Groundwater Quality and Heavy Metal Variability in Post-Conflict Mosul, Iraq: Seasonal and Annual Assessment (2022–2023) and Implications for Environmental Sustainability

This study examines the post-war evolution of groundwater quality in Mosul by evaluating the seasonal and annual behavior of physicochemical parameters and heavy metals, while differentiating the responses of shallow and deep aquifers and determining whether groundwater conditions during the early recovery period (2022–2023) indicate natural improvement or continued deterioration. Groundwater samples from shallow (W5–W8) and deep (W1–W4) wells were collected across four sampling campaigns representing both wet and dry seasons. Shallow wells exhibited marked seasonal increases, with pH, electrical conductivity (EC), and total dissolved solids (TDS) increasing during the dry season, driven by evaporation and limited recharge. Nutrient concentrations (PO 4 3− , NO 3 − , SO 4 2− ) showed similar seasonal rises but declined slightly in 2023 following reduced rainfall. Heavy metals (Cd, Pb, Cr, Ni, Zn) displayed pronounced seasonal peaks in the wet season and higher annual averages in 2023, suggesting delayed mobilization from contaminated soils. In contrast, deep wells remained relatively stable, reflecting the buffering capacity of deeper geological formations. Statistical analyses supported these patterns: shallow wells demonstrated significant seasonal variability ( p < 0.05) across most parameters, whereas deep wells exhibited limited seasonal differences and no significant annual variation. These findings indicate that shallow aquifers—particularly those constructed during the conflict—are more vulnerable to post-war environmental stresses, while deeper aquifers retain greater resilience. Overall, the study underscores progressive degradation of shallow groundwater linked to post-conflict conditions and highlights the need for sustained monitoring, stricter regulation of groundwater use, and targeted remediation strategies to protect drinking and irrigation resources in conflict-affected regions. These insights are crucial for developing sustainable groundwater management strategies in post-war urban environments.