Occurrence and Polymer Types of Microplastics from Surface Sediments of Molawin Watershed of the Makiling Forest Reserve, Los Baños, Laguna, Philippines

Abstract

Microplastic pollution is an emerging topic in environmental science. However, information about its prevalence in the freshwater ecosystems is still scarce. This study quantified and identified microplastic form and polymer types from surface sediments of the Molawin River. Sediment samples were collected from the upstream, midstream, and downstream stations of the river. Isolation of microplastics was performed through a modified granulometric approach, density separation, and filtration. Stereoscopic microscopy and Fourier-transform infrared spectroscopy (FTIR) were conducted to quantify and describe microplastics and identify the polymer types based on the infrared spectrum of absorption, respectively. The highest concentration of microplastics was found in the downstream station, with an average number of 97±12 items/100 g and 47.33±11.39 items/100 g sediment dry weight in the bank and channel, respectively. The isolated microplastics were dominated by ≥100 to ≤200 μm size range. Based on stereoscopic microscopy, microfragments and microfibers were the most common microplastic type, while polyethylene (PE) and polypropylene (PP) were the polymer types identified based on FTIR analyses. This study revealed the presence of microplastics and confirmed the microplastics polymers present in the Molawin Watershed of Makiling Forest Reserve.

Microplastics in surface water of Laguna de Bay: first documented evidence on the largest lake in the Philippines

“…Another study conducted in surface water from eastern coastal areas of Guangdong, South China, showed mean abundance of microplastics of 8,895 items/m 3 , with small white fragments dominating character (Zhang et al 2020 ). In the Philippines, a study conducted in Molawin Creek in Makiling Forest Reserves indicated that it is also being polluted by these micropollutants, which are primarily coming from the area’s residential, commercial, and university facilities, causing an intrusion into the ecological services provided by the watersheds (Limbago et al 2021 ). Furthermore, microplastic fragments measuring < 2.5 mm in length were microplastic observed in the Pasig River (Deocaris et al 2019 ).…”

Microplastic accumulation in local dominant shellfish from the Khwae Noi Basin in Western Thailand and its environmental factors

“…industry and tourism, contribute to the dispersion of MP in the Taihu Lake environment in China [37]. According to Limbago et al [38] the occurrence of MP accumulation in water is positively correlated to areas downstream of urbanization, including high MP density in water body of upstream region where is on urbanization [39]. Hence, MP accumulations in water and sediment of streams, lakes, and coastal regions cause accumulation in aquatic organisms from various point and non-point sources of anthropogenic activities [40].…”

Development of Microplastic Research in ASEAN

“…The types of microplastics found in various studies in ASEAN are diverse, but not all studies have tested all the types of microplastics. Some of the types found in ASEAN include fiber [38], polietilen [39]; [40], polypropylene [1]; [41], etc. The number of studies related to the types of microplastics has not been widely conducted, but several sampling techniques have been done in several studies such as [42].…”