<p>Groundwater contamination by emerging contaminants is an increasing concern, particularly in arid and semi-arid regions like northeastern Tunisia, where aquifers are vital for water supply. This study investigates the influence of hydrogeological characteristics specifically lithology and groundwater flow dynamics on the fate, mobility, and retention of emerging contaminants (CECs) and pesticides within the Grombalia aquifer system. By integrating geological, hydrogeochemical, and spatial analyses, the study reveals that lithological heterogeneity plays a decisive role in shaping contaminant behavior. Clay-rich layers act as natural barriers that retard the migration of pollutants, while sandy formations enhance infiltration and transport. Variations in contaminant concentrations particularly the attenuation of pharmaceuticals such as acetaminophen, ibuprofen, and sulfamethoxazole, as well as pesticides like mexacarbate and atrazine-desethyl highlight the impact of subsurface composition. Moreover, zones with converging groundwater flow paths and high-permeability sediments are shown to promote localized contaminant accumulation. These findings underscore the importance of coupling lithological assessments with hydrogeological data to better understand contaminant transport processes.</p>