FT-IR Spectroscopy Links Tourism Intensity to Microplastic Pollution in Island Waters

A new study published in Civil Engineering Journal offers new evidence that tourism-driven activities are closely tied to the occurrence and spatial distribution of microplastics (MPs) in fragile island ecosystems (1). The research focused on Gili Trawangan Island, which is a popular island resort in Indonesia. The team, comprised of scientists from institutions in Indonesia and Taiwan, demonstrated how Fourier transform infrared (FT-IR) spectroscopy can be used to reveal the extent of microplastic contamination across coastal waters, sediments, and marine life. The insights contribute to our understanding of the anthropogenic impact on the environment.

Gili Trawangan is a small island located off the coast of Lombok, and it is a popular stop for visitors exploring Bali (2). Known for its reputation as a popular spot for party goers, it has experienced rapid tourism growth over the past decade (2). The island also offers numerous outdoor activities for visitors, including snorkeling, hiking, and cycling (2).

Although this explosion of visitors has been beneficial for the local economy, there have been several negative externalities. One of those negative side effects has been the impact of overtourism on local waste management systems. Because the waste management systems on the island are not equipped to handle all this tourist traffic, the coastal environment is being negatively affected by tourism.

What did this study examine?

The researchers sought to better understand the extent to which tourism has impacted the coastal ecosystem surrounding Gili Trawangan. Collecting water samples, sediment samples, and fish from three areas (seaport, a recreational beach, and a mangrove ecosystem), the team analyzed the MPs using standardized filtration and density separation techniques, followed by FT-IR spectroscopy (1). They identified and characterized microplastics by shape, size, color, and polymer composition. Data were gathered over an extended 44-month period, allowing for a more robust assessment of spatial patterns and environmental variability than many previous studies (1).

What did the findings reveal?

The researchers found that MP concentration varied depending on the region. For example, recreational beaches showed the greatest abundance of MPs in coastal waters, reaching 19.25 particles per liter, which suggests a direct correlation between the number of tourists and the amount of MP pollution (1).

In contrast, the seaport area recorded the highest levels of MPs in sediments and fish. Sediment samples from this zone contained up to 23.15 particles per kilogram, while fish collected nearby averaged as many as 17.5 particles per individual (1). According to the researchers, this pattern likely reflects the combined influence of maritime traffic, port-related activities, and sedimentation processes that cause microplastics to accumulate on the seafloor and enter the food web (1).

The mangrove area consistently exhibited the lowest MP concentrations, with 5.89 particles per liter in water and 3.00 particles per kilogram in sediment (1). This supports the theory that mangrove root systems can act as natural filters, trapping debris and reducing the movement of microplastics into surrounding waters. However, the presence of MPs in fish from this zone underscores that even relatively protected habitats are not immune to plastic pollution (1).

What did the polymer analysis reveal in the study?

The researchers also classified the polymer type most present in the MPs. They found that polystyrene (PS), polyethylene (PE), and low-density polyethylene (LDPE) were the most prevalent materials, which are plastics commonly associated with packaging and consumer products (1).

The study also highlighted the ecological and potential human health implications of MP pollution. MPs can cause physical harm to marine organisms through ingestion and abrasion, while also acting as carriers for toxic chemicals and microorganisms (1). Their accumulation in fish raises concerns about bioaccumulation and biomagnification, particularly in regions where seafood is a dietary staple and tourism depends on healthy marine ecosystems (1).

By simultaneously examining water, sediment, and biota, the researchers provided a more comprehensive picture of microplastic pathways and persistence than studies that focus on a single environmental compartment (1). The integration of ecological variables with anthropogenic factors, such as tourism intensity, allows for a clearer understanding of how human behavior translates into environmental risk.

The authors emphasize that these findings have direct implications for policy and environmental management on Gili Trawangan and similar island destinations worldwide (1). Targeted interventions, such as reducing single-use plastics, improving waste collection and treatment infrastructure, and enforcing port and tourism regulations, could significantly mitigate microplastic inputs.

References

1. Chairunnisa, N. K.; Adam, M. A.; Kristianto, S.; et al. Linking the Tourism Activity to the Occurrence and Distribution of Microplastics. Civ. Eng. J. 2025, 11 (7), 2811–2825. DOI: 10.28991/CEJ-2025-011-07-010
2. Lopez, J. A Complete Gili Trawangan Guide + Insider Tips & Tricks. Travel Lush. Available at: https://travel-lush.com/gili-trawangan-guide/ (accessed 2025-12-16).