Microplastics in Sediment of Kuakata Beach, Bangladesh: Occurrence, Spatial Distribution, and Risk Assessment

Kuakata beach, known as Daughter of Sea in Bangladesh, has drawn a growing number of tourists from all over the world, leading to the higher use of single plastic products. This study was a first attempt to describe the occurrence, spatial distribution, and ecological risk of microplastics (MPs) in Kuakata beach sediments. A total of 24 surface sediment samples were collected from the intertidal zone of the beach, and MPs were extracted using the density separation method and a stereomicroscope. Fourier transform infrared (FTIR) spectroscopy was used for qualitative and quantitative identification. The results revealed that the average MPs in the beach sediment were 232 +/- 52 items kg(-1) dry weight, which was much higher than many other sandy beaches throughout the world. Analyses of variance showed a significant (p < 0.01) difference among the mean abundance of MPs in sampling points. Fibers were dominated in every sampling point with an average of 123 +/- 27 item kg(-1). Most of the MPs observed were colored (60%), and the rest were transparent (40%). It was found that the size range of 1-5 mm MPs constituted over half (55%) of total MPs covering an average value of 127 +/- 34 items kg(-1). Three polymer types were identified in the sediment samples through FTIR analysis which followed the decreasing order of polyethylene terephthalate > polyethylene > polypropylene. Correlation analysis showed a positive relationship between the abundance of MPs and the finer grain size of sediment (p = 0.055; r = 0.7), indicating grain size-controlled the density of MPs. The pollution load index was assessed to estimate the ecological risk and found that the beach sediment of Kuakata belonged to the risk category I of the pollution index. This investigation provided preliminary information on MPs pollution in the marine ecosystem that the policymakers can use to take appropriate management approaches.

Automated summary

This study provides a description of the occurrence and distribution of microplastics in the sediment of Kuakata beach in Bangladesh. The results show a high abundance of microplastics, with fibers as the dominant type. The abundance of microplastics is positively correlated with the finer grain size of the sediment. The beach sediment of Kuakata is categorized as high ecological risk according to the pollution load index.