Development of methods to improve knowledge of tritium inputs to the ocean
Development of methods to improve knowledge of tritium inputs to the ocean
The available precipitation dataset is used to construct a global model function which calculates the isotopes concentration in precipitation at any location. This was then used to calculate a North Pacific tritium budget using a simple multi-box model of the shallow circulation of this basin, the results of which were compared with inventories calculated from the WOCE and GEOSECS cruises. The calculated model inventory of 25.1 ± 3.3kg is in close agreement with the WOCE value of 23.4 ± 2.0kg. Once developed, the atmospheric deposition terms and flows in the kinematic model were modified to match the available tritium data. This served to emphasise the importance of vapour deposition to the budget and predicted a value for the Indonesian Throughflow at the upper end of the upper end of other observational based estimates (15.8Sv). However, the modelling work served to highlight the limitations of tritium in such quantitative circulation studies, as tight constraints could not be placed on any of the advective terms in the model because of the significant uncertainty in the atmosphere deposition terms.
To improve knowledge of the tritium input to the oceans a technique was developed to measure tritium concentrations in annual tree rings, as it was hypothesised that these should reflect ambient precipitation. Measurements were made on cellulose, the primary constituent of wood, as the isotopic signal of is carbon bound hydrogen atoms shouldn’t have changed since biosynthesis. Traditional cellulose extraction techniques from softwoods are slow and were found to not give a reproducibly clean product. Therefore a new microwave method was developed which reduced extraction times from 305 days to approximately 3 hours. Potential contamination from the hydroxyl groups of the cellulose molecule was subsequently removed by exchange with tritium free NaOH, thus avoiding the dangers of working with large amounts of cellulose nitrate.
University of Southampton
Stark, Sheila
41732f9b-cf02-4fa2-9ed9-901c9567720d
2003
Stark, Sheila
41732f9b-cf02-4fa2-9ed9-901c9567720d
Stark, Sheila
(2003)
Development of methods to improve knowledge of tritium inputs to the ocean.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
The available precipitation dataset is used to construct a global model function which calculates the isotopes concentration in precipitation at any location. This was then used to calculate a North Pacific tritium budget using a simple multi-box model of the shallow circulation of this basin, the results of which were compared with inventories calculated from the WOCE and GEOSECS cruises. The calculated model inventory of 25.1 ± 3.3kg is in close agreement with the WOCE value of 23.4 ± 2.0kg. Once developed, the atmospheric deposition terms and flows in the kinematic model were modified to match the available tritium data. This served to emphasise the importance of vapour deposition to the budget and predicted a value for the Indonesian Throughflow at the upper end of the upper end of other observational based estimates (15.8Sv). However, the modelling work served to highlight the limitations of tritium in such quantitative circulation studies, as tight constraints could not be placed on any of the advective terms in the model because of the significant uncertainty in the atmosphere deposition terms.
To improve knowledge of the tritium input to the oceans a technique was developed to measure tritium concentrations in annual tree rings, as it was hypothesised that these should reflect ambient precipitation. Measurements were made on cellulose, the primary constituent of wood, as the isotopic signal of is carbon bound hydrogen atoms shouldn’t have changed since biosynthesis. Traditional cellulose extraction techniques from softwoods are slow and were found to not give a reproducibly clean product. Therefore a new microwave method was developed which reduced extraction times from 305 days to approximately 3 hours. Potential contamination from the hydroxyl groups of the cellulose molecule was subsequently removed by exchange with tritium free NaOH, thus avoiding the dangers of working with large amounts of cellulose nitrate.
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Published date: 2003
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Local EPrints ID: 465085
URI: http://eprints.soton.ac.uk/id/eprint/465085
PURE UUID: e9129f94-b092-44fa-9a17-1c89db36720a
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Date deposited: 05 Jul 2022 00:22
Last modified: 16 Mar 2024 19:56
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Author:
Sheila Stark
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