing crop flux and within two standard deviations of the flux as measured by benthic chambers. The 224Ra flux measurements have been complicated by minor disturbances of cores during collection and the removal of its 228Th parent from core top water during incubation. 224Ra flux was approximated using the data collected from the least disturbed sediment cores. The accuracy of this flux was not assessed due to the lack of detailed data on the 228Th profile in these sediments. The averaged incubation fluxes of 228Ra are within one standard deviation of predictions from modeling solid phase profiles of radioisotopes in sediments. However, the uncertainty of the averaged flux is large and improvements to the precision of 228Ra measurements are necessary for the core incubation method to be an adequate technique for estimating 228Ra flux from sediments. |
| Keyword | USA; California; San Pedro Bay; benthic flux; core incubation; radon; radium; accuracy |
| 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-m3848 |
| Rights | Wolfe, Christa Iris |
| Repository name | Libraries, University of Southern California |
| Repository address | Los Angeles, California |
| Repository email | http://www.usc.edu/isd/libraries/services/ask_a_librarian/email/ |
| Filename | etd-Wolfe-4541 |
| Archival file | uscthesesreloadpub_Volume32/etd-Wolfe-4541.pdf |
Description
| Title | Page 1 |
| Full text | THE ACCURACY OF CORE INCUBATIONS TO DETERMINE BENTHIC FLUXES OF 222-RADON, 224-RADIUM AND 228-RADIUM by Christa Iris Wolfe ________________________________________________________________________ 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 (GEOLOGICAL SCIENCES) May 2011 Copyright 2011 Christa Iris Wolfe |
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