Results of the Determination of He in Cenozoic Aquifers Using the GC Method

Abstract

Applications of the Helium (He) method known so far consisted mainly of 4He measurements using a special mass spectrometer. 4He measurements for groundwater dating purposes can be replaced by total He (3He+4He) concentration measurements because the content of 3He can be ignored. The concentrations of 3He are very low and 3He/4 He ratios do not exceed 1.0·10(-5) in most cases. In this study, the total He concentrations in groundwater were determined using the gas chromatographic (GC) method as an alternative to methods based on spectrometry measurement. He concentrations in groundwater were used for the determination of residence time and groundwater circulation. Additionally, the radiocarbon method was used to determine the value of the external He flux (JHe) in the study area. Obtained low He concentrations and their small variation within the ca. 65 km long section along which groundwater flows indicate that it is likely there is relatively short residence time and a strong hydraulic connection between the aquifers. The estimated residence time (ca. 3000 years) is heavily dependent on the great uncertainty of the He concentration resulting from the low concentrations of He, the external 4He flux value adopted for calculation purposes and the 14C ages used to estimate the external 4He flux.

Analysis of the interaction between surface water and groundwater using gaseous tracers in a dynamic test at a riverbank filtration intake

“…Due to the low He concentrations in the analysed waters, the analysis of the samples was performed using an additional chromatographic system with a cryogenic sample enrichment system ( Śliwka et al, 2004). In the case of He, which is a mixture of 3 He and 4 He isotopes, measurement of the total He concentration provides a good approximation of the amount of the 4 He isotope migrating from the deeper bedrock into the aquifer (Kotowski & Najman, 2015). More information on the sampling and measurement methodology using the GC method is provided in the papers of Śliwka et al (2004) and Najman and Śliwka (2016).…”

Calibrated geochemical ages of the Baltic Artesian Basin groundwater

“…Tritium and krypton-85 are used for an age range <50 a, argon-39 covers 50-1,000 a, radiocarbon ( 14 C) 4-40 ka, chlorine-39 0.1-1 Ma and radiokrypton ( 81 Kr) is applied for the 0.15-1.5 Ma range (Winsberg, 1956;IAEA, 2013;Atkinson et al, 2014;Mace et al, 2017). Conventional helium and helium isotopic dating techniques have been broadly used as continuous and linear dating methods (Ciężkowski et al, 1992;Zuber et al, 1995Zuber et al, , 1997Kotowski and Najman, 2015). However, in the latest research where helium dating techniques were compared to kryp-ton-81 and modelled ages reveal that uncertainties may be huge due to the geological settings of a particular site or basin (Mokrik et al, 2021).…”