The Philippine Nuclear Research Institute (PNRI) is a government agency under the Department of Science and Technology mandated to undertake research and development activities in the peaceful uses of nuclear energy, institute regulations on the said uses, and carry out the enforcement of said regulations to protect the health and safety of radiation workers and the general public.
Mercury speciation and isotopic composition was determined in ore, soil, sediment, and biota (lobster) samples collected from the vicinity and coastal area near the abandoned mercury mine in Palawan, Philippines. This study reported significant mass-dependent mercury isotopic fractionization among ore, soil, sediment and biota in the vicinity of abandoned mercury mine. Mercury isotopes in ore, soil and sediment samples had the lowest δ202Hg (-0.59‰ to -1.61‰) and Δ199Hg (+0.00 to +0.24‰) and small variance measured values but there was significant positive Δ199Hg and negative δ202Hg values in the biota that were correlated with light penetration depth in the sea. This suggests photochemical degradation of methylmercury prior to incorporation of remaining mercury into the food web. Mercury speciation identified oxidized Hg(II) as the dominant species in the marine sediment which is explained by quick transport of soil particles from the mine to the coast during heavy rains and flooding. Fewer Hg(I) were measured in the sediment, suggesting partial photoreduction of Hg(II) to Hg(0).
Jose Panganiban, Camarines Norte, is notable for small-scale gold mining, which produces waste stored in tailings storage facilities such as tailings ponds. These operations potentially pose environmental risks to nearby ecosystems and local communities due to hazardous substances, including mercury (Hg) used in ore processing, and elevated radionuclide concentrations from land disturbance. This study assessed the presence of the abovementioned pollutants in a legacy tailings pond to evaluate human and environmental risks. Sampling points were established around the pond for in-situ gamma-ray spectrometry measurements of radionuclides and for laboratory analysis of mercury. Assessment of radiological risk parameters showed that computed values were well below established global averages. Radiological assessments used NORMALYSA simulation, and results indicated that the absorbed dose rate in the study area remains below the public safety limit of 1 mSv/year. In contrast, mercury analysis revealed that certain sampling points exceeded the global background for soils, indicating localized contamination. Mercury speciation analysis reveals that Hg(I) was the predominant mercury species identified in soil samples. The geoaccumulation index assessment indicated that some sites are strongly to extremely contaminated with mercury, while locations farther from the tailings pond exhibited minimal risk of mercury contamination. Although radiometric analysis did not detect anomalous radionuclide elevation attributable to mine waste, localized mercury contamination remains a significant environmental concern.
Climate change-driven heat and drought stresses during reproductive stages significantly threaten wheat productivity. To investigate the genetic and physiological basis of combined heat-drought (HD) tolerance, we evaluated 345 wheat genotypes under three environments of HD stresses, non-stress glasshouse conditions and a late-sowing field trial. HD stresses caused significant reductions in chlorophyll content, flag leaf area, biomass, seed-setting rate and grain weight-related traits. Notably, HD-tolerant lines maintained higher grain weight, grain number and chlorophyll retention, with less than half the reductions observed in sensitive genotypes. A genome-wide association study using a 40K single-nucleotide polymorphism (SNP) array identified 124 candidate SNPs (cSNPs) associated with 51 traits across three environments with 78 cSNPs associated with HD tolerance. In total, 24 cSNP blocks exhibited pleiotropic associations with multiple traits under those three environments. Tight genomic co-localisations were detected between chlorophyll content (SPAD or CCM200 values), flag leaf width, seed-setting rate and grain yield components (thousand grain weight, grain number per spike), with superior haplotypes identified, supporting their utility in selections. Stay-green traits appeared to contribute significantly to yield stability under HD stresses. Those results provide valuable genomic and physiological insights into wheat HD tolerance for future targeted wheat breeding.
Iodine-129 is a long-lived radioisotope that is considered an excellent environmental tracer due to its unique and conservative properties and as an emerging tracer in hydrological studies. In April 2022, groundwater and seawater samples collected from Boracay island, southwestern Philippines, were analyzed for 129I, 127I, chemical and stable isotopes of 2H and 18O. One groundwater sample with elevated salinity suspected due to seawater intrusion was proven to be caused by other factors as indicated by low 129I/127I supported by stable 2H and 18O isotopes. Moreover, two seawater samples had relatively low 129I values, indicating possible freshwater dilution from a nearby treatment plant. In general, 129I/127I ratios measured in seawater were 100 to 150 times higher than prenuclear level (129I/127I (prenuclear) = 1.50 x 10-13), while groundwater 129I/127I ratios were measured to be 17 to 140 times higher than prenuclear level indicating effects of anthropogenic inputs. Since no known nuclear activities are recorded in the country, the anthropogenic 129I must have originated from transboundary sources and transported by atmospheric deposition and ocean currents. Our results demonstrate the use of 129I as a tracer of anthropogenic inputs in the water resources of Boracay island and also provide essential data in evaluating the possible effects of various NPPs along the seas of the Philippines in the future.
Soil samples from selected rice farm in the municipalities of Aliaga and Bongabon, Nueva Ecija, Philippines were collected to assess the natural radioactivity levels and associated radiological health risks. Soil samples were analyzed using a high-purity germanium (HPGe) detector to determine the activity concentrations of the primordial radionuclides uranium-238 ( 238 U), thorium-232 ( 232 Th), and potassium-40 ( 40 K). The measured mean activity concentrations were 2.45 ± 0.05, 2.45 ± 0.47, 158.5 ± 9.2 Bq/kg for 238 U, 232 Th, and 40 K, respectively. The corresponding absorbed dose rate in air (ADRA), annual effective dose equivalent (AEDE), and excess lifetime cancer risk (ELCR) were 9.3 nGy/h, 0.0113 mSv/y, and 3.975 x 10 − 5, respectively. All measured values were significantly below the global reference levels reported by UNSCEAR (2000), indicating minimal radiological health risk to the local population. Pearson’s correlation analysis showed strong positive associations between natural radionuclide concentrations and radiological risk parameters, while hierarchical cluster analysis indicated that 232 Th and 238 U are the primary contributors to external gamma dose, with 40 K showing lesser influence. The results confirm that the rice field soils in the study area are radiologically safe for agricultural activities. These findings provide essential baseline data to support continued environmental monitoring and informed land-use planning.
