| Environmental tritium (3H) tracer has been widely utilized in New Zealand and Australia for characterizing catchment scale surface and groundwater dynamics and improving simulations of water movement and nutrient transport models. Tritium, which is a radioactive isotope of hydrogen with a half-life of 12.32 years, is a direct tracer of water movement as a part of water molecule making it particularly useful to estimate water transit times even with the atmospheric concentrations at ambient levels. However, this requres ultra-low level precision of tritium measurements and requires a good understanding of the tritium concentraions and water inputs into hydrologic systems, including their main trends due to latitudinal, seasonal and altitudinal effects. These effects are investigated with stable (2H and 18O) isotopes or local tritium measurements in monthly precipitation. Recent tritium study in Hokkaido, Japan, by Gusyev et al. (2016) has used the tritium tracer with lumped parameter models providing useful metrics of mean transit times (MTTs) and groundwater storage volume. These promising results encrourage the future use of tritium tracer in water of Japan and other countries in the Northern Hemisphere. |
