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First evidence of microplastics in atmospheric deposition over the Gulf of Thailand: Distribution, characteristics, and ecological risk
Author(s)
Chinfak, Narainrit
Gunasekaran, Kannan
Jandang, Suppakarn
Li, Qipei
Kayee, Jariya
Charoenpong, Chawalit
Sompongchaiyakul, Penjai
Zhang, Jing
Date Issued
September 15, 2026
Type
Article
Abstract
Microplastics (MPs) have been extensively studied in aquatic environments; however, their occurrence in atmospheric deposition remains poorly understood. This study provides the first insights into the distribution of MPs in wet deposition across different locations and evaluates their potential environmental risks in the Gulf of Thailand (GoT). The ocean is likely a sink for MPs, with approximately 10% of the total MPs in atmospheric deposition detected in oceanic rainwater. MP abundances in terrestrial rainwater, including urban and agricultural rainwater (62.70 ± 15.89 items/m2 and 29.37 ± 12.29 items/m2, respectively) were significantly higher than those in the GoT rainwater (9.72 ± 3.70 items/m2) ( p = 0.001), with greater MPs abundance observed in the urban center. MPs exhibited similar morphological (shape and color) and compositional characteristics across all locations. Fibrous MPs (100–500 μm) dominated urban (42%) and agricultural (55%) rainwater, whereas smaller fibers (<100 μm) were predominant in the GoT (69%). White and black were the dominant colors found in both terrestrial and GoT rainwater. Low-density polymers (PE, PP and PS) were the most frequently detected polymers, comprising up to 80% of the total MPs. Among them, PE was predominant, accounting for 48%, 51%, and 62% of all MPs identified in urban, agriculture and the GoT rainwater, respectively. Ecological risk assessment indicated a minor potential ecological risk associated with MPs in wet deposition. Future studies investigating both wet and dry deposition, as well as factors influencing MP distribution and transport in the GoT, are needed to support transport modeling, identify potential sources, and assess the impact of climate forcing on MP distribution.
Citation
Estuarine Coastal and Shelf Science, 339, 2026