The fractionation of the elements in river waters with respect to the continental crust: a UK perspective based on a river enrichment factor approach

Abstract. The fractionation in chemical elements for UK river waters is described relative to the continental crust based on data collected within studies of upland acidic catchments in mid-Wales and major eastern-UK rivers. Four types of river are examined (upland, rural, agricultural and industrial/urban) together with an average for the UK based on a "river enrichment factor", REF. Here, the REF is defined as the ratio of the median river water concentration to the average abundance for the upper continental crust for each element. For this purpose, graphical representations of the logarithm of the REF are presented sequentially in increasing order of magnitude. The results demonstrate vividly the high fractionating of the more volatile, anionic and ‘sea-salt' elements to the aqueous phase and the retention of transition elements of high charge due to solubility controls with intermediate controls for the divalent base cations of intermediate solubility. They also show the increasing significance of pollutants in the agriculturally and industrially/ urban impacted environments.

Keywords: Elements; major elements; trace elements; nutrients; river; hydrochemistry; enrichment factor; river enrichment factor; LOIS; Plynlimon; River Severn; Afon Hafren; River Tweed; River Aire; River Thames