Modelling Denitrification In Soil

Bocking, Christopher (2013) Modelling Denitrification In Soil. Doctoral thesis, University of East Anglia.

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Abstract

Denitrification is a process used by many bacterial species to support anaerobic respiration,
where, faced with a lack of oxygen, energy is instead created from available nitrates.
Arable soils with high nitrogen content, and commonly-used fertilisers, encourage this
process. Unfortunately, the ultimate impact on the environment is negative since nitrous
oxide gas, which emerges as a bi-product, escapes into the atmosphere where it presents a
300-fold greater danger for global warming than carbon dioxide. The aim of this thesis is
find a way to estimate the level of nitrous oxide which may escape into the atmosphere
from denitrifying soil.
Traditionally, the chain of chemical reactions followed in the denitrification process
is modelled using Michaelis-Menten kinetics. We begin this thesis by reviewing existing
work, discussing some of its limitations and proposing various alterations.
Later, we present a preliminary model of the oxygen distribution within a soil with
the aim of identifying anaerobic micro-sites where bacteria can denitrify. Our first models
consist of a solitary circle of oxygen-absorbing soil residing beneath ground level in an
environment saturated with oxygen. We show that normal respiration occurs inside the
circle except within a core anaerobic region where denitrification occurs.
We extend the oxygen distribution model by generalising to multiple oxygen-absorbing
regions. The model is then considered from two viewpoints. We either think of the model
as an aggregated soil where each circle represents an individual aggregate surrounded by
air. Or we think of the model as a solid non-aggregated soil, where each circle represents a
high respiration area. For both of these viewpoints results are found for realistic parameters
and levels of denitrification within the soil can be estimated.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Mathematics
Depositing User: Mia Reeves
Date Deposited: 11 Mar 2014 11:19
Last Modified: 11 Mar 2014 11:19
URI: https://ueaeprints.uea.ac.uk/id/eprint/48043
DOI:

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