42-6 Microplastic Distribution, Abundance, and Characteristics in Belizean Surface Water and Groundwater Systems

Abstract:

The global prevalence of microplastic contamination in hydrologic systems is a growing concern for human and ecosystem health. However, few studies have addressed the movement and characteristics of microplastics across environmental settings, especially in tropical and developing regions with limited environmental monitoring infrastructure. This project therefore characterized microplastic concentrations across a diverse range of Belizean surface water and groundwater systems to establish baseline conditions, investigate the distribution of microplastics across interconnected tropical aquatic ecosystems, and advance our understanding of plastic pollution in an understudied biodiversity hotspot. Sampling sites encompassed a broad geographic and hydrologic range across Belize, including tidal creeks, freshwater streams, lagoons, wetlands, caves, and urban canals. Water samples were collected in glass bottles and transported to the United States for filtration through 0.45-µm cellulose membrane filters. Microscopy and established identification criteria were used to distinguish microparticles of anthropogenic origin from naturally occurring materials. These suspected microplastics were then characterized by their size, shape, and color and mounted on microscope slides for future material classification efforts with Fourier transform infrared spectroscopy. Microplastics were detected in nearly all water samples, with a concentration average and standard deviation of 4.1±8.5 counts/L and range of 0.0-31.0 counts/L (compared to procedural blanks at 3.0±2.8 counts/L). Fibers were the most frequently observed morphology in our water samples (93% of all microparticles), while common colors included clear, blue, and brown. The highest microplastic concentrations were found near ecotourism sites and urban areas, which may be due to recreational activities and waste inputs into the sampled waterbodies. Additionally, although fibers with clear, blue, or brown coloration were the most often observed morphology-color combinations across all samples, sites near anthropogenic influence exhibited a greater diversity of microparticle morphologies and colors. These preliminary results indicate that microplastics are concentrated in Belizean surface water and groundwater systems near human-impacted areas. The prevalence of fibers in our samples also suggests a regional microplastics source that is potentially associated with textile use. Our data help establish baseline microplastic pollution conditions in understudied Belizean aquatic systems, while also providing insight into microparticle characteristics that may inform future monitoring and mitigation efforts.

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