Environmental distribution and polymer characterization of microplastics in the Miagao Estuary, Iloilo, Philippines

Abstract

The Philippines contributes significantly to marine plastic pollution, yet little is known about microplastics (MPs) in its many estuaries. This study was the first to examine how many MPs are present, where they are located, and what types are present in Brgy. Baybay Sur, Miagao, Iloilo. Surface water samples were collected from three sampling sites: sample site 1 (SP1), sample site 2 (SP2), and sample site 3 (SP3) along the estuary, then separated, and MPs were isolated. Visualization of MPs was performed using a microscope and Nile Red Dye, which makes the MPs glow under UV light. The number of MPs ranged from 11 ± 6.02 to 20 ± 13.8 particles per liter. Water movement allows MP deposition near the mouth of the estuary. The morphology of MPs was dominated by fibers (72–85%), suggesting sources such as wastewater and fishing gear. Fragments (15–28%) were also found in the area. The Nile red test showed that the majority of the plastics present were polyester (blue) and polyethylene (yellow). Results showed that the method works well for most plastics (recovering 90.9–100%), but the dye did not work equally for all kinds. These results show that this estuary acts as a collection point for MPs from both land and sea activities. This study sets a starting point for future research and shows that Nile Red can be used to monitor MPs, but it also highlights the need for further testing to accurately identify plastic types in tropical estuaries.