Baseline Groundwater Quality : a comparison of selected British and Norwegian aquifers

Abstract

The aim of this work is to present a discussion on the concept of baseline and to compare the natural variations in inorganic water quality present in a selection of British and Norwegian groundwaters. The use of boxplots and cumulative frequency plots facilitates comparison between individual rock aquifers, different regions with divergent geological and climatic records, and between various elements and parameters. The range of baseline concentrations is often large; e.g. uranium concentrations in Precambrian granitic groundwaters in Norway spans almost 4 orders of magnitude. Baseline values are useful as a means to assess pollution or to set a realistic base for remediation. The EU Maximum Admissible Concentrations (MAC values) of drinking water should be set on toxicological criteria only, as natural unpolluted groundwater sometimes contain elements in concentrations deemed to be harmful. Most of the hard rock groundwaters in Norway have relatively high pH compared with those of the UK. Na-HCO3 type waters seem to be much more common in Norway than in the UK where Ca-HCO3 type water dominate. High F, U and Rn concentrations are found in many granitic and sedimentary groundwaters in Norway, while Ba concentrations tend to be higher in the UK sedimentary aquifers. Universal baseline values do not exist for any element and statistical representative sampling from all aquifers is necessary to establish reliable knowledge about the natural groundwater quality in each area. A suggested series of methodologies are suggested which can be applied to aquifers where the effects of anthropogenic pollution are present. There is a strong need for timeseries data on a wide range of parameters to ascertain the long-term effects of human activity on groundwater quality. The trends of groundwater quality with depth should also be studied more thoroughly. In order for a European wide policy to be implemented it is necessary to establish protocols for criteria related to data quality, sampling and analytical wor