Microplastics Abundance, Distribution and Impacts in Tropical Urban Fresh Waters: A Singapore Case Study

Plastic aquatic pollution has garnered much scientific attention in recent years, revealing potential impacts on biodiversity and human health. However, information surrounding microplastics in fresh waters remains scant. To address this knowledge gap, we first conducted a literature review, focusing on the global distribution and abundance of microplastics in fresh waters. Early findings from the review identify the recurring source of microplastics as wastewater effluents, indicating a spatial association between the presence of plastic with its proximity to urban areas. Finding a paucity of research in tropical freshwater systems, we followed this up with a study on selected reservoirs and canals of Singapore. Through in-situ sampling, chemical digestion, filtration, and microscopy classification, we identified the most abundant type of microplastic pollution (particle size < 5 mm) across five freshwater systems (both lotic and lentic), and suggest key factors that could contribute to this abundance. Our results represent an important first step towards understanding the impacts of microplastic pollution in Singapore, and possibly other tropical freshwater systems.