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Dating young groundwater with sulfur hexafluoride: Natural and anthropogenic sources of sulfur hexafluoride
Author(s) -
Busenberg Eurybiades,
Plummer L. Niel
Publication year - 2000
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/2000wr900151
Subject(s) - groundwater , groundwater recharge , aquifer , sulfur hexafluoride , geology , volcano , hydrology (agriculture) , sedimentary rock , environmental science , geochemistry , chemistry , geotechnical engineering , organic chemistry
Sulfur hexafluoride (SF 6 ) is primarily of anthropogenic origin but also occurs naturally. The troposphere concentration of SF 6 has increased from a steady state value of 0.054±0.009 to more than 4 parts per trillion volume during the past 40 years. An analytical procedure was developed for measuring concentrations of SF 6 to less than 0.01 fmol/L in water. Groundwater can be dated with SF 6 if it is in equilibrium with atmospheric SF 6 at the time of recharge and does not contain significant SF 6 from other sources. The dating range of SF 6 is currently 0 to 30 years. The tracer was successfully used to date shallow groundwater of the Atlantic Coastal Plain sand aquifers of the United States and springs issuing near the top of the Blue Ridge Mountains of Virginia. Significant concentrations of naturally occurring SF 6 were found in some igneous, volcanic, and sedimentary rocks and in some hydrothermal fluids.