Microplastic occurrence in rural and urban surface waters: the cases of Lake Sampaloc and Lake Yambo in San Pablo City, Laguna, Philippines

The widespread microplastic occurrence has invaded both marine and freshwater ecosystems. However, most studies are focused on marine microplastics and there is still insufficient knowledge and understanding of microplastics in freshwater ecosystems like small lakes. Known as one of the largest contributors of plastics to the aquatic environment, the Philippines has begun ventures on studying microplastic pollution, although, still, there are no accurate figures on the extent of the microplastic problem in the country, especially in its freshwater environment. In this study, a comparative assessment of microplastic concentration and characterization between Lake Yambo, an ecotourism and rural lake, and Lake Sampaloc, an aquaculture and urbanized lake, in San Pablo City, Laguna, Philippines was conducted through microplastic isolation and optical examination. Results revealed that the average microplastic concentration in Lake Sampaloc and Lake Yambo ranges from 483 to 989 n/m3 and 344 to 789 n/m3, respectively. Generally, the sampling sites in Lake Sampaloc had a higher mean concentration of microplastics than those in Lake Yambo. The key features of the microplastics detected in the surface waters of the studied lakes are fibrous, colored, and small-sized (<2 mm). In addition to proving the assumption that there are more microplastics observed in a highly-populated or urbanized freshwater ecosystem like Lake Sampaloc, this study also contributed to the meager evidence that microplastics are present even around scarcely-populated lakes like Lake Yambo. The outcome of this study is relevant for the local government unit (LGU) of San Pablo to make sustainable environmental policies regarding plastic waste management and disposal.