This year's annual meeting of the German Association for Stabile Isotope Research (GASIR) was organized by the team headed by Prof. Florian Einsiedl (Chair of Hydrogeology). With 107 participants, a total of 35 lectures and 31 poster contributions were discussed. The main topics of the stable isotope research this year were: (1) Analytics, methods, techniques and quality assurance, (2) Food, forensics, doping, (3) Hydrology, hydrogeology, (4) Soil - plants – atmosphere, (5) Climate research and material cycles, (6) Physiology and metabolism. In addition, Monday morning was marked by presentations and presentations by companies that provided new insights into instruments, peripherals, equipment and accessories for isotope research. This diverse audience enabled presentations and discussion to be multifarious and interdisciplinary. During this meeting I gave the 20 min speech about my research and the recent results of my work.

Abstract: Aquifer thermal energy storage (ATES) may be considered beneficial due to lack of negative environmental impact, innovation and potential for further development. The state of knowledge on ATES and its potential to be combined with groundwater remediation was analyzed on the basis of literature data and operating experience. Chlorinated hydrocarbons and BTEX are the contaminants most frequently occurring at depths, where ATES systems usually operate. The following remediation techniques that potentially could be combined with ATES systems were discussed: ‛pump and treat’, natural (NA) and enhanced natural attenuation (ENA) via biostimulation and bioaugmentation, as well as in situ chemical oxidation (ISCO) and enhanced reductive dechlorination (ERD) under anaerobic conditions. Development of such solutions is constrained by problems related mainly to the risk of accelerated contaminant migration and reduction of their biodegradation rates as a result of changes in redox potential due to ATES system operation and well screen clogging. Further research is required to confirm the effectiveness of the combined application of ATES and groundwater remediation in practice as the knowledge of the aquifer processes upon thermal energy storage is incomplete and the operating experience limited.