SPATIAL AND TEMPORAL DISTRIBUTION OF MICROPLASTICS IN SURFACE WATER OF BOLGODA LAKE, SRI LANKA

Abstract

Microplastic (MP) pollution is often referred to as the invisible threat of our era due to its minute size. Microplastics are defined as plastic particles less than 5 mm in size and can be transported across various ecosystems, including the atmosphere. They also have the potential for bioaccumulation and biomagnification within food chains. This study investigates microplastic pollution in Bolgoda Lake and examine the temporal variation of microplastics during the wet and dry seasons. Fifteen water samples were collected from randomly selected different locations across the lake during both seasons, with duplicates taken to ensure accuracy. A total of 25 liters of water were filtered using a 300 µm sieve, and the residue was collected for analysis. This residue underwent a digestion process followed by density separation. The extracted microplastics were then observed using a stereo microscope. The results indicated that the wet season exhibited a higher abundance of microplastics compared to the dry season. The concentration of microplastics in surface water was higher during the wet season (372 ± 143 MPs/m³) than in the dry season (252 ± 198 MPs/m³). In both seasons, microfibers were the predominant type of microplastic observed. Regarding color distribution, the microplastics observed during the wet season followed this order: Black > Red > Blue > Transparent > Green > Yellow > White. A similar pattern was found during the dry season, with the order being: Black > Red > Blue > Green > Transparent > Yellow > White. Results further indicated that areas near urban development recorded a higher abundance of microplastics compared to more isolated regions. This study highlights that Bolgoda Lake exhibits the highest concentration of microplastics in its surface waters. These findings provide crucial baseline data for understanding the sources, threats, and seasonal distribution of microplastic pollution in Bolgoda Lake and provide valuable insights for policymakers, researchers, and local communities.