To ensure that clean freshwater reaches residents in Pampanga, scientists from the Department of Science and Technology-Philippine Nuclear Research Institute (DOST-PNRI) together and the University of the Philippines–Diliman (UP Diliman) partnered up using nuclear techniques to analyze where the salinity of the groundwater is coming from.

The  researchers assessed the groundwater in Pampanga and whether its salinity comes from the sea or from other sources since seawater coming from Manila Bay may contaminate the fresh groundwater in the coastal municipalities in the southern border of the province. This will also help authorities prepare the proper mitigation strategies.

Wells and other groundwater sources are vital to Pampanga residents’ homes and businesses, according to earlier studies by the Department of Environment and Natural Resources (DENR).

They studied the isotopes of iodine to learn about the movement between various sources. Iodine 129, in particular, is a radioactive isotope prominently used in the study.

While Iodine 129 is commonly known as a byproduct of nuclear weapons testing, nuclear fuel reprocessing, or nuclear accidents, the said isotope is a suitable tool for tracing because it has distinct signatures in various bodies of water, such as in rain, seawater, river water, and in groundwater.

Out of the 32 samples studied, seven contained elevated traces of salinity. The good news is that none of the samples so far showed salinity from seawater intrusion from Manila Bay. As it turns out, the salinity of one of the samples was from brine fossil water trapped underground, while the rest was due to evaporation, which actually increases groundwater salinity.

Beyond being helpful to zoning, monitoring, and crafting of water resources management policies in the country, the results of the study also proved that isotope and nuclear techniques can be applied in other regions with problems in groundwater contamination.

The study was led by Dr. Sunshine Tan of UP Diliman’s Environmental Engineering Program, under the mentorship of Dr. Angel Bautista VII of the DOST-PNRI’s Nuclear Analytical Techniques Applications Section. The study also received assistance from the Mines and Geosciences Bureau of the Department of Environment and Natural Resources and the Micro Analysis Laboratory, Tandem Accelerator of the University of Tokyo, where the samples were analyzed.

Dr. Tan is a grantee of DOST-PNRI’s Graduate Student Research Grant Program (GSRGP). Her dissertation went on to win First Place for Best Oral Presentation Award at the 2019 International Conference on Environmental Radioactivity in Prague, Czech Republic, with participants from 41 countries.

The PNRI GSRGP is a research grant program implemented by DOST-PNRI and funded by the DOST - Philippine Council for Industry, Energy and Emerging Technology Research and Development.