Email l.allen@ulster.ac.uk
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Contact Us
Environmental Sciences Research Institute
Shijie Li
Room G077
School of Environmental Sciences
University of Ulster
Cromore Road
Coleraine
Northern Ireland
BT52 1SA
Tel: +44 (0)28 7032 4085
e-mail: li-s@email.ulster.ac.uk
Academic History
2002–2006 BSc Hons Environmental Sciences with Diploma in Industrial Studies (1st class), University of Ulster, Coleraine; Industrial placement: waste management, University of Ulster, Coleraine; Dissertation: ‘Potential river-bed sediment phosphorus release and uptake in part of the Blackwater catchment area in County Monaghan’.
2006-present PhD studies, University of Ulster, Coleraine
Associated Projects
Phosphorus retention and release from agricultural ditch networks (PhD project, funded by the Vice-Chancellor’s Research Scholarships, University of Ulster).
Supervisors: Dr Philip Jordan and Dr Joerg Arnscheidt
Freshwater eutrophication caused by phosphorus (P) is one of the longstanding and most challenging water quality issues in Europe (Neal and Heathwaite, 2005). Despite considerable efforts to control major external point sources in recent years (Heathwaite and Dils, 2000; Muscutt and Withers, 1996), in many cases the eutrophication problem is far from being resolved, as P input from diffuse sources that are less well managed becomes increasingly dominant (Sas, 1989; Withers et al., 2000). Although P reduction at the major external sources is considered a long-term solution, there are concerns that internal P loading from bed sediments in rivers and lakes will pose new problems to P management: for instance, by means of internal P loading from bed sediments in rivers and lakes (Foy et al., 2003) and P transfer between inter-linked systems (Haygarth et al., 2005).
In the agricultural landscape, rural streams and ditches constitute an extensive drainage network which can be regarded collectively as a conduit of P transfer into receiving waterbodies, such as large rivers and lakes, where eutrophication may be a major problem (Brookes et al., 1997; Nguyen and Sukias, 2002). Bed sediments in rural streams and ditches are capable of retaining P, and this can potentially amount to significant quantities over prolonged periods of P loading from fields and rural point sources prior to nutrient management. Conversely, adsorbed P and particulate P deposited in the sediments are also liable to release into the water column, particularly during periods of stable low flow in the summer, when the risk of eutrophication is the highest (House, 2003; Jarvie et al., 2005). In contrast, under high flow conditions, and particularly during storm events, PP transported in the water column, including a portion re-suspended from the stream bed, is believed to account for a highly significant proportion of the annual total P (TP) export budget from the stream systems (e.g. Jordan et al., 2005; Bechmann et al., 2005).
The aim of the study is to investigate the potential of sediment P retention and release in agricultural ditch networks. The objectives (main methodology in brackets) are as follows:
1. To assess the magnitude of sediment P retention in agricultural ditches (sediment P fractionation);
2. To assess the magnitude of soluble P release from sediments in agricultural ditches (sediment EPC0 and redox conditions);
3. To examine the diurnally cyclic patterns in the variations of P concentrations observed under stable flow conditions and to explore the underlying processes (continuous stream TP monitoring and Fe redox cycles);
4. To investigate animal and human P sources in ditch networks and their relative contribution to stream water transfers (faecal sterol biomarkers).
The study is being undertaken at three locations in Counties Tyrone, Monaghan and Armagh within the cross-border River Blackwater catchment area, where the CHASM and Blackwater TRACE projects have been based (Jordan et al., 2007).
References
Bechmann, M.E., Berge, D., Eggestad, H.O. and Vandsemb, S.M. (2005) ‘Phosphorus transfer from agricultural areas and its impact on the eutrophication of lakes – two long-term integrated studies from Norway’ Journal of Hydrology, 304: 238-250.
Brookes, P.C., Heckrath, G., De Smet, J., Hofman, G. and Vanderdeelen, J. (1997) ‘Losses of phosphorus in drainage water’, in: Tunney, H., Carton, O.T., Brookes, P.C. and Johnston, A.E. (eds.) Phosphorus Loss from Soil to Water. CAB International, Wallingford, 253-271.
Foy, R.H., Lennox, S.D. and Gibson, C.E. (2003) ‘Changing perspectives on the importance of urban phosphorus inputs as the cause of nutrient enrichment in Lough Neagh’ Science of the Total Environment, 310: 87-99.
Haygarth, P.M., Wood, F.L., Heathwaite, A.L. and Butler, P.J. (2005) ‘Phosphorus dynamics observed through increasing scales in a nested headwater-to-river channel study’ Science of the Total Environment, 344: 83-106.
Heathwaite, A.L. and Dils, R.M. (2000) ‘Characterising phosphorus loss in surface and subsurface hydrological pathways’ Science of the Total Environment, 251/252: 523-538.
House, W.A. (2003) ‘Geochemical cycling of phosphorus in rivers’ Applied Geochemistry, 18: 739-748.
Jarvie, H.P., Jürgens, M.D., Williams, R.J., Neal, C., Davies, J.J.L., Barrett, C. and White, J. (2005) ‘Role of river bed sediments as sources and sinks of phosphorus across two major eutrophic UK river basins: the Hampshire Avon and Herefordshire Wye’ Journal of Hydrology, 304: 51-74.
Jordan, P., Arnscheidt, J., McGrogan, H. and McCormick, S. (2007) ‘Characterising phosphorus transfers in rural catchments using a continuous bank-side analyser’ Hydrology and Earth Systems Sciences, 11(1): 372-381.
Muscutt, A.D. and Withers, P.J.A. (1996) ‘The phosphorus content of rivers in England and Wales’ Water Research, 30(5): 1258-1268.
Neal, C. and Heathwaite, A.L. (2005) ‘Nutrient mobility within river basins: a European perspective’ Journal of Hydrology, 304: 477-490.
Nguyen, L. and Sukias, J. (2002) ‘Phosphorus fractions and retention in drainage ditch sediments receiving surface runoff and subsurface drainage from agricultural catchments in the North Island, New Zealand’ Agriculture, Ecosystem and Environment, 92: 49-69.
Sas, H. (1989) Lake Restoration by Reduction of Nutrient Loading: expectations, experiences, extrapolations. Academia-Verlag Richarz., St. Augustine.
Withers, P.J.A., Davidson, I.A. and Foy, R.H. (2000) ‘Prospects for controlling diffuse phosphorus loss to water’ Journal of Environmental Quality, 29: 167-175.
Research Interests
Sediment phosphorus analysis; phosphorus sorption and sediment equilibrium phosphorus concentration; sediment-water interactions; and internal cycling of phosphorus in relation to redox conditions.
Publications / Presentations
Arnscheidt, J., Jordan, P., Li, S., McCormick, S., McFaul, R., McGrogan, H.J., Neal, M. and Sims, J.T. (2007) ‘Defining the sources of low-flow phosphorus transfers in complex catchments’ Science of the Total Environment, 382: 1-13.
Li, S., Arnscheidt, J. and Jordan, P. (2007) ‘Stream bed sediments as potential sinks and sources of soluble reactive phosphorus – 2006 ESAI bursary study’, at Environ 2007: the 17th Irish Environmental Sciences Researchers Colloquium, Institute of Technology Carlow (poster presentation).
Li, S., Jordan, P. and Arnscheidt, J. (2006) ‘Stream bed sediments as potential sinks and sources of soluble reactive phosphorus’, at Environ 2006: the 16th Irish Environmental Sciences Researchers Colloquium, University College Dublin (awarded Best Student Oral Presentation prize).