Does tourism enhance microplastic pollution in the ecologically critical areas of Bangladesh? Evidence from Tanguar Haor, Kaptai Lake, and the Sundarbans

• MPs abundance in the ecologically critical areas ranges from 3 to 25 particles/L • MP abundance ranked Tanguar Haor < Kaptai Lake < Sundarbans • FTIR identified PETE as common, linked to bottles and food packs from tourism • A correlation was observed between MP abundance and proximity to pollution sources • Tourism and human activities drive MP pollution in these vital ecosystems Microplastic (MP) pollution is a growing environmental threat, particularly in ecologically sensitive and biodiverse aquatic ecosystems. This study assessed the abundance, composition, and potential sources of MPs at three prominent tourist destinations in Bangladesh: Tanguar Haor, Kaptai Lake, and Sundarbans. A total of 60 surface water samples (20 per site) were collected and analyzed using density separation followed by visual identification. The results showed that the abundance of MPs in the Sundarbans was 23.25 ± 2.55 particles/L, followed by Kaptai Lake at 12.00 ± 1.22 particles/L, and Tanguar Haor at 9.42 ± 1.10 particles/L. The polymer types were confirmed using Fourier-transform infrared (FTIR) spectroscopy, with polyethylene terephthalate being common across all locations. Environmental risk was evaluated using multiple indices including the Pollution Load Index (PLI), Polymeric Risk Assessment (PRA), Pollution Risk Index (PRI), and Polymeric Hazard Index (PHI), which indicate varying levels of ecological threat. These findings highlight the influence of tourism and associated anthropogenic activities on MP contamination in these ecologically critical areas. This study emphasizes the urgent need to promote eco-tourism, implement targeted mitigation strategies, improve waste management, and establish long-term monitoring programs to protect vulnerable ecosystems from increasing MP pollution.