The use of O, H, B, Sr and S isotopes for tracing the origin of dissolved boron in groundwater in Central Macedonia, Greece

• Published in: Applied geochemistry 2010-11, Vol.25 (11), p.1783-1796
• Main Authors: Dotsika, E., Poutoukis, D., Kloppmann, W., Guerrot, C., Voutsa, D., Kouimtzis, T.H.
• Format: Article
• Language: English
• Subjects: Boreholes; Dissolution; Drinking water; Earth Sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Environmental Sciences; Exact sciences and technology; Geochemistry; Geothermal; Global Changes; Groundwater; Isotopes; Origins; Pollution, environment geology; Sciences of the Universe; Strontium
• ISSN: 0883-2927; 1872-9134
• DOI: 10.1016/j.apgeochem.2010.09.006

► Multi-isotopic approach for the investigation of pollution in groundwater aquifers in Central Macedonia, Greece. ► Origin of Boron using isotope of B. ► Combination of geochemical parameters with multi-isotopic tools. The groundwater B concentration in Mesozoic karst, Neogene and alluvial aquifers in the West part of Chalkidiki province in Central Macedonia, Greece reaches 6.45 mg L −1, which exceeds the limit of 1 mg L −1, set by the European Union for drinking water. The high B contents have been detected in this area, not only near the shoreline, where seawater intrusion occurs, but also in the inland part of the basin. Multi isotope ( 2H, 18O, 34S, 18O (SO4), 11B, 87Sr/ 86Sr) data from borehole and thermal water springs allow identification of the possible B sources. The B dissolved in groundwater in the Chalkidiki area is mainly geogenic. The low δ 11B values, 0–1‰, similar to those of thermal fluids from continental geothermal fields, and the low Cl/B ratio compared to seawater both indicate a geothermal origin for B and reflect deep circulation and interaction with igneous rocks. The 87Sr/ 86Sr ratio also indicates that the deep-aquifer granodiorite is the predominant rock source of Sr, while the shallow limestone unit has negligible effects on the dissolved Sr budget in these thermal karst waters which O and H isotopes show to be of meteoric origin. The main source of high B in borehole water is mainly mixing with B-rich geothermal water. The mixing between geothermal water and water from the Neogene aquifer is also reflected by isotopic contents of SO 4.