Microplastics in Northern Laguna Lake’s Shoreline Sediments

Microplastic pollution, a pervasive problem in the natural environment, is hardly investigated in the largest lake in the Philippines: Laguna de Bay or Laguna Lake. This study was done to determine the microplastic profile (content and type) of the shore sediments taken from northern Laguna Lake and to identify possible sources of the microplastics found. The microplastics from the sediments were extracted and isolated using the chemical oxidation and density floatation method. To identify the possible microplastic source, a comparison of Fourier transform infrared (FTIR) spectra of the microplastics extracted with sample plastic materials found on the sites was done. Results showed that during the dry season, the mean microplastic contents of Binangonan, Tanay, and Angono sediments were 1524.42 ± 1593.45, 815.41 ± 593.64, and 295.51 ± 140.16 microplastics per kg sediment, respectively. During the wet season, the mean microplastic contents of the sediments in Binangonan, Tanay, and Angono were 1826.05 ± 614.19, 1250.73 ± 220.03, and 353.82 ± 173.07 microplastics per kg sediment, respectively. The variations observed with season might be associated with tidal and current effects on the shoreline sediments and not due to changes from the dry to the wet season. FTIR analysis of microplastic type showed that prominently occurring microplastics in the three towns varied depending on the materials associated with human activities such as fish farming (aquaculture), clothing materials, and plastic packaging. The results of this study show significant implications on the effect of anthropogenic activities on the type and abundance of microplastics found in the environment, and knowledge of the microplastic profile in Laguna Lake could help not only in its clean-up but also in the proper disposal of plastics in the area to prevent its presence in the natural environment.