Abstract
Jabi Lake, an urban lake in Abuja, Nigeria, faces growing pressure from stormwater runoff and residential expansion. Lead (Pb), chromium (Cr), arsenic (As), and cadmium (Cd) were quantified by atomic absorption spectrometry in surface water from 29 sites across the dry and wet seasons of 2024-2025. Mean concentrations ranked Cr (0.023 mg L⁻¹) > Pb (0.006) > As (0.005) > Cd (0.0015 mg L⁻¹); most were within World Health Organization limits, though Pb and Cr were locally elevated. Wet-season concentrations were higher for all four metals (p < 0.01), confirming runoff as the dominant input pathway. Inverse distance weighting mapped hotspots along the lake margins, and a Heavy Metal Pollution Index of 51.1 indicated moderate pollution. Ingestion dominated exposure, and non-carcinogenic hazard indices remained below 1. Arsenic returned a total incremental lifetime cancer risk of 2.16 × 10⁻³, exceeding acceptable limits and indicating a need for targeted, spatially explicit monitoring.