Dating groundwater in the Bohemian Cretaceous Basin: Understanding tracer variations in the subsurface ...

• Main Authors: Purtschert, Roland, Corcho Alvarado, J. A., Paces, T.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Pergamon 2013
• Subjects: 530 Physics; permafrost
• Online Access: https://dx.doi.org/10.7892/boris.47737; http://boris.unibe.ch/47737/

The northern section of the Bohemian Cretaceous Basin has been the site of intensive U exploitation with harmful impacts on groundwater quality. The understanding of groundwater flow and age distribution is crucial for the prediction of the future dispersion and impact of the contamination. State of the art tracer methods (3H, 3He, 4He, 85Kr, 39Ar and 14C) were, therefore, used to obtain insights to ageing and mixing processes of groundwater along a north–south flow line in the centre of the two most important aquifers of Cenomanian and middle Turonian age. Dating of groundwater is particularly complex in this area as: (i) groundwater in the Cenomanian aquifer is locally affected by fluxes of geogenic and biogenic gases (e.g. CO2, CH4, He) and by fossil brines in basement rocks rich in Cl and SO4; (ii) a thick unsaturated zone overlays the Turonian aquifer; (iii) a periglacial climate and permafrost conditions prevailed during the Last Glacial Maximum (LGM), and iv) the wells are mostly screened over large ...