Abundance, composition, and fate of microplastics in water, sediment, and shellfish in the Tapi-Phumduang River system and Bandon Bay, Thailand

Narainrit Chinfak; Penjai Sompongchaiyakul; Chawalit Charoenpong; Huahong Shi; Thamasak Yeemin; Jing Zhang

doi:10.1016/j.scitotenv.2021.146700

Abundance, composition, and fate of microplastics in water, sediment, and shellfish in the Tapi-Phumduang River system and Bandon Bay, Thailand

Sci Total Environ. 2021 Aug 10:781:146700. doi: 10.1016/j.scitotenv.2021.146700. Epub 2021 Mar 25.

Authors

Narainrit Chinfak¹, Penjai Sompongchaiyakul², Chawalit Charoenpong³, Huahong Shi¹, Thamasak Yeemin⁴, Jing Zhang¹

Affiliations

¹ State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai 200062, China.
² Department of Marine Science, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand. Electronic address: penjai.s@chula.ac.th.
³ Department of Marine Science, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand.
⁴ Marine Biodiversity Research Group, Department of Biology, Faculty of Science, Ramkhamhaeng University, Bangkok 10240, Thailand.

PMID: 33812121
DOI: 10.1016/j.scitotenv.2021.146700

Abstract

Microplastic contamination in the environment is a global problem, as evidenced by the increasing amount of research worldwide. To our knowledge, this study is the first to investigate the microplastic distribution in Bandon Bay, one of the most important maricultural areas of Thailand. Water and sediment samples from the Tapi-Phumduang River system (n = 10) and Bandon Bay (n = 5) were collected. Water sampling at the river mouth was carried out during a complete tidal cycle to estimate the microplastic flux to the bay during the wet season. Moreover, two commercial bivalve species grown in the bay, the green mussel (Perna viridis) and lyrate Asiatic hard clam (Meretrix lyrata), were analyzed. More items of microplastics were found in the river system than in the bay. During the tide cycle, one-third of the microplastics entering the bay were washed back upstream during high tide. This backflow consisted mainly of larger microplastics. The average daily load of microplastics to the bay was 22.4 × 10⁹ items day^-1. The load during low tide was approximately 4-5 times higher than that during high tide. The overall accumulation of microplastics in the bottom sediments of the river and in the bay was similar (p < 0.05). Green mussels showed significantly higher contamination with microplastics than clams. Notably, the small-sized shellfish contained more particles (items/g) than the large ones (p < 0.05). Fibers were detected in virtually all samples: water (98%), sediment (94%), mussels (100%), and clams (95%). Among these, microfibers (<1 mm) were detected in water (71%), sediment (63%), green mussels (63%), and clams (52%). Blue and white particles were the two most frequently observed colors, while the most dominant polymers were rayon, followed by polypropylene (PP) or polyethylene (PE), polyethylene terephthalate (PET), and nylon. To this end, we posit that river discharge was a significant source of microplastics in Bandon Bay, with minor additional contributions from fishing and mariculture activities within the bay. Ultimately, these microplastics may end up in the sediments and living organisms.

Keywords: Daily load; Meretrix; Microfiber; Perna; Shellfish size; Tidal cycle.