The natural inorganic chemical quality of crystalline bedrock groundwaters of Norway

Frengstad, B. and Banks, D. (2008) The natural inorganic chemical quality of crystalline bedrock groundwaters of Norway. In: Edmunds, W.M. and Shand, P. (eds.) Natural Groundwater Quality. Blackwell: Malden, MA, USA, pp. 421-440. ISBN 9781405156752 (doi:10.1002/9781444300345.ch20)

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Abstract

One thousand, six hundred and four groundwater samples from crystalline bedrock aquifers in Norway have been analysed for pH, alkalinity, radon, major ions, and metals. A subset of 476 samples was further analysed for a range of trace elements by ICP-MS. For most major ion parameters, including pH, the median values display modest dependence on lithology, while there is a large variation in hydrochemistry within each lithological subset. Three main water types can be distinguished: Na–Cl waters, Ca–HCO3 waters and Na–HCO3 waters, of which the latter group comprises 25% of the samples. Many trace elements show a clear dependence on lithology with enrichments in aquifers of Precambrian granites relative to Precambrian anorthosites. Concentrations of fluoride, radon and uranium are above given drinking water limits for a significant part of the samples, while elevated concentrations of, for example, arsenic and nitrate seem to be rare. A comparison of two granitic aquifers in southern Britain and Norway, respectively, illustrates the importance of glacial and postglacial weathering history for the hydrochemistry. PHREEQC modelling reveals that a common hydrochemical evolutionary pathway exists for most silicate crystalline rock aquifers, independent of lithology. The main controlling factors are the initial PCO2 of groundwater recharge, the plagioclase composition of the host rock, the extent to which initial CO2 has been converted to HCO3 by hydrolysis, whether the system is ‘open’ with regards to CO2, and to which extent plagioclase hydrolysis has progressed after calcite saturation has been reached.

Item Type:Book Sections (Other)
Status:Published
Glasgow Author(s) Enlighten ID:Banks, Mr David
Authors: Frengstad, B., and Banks, D.
Subjects:Q Science > QD Chemistry
Q Science > QE Geology
College/School:College of Science and Engineering > School of Engineering > Systems Power and Energy
Publisher:Blackwell
ISBN:9781405156752

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