A new airtight sampling method for sulfur hexafluoride (SF6) in groundwater
Abstract
In the past 20 years, sulfur hexafluoride (SF6) has been considered a highly reliable tracer for assessing modern water (< 65 yrs old) in groundwater. However, modern-air contamination may introduce complications in interpreting data obtained using current sampling methods. A new airtight methodology isolates the sample from modern ambient air; thus, returning more reproducible and reliable results when compared to two traditional (air-sensitive and non-airtight) methods. The new airtight method returned results within 0.03–0.05 fmol/L SF6 of expected SF6 concentration for pre-modern waters (0.02–0.09±0.01 fmol/L). In contrast, the air-sensitive and non-airtight traditional methods returned results within 0.00–0.90 fmol/L and 0.02–1.21 fmol/L of the expected value, respectively. It is suspected that transformers in proximity to wells leak SF6 which subsequently partitions into the samples obtained using traditional air-sensitive and non-airtight methods, thus creating erratic SF6 results. • Comparative analyses of a new airtight method with traditional methods were performed and returned lower SF6 concentrations with the new 2022 airtight method. • The new airtight method shows reproducible low-level detection of SF6 concentrations and may reduce sampling error in production wells in urban areas that are co-located with transformers which are SF6-emitting sources.
Publication Title
MethodsX
Recommended Citation
Sunderland, R., Larsen, D., Schoefernacker, S., & Leslie, D. (2025). A new airtight sampling method for sulfur hexafluoride (SF6) in groundwater. MethodsX, 14 https://doi.org/10.1016/j.mex.2024.103120
