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Production and consumption of organic carbon and oxygen in Sechelt Inlet, British Columbia Timothy, David Andrew
Abstract
In an effort to better understand the relationships of hydrodynamic, biological and chem ical processes in British Columbia fjords, multi-disciplinary oceanographic data were col lected from Sechelt Inlet between the end of January and the end of June, 1991. The purpose of this thesis is to provide depth dependent rates of oxygen production and consumption. Oxygen dynamics are inferred from changes in organic carbon content. Autotrophic ‘4C uptake is normalized to estimates of the daily average irradiance to which phytoplankton had been exposed before being collected for incubation. The normalized 1C4 assimilation values are used to estimate daily rates of oxygen production in the euphotic zone and they are correlated with chlorophyll a concentration. The relationship between ‘4C uptake and chla is not directly used for estimates of oxygen production during the five month study period, but may be applied where chla but not photosynthetic carbon assimilation data exist. Oxygen consumption in the water column below the euphotic zone and in the sedi ments is estimated from analyses of sediment trap data collected monthly at three sta tions. Water column oxygen consumption is determined using an algorithm which esti mates the rate of decay with depth of the organic carbon flux, despite measured increases in flux with depth. The algorithm also provides estimates of the composition of the ma terial caught in lower but not upper sediment traps. Following a discussion of possible causes of measured flux increases with depth, it is concluded that changes in trapping efficiency were largely responsible for the pattern of flux observed in Sechelt Inlet during the experiment. Benthic oxygen demand is estimated by degrading a constant fraction of the trap-measured flux of organic carbon to the sediments. The estimates of sediment oxygen demand are found to agree with direct measurements of benthic oxygen demand in other temperate fjords. This work is concluded by comparing predicted and trap measured fluxes of organic carbon, where predicted fluxes are estimated from primary production and an estimate of the f-ratio (= new production/total production) during the experiment. A method is described in which fNQ- (= nitrate uptake/total nitrogen uptake) can be used to pre dict the export flux of organic carbon during ecologically and hydrographically dynamic periods. A large discrepancy is found between predicted and measured fluxes of organic carbon during the study period in Sechelt Inlet. It is suggested that this discrepancy was caused by dissolved and/or fine organic matter that was not caught by the sediment traps and was eventually consumed in the water column, probably by free-living, motile bacteria.
Item Metadata
Title |
Production and consumption of organic carbon and oxygen in Sechelt Inlet, British Columbia
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Creator | |
Publisher |
University of British Columbia
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Date Issued |
1994
|
Description |
In an effort to better understand the relationships of hydrodynamic, biological and chem
ical processes in British Columbia fjords, multi-disciplinary oceanographic data were col
lected from Sechelt Inlet between the end of January and the end of June, 1991. The
purpose of this thesis is to provide depth dependent rates of oxygen production and
consumption. Oxygen dynamics are inferred from changes in organic carbon content.
Autotrophic ‘4C uptake is normalized to estimates of the daily average irradiance
to which phytoplankton had been exposed before being collected for incubation. The
normalized 1C4 assimilation values are used to estimate daily rates of oxygen production
in the euphotic zone and they are correlated with chlorophyll a concentration. The
relationship between ‘4C uptake and chla is not directly used for estimates of oxygen
production during the five month study period, but may be applied where chla but not
photosynthetic carbon assimilation data exist.
Oxygen consumption in the water column below the euphotic zone and in the sedi
ments is estimated from analyses of sediment trap data collected monthly at three sta
tions. Water column oxygen consumption is determined using an algorithm which esti
mates the rate of decay with depth of the organic carbon flux, despite measured increases
in flux with depth. The algorithm also provides estimates of the composition of the ma
terial caught in lower but not upper sediment traps. Following a discussion of possible
causes of measured flux increases with depth, it is concluded that changes in trapping
efficiency were largely responsible for the pattern of flux observed in Sechelt Inlet during
the experiment. Benthic oxygen demand is estimated by degrading a constant fraction
of the trap-measured flux of organic carbon to the sediments. The estimates of sediment oxygen demand are found to agree with direct measurements of benthic oxygen demand
in other temperate fjords.
This work is concluded by comparing predicted and trap measured fluxes of organic
carbon, where predicted fluxes are estimated from primary production and an estimate
of the f-ratio (= new production/total production) during the experiment. A method is
described in which fNQ- (= nitrate uptake/total nitrogen uptake) can be used to pre
dict the export flux of organic carbon during ecologically and hydrographically dynamic
periods. A large discrepancy is found between predicted and measured fluxes of organic
carbon during the study period in Sechelt Inlet. It is suggested that this discrepancy
was caused by dissolved and/or fine organic matter that was not caught by the sediment
traps and was eventually consumed in the water column, probably by free-living, motile
bacteria.
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Extent |
3589935 bytes
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Genre | |
Type | |
File Format |
application/pdf
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Language |
eng
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Date Available |
2009-03-05
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Provider |
Vancouver : University of British Columbia Library
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Rights |
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
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DOI |
10.14288/1.0053279
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
1994-11
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Campus | |
Scholarly Level |
Graduate
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Aggregated Source Repository |
DSpace
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Item Media
Item Citations and Data
Rights
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.