Microplastic pollution of thermal waters in Kütahya, Turkey

Microplastics (MPs) are emerging pollutants in aquatic systems, but their presence in groundwater, particularly thermal waters, is understudied. This study investigates the prevalence and characteristics of MPs in the thermal waters of Kütahya, Turkey, marking the first such exploration in the country and globally in thermal groundwater systems. Twenty-one samples (3 L each) were collected across nine regions and filtered using GF/C filters (0.45-µm pore size). Microscopic examination and μ-Raman spectroscopy revealed an average MP concentration of 0.85 ± 0.71 MPs/L (850 MPs/m³), with the highest at ST-8 (4.88 ± 2.98 MPs/L). Fibers (50%), fragments (39.8%), and films (10.2%) were identified, with polyethylene (22.2%) being the most common polymer type. Variability in MP abundance across stations suggests multiple contamination sources, including agricultural runoff, anthropogenic activities, and material used in water transport infrastructure. The findings indicate low-level MP contamination in thermal groundwater systems, which could influence both ecological health and human activities relying on these waters, such as thermal tourism and greenhouse irrigation. This pioneering study highlights the necessity for integrated waste management policies to mitigate MP pollution and underscores the role of thermal waters in understanding the transport dynamics of MPs in groundwater systems.