Dating groundwater in the Bohemian Cretaceous Basin: Understanding tracer variations in the subsurface
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...
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ftunivbern:oai:boris.unibe.ch:47737 2023-08-20T04:09:15+02:00 Dating groundwater in the Bohemian Cretaceous Basin: Understanding tracer variations in the subsurface Corcho Alvarado, J. A. Paces, T. Purtschert, Roland 2013 application/pdf https://boris.unibe.ch/47737/1/1-s2.0-S0883292712003307-main.pdf https://boris.unibe.ch/47737/ eng eng Pergamon https://boris.unibe.ch/47737/ info:eu-repo/semantics/restrictedAccess Corcho Alvarado, J. A.; Paces, T.; Purtschert, Roland (2013). Dating groundwater in the Bohemian Cretaceous Basin: Understanding tracer variations in the subsurface. Applied geochemistry, 29, pp. 189-198. Pergamon 10.1016/j.apgeochem.2012.11.014 <http://dx.doi.org/10.1016/j.apgeochem.2012.11.014> 530 Physics info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion PeerReviewed 2013 ftunivbern https://doi.org/10.1016/j.apgeochem.2012.11.014 2023-07-31T21:06:02Z 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 depth intervals. Large disagreements in 85Kr and 3H/3He ages indicate that processes other than ageing have affected the tracer data in the Turonian aquifer. Mixing with older waters (>50 a) was confirmed by 39Ar activities. An inverse modelling approach, which included time lags for tracer transport throughout the unsaturated zone and degassing of 3He, was used to estimate the age of groundwater. Best fits between model and field results were obtained for mean residence times varying from modern up to a few hundred years. The presence of modern water in this aquifer is correlated with the occurrence of elevated pollution (e.g. nitrates). An increase of reactive geochemical indicators (e.g. Na) and radiogenic 4He, and a decrease in 14C along the flow direction confirmed groundwater ageing in the deeper confined Cenomanian aquifer. Radiocarbon ages varied from a few hundred years to more than 20 ka. Initial 14C activity for radiocarbon dating was calibrated by means of 39Ar measurements. The 14C age of a ... Article in Journal/Newspaper permafrost BORIS (Bern Open Repository and Information System, University of Bern) Applied Geochemistry 29 189 198 |
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English |
topic |
530 Physics |
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530 Physics Corcho Alvarado, J. A. Paces, T. Purtschert, Roland Dating groundwater in the Bohemian Cretaceous Basin: Understanding tracer variations in the subsurface |
topic_facet |
530 Physics |
description |
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 depth intervals. Large disagreements in 85Kr and 3H/3He ages indicate that processes other than ageing have affected the tracer data in the Turonian aquifer. Mixing with older waters (>50 a) was confirmed by 39Ar activities. An inverse modelling approach, which included time lags for tracer transport throughout the unsaturated zone and degassing of 3He, was used to estimate the age of groundwater. Best fits between model and field results were obtained for mean residence times varying from modern up to a few hundred years. The presence of modern water in this aquifer is correlated with the occurrence of elevated pollution (e.g. nitrates). An increase of reactive geochemical indicators (e.g. Na) and radiogenic 4He, and a decrease in 14C along the flow direction confirmed groundwater ageing in the deeper confined Cenomanian aquifer. Radiocarbon ages varied from a few hundred years to more than 20 ka. Initial 14C activity for radiocarbon dating was calibrated by means of 39Ar measurements. The 14C age of a ... |
format |
Article in Journal/Newspaper |
author |
Corcho Alvarado, J. A. Paces, T. Purtschert, Roland |
author_facet |
Corcho Alvarado, J. A. Paces, T. Purtschert, Roland |
author_sort |
Corcho Alvarado, J. A. |
title |
Dating groundwater in the Bohemian Cretaceous Basin: Understanding tracer variations in the subsurface |
title_short |
Dating groundwater in the Bohemian Cretaceous Basin: Understanding tracer variations in the subsurface |
title_full |
Dating groundwater in the Bohemian Cretaceous Basin: Understanding tracer variations in the subsurface |
title_fullStr |
Dating groundwater in the Bohemian Cretaceous Basin: Understanding tracer variations in the subsurface |
title_full_unstemmed |
Dating groundwater in the Bohemian Cretaceous Basin: Understanding tracer variations in the subsurface |
title_sort |
dating groundwater in the bohemian cretaceous basin: understanding tracer variations in the subsurface |
publisher |
Pergamon |
publishDate |
2013 |
url |
https://boris.unibe.ch/47737/1/1-s2.0-S0883292712003307-main.pdf https://boris.unibe.ch/47737/ |
genre |
permafrost |
genre_facet |
permafrost |
op_source |
Corcho Alvarado, J. A.; Paces, T.; Purtschert, Roland (2013). Dating groundwater in the Bohemian Cretaceous Basin: Understanding tracer variations in the subsurface. Applied geochemistry, 29, pp. 189-198. Pergamon 10.1016/j.apgeochem.2012.11.014 <http://dx.doi.org/10.1016/j.apgeochem.2012.11.014> |
op_relation |
https://boris.unibe.ch/47737/ |
op_rights |
info:eu-repo/semantics/restrictedAccess |
op_doi |
https://doi.org/10.1016/j.apgeochem.2012.11.014 |
container_title |
Applied Geochemistry |
container_volume |
29 |
container_start_page |
189 |
op_container_end_page |
198 |
_version_ |
1774722072327487488 |