UNESCO World Heritage Site Park Acts as a Large Natural Attenuation Unit for a Broad Spectrum of Pharmaceuticals.

Pharmaceutical pollution is a global concern due to its pervasive impact on water quality, affecting diverse ecosystems. Despite this fact, contamination within UNESCO heritage natural sites remains understudied. To address this gap, our study focused on assessing pharmaceutical pollution in Pruhonice Park, screening water samples for 98 pharmaceuticals across nine different sites throughout the Park during all four seasons, using liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. Our findings identified the wastewater treatment plant (WWTP) effluent upstream of the Park boundaries and a tributary from an adjacent village as the primary sources of pollution. Concentrations of 20 pharmaceuticals were above the limit of detection, with gabapentin, metformin, caffeine, diclofenac, and carbamazepine among the most prevalent, reaching concentrations up to 2120 ng/L. Seasonal variations were substantial, with significantly lower concentrations detected in winter and spring. Risk quotients for more than half of detected analytes indicated high predicted risk for the aquatic environment in at least one sampling site, with carbamazepine and diclofenac exceeding the extreme risk threshold. Despite high upstream contamination, the outflow from the Park exhibits a significant reduction in pollution as compared to the inflow. Our results suggest that the combination of physical, chemical and biological processes can contribute to the reduction of human-derived contaminants within the biodiverse UNESCO natural park. To enhance these natural attenuation mechanisms, our findings highlight the need for targeted policy measures, including stricter discharge regulations, improved wastewater management, and systematic monitoring programs implemented by governmental authorities.