Niel Plummer Solomon D. Kip E. Busenberg Y.-J. Kim H.-W. Chang D.-C. Koh 2006 <div id="abstracts" class="Abstracts"><div id="aep-abstract-id22" class="abstract author" lang="en"><div id="aep-abstract-sec-id23"><p>Tritium/helium-3 (³H/³<span>He) and chlorofluorocarbons (CFCs) were investigated as environmental tracers in ground water from Jeju Island (Republic of Korea), a basaltic&nbsp;volcanic island. Ground-water mixing was evaluated by comparing&nbsp;</span>³H and CFC-12 concentrations with lumped-parameter dispersion models, which distinguished old water recharged before the 1950s with negligible<span>&nbsp;</span>³H and CFC-12 from younger water. Low<span>&nbsp;</span>³<span>H levels in a considerable number of samples cannot be explained by the mixing models, and were interpreted as binary mixing of old and younger water; a process also identified in&nbsp;alkalinity&nbsp;and pH of ground water. The ground-water CFC-12 age is much older in water from wells completed in confined zones of the hydro-volcanic Seogwipo Formation in coastal areas than in water from the basaltic&nbsp;aquifer. Major&nbsp;cation&nbsp;concentrations are much higher in young water with high&nbsp;nitrate&nbsp;than those in uncontaminated old water.&nbsp;Chemical evolution&nbsp;of ground water resulting from&nbsp;silicate&nbsp;weathering in basaltic rocks reaches the zeolite–smectite phase boundary. The&nbsp;calcite&nbsp;saturation state of ground water increases with the CFC-12 apparent (piston flow) age. In agricultural areas, the temporal trend of nitrate concentration in ground water is consistent with the known history of&nbsp;chemical fertilizer&nbsp;use on the island, but increase of nitrate concentration in ground water is more abrupt after the late 1970s compared with the exponential growth of nitrogen inputs.</span></p></div></div></div> application/pdf 10.1016/j.jhydrol.2005.11.021 en Elsevier Application of environmental tracers to mixing, evolution, and nitrate contamination of ground water in Jeju Island, Korea article