1School of Environmental Sciences, University of East Anglia, Norwich, NR4 7TJ, UK
2Centre for Ecology and Hydrology, Maclean Building, Crowmarsh Gifford, Wallingford, Oxon, OX10 8BB, UK
3Centre for Ecology and Hydrology, Bangor Research Unit, UWB, Deiniol Road, Bangor, Gwynedd, LL57 2UP, UK
Email for corresponding author: L.Ness@uea.ac.uk
Abstract. Analysis of winter stream chemistry data from the Afon Hafren in mid-Wales reveals links between stream chemistry and the North Atlantic Oscillation (NAO). K, Y, Al and dissolved organic carbon (DOC) concentrations increase during high NAO index months (relatively warm and wet weather), while Ca, Mg and NO3 concentrations increase during low NAO months (relatively cold and dry conditions) with the increased concentrations lasting into the next month. The cause of the concentration changes varies between constituents: Y, Al and DOC are impacted by short term variations in rainfall; Mg and Ca are influenced by flow conditions; and NO3 is temperature controlled. The dominant control mechanism for K concentration seems to be related to rainfall after tree felling has taken place but, prior to felling, the relationships are less certain.
Keywords: nitrate, potassium, yttrium, aluminium, Dissolved Organic Carbon, magnesium, calcium, North Atlantic Oscillation, stream chemistry, Plynlimon, Hafren
Ness, L., Neal, C., Davies, T. D., and Reynolds, B.: Impacts of the North Atlantic Oscillation on stream water chemistry in mid-Wales, Hydrol. Earth Syst. Sci., 8, 409-421, doi:10.5194/hess-8-409-2004, 2004.