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The enrichment levels of potentially toxic elements (PTEs) have recently attracted global concerns due to their associated environmental risks and threats to human health. This study, therefore, aims to assess the pollution impacts of these PTEs from 53 marine sediment samples from Puerto Princesa Bay, Palawan, the Philippines. The concentrations of eight PTEs (As, Co, Cr, Cu, Hg, Mn, Ni, and Zn) were determined using portable X-ray fluorescence spectroscopy and direct mercury analyzer. Spatial distribution maps of the bay revealed similar trends for Cr, Co, Cu, Mn, Ni, As, and Zn, with higher concentrations found at the north-western side of Puerto Princesa Bay. Factor analysis revealed that this trend can be attributed to natural provenance. Moreover, a higher concentration of As was concentrated in the southern part of the bay adjacent to the built-up areas of Puerto Princesa City, whereas Hg had higher concentrations in the northern part. Their distribution can be attributed to anthropogenic influence: Hg transport exacerbated by historical mercury mining upstream and industrial activities in the built-up bay that lead to the enrichment of As. Further assessment using the enrichment factor and index of geoaccumulation indices support the mentioned factors of PTEs based on their enrichment and contamination levels. Lastly, the total potential ecological risk index revealed Co, Hg, and Ni - which are most likely to be the main pollutants - particularly in the northern part of the bay. Based on the evaluated indices, these PTEs are potential sources of ecological risks to the environment, as well as to the inhabitants of the area. The results are significant inputs in baselining the current PTE pollution caused in Puerto Princesa Bay, Palawan, as well as for decisions regarding mixed-use planning of the bay area. [ABSTRACT FROM AUTHOR]

Critical minerals (CMs) such as nickel (Ni), cobalt (Co) Co, chromium (Cr), manganese (Mn), and zinc (Zn) are materials essential to the economy, but the supply is vulnerable to disruption. Ni laterite deposits are considered potential sources of these CMs. In this study, the Ni, Co, Cr, Mn, and Zn contents of 15 Ni laterite samples from Zambales and Surigao were determined using handheld laser-induced breakdown spectroscopy (hLIBS) and handheld X-ray fluorescence (hXRF) analyzers. The samples were also analyzed using inductively coupled plasma mass spectrometry (ICP-MS) to compare the handheld analyzers with the established laboratory technique. The two-sided t-tests show no significant differences between the average Ni, Cr, Mn, and Zn results of hLIBS and hXRF with respect to ICP-MS. The average hXRF result of Co significantly differs from ICP-MS, whereas hLIBS has no significant difference from ICPMS. Therefore, hLIBS and hXRF can be used to determine the Ni, Cr, Mn, and Zn contents in laterites, whereas hLIBS can be utilized to determine the Co values of laterites. Both hLIBS and hXRF analyzers can be for CM exploration of Ni laterite deposits. [ABSTRACT FROM AUTHOR]

In the Philippines, legacy mines and active mine wastes pose potential threats since these may contain elevated concentrations of potentially toxic elements (PTEs) and high natural radioactivity. In this study, legacy mine wastes from the Philippine Iron Mine (PIM), Barlo Mine (BM), and Rapu-Rapu Mine (RRM) and active mine tailing from Padcal Mine (PM) were analyzed to determine the concentrations of fifteen (15) PTEs and the activity concentrations of natural radionuclides. Several quantitative risk indicators and radiological health risk parameters were utilized to determine the potential effects of these mine wastes to the natural environment and to human health. Legacy mine wastes have higher contents of PTEs and are more polluted by PTEs than PM tailing. Both enrichment factor (EF) and geoaccumulation index (Igeo) values suggest that legacy mine wastes are strongly polluted by As, Cd, Cu, and Mo. BM and RM wastes are also polluted by Pb, Sb, and Zn; PIM waste is polluted by Ni and V; and BM waste is polluted by Tl. Padcal mine tailing is only moderately polluted by Cu and Mo. The natural radionuclide activity concentrations of legacy and active mine wastes are below the global background values and the radiological hazard indices are also all lower than their permissible limits, except for 40K, 238U, and absorbed gamma dose rate in PIM due to a geogenic source. Unlike the PTEs, radioactivity in the legacy and active mine wastes are not enhanced by mining activities and is not a significant risk factor to human health. [ABSTRACT FROM AUTHOR]