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The mass production and consumption of plastics have serious effects on the environment, human health, and livelihood. Hence, global efforts to reduce plastic generation must be realized. This study aimed to determine the prevalence of microplastics in mangrove sediments of Cabadbaran, Buenavista, and Nasipit in Butuan Bay, Philippines. Seventy-two (72) microplastic particles were extracted from mangrove sediments dominated by fibrous type (71%) and blue (35%) as the most common color. Attenuated total reflectance–Fourier transform infrared (ATR–FTIR) spectroscopy was used to assess the polymer type of microplastics. Results reveal a total of six polymer types including high-density polyethylene, low-density polyethylene, polyethylene terephthalate, ethylene-vinyl acetate, polyamide, and polypropylene, with the latter comprising 39% of samples, the highest among the extracted particles. Overall, Nasipit (71.1/kg) obtained the highest microplastic density followed by Buenavista (48.9/kg) and Cabadbaran (40.0/kg). These data will serve as a piece of baseline information in crafting important environmental policies to address plastic pollution issues in the area. Long-term studies are recommended to better understand, monitor, and prevent further microplastic pollution in Butuan Bay.

In this study, chemical and mineralogical characterizations of gold-mine tailings in key mining areas in Mindanao, Philippines were investigated for possible utilization as geopolymeric source material. Results of X-ray fluorescence (XRF) and energy dispersive X-ray spectroscopy (EDS) showed that the mine tailings samples have significant amounts of silicon, aluminum and calcium, which are crucial elements needed for geopolymerization. This was confirmed by the IR spectroscopic and mineralogical characteristics of the tailings where vibration bonds and minerals associated with Al and Si such as kaolinite and zeolite are detected. These minerals are already established as indicators for a material to be a good feedstock for geopolymerization. Furthermore, one of the tailings samples had an Si/Al ratio of 4.81, which was close to the recommended value of 3.0 for geopolymerization. The compressive strength of the synthesized geopolymer bricks gained an average of 5.48 MPa. The results suggested that gold mine tailings from key mining areas in Mindanao, Philippines could be used as geopolymer source material.

The pollution of aquatic systems by microplastics is a well-known environmental problem. However, limited studies have been conducted in freshwater systems, especially in the Philippines. Here, we determined for the first time the amount of microplastics in the Philippines’ largest freshwater lake, the Laguna de Bay. Ten (10) sampling stations on the lake’s surface water were sampled using a plankton net. Samples were extracted and analyzed using Fourier-transform infrared spectroscopy (FTIR). A total of 100 microplastics were identified from 10 sites with a mean density of 14.29 items/m 3 . Most microplastics were fibers (57%), while blue-colored microplastics predominated in the sampling areas (53%). There were 11 microplastic polymers identified, predominantly polypropylene (PP), ethylene vinyl acetate copolymer (EVA), and polyethylene terephthalate (PET), which together account for 65% of the total microplastics in the areas. The results show that there is a higher microplastic density in areas with high relative population density, which necessitates implementing proper plastic waste management measures in the communities operating on the lake and in its vicinity to protect the lake's ecosystem services. Furthermore, future research should also focus on the environmental risks posed by these microplastics, especially on the fisheries and aquatic resources.

Agusan Marsh, the Philippines' largest wetland, is in the middle of the Agusan River and serves as a catchment basin for excess flood water from upstream tributaries. This study characterizes and quantifies the level and types of microplastics (MPs) present in the surface water and gastrointestinal tract (GIT) of demersal fish Cyprinus carpio and Oreochromis niloticus from two prominent lakes in the marsh, Lake Panlabuhan, and Lake Tugno. KOH digestion, density separation, and Fourier-Transform Infrared spectroscopy (FTIR) analysis were implemented to extract and identify suspected MP particles. Analysis of water samples found microplastic abundances at 340 ± 36.25 pa/m 3 and 240 ± 33.17 pa/m 3 for Lake Tugno and Lake Panlabuhan, respectively. These microplastics varied in size, shape, and color. A total of 20 polymer types were identified in water samples with Rayon (49%) and Polyester (15%) as the most abundant types. There are 13 color variations detected from water samples with yellow and black as the most dominant colors. Further, 84% of the collected fish had MPs in the GIT. The GIT of O. niloticus of Lake Tugno had the highest average MPs (3.2 ± 1.0 MP/GIT), followed by C. carpio (2.73 ± 0.55 MP/GIT) from Lake Panlabuhan. Oreochromis niloticus of Panlabuhan had the fewest MPs (1.7 ± 0.33 MP/GIT). Fragments and fibers dominate isolated MPs, while brown MPs are consistently recorded across all samples. Ten different kinds of polymers were identified from the fish GIT with Ethylene vinyl acetate (26%), polyvinyl chloride (17%), and nylon-6 polyamide (14%) as the three most prevalent types of polymers. The MPs of different types and origins in the water and demersal fish indicate that microplastic pollution is present in the lakes of Agusan Marsh. Assessment of MPs from other fish species and lakes, as well as the possible point and non-point origins of MP in Agusan Marsh is recommended to determine the extent of MP pollution in this internationally important wetland. Highlights KOH digestion and FTIR-ATR confirmation was used to assess microplastics in the gastrointestinal tracts of demersal fishes from Agusan Marsh. Results show that 84% of the collected fish had microplastics in their gastrointestinal tract. Majority of the morphology of the microplastics are fragment and fibers. The detected microplastics were: ethylene–vinyl acetate (EVA), polyvinyl chloride (PVC), nylon-6 polyamide (NY6-Polyamide), low-density polyethylene (LDPE), high-density polyethylene (HDPE), polyethylene terephthalate (PET), polypropylene (PP), polybutylene (PBT), general-purpose polystyrene (GPPS), and polymethyl methacrylate (PMMA).

Recent reports identify the Philippines as a major contributor to plastic pollution in river systems. However, these claims often lack empirical field data, limiting our understanding of plastic transport dynamics in heavily urbanized waterways. This study addresses this gap by investigating the volume, composition, and transport of plastic debris in the downstream segments of the Cagayan de Oro River, a vital waterway influenced by a dense population and challenges in waste management. Over a ten-day period, macroplastic flux, polymer composition, and flow velocity were monitored at three strategic bridge locations. Results indicate that the river serves as a significant conduit for land-based plastic waste entering the marine environment, with an average plastic debris influx of 10.5 items per hour. Food packaging, plastic bottles, and plastic bags—primarily composed of polyethylene and multilayer materials—were the most common pollutants. These findings emphasizes the urgent need for targeted waste management interventions, particularly in upstream urban areas, to mitigate riverine plastic pollution and its downstream impacts on coastal and marine ecosystems.

Microplastics pollution in the Philippines presents significant risks to human health, food security and marine ecosystems. Davao Gulf, a biodiversity hotspot and vital fishing ground, is increasingly affected by this contamination. This study assessed the abundance and characteristics of microplastics in the gulf through sea surface water trawling and sediment sampling across multiple sites. Microplastics were detected in all samples, with average surface water concentrations of 0.097, 0.75 and 0.14 particles/m 3 for Trawls 1,2 and 3, respectively. Sediment concentrations averaged 15.55, 40.00 and 110.27 particles/kg at sites 1, 2 and 3, respectively. Microplastics exhibited diverse colors, morphologies and polymer types. Water samples displayed 12 color variants, predominantly white (31.34%), blue (14.43%), and black (14.10%), with fragments (41.21%) and films (30.15%) as dominant morphologies. Sediment samples showed seven color variants with brown (39.19%) and black (27.03%) prevalent, and filaments (32.43%) and fibers (24.32%) dominating. ATR-FTIR spectroscopy identified 31 polymer types in water and 12 in sediments. Polypropylene (51.41%), high-density polyethylene (21.15%) and polyethylene (5.97%) dominated in water, while azlon (33.78%) and rayon (24.32%) prevailed in sediments, indicating contributions from single-use plastics, packaging, household effluents and textile-based industries. These results highlight extensive microplastic pollution in Davao Gulf and emphasize the urgent need to upgrade wastewater treatment to capture even textile-based pollutants, promote sustainable materials and circular design, and implement coordinated regional monitoring and policies to mitigate microplastic pollution. Highlights Microplastics were detected in all sea surface trawl and sediment sampling sites from Davao Gulf. Color distribution of microplastics varied by environment with white dominant in water and brown in sediments. Surface waters were dominated by fragments and films while filaments and fibers prevailed in sediments. Polypropylene was the dominant polymer in surface water while azlon and rayon were prevalent in sediments. Microplastic distribution in Davao Gulf is strongly linked to riverine inputs with significant contributions from single-use plastics, packaging, household effluents and textile-related sources. Findings reveal diverse sources and physicochemical characteristics of microplastic pollution in the gulf, highlighting the urgent need for evidence-based, multi-level policy actions to protect marine ecosystems and dependent communities.