This review synthesizes four decades (1980–2024) of marine oil spill research in the Philippines, analyzing 80 peer-reviewed publications sourced from Scopus, Web of Science, Clarivate, and Google Scholar. Findings show that oil spill research activity spikes after major spills, particularly the 2006 Guimaras incident, which accounts for over half of the reviewed studies and were mostly concentrated in the field of biology, followed by social sciences. Mangroves are the most studied as they are the widely affected ecosystem in the Philippines. Despite the number of published articles on oil spills in the Philippines, only the major events were emphasized, and small-scale spills remain under documented. Research on small-scale oil spills and the country’s two recent big oil spills (Mindoro Oil Spill and Manila Bay Oil Spill), particularly in a country’s environmentally sensitive areas, must be conducted in collaboration with academic institutions and relevant stakeholders to gain a deeper understanding and formulate appropriate countermeasures in the event of future spills. The review also highlights limited application of advanced techniques such as hydrocarbon fingerprinting, geospatial analysis, and next-generation DNA sequencing, limiting comprehensive assessments of oil fate and ecological effects. Addressing these gaps through interdisciplinary collaboration is critical to improving oil spill response, environmental management, and policy formulation in the Philippines’ complex archipelagic setting.

In the Philippines’ agricultural setup, pre-harvest cacao (Theobroma cacao) fruits are wrapped with low-density polyethylene (LDPE) for moisture retention and damage protection. Responding to the growing concern for its waste volume and scarcity of treatment, this research explores the co-hydrothermal carbonization (co-HTC) of cacao shells (CS) and LDPE as a method to convert agricultural waste with plastic into hydrochar for potential energy applications. Thus, observations on the thermal, physicochemical, and morphological changes from feedstocks to hydrochar are carried out. Optimal conditions of 200 °C for 60 min resulted in hydrochar with 21.11 MJ/kg and appreciable thermal properties. SEM micrographs show that hydrochar had increased surface area, a good fuel characteristic, and surface flaking on oversized LDPE film, suggesting relative LDPE degradation. EDX analysis reveals C, K, Ca, and Zn metals that affect chemical pathways. FTIR analysis further supports chemical synergy by preservation of functional groups innate from both parent materials. Kinetic and thermal evolutions are also investigated to reveal the influence of pretreatment on the stability of cacao shell-dominated hydrochar and the effectivity of biomass integration to facilitate relatively easier cracking of LDPE. The findings support co-HTC as a viable technology to enhance the circular economy by valorizing LDPE and cacao shells while promoting energy recovery and solid fuel production.

Marine plastic pollution has become a growing environmental concern, particularly in coastal regions where plastic waste directly threatens marine ecosystems and the socio-economic conditions of coastal communities. Despite this, limited studies have focused on macroplastic litter in the coastal areas of Southern Philippines, particularly the factors contributing to its accumulation, such as local waste management practices and community behaviors. This study assessed the prevalence, types, and density of macroplastics in three coastal municipalities along Iligan Bay: Naawan, Manticao, and Lugait. Results showed that macroplastic litter was abundant in all sites, with Lugait recording the highest density (1.04/m²), followed by Naawan (0.83/m²), and Manticao (0.80/m²). The most common waste items were food packaging (25%), plastic bottles (22%), and plastic bags (17%), resulting in Multilayers (30%), PET (25%), and PP (20%) as the most prevalent polymer types. Clean-coast-index (CCI) classified Lugait as an extremely dirty coast, while Naawan and Manticao were classified as dirty. The focus group discussion revealed that poor waste management and residents' disposal practices can be attributed to the abundance of macroplastics. Overall, this study highlights the critical need for targeted interventions by Local Government Units to improve waste management and mitigate macroplastic accumulation in Iligan Bay.