Geochemistry and classification of cold groundwater in Iceland

In a comprehensive study of Icelandic groundwater special attention was paid to the chemical types of cold groundwaters and the correlation with the local geological and meteorological conditions. Before the chemistry of cold groundwater has been poorly investigated, even though over 90% of potable water is groundwater. The main factors affecting chemistry of the groundwater are age and type of the reservoir rocks, distance from sea and local meteorological conditions. Typical water from the Tertiary basaltic reservoir rocks has a pH of about 8.5-8.9, TDS of 60-100 mg/L and chloride concentration about or below 10 mg/L. Water from the recent basaltic bedrock of the active zones of rifting and volcanism is distinctly more alkaline with pH above 9. TDS is generally lower, 30-60 mg/L. Chloride concentration and TDS are higher nearer the coast. Water from the older Quaternary rock formations shows similarities to groundwater in the Tertiary rock formations.