FLUXES OF MICROPLASTICS 1-5,000 MICROMETER IN URBAN WASTEWATER FLOWING INTO BIVALVE MARICULTURE ALONG THE CHONBURI COAST

Abstract

The coastal areas of Chonburi Province, particularly in Mueang and Si Racha districts, are key aquaculture zones for mussels, blood cockles, and oysters. These areas also receive municipal wastewater, which increasingly contains microplastic contamination. This study aimed to analyze the quantity and transport of microplastics in community wastewater discharged into the sea and assess their relationship with bivalve aquaculture zones. Wastewater samples were collected from four sites: Khlong Sangkhep, Khlong Bang Phong, Wonapha Beach drainage, and Ko Loi Bridge drainage. Microplastics were isolated through filtration and analyzed using optical microscopy and Fourier Transform Infrared Spectroscopy (FTIR). The results showed that microplastic transport ranged from 3.30×10¹¹ to 2.90×10¹³ particles per day, with particles sized 1–60 micrometers accounting for over 99% of the total. The most common shapes were fragments and fibers, with polymer types including polyethylene (PE), polypropylene (PP), and polyester. These microplastics originated mainly from human activities, such as plastic bags, synthetic fabrics, and packaging. The findings highlight that municipal wastewater is a significant source of microplastic transport into the marine environment and suggest that bivalves cultivated in these areas may accumulate high levels of microplastics. This research provides essential data for developing strategies to mitigate microplastic pollution at its source and promote sustainable coastal aquaculture management.