Microplastics Occurrence in Surface Waters and Sediments in Five River Mouths of Manila Bay

Abstract

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.

Assessment of Microplastics in the Surface Water of Sitio Pulo, Navotas, Metro Manila

“…Thus, film microplastics can be more detectable in sediment samples than surface water. This observation supports Osorio et al [20] study, as they found that plastic films are uncommon to surface water but more present in their sediments, especially in Mecauayan and Tullahan Rivers.…”

“…These are commonly used as food and product containers and as floats and rafts in fishing. According to the study of Osorio et al [20]. Foams are abundant in Mecauayan, and Tullahan Rivers compared to other main rivers connected in Manila Bay from October 2018 to March 2019.…”

“…On the other hand, PET is widely used as a beverage container, but the fragments collected are low compared to polyethylene. This may be due to recycling activities as PET bottles are collected by waste pickers they can be sold in junk shops and recycling facilities [20]. Compared to other plastics, PET bottles are easier to identify as valuable plastic waste compared to other plastic products.…”

“…Furthermore, it was reported that 4,319,981 anthropogenic litter were collected from land, underwater, and watercraft cleanups last 2017, wherein mostly were plastic debris [15] which indicated that the Philippines was no exception from the presence of microplastics. The occurrence of microplastics from Majalar Bay [16], Molawin watershed in Laguna [17], Laguna de Bay [18], and from the surface water of five rivers connecting to Manila Bay namely: Cañas River; Meycauayan River; Parañaque River; Pasig River; and Tullahan River [19][20] was recently determined. Microplastics were also isolated in the aciddigested mussel soft tissue of Asian green mussels cultured in Bacoor Bay [9], in detritus-feeding mullets, and herbivorous rabbit fish in Eastern Visayas [21][22].…”

Kıyı Lagün Sedimentlerinde Mikroplastiklerin Oluşumları ve Mekansal Dağılımları: Küçükçekmece Lagünü Örneği

“…2022 yılında Pakistan, Rawal Gölü'ndeki siyah MP'lerin, diğer renklere göre %25 ile %48 arasında daha baskın olduğu ve siyah MP'lerin lastikler, plastik torbalar ve sentetik tekstil ürünlerinden kaynaklanabileceği ifade edilmiştir (Alfonso et al, 2020;Nousheen et al, 2022). Yapılan çalışmalarda, balıkların yanlışlıkla planktonik avlarına benzeyen beyaz, kahverengi ve sarı renklere sahip MP'ler ile beslendiği (Shaw & Day, 1994;Boerger et al, 2010;Osorio et al, 2021) benzer şekilde deniz kuşlarının da bazı şekil ve renklerde plastikleri yanlışlıkla yuttuğu tespit edilmiştir (Barboza & Gimenez, 2015;Osorio et al, 2021).…”