Influence of precipitation composition on the chemistry of streams draining from peat examined using Na:Ca:Mg ratio

It is hypothesised that, since precipitation chemistry regulates the constitution of the base cations occupying the cation exchange sites of peat soils, and the latter in turn directly regulates the relative abundance of the corresponding base cations in drainage waters, the ratios of base cations in precipitation and drainage waters from peats should be very similar. The hypothesis is confirmed using data for 45 streams in western Scotland sampled under baseflow conditions, and for three streams in northeastern Scotland sampled along their length under baseflow conditions and also throughout a sequence of three successive storms. During the latter, as the soils became progressively wetter, and flow through or over surface organic horizons started to make an increasing relative contribution to total discharge, the difference between cation ratios in precipitation and river water was reduced. The effects of changing hydrological pathway in the three catchments were confirmed by changes in Al:Ca:Mg ratios between baseflow and storm water samples. (C) 1997 Elsevier Science Ltd.