Isotope techniques used to ensure clean freshwater in Pampanga

A researcher collects water samples from production and domestic wells in Pampanga to analyze for salinity and possible contamination of the groundwater in the area.

The new coronavirus pandemic underscores the need for freshwater for health and hygiene. Thus, constant water shortages in various parts of the country are not only inconvenient but also pose a threat to efforts in preventing the spread of Covid-19.

To help ensure that the precious freshwater sources are not only available but also free of salinity contamination, scientists from the University of the Philippines–Diliman (UP Diliman) and the Department of Science and Technology-Philippine Nuclear Research Institute (DOST-PNRI) used nuclear techniques to analyze where the salinity of the groundwater in different localities in Pampanga province is coming from.

The abstract of the research explained that Pampanga relies heavily on groundwater for freshwater sources.

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.

However, seawater coming from Manila Bay may contaminate the fresh groundwater in the coastal municipalities in the southern border of the province.

To help authorities prepare the proper mitigation strategies, the researchers assessed the groundwater in Pampanga on whether its salinity comes from the sea or from other sources.

They studied the isotopes of iodine to learn about the movement between different sources. Iodine 129, in particular, is a radioactive isotope prominently used in the study. Isotopes are atoms with the same number of protons, but differ in numbers of neutrons.

While Iodine 129 is commonly known as a byproduct of nuclear weapons testing, nuclear fuel reprocessing, or nuclear accidents, it 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 turned out, the salinity of one of the samples was from brine (salty) fossil water trapped underground, one sample from possible wastewater, while the rest were due to evaporation, which actually increases groundwater salinity.

The abstract said: “The results of this study will be helpful to the government, civil society, and other organizations for monitoring, policy-making, and management of the groundwater and the subsurface formations that will be crucial to continuously supply the freshwater needs of the present and future generation.”

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 PNRI news release said.

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.

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.

The study was published recently published in the Journal of Environmental Radioactivity.

S&T Media Service

Image credits: PNRI



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