Contaminants of Emerging Concern as Tracers of Pollution and Hydrological Processes in an Anthropized Mediterranean Basin: The Kasserine Basin (Central Tunisia)

This study provides a detailed investigation of emerging contaminants of concern (CECs) in surface water and groundwater within the semi-arid Mediterranean basin of Kasserine (central Tunisia, North Africa). During a monitoring campaign conducted in May 2023, 368 CECs were analysed, of which 101 compounds were detected across the sampled waters. Detection frequencies and concentrations were generally higher in surface waters, indicating that wastewater inputs to river systems constitute the main source of organic contamination. Pharmaceutical compounds were the most commonly detected class, reflecting their widespread occurrence in the aquatic environment. Hydrophobic CECs showed the highest concentrations and detection frequencies, while hydrophilic compounds, although more readily biodegradable, exhibited greater mobility and were efficiently transported towards downstream areas of the catchment. The shallow Plio-Quaternary aquifer, characterised by highly permeable sand and gravel formations, is hydraulically connected to surface waters, enabling rapid contaminant transfer from surface sources to groundwater. This geological context strongly enhances aquifer vulnerability to contamination. Based on these findings, a conceptual model is proposed to characterise aquifer sensitivity to urban pressures and to assess the potential impacts of future urbanisation on groundwater quality. The results emphasise the necessity for strengthened monitoring and management strategies to mitigate CEC contamination and safeguard water resources in vulnerable semi-arid environments.