Microplastics in Aquatic Environments: Sources, Impacts, and Implications
Bao-Son Trinh
Visiting Professor at Northern Illinois University
Fullbright Scholar in Residence Program
Microplastics (MiPs) have emerged as pervasive contaminants in aquatic environments worldwide, yet their sources, environmental behavior, and biological impacts remain
insufficiently understood in many rapidly developing regions. This lecture presents an integrated assessment of microplastic pollution in the Sai Gon–Dong Nai River system of southern Vietnam—one of the country’s most economically vital yet environmentally stressed watersheds. Comprehensive field sampling between 2020 and 2022 captured both macroplastics (>5 mm) and microplastics (≤5 mm) from surface waters, riverbed sediments, and aquatic organisms, including zooplankton, fish, and benthic invertebrates. Findings revealed substantial spatial variation in plastic contamination, with polyethylene and polypropylene dominating across matrices. Microscopic and spectroscopic analyses confirmed ingestion and accumulation of microplastics by multiple taxa, demonstrating trophic transfer potential at early food-web levels. Field and laboratory investigations further showed that microplastics act as vectors for legacy pollutants—such as PCBs and DDTs—and harbor pathogenic bacteria including E. coli, Coliforms, and Vibrio spp. Controlled exposure assays using Moina macrocopa, Daphnia magna, Macrobrachium rosenbergii, and Meretrix lyrata revealed significant effects on organismal health, including altered reproduction, survival, and contaminant uptake when microplastics were combined with PCB153. Collectively, these findings highlight the ecological implications of microplastics in tropical aquatic environments and underscore the urgency of improved plastic waste management, environmental monitoring, and risk assessment frameworks in Vietnam and comparable regions
Microplastics in Freshwater Environment
Chit Wityi Oo
Research Associate
Department of Earth, Atmosphere, and Environment, Northern Illinois University
Microplastics (MPs) are increasingly recognized as emerging contaminants in freshwater environments, with growing concern about their persistence, transport, and potential impacts on water quality and public health. Freshwater systems, including rivers, lakes, and groundwater, act as important pathways connecting terrestrial sources to downstream ecosystems. However, the occurrence and behavior of MPs in these systems remain insufficiently understood, particularly under varying environmental and hydrological conditions. This talk presents recent findings on microplastic contamination in freshwater environments, emphasizing their
distribution across water and sediment matrices in mixed-use watersheds. Field observations indicate that MPs are widely present, with smaller particles dominating due to fragmentation processes. Their abundance and composition are influenced by land use, wastewater inputs, and rainfall-driven runoff, demonstrating strong links between human activities and environmental contamination. To ensure reliable detection, standardized sample preparation and analytical techniques are essential. Samples are typically subjected to chemical digestion using oxidizing agents to remove organic matter, followed by density separation to isolate plastic particles from
sediments and debris. Advanced spectroscopic techniques, particularly laser direct infrared (LDIR) imaging, are used for polymer identification and particle characterization, including size, shape, and composition. Quality assurance measures, including blanks and replicates, are critical to minimize contamination and ensure data accuracy. These methodological approaches provide a robust foundation for understanding microplastic occurrences and behavior in freshwater systems. The talk highlights the role of freshwater systems as critical control points for reducing microplastic pollution before it reaches marine environments.