As part of its advisory mandate, the Federal Institute for Geosciences and Natural Resources (BGR) is also dealing with the environmental hazard posed by geogenically elevated radioactivity (NORM - Naturally Occurring Radioactive Material) in usable water resources. This problem is relevant even outside of regions with active/former (uranium) mining. Elevated NORM levels can pose an obstacle problem for drinking water supplies during the exploration and development of new groundwater resources, for example in Burundi as well as in North Africa and the Middle East.
Against this background, the BGR, in collaboration with radioecologists from the Institute of Radioecology and Radiation Protection (IRS) at Leibniz University Hannover and the Federal Office for Radiation Protection (BfS), investigated the occurrence and spread of dissolved NORM contents (in particular the radionuclides of uranium, radium and polonium) in groundwater. Other cooperation partners included regional authorities such as the Lower Saxony State Office for Mining, Energy and Geology (LBEG), the Lower Saxony Water Management, Coastal and Nature Protection Agency (NLWKN) and the Saxony-Anhalt State Agency for Flood Protection and Water Management (LHW).
The decay products of uranium-238 and thorium-232 are ubiquitously distributed radionuclides that can also occur widely in shallow aquifers. In contrast to uranium (U) and thorium (Th), the radiotoxic nuclides of radium (Ra) and polonium (Po) in particular can only be determined using complex radiometric methods. Therefore, little is known about the mobilisation and accumulation of these radionuclides in groundwater. From available data and international publications, it is known that locally highly elevated U and Ra levels, as well as Po-210 levels in individual cases, can severely restrict the use of groundwater as a drinking water resource.
While a large number of data/publications are available for dissolved uranium in groundwater, the project investigated the occurrence and genesis of further geogenic radionuclides (Ra, Po) in groundwater based on national and international case studies. The focus was on shallow aquifers as well as aquifers relevant for drinking water supply. The work comprised an inventory of worldwide reports on NORM in groundwater, as well as own investigations on national (Lower Saxony, Saxony-Anhalt) and international (Burundi, Namibia) case studies. The aim was to characterise the processes relevant to NORM mobilisation and, based on this, to make statements about the extent to which and under what conditions a supra-regional spread of geogenic radiotoxic substances in groundwater is to be feared.
Despite pandemic restrictions, several groundwater and drill core samples from Burundi, Namibia, Lower Saxony and Saxony-Anhalt were collected and analysed during the project. The results show significantly elevated levels of dissolved NORM in commercially used groundwater resources, both nationally and internationally, and allow an assessment of the hydrogeological and geochemical conditions that may lead to the accumulation of dissolved NORM in groundwater.
Literature
Papers
- MÜHR-EBERT, E.L., WAGNER, F. & WALTER, C. (2019): Speciation of uranium: Compilation of a thermodynamic database and its experimental evaluation using different analytical techniques. – Applied Geochemistry, 100: 213–222. DOI: 10.1016/j.apgeochem.2018.10.006
- WAGNER, F., ALTFELDER, S., HIMMELSBACH, T. & JUNG, H. (2019): Uranium mill tailings affecting water resources in Mailuu Suu Valley, Kyrgyzstan. In: Uranium Production Cycle Selected Papers 2012–2015. – Proceedings of a Series of Technical Meetings: 55–62. IAEA-TECDOC-1873, IAEA, Vienna.
Conference contributions
- HOFMANN, P., WAGNER, F., LUCKS, C. & WITTWER, C. (2021): Occurrence and origin of polonium-210 in a sandstone aquifer in Germany. – EGU 2020, Session EGU21–69, GI6.2, Vienna.
- SCHULTE, V., WAGNER, F., MÜHR-EBERT, E.L., WALTHER, C. & METSCHIES, T. (2019): Evaluation of in-situ immobilisation of Uranium in tailing material on a laboratory scale. –Proceedings of WISSYM 2019 (4. Internationales Bergbausymposium), 9.–11.10.2019: 175–184; Chemnitz.
Partner
- Federal Office for Radiation Protection (BfS)
- Institute of Radioecology and Radiation Protection (IRS) at Leibniz University Hannover (LUH)
- Saxony-Anhalt State Agency for Flood Protection and Water Management (LHW)
- Lower Saxony Water Management, Coastal and Nature Protection Agency (NLWKN)
- Lower Saxony State Office for Mining, Energy and Geology (LBEG)