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Title: Drivers of microbial metabolism, nutrient cycling and greenhouse gas production in agricultural streambed sediments
Author: Comer-Warner, Sophie
ISNI:       0000 0004 8499 825X
Awarding Body: University of Birmingham
Current Institution: University of Birmingham
Date of Award: 2019
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Drivers of carbon and nitrogen cycling, and associated greenhouse gas (GHG) production, were investigated in streambed sediments. Research was conducted to address a lack of availability of adequate porewater sampling technologies and standard protocols, and to determine the effect of temperature, sediment properties and season as primary drivers of nutrient cycling and GHG production in the streambed. A high-resolution sampler of nitrate isotope and concentration data was developed by confirming diffusive equilibrium in thin-film (DET) gel samplers did not cause fractionation of nitrate isotopes. An investigation of commonly used sampling techniques provided information on the most appropriate samplers to use and illustrated that ammonium concentrations vary significantly between sampling techniques. Thermal sensitivity of CO₂ and CH₄ emissions was dependent on sediment type, organic matter and geology, with these factors having a major effect. CO₂ and CH₄ concentrations were higher in sand than gravel sediments, but season had a minor influence. Nitrogen cycling was highest in sand than gravel sediments, resulting in high rates of denitrification and low N₂O concentrations in the sand sediments. Nitrogen cycling and associated N₂O concentrations varied greatly with season in gravel sediments. This indicates that different greenhouse gases may be produced in different areas of the streambed.
Supervisor: Not available Sponsor: European Commission ; ERC ; Leverhulme Trust ; NERC
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: GB Physical geography