Isotope heterogeneity of Pre-Holocene groundwater in Iceland

• Main Authors: Sveinbjörnsdóttir, Á.E., Arnorsson, S., Heinemeier, Jan
• Other Authors: Bullen, Thomas D., Wang, Yanxin, Wuhan, P. R.
• Format: Book Part
• Language: English
• Published: Taylor & Francis 2007
• Subjects: Iceland
• Online Access: https://pure.au.dk/portal/da/publications/isotope-heterogeneity-of-preholocene-groundwater-in-iceland(c0bbe42c-7a6f-4ee4-8e84-58ee72379e22).html; https://doi.org/10.1201/NOE0415451369.ch165

In recent years, it has been shown that groundwater with a Pre-Holocene component is more common in the Icelandic bedrock than previously thought. Some of the Pre-Holocene water samples are more depleted in delta H-2 and delta O-18 than any mean annual precipitation in Iceland today due to the cold climate at that time. However, most often Pre-Holocene water components cannot be detected based on the water isotopes alone due to mixing with younger and isotopically heavier water. The Cl concentration in relation to the water isotopes in specific areas has proved to be a good indicator of a Pre-Holocene component in the groundwater. The deuterium excess value may also help to identify water from a different climate regime, if no oxygen shift has occurred. The relative abundance of a Pre-Holocene water component of the Icelandic groundwater has led to the understanding that combined interpretation of water-isotopes, water chemistry and hydrogeology is essential to delineate flow direction and trace the origin of thermal and non-thermal groundwaters.