Occurrence of microplastics in freshwater gastropods from a tropical river U-Taphao, southern Thailand.

The MPs found were as follows: 4.76 particles/individual were found in upstream, 5.20 particles/individual were found in downstream, 7.28 particles/individual were found in upstream, and 4.00 particles/individual were found in downstream. It was found in the two-way ANOVA that the accumulation of MPs in gastropods was affected by species and study sites (upstream and downstream). There was a significant difference in the amount of MPs in between upstream and downstream sites ( = 0.003). Fibers were the most common MPs in both species. Moreover, upstream had the most significant amount of MPs. The smallest amount of MPs was recorded for downstream, but there was great diversity in shape, size, and polymer type. MPs sized 500 μm mm were the most common in both species. Fourier transform infrared spectroscopy revealed six polymers: poly (ethylene terephthalate), polypropylene, rayon, polyethyleneimine, polyamine, and poly propylene: ethylene). The occurrence of MPs in gastropods is alarming for food security in Thailand. The results of this study can be used to support baseline data on MP accumulation among freshwater gastropods.