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University of Oxford
School of Geography and the Environment

 School of Geography and the Environment

Dr Jill Crossman

Academic Profile

Dr Jill Crossman is a postdoctoral researcher in the School of Geography and the Environment, and assistant to Professor Paul Whitehead, the Director of the NERC Macronutrients Cycles Programme. She has a PhD in the Hydroecology of Groundwater-Fed Streams in Glacierised Catchments (Birmingham) and an MSc in Catchment Dynamics and Management (Leeds). Prior to joining the Macronutrients Cycles Programme at Oxford, Jill conducted research on groundwater-fed streams in interior Alaska, focusing upon the interactions between freshwater biota, organic matter, groundwater flow pathways, water chemistry and nutrients. Dr Crossman has a specific interest in the seasonal dynamics of these relationships, and in using GIS and remote sensing tools to model nutrient flows. During her PhD Jill developed a methodology of locating biogeochemical 'hotspots' using remote sensing techniques.

Jill Crossman has been granted two NERC awards, for her MSc and PhD, and has been successful in securing a further two travel awards (JNABS presidents travel award, $1,200, and the Royal Geographic 30th International Geographical Congress Award, £500). Jill has also delivered presentations at a range of international conferences and meetings, including the North American Benthological Society meeting in Santa Fe, New Mexico; the British Hydrological Society conference in Newcastle Upon Tyne; and the Murie Science and Learning Centre in Denali National Park, Alaska.

Current Research

Macronutrient Cycles Programme

Jill is assisting Professor Paul Whitehead and Dr John Bromley in the implementation of the new Macronutrients Cycles Programme (MC). The MC is a major new NERC funded research programme, which focuses upon the interactions of Nitrogen (N), Phosphorus (P) and Carbon (C) cycles, and aims to quantify both the scale and nature of nitrogen and phosphorus fluxes throughout the catchment, under a changing climate. These nutrients influence terrestrial, atmospheric, freshwater, estuarine, coastal and marine ecosystems, and thus a knowledge of nutrient cycle interactions is key to understanding environmental dynamics on local to global scales. The programme is designed to support inter-disciplinary science, integrating across relevant communities, including atmospheric, terrestrial, freshwater and estuarine. The knowledge attained will be implemented into the development of new models, designed to describe the complex N, P and C interactions, on both catchment and earth system scales. These models will be used in the interpretation of field or experimental data, in the enhancement of existing earth system models, and in determining information on flux delivery to coasts and the sea shelf.

Hydroecology of Groundwater-fed Streams in Glacierised Catchments

Jill is continuing her research into local spatial and temporal variability in groundwater-fed streams, using data collected in Denali National Park, Alaska. Within glacierised catchments the percentage contribution of groundwater to streams is likely to increase, as climate change-induced glacial recession results in long term reductions in supplies of glacial meltwater. Knowledge of the influence of groundwater inputs upon keystone species, such as macroinvertebrates, is therefore vital in understanding the potential impact of climate change. Within glacierised catchments, streams receiving groundwater input may support greater macroinvertebrate diversity, as a result of the stabilising influence of groundwater flow upon temperature and river stage, and reduction in stream turbidity. The physicochemistry of groundwater may vary significantly on even a local scale however, and can result in marked differences in macroinvertebrate diversity between streams fed solely by groundwater. Jill's research focuses upon these local scale physicochemical and ecological dynamics.

Jill's work involves GIS and remote sensing modelling of biogeochemical hotspots, establishing variability (spatial and temporal) in water sources and flow pathways of groundwater-fed streams, and exploring the associations between both benthic and hyporheic macroinvertebrate populations and groundwater-flow dynamics.

Doctoral Thesis

The hydroecology of groundwater-fed streams in a glacierised catchment (2010). University of Birmingham.

Selected Publications

In Re-submission
  • Crossman, J.H., Boomer, I.A., Bradley, C. and Milner, A.M. (submitted, 2010) Water flow dynamics of groundwater streams and their ecological significant in a glacierised catchment. Arctic, Antarctic and Alpine Research. April 2010.
In Preparation
  • Crossman, J.H., Bradley, C., Milner, A.M. and Pinay, G. (in prep.) Influence of environmental stability of groundwater-fed streams on hyporheic fauna, on a glacial floodplain, Denali National Park, Alaska.
  • Crossman, J.H., Bradley, C. and Milner, A.M. (in prep.) The influence of groundwater flow dynamics upon benthic macroinvertebrates, in a glacierised catchment.
  • Crossman, J.H., Bradley, C. and Milner, A.M. (in prep.) Determining the geographical extent of groundwater-fed streams using digital remote sensing.
Conferences / Presentations
  • "Characterising flow variability and hydrochemistry in water supplied to groundwater streams, and the ecological significance of water source dynamics in a glacierised catchment." British Hydrological Society Third International Symposium; Newcastle Upon Tyne. July 2010.
  • "Macroinvertebrate community and source water dynamics of spring-fed systems, of a glacierised catchment in interior Alaska." JNABS/ASLO International Conference; Santa Fe. June 2010.
  • "Ecological significance of groundwater flow dynamics upon ecological systems within a glacierised catchment." Water Sciences Seminar; University of Birmingham. April 2010.
  • "Comparisons of stream stability between groundwater upwellings: affects on hyporheic fauna in a glacial floodplain." GEES Brown Bag Series; University of Birmingham. March 2009.
  • "Hydroecology of upwelling zones in a glacierised catchment." [Poster]. British Hydrological Society National Meeting; University of Birmingham. December 2008.
  • "The geography of Newcastle." EGEA International Conference; Holland. 2004