The Chemical Composition of Geothermal Hot Springs as an Indicator of Various Geologic Subsurfaces in Iceland and Serbia
PETKOVIC Ivana, ĐORĐEVIĆ Dragana, ASBJORNSSON Einar Jon, MIHAJLIDI Aleksandra, SAKAN Sanja, FINGER David
[Institute of Chemistry, Technology and Metallurgy, Serbia]
Geothermal hot springs are frequently located along tectonic boundaries proving environmentally friendly energy source to fulfill energy demand. Generally, geothermal activity emerges near divergent tectonic plate boundaries as in the Icelandic case or in orogeny geological settings as in the Serbian case. The chemical composition of a hot spring is a signature of the sub-surface geology and its chemical composition. The sub-surface geology and composition of sources in Iceland have been studied intensively using geophysical methods and exploration drilling as required for estimating the geothermal potential of a source. Hence, the comparison of the chemical composition of geothermal sources can help us provide more detailed information prior to subsurface exploration. In order to assess the suitability of geothermal sources we analyzed and compared the chemical composition in Icelandic and Serbian geothermal sources. For this purpose, samples were collected from various hot springs in Iceland and in Serbia and analyzed using ion chromatography (IC) to determine ion concentrations and using inductively coupled plasma-optical emission spectrometry (ICP – OES) and inductively coupled plasma mass spectrometry (ICP - MS) to determine other elements concentrations. The results reveal that chemical composition reflects differences between locations of sampling or host rock composition. In general, sodium (Na+) is the dominating ion in all samples. The data obtained from the chemical analysis from sources located near to the ocean in Iceland indicate a high concentration of sodium (Na+), potassium (K+) and chloride (Cl-) ions, revealing an inflow of seawater. The dominant elements in Icelandic geothermal hot springs are iron (Fe), strontium (Sr), boron (B), barium (Ba) and aluminium (Al) The data from the chemical analysis of the samples obtained from sources in Serbia, however, shows a high concentration of sodium (Na+), calcium (Ca2+) and sulfate (SO42-). The dominant elements are boron, strontium, and arsenic. These results reveal that Serbian geothermal sources are characterized by very hard water and accordingly have to be used with precaution. Further analysis of the temporal evolution of the chemical composition is advisable before sub-surface exploration.
|        Topic: Geochemistry||Paper Number: 14093|