PhD Project - SAGES funded at the School of Geographical & Earth Sciences - Carbon evasion dynamics in aquatic ecosystems: the devil is in the (positional) detail

The carbon (C) cycle in aquatic systems is a dynamic process, amalgamating production, processing, storage, and loss pathways, operating at a range of temporal and spatial scales. Understanding these processes is of significance as freshwater systems are now recognised as substantial sources of carbon dioxide (CO2) to the atmosphere. Evidence suggests that CO2 evasion is primarily controlled by fluid turbulence and the partial pressure of dissolved CO2 in river systems (Long et al. 2015), with biological controls a concurrent factor in non-flowing systems (Bass et al. 2014). Further understanding is required to assess the effect that freshwater CO2 efflux and associated land-use change and management will have on global C-cycle processes.

As turbulence in rivers is spatially and temporally variable, hence controlling C-concentration and evasion, there is a requirement to consider these systems in suitably fine detail. This PhD will use state of the art, high-accuracy light weight GPS technology (U-blox; ±20-50 mm) combined with in-situ CO2 sensors to quantify dissolved CO2 dynamics in rivers and lakes, a combination of techniques not yet implemented. This interdisciplinary approach is supported by the expertise of the supervisory team, including geomatics (Petrie) and aquatic C biogeochemistry (Bass & Heal). High spatial and temporal resolution hydraulic and CO2 efflux data will be combined with concurrent measurements of aquatic chemistry and other C-fractions to elucidate the fine scale controls and produce process-based models on C flux, both spatially and vertically. The combination of lightweight GPS sensors and in-situ CO2 sensors will allow measurements on an array of field sites, including large rivers that are problematic to sample via standard means. Using this methodology, the CO2 dynamics will be characterised in detail over river reaches, enabling point measurements to be upscaled.The initial set of science experiments following successful pilot testing will be conducted in previously studied Scottish river sites (River Kelvin, an urban location and Drumtee Water, an upland agriculture/peatland location). Repeated measurement runs will be made and partnered with CO2 efflux measurements from a fixed position (via floating chamber methods). Sites will be visited throughout the year to obtain a range of discharge and C-transport conditions. Stream chemistry, including dissolved and particulate C will also be recorded. Once experience had been obtained with this new methodology in local field sites, the equipment would then be used to build up an understanding of the relationship between hydraulics and CO2 efflux at a wider range of sites, both geographically and by studying lake sites.

Apply: Please refer to the following website for details on how to apply:
http://www.gla.ac.uk/research/opportunities/howtoapplyforaresearchdegree/.
See also http://www.sages.ac.uk/graduate-school/ for more information on SAGES.
For more information on the project contact [Email Address Removed]