Determination of groundwater flow in SW Iceland with environmental tracers

• Main Author: Cypaité, Vaiva, 1990-
• Other Authors: Háskóli Íslands
• Format: Thesis
• Language: English
• Published: 2015
• Subjects: Jarðfræði; Grunnvatn; Rannsóknir; Suðvesturland; Reykjavík; Iceland
• Online Access: http://hdl.handle.net/1946/21739

The project aims at using natural tracers to determine groundwater origin and map groundwater flow in SW Iceland. During one year (March 2014 - March 2015), 208 water samples were collected. In the samples F, Cl and SO4 were measured with an Ion Chromatograph at the laboratory of Reykjavík Energy and stable isotopes of hydrogen and oxygen with the Picarro isotope analyser at the Institute of Earth Sciences, University of Iceland. In addition CO2 was extracted from 10 samples for carbon stable isotope measurements by using the carbon free vacuum line at the Institute of Earth Sciences. Those measurements were carried out on the IsoPrime stable isotope ratio mass spectrometer at the AMS Centre, University of Aarhus, Denmark. The project is twofold. Firstly, environmental tracers (δ2H, δ18O and Cl) were monitored during a full year in eight locations, where samples were taken every three weeks. The results showed minor seasonal variability and only in three locations the standard deviation from the mean was higher than the analytical errors. Hence a single sample taken form a sampling location will in most cases represent mean annual values of groundwater. Isotope fractionation, preferential elution of ions and anthropogenic impact are the main forces, which influence groundwater tracers. Secondly, 63 samples were collected in the area during the summer 2014 to study the spatial distribution of chloride and stable isotopes of oxygen and hydrogen. The main outcome of this part of the study was a deuterium chloride system which is based on combining the conceptual models of chloride and deuterium distribution. This work was performed in ArcGIS. The results were compared to Vatnaskil physical groundwater flow model of the area. In the project it is demonstrated how carbon isotopes can give additional information on groundwater hydrology.