The University of Southampton
University of Southampton Institutional Repository

Studies of nitrous oxide and the nitrogen cycle in a temperate river-estuarine system

Studies of nitrous oxide and the nitrogen cycle in a temperate river-estuarine system
Studies of nitrous oxide and the nitrogen cycle in a temperate river-estuarine system
Nitrous oxide (N2O), the third most important greenhouse gas in terms of
anthropogenic climate forcing, is also one of the most important trace gases in
driving atmospheric chemistry. It is a potent greenhouse gas, having a global
warming potential per mole about 300 times that of carbon dioxide, and it is an
intermediate in the destruction of stratospheric ozone. Unfortunately, the N2O global
budget, and in particular the cause of its steady rise over the past century, is not well
defined. The natural and anthropogenic sources for its increase are probably not all
identified and certainly not well quantified. Recent studies show that when estuarine
and coastal regions are included in the global N2O budget, a considerable portion of
the global marine N2O flux is from estuarine and coastal regions, mainly due to high
emissions from estuaries. To examine the contribution of estuaries to N2O emissions,
nitrous oxide concentrations in the water were measured by gas chromatography on
a monthly basis in the River Itchen and Itchen Estuary - UK, from November 2001 to
December 2002. Water column concentrations of N2O in both, river and estuary were
supersaturated with respect to air (mean saturation 325% and 162%, respectively),
indicating that they were sources of N2O to the atmosphere. High N2O
concentrations in the river appear related to high concentrations in the groundwater.
Highest N2O concentrations in the estuary were generally observed at lower salinities
(up to 79nM and saturation = 679%) when compared with concentrations at the high
salinity (average saturation = 87%). Nitrite had the strongest correlation with N2O for
all surveys (r=0.78; p<0.05), suggesting that nitrite is linked to nitrous oxide
production in estuaries. Fluxes from the River Itchen and Itchen Estuary extrapolated
to the UK systems and compared with other anthropogenic sources of nitrous oxide
to the atmosphere, showed that these systems are significant sources and should be
included in the N2O budget. Incubation experiments were done with sediment
collected from the Itchen Estuary to investigate N2O production. Initial experiments
on a whole core showed the importance of temperature on N2O production, and also
the potentially complicating impact of biological activity. In subsequent experiments,
homogenized and sieved sediment material were used, in which macro benthos
were excluded. N2O fluxes from the sediment were estimated and denitrification was
suggested as the main process producing N2O in the sediments of the incubated
cores.
Veeck, Luciane
20be7736-9317-42e0-a6fb-65409c23110b
Veeck, Luciane
20be7736-9317-42e0-a6fb-65409c23110b

Veeck, Luciane (2007) Studies of nitrous oxide and the nitrogen cycle in a temperate river-estuarine system. University of Southampton, School of Ocean and Earth Science, Masters Thesis, 124pp.

Record type: Thesis (Masters)

Abstract

Nitrous oxide (N2O), the third most important greenhouse gas in terms of
anthropogenic climate forcing, is also one of the most important trace gases in
driving atmospheric chemistry. It is a potent greenhouse gas, having a global
warming potential per mole about 300 times that of carbon dioxide, and it is an
intermediate in the destruction of stratospheric ozone. Unfortunately, the N2O global
budget, and in particular the cause of its steady rise over the past century, is not well
defined. The natural and anthropogenic sources for its increase are probably not all
identified and certainly not well quantified. Recent studies show that when estuarine
and coastal regions are included in the global N2O budget, a considerable portion of
the global marine N2O flux is from estuarine and coastal regions, mainly due to high
emissions from estuaries. To examine the contribution of estuaries to N2O emissions,
nitrous oxide concentrations in the water were measured by gas chromatography on
a monthly basis in the River Itchen and Itchen Estuary - UK, from November 2001 to
December 2002. Water column concentrations of N2O in both, river and estuary were
supersaturated with respect to air (mean saturation 325% and 162%, respectively),
indicating that they were sources of N2O to the atmosphere. High N2O
concentrations in the river appear related to high concentrations in the groundwater.
Highest N2O concentrations in the estuary were generally observed at lower salinities
(up to 79nM and saturation = 679%) when compared with concentrations at the high
salinity (average saturation = 87%). Nitrite had the strongest correlation with N2O for
all surveys (r=0.78; p<0.05), suggesting that nitrite is linked to nitrous oxide
production in estuaries. Fluxes from the River Itchen and Itchen Estuary extrapolated
to the UK systems and compared with other anthropogenic sources of nitrous oxide
to the atmosphere, showed that these systems are significant sources and should be
included in the N2O budget. Incubation experiments were done with sediment
collected from the Itchen Estuary to investigate N2O production. Initial experiments
on a whole core showed the importance of temperature on N2O production, and also
the potentially complicating impact of biological activity. In subsequent experiments,
homogenized and sieved sediment material were used, in which macro benthos
were excluded. N2O fluxes from the sediment were estimated and denitrification was
suggested as the main process producing N2O in the sediments of the incubated
cores.

Text
Veeck_2007_MPhil.pdf - Other
Download (3MB)

More information

Published date: June 2007
Additional Information: 124pp & appendices
Organisations: University of Southampton

Identifiers

Local EPrints ID: 63140
URI: http://eprints.soton.ac.uk/id/eprint/63140
PURE UUID: e15ab5d7-849b-4478-bff4-bf37c6484e1c

Catalogue record

Date deposited: 12 Sep 2008
Last modified: 15 Mar 2024 11:36

Export record

Contributors

Author: Luciane Veeck

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×