Microplastics have been increasingly documented globally in numerous environmental compartments. However, little information exists in the Philippines despite the fact that the country is considered to be one of the largest contributors of plastics in oceans. This study, considered as one of the pioneering microplastic research, evaluated the abundance, distribution, and composition of microplastic pollution in the mouths of five rivers, namely Cañas, Meycauayan, Parañaque, Pasig and Tullahan, draining to Manila Bay. Surface water and sediments samples were collected, then passed through a stack of sieves with sizes from 2.36 mm at the top to 0.075 mm at the bottom. These samples were digested to remove organic matter, and salt solutions were added to allow the microplastics to float. Extracted particles were examined under a stereo microscope, and quantified and categorized into shape, size, color, and type. Results show that microplastics were present ubiquitously at all river mouths but with concentrations varying from 1,580 to 57,665 particles/m3 (surface water) and 386 to 1,357 particles/kg (dry sediment). Fragment was the most abundant shape, while white, blue, and transparent were the most prevalent colors. Fourier Transform Infrared Spectroscopy (FTIR) analysis revealed that polypropylene (PP), high and low-density polyethylene (high-density polyethylene and low-density polyethylene) and polystyrene were the main types of microplastics present in the river mouths.

<p>Philippines is considered as one of the top contributors of plastic wastes in the oceans globally. Lack of strict implementation of solid waste management regulations has led to mismanaged wastes, especially plastics, that eventually end up in water bodies. This study focuses on characterizing plastic waste pollution in Sapang Baho River in the province of Rizal. The river is located in an urban area and is a significant tributary of Laguna Lake, the largest lake in the country. Through this study, macrowastes and microplastics in Sapang Baho River, Rizal were characterized and analyzed to provide baseline information and to raise awareness to address plastic pollution, in macro- and micro-scale. This study also determined possible sources of microplastics by relating the particles to the plastic wastes present as well as activities in the sites. Waste analysis and characterization studies (WACS) were conducted for four sampling stations along the river. Microplastic samples were also collected from surface water and were characterized based on form such as filament, fragment, film, foam, and pellet through microscope examination. Representative samples were subjected to Raman spectroscopy testing to identify the polymer types. Results show that macrowaste samples were mostly plastic wastes (27.33%) in terms of mass. Plastic wastes were composed of film plastic (47%). Most of the microplastic particles were in the form of filaments (92.24%) which were fragmented from textile wastes and cloth washing. In terms of color, transparent particles were dominant and particles in the lower size range (0.3 mm - 0.8 mm) were predominant. Samples subjected to Raman spectroscopy were mainly polyethylene (PE), a material used in containers and packaging. Lastly, it was calculated that the surface water of Sapang Baho River contributes approximately 24 - 362 microplastic particles to Laguna Lake.</p>