Niel Plummer Eurybiades Busenberg Yongje Kim Dong-Chan Koh 2007 <p><span>Measurements of the concentrations of dichlorodifluoromethane (CFC-12), tritium (</span>³<span>H), and sulfur hexafluoride (SF</span>₆<span>) in groundwater from basaltic aquifers in Jeju Island, Korea, demonstrate a terrigenic source of SF</span>₆<span>. Using a lumped-parameter dispersion model, groundwater was identified as young water (&lt;15 years), old water with negligible CFC-12 and<span>&nbsp;</span></span>³<span>H, and binary mixtures of the two. Model calculations using dispersion models and binary mixing based on<span>&nbsp;</span></span>³<span>H and CFC-12 concentrations demonstrate a non-atmospheric excess of SF</span>₆<span><span>&nbsp;</span>relative to CFC-12 and<span>&nbsp;</span></span>³<span>H concentrations for more than half of the samples. The non-atmospheric excess SF</span>₆<span><span>&nbsp;</span>may have originated from terrigenic sources in relict volcanic fluids, which could have acquired SF</span>₆<span><span>&nbsp;</span>from granites and basement rocks of the island during volcanic activity. Local excess anthropogenic sources of SF</span>₆<span><span>&nbsp;</span>are unlikely. The SF</span>₆<span><span>&nbsp;</span>age is biased young relative to the CFC-12 age, typically up to 20 years and as high as 30 years. This age bias is more pronounced in samples of groundwater older than 15 years. The presence of terrigenic SF</span>₆<span><span>&nbsp;</span>can affect the entire dating range for groundwater in mixtures that contain a fraction of old water.</span></p> application/pdf 10.1016/j.jhydrol.2007.03.011 en Elsevier Evidence for terrigenic SF6 in groundwater from basaltic aquifers, Jeju Island, Korea: Implications for groundwater dating article