Microplastic Pollution of Thermal Waters in Kütahya, Türkiye

<title>Abstract</title> Microplastics have become ubiquitous pollutants everywhere. However, there is still limited data on the presence of microplastics in some ecosystem compartments. Groundwater resources, particularly thermal waters, are also an environment with little-known microplastic pollution. In this study, the presence of microplastics in thermal water resources used for geothermal applications in Kütahya region was investigated for the first time in Turkey. In the study, 3 liters of sample per location were taken from 21 thermal points in 9 regions in amber glass bottles of 1.5 liters each. The samples were filtered directly through cellulose acetate filters with a 0.45 µm filter paper using a vacuum pump. The filter papers were subjected to microscopic examination and µ-Raman analysis directly. As a result of microscopic examination, a total of 88 microplastic-like particles were detected, and µ-Raman analysis confirmed that 68.11% of them were microplastics. Thus, an average of 0.85 ± 0.71 MPs/L (850 MPs/m³) was detected from all locations. The highest microplastic concentration was found at the ST-8 station with 4.88 ± 2.98 MPs/L. No particles were found in the ST-7, ST-10, and ST-20 stations. Of the particles detected, 50.0% were fiber, 10.2% were film, and 39.8% were fragment types. The µ-Raman analysis confirmed that the polymers found were cellulose, PE, PET, PP, PS, and PET, and the most commonly found polymer was PE at 22.2%. The results obtained from this first-ever study of microplastics in geothermal waters demonstrate that microplastics can be found in low amounts in thermal groundwater resources.