The modern water interface: recognition, protection and development — advance of modern waters in European aquifer systems

Abstract

Abstract:Modem groundwater that has recharged aquifers within the past 50 a shows the influence of humans globally, either by the presence of small concentrations of environmental tracers or in some cases by severe pollution. This study describes important environmental tracers (e.g. 3H, 85Kr, chlorofluorocarbons, SF6) and contaminants (e.g. NO3-, pesticides, chlorinated solvents) for modem groundwater dating and recognition of human impacts. Some applications of the described tracers in aquifers investigated in the PALAEAUX study are presented in order to illustrate the advance of modem waters in European aquifer systems. The study shows that the location of the modern water interface varies within a range of between c. 10 and c. 100 m in the investigated aquifers due to variations in hydrogeological setting, climate and exploitation of the groundwater resource. The subsurface distribution of the modem water indicators and contaminants demonstrate that the advance of modem groundwaters and the fate of harmful substances in them have important implications for protection and development of the water resources. Contaminants that do not degrade or degrade only very slowly will advance further into the aquifers and may eventually contaminate even deep groundwater systems.

The Miocene Sand Aquifers, Jutland, Denmark

“…Hence, for the majority of the major elements the composition of the Ribe Formation groundwaters is inherited from rainwater percolating through the Quaternary sands above undergoing carbonate dissolution and oxygen and nitrate reduction. No indicators of human impact (Hinsby et al 2001b) have been found in the Ribe Formation groundwater.…”

Beneath the surface of global change: Impacts of climate change on groundwater

“…Tracer methods are standard tools of hydrologists to obtain constraints on the age of groundwater and on processes and conditions water samples experienced during recharge and upon transit in the groundwater system (Plummer, 1993;Clark and Fritz, 1997;Cook and Herczeg, 2000;Hinsby et al, 2001;Loosli et al, 2001;Kooi, 2008a). In the following, key methods are summarised, and their potential for detecting temporal change in groundwater systems is discussed, focusing on relatively short time scales (less than 100 years).…”

Application of stable isotopes (δ34S-SO4, δ18O-SO4, δ15N-NO3, δ18O-NO3) to determine natural background and contamination sources in the Guadalhorce River Basin (southern Spain)

“…Application of radioactive and stable isotopes are useful tools for assessing human impacts on groundwater quality, e.g., through evaluation of groundwater residence times, pollution history and trends in groundwater bodies (Bohlke and Denver, 1995;Hinsby et al, 2001Hinsby et al, , 2007Visser et al, 2007), and for identification of different pollution sources (Aravena et al, 1993 etc. ).…”