Heavy metals occurrence in groundwater of the Mitidja plain (Northern Algeria)

The Mitidja plain, located in northern Algeria, is a major industrial and agricultural region where groundwater quality is increasingly impacted by industrial effluents, domestic sewage, and agricultural drainage. This study aims to assess groundwater contamination by heavy metals and identify their potential sources. Groundwater samples were collected from 17 sites and analyzed for Fe, Mn, Pb, Cr, Cu, Cd, and Zn, In addition, major physicochemical parameters were measured at 41 sampling points.The results indicate that metal concentrations generally follow the order Fe > Zn > Mn > Pb > Cu > Cr > Cd, with several samples exceeding World Health Organization (WHO) guideline values. Multivariate statistical analysis (principal component analysis) revealed contributions from both natural geochemical processes and anthropogenic activities. The Heavy Metal Pollution Index (HPI), highlights significant heavy metal pollution in the study area, indicating that the groundwater is seriously polluted for drinking purposes. The health risk assessment revealed hazard index (HI) values exceeding 1 for both adults and children, with higher values observed in children, indicating a greater non-carcinogenic risk. The incremental lifetime cancer risk (ILCR) values calculated for Cd, Cr, and Pb were within acceptable limits for adults; however, for children, (Cr) exceeded the acceptable carcinogenic risk threshold.