PhD Research Project: CENTA NERC - Hydrological and biogeochemical dynamics of headwater wetlands o
Wetlands extend across ~50% Alaska and have a fundamental role in hydrological and biogeochemial cycling, performing a number of vital ecosystem services. However, wetlands in sub-arctic catchments are currently poorly understood although such wetlands have been associated with elevated CH4 concentrations, thus influencing GHG emissions (Umezawa et al., 2011). Their stable hydrological and thermal regime contributes to high biodiversity, and seepage from these wetlands represents an important source of DOC to fluvial systems, albeit highly vulnerable to changing climate (Hood et al., 2009).
Dissolved organic carbon (DOC) is largely derived from the breakdown and leaching of organic matter and has a fundamental role in aquatic ecosystem functioning, contributing to ecosystem metabolism. Riverine DOC concentrations are highly variable both temporally and spatially reflecting biotic and abiotic processing of DOC. This is particularly the case in Arctic and sub-arctic catchments where DOC levels are linked to soil activity and the depth of the ‘active’ layer within the catchment.
Methodology: The proposed project will use new hydrochemical (fluorescence) and geochemical (stable isotope) techniques to examine the hydrological pathways of DOC and quantify DOC transport in headwater catchments of the Yukon River. Recent studies of DOM quantity and quality in the main stem of the Yukon River have identified higher than expected export levels (Spencer et al. 2009); however, essential research is required to related DOM fluxes to catchment hydrogeomorphology (snow and ice cover; basin hypsometry; geology and landform units). Characterisation of organic matter and biogeochemical analysis will be used to determine seasonal changes in organic and inorganic geochemistry, and its relation to the hydrogeomorphology of the catchment. This will enable a quantitative evaluation of the extent to which fluxes of DOC influence ecological communities. This is an area of active interest in the international research community and will allow a scaling up of the role of these tributaries in influencing DOC concentrations in large rivers.
In addition to completing an online application form, you will also need to complete and submit the CENTA studentship application form available from www.centa.org.uk.
CENTA studentships are for 3.5 years and are funded by the Natural Environment Research Council (NERC). In addition to the full payment of their tuition fees, successful candidates will receive the following financial support.
Annual stipend, set at £14,296 for 2016/17
Research training support grant (RTSG) of £8,000
CENTA students are required to undertake from 45 days training throughout their PhD including a 10 day placement.
Crossman, J., C. Bradley, J. David, & AM. Milner. 2012. Identifying spring-fed hotspots of environmental stability and potential biogeochemical hotspots in glacerised floodplains by remote sensing. Remote Sensing of the Environment 123, 116-126
Harun, S., A. Baker, C. Bradley, I. Boomer, E. Hamilton & GE Pinay. 2015. Characterisation of dissolved organic matter in the lower Kinabatangan River, Sabah, Malaysia. Hydrology Research 46 (3): 411-428
Khamis, K, J.P.R. Sorensen, C. Bradley, D.M. Hannah, D.J. Lapworth, & R. Stevens. 2015. In-situ tryptophan-like fluorometers: assessing turbidity and temperature effects for freshwater applications. Environmental Science Processes and Impacts 17: 740-752.
Hood, E, J Fellman, RGM Spencer, PJ Hermes, R Edwards, D D’Amore, S Scott. 2009. Glaciers as a source of ancient and labile organic matter to the marine environment. Nature, 462, 7276, 1044-U100
Spencer RGM, GR Aiken, KD Butler, MM Dornblaser, RF Striegl, PJ Hernes. 2009. Utilizing chromophic dissolved organic matter measurements to derive export and reactivity of dissolved organic carbon exported to the Arctic Ocean: a case study of the Yukon River, Alaska. Geophysical Research Letters, 36, L06401
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