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.


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. 

Training and Skills

CENTA students are required to complete 45 days training throughout their PhD including a 10 day placement. In the first year, students will be trained as a single cohort on environmental science, research methods and core skills. Throughout the PhD, training will progress from core skills sets to master classes specific to the student's projects and themes. 

The research student will benefit from designing a field programme and working in a multidisciplinary team and from participating in a large and active graduate research school within the School of Geography and Environmental Sciences. The research programme will provide the student with training in hydrology; biogeochemistry; ecology; remote fieldwork and desk-based research methods; and analysis of environmental data.


Year 1: Planning, and field season 1

Year 2: Analyses and field season 2

Year 3: Data analyses and write-up

Partners and collaboration (including CASE)

The project would have links with the US National Park Service who would supply logistical support and access to supplementary data on climate records and flow gaging.  Rob Spencer (University of California) has been consulted about possible co-operation, and we will seek to develop this link if the project proceeds. The USGS also have a strong interest in this area, and we will investigate possibilities for additional co-operation. Dr Eran Hood of the University of Alaska, southeast has agreed to be a collaborator and assist with analysis and loan of sensor equipment.

Further Details

Professor Alexander Milner (a.m.milner@bham.ac.uk)

Dr. Chris Bradley (C.Bradley@bham.ac.uk)