Establishment of tritium dating facility for hydrological studies in PNRI

The release of excess tritium (3H) into the atmosphere from nuclear weapons tests conducted between 1952 and 1963 'tagged' rain water, and thereby all surface waters with 3HHO. Measurement of 3H concentrations in rain, surface water and groundwater is useful index of vulnerability and sustainability of the aquifer to pollution and human exploitation. These determinations are currently being used in the characterization of different environments and in pollution studies, in the framework of research projects, international collaborations and services. Liquid scintillation counting (LSC) was the method of choice for the evaluation of the tritium concentrations in precipitation, groundwater and surface water samples. Prior to counting process, the samples are enriched in tritium by an electrolysis procedure to improve the overall detection limit. Low-level hydrological water samples go through an electrolytic enrichment step, in which tritium concentrations are increased to about seventy-fold through volume reduction. The amount of tritium in water is expressed in tritium units (TU). Water samples taken from selected areas of Bulacan province within the period of 2007 and 2008 were analyzed as part of the current hydrological studies being done by our group in PNRI. The typical tritium values for the rain water, surface water, and groundwater were found to be 1.20±0.11 TU, 1.12±0.11 TU, and 0.40±0.07, respectively. Procedures are now available in our laboratory for measurement of tritium in water samples of different water types. (author)