Dating problems with selected mining lakes and the adjacent groundwater body in Lusatia, Germany

• Published in: Isotopes in environmental and health studies 2010-09, Vol.46 (3), p.291-298
• Main Authors: Seebach, Anne, von Rohden, Christoph, Ilmberger, Johann, Weise, Stephan M., Knöller, Kay
• Format: Article
• Language: English
• Subjects: Chronology as Topic; deuterium; Deuterium - analysis; Environmental Monitoring; Fresh Water - analysis; Fresh Water - chemistry; Freshwater; Germany; groundwater dating; Isotopes - analysis; Mining; Oxygen Isotopes - analysis; oxygen-18; Radiometric Dating; stable isotope tracer techniques; Sulfur Hexafluoride - analysis; sulphurhexafluoride; tritium; Tritium - analysis; Water Supply - analysis; Water Supply - standards
• ISSN: 1025-6016; 1477-2639
• DOI: 10.1080/10256016.2010.502592

This study presents selected results, applying environmental tracers to investigate lake water-groundwater interactions at two study sites located in Lusatia, Germany. The focus of the investigations were two meromictic pit lakes and their adjacent aquifers. In order to follow hydrodynamic processes between lake and groundwater, mixing patterns within the lakes as well as ages of lake and groundwater, water samples of ground- and lake water were collected at three occasions, representing summer and winter conditions in the aquatic systems. The water samples were analysed for stable isotopes (deuterium, oxygen-18) and tritium and sulphurhexafluoride (SF 6 concentration). Lake water profiles of conductivity and 18 O could validate the permanent stratification pattern of both the lakes. Groundwater data sets showed a heterogeneous local distribution in stable isotope values between rain and lake water. A two-component mixing model had been adopted only from 18 O data to determine lake water proportions in the surrounding groundwater wells in order to correct measured tritium and SF 6 concentrations in groundwater samples. This procedure had been hampered by upstream-located wells indicating strong 18 O enrichment in groundwater samples. However, rough groundwater ages were estimated. For both study sites, Piston flow ages between 12.9 and 27.7 years were calculated. The investigations showed the good agreement between two different environmental dating tools, considering the marginal data sets.