Sprungmarken

 
Popp, A*; Brennwald, M; Kipfer, R: Using dissolved gases to determine groundwater origin
Talk, Developments In Noble Gas Understanding and Expertise (workshop), Nancy: 2016-04-13 - 2016-04-15

Abstract:
During a three week groundwater pumping test, we investigated water mixing between young and old groundwater with the help of an on-site mass spectrometry system that quasi-continuously measures dissolved (noble) gases in water. The study site – a groundwater field for drinking water production – is located in northern Switzerland on the border to Germany. There, groundwater is artificially recharged by adding surface water originating from the river Rhine on an excavated system of channels and ponds to fed the underlying ground water. The hypothesis is that intensive pumping of the pumping wells might lead to an inflow of older (e.g., 'Helium-rich') and potentially contaminated groundwater from deeper aquifers through the geologic fault system into the upper aquifer being used to produce drinking. Therefore, for our experiment only water from one well was continuously abstracted while other wells in the direct vicinity of the pumped well were not in operation. The pumped well is known to lie above a fault zone by previous investigations [1]. First results of the helium isotopic pattern suggest slightly older water compared to water from other wells on the study site. However, the long-term pumping does not seem to influence He abundance at least for the time of the groundwater pumping test. The experiment proves that He and other (noble) gas concentrations can be determined in the field in a quasi-continuous mode (e.g., determination of dissolved concentrations of He, Ar, Kr, O2, N2, CO2 and CH4 every 15 minutes [2]) over weeks. Such continuous time series of dissolved gas concentrations open a new analytical route in tracer hydrology and environmental science to investigate gas evolution in aquatic systems. References: [1] Spottke I. Et al. (2005) Int. J. Earth. Sci., 94, 580–593. [2] Mächler et al. (2012) Environ. Sci. Technol., 46, 8288−8296.

last modified 2016-11-23