Petroleum hydrocarbons contamination in water from Alau Dam in Konduga Local Government Area Borno State Nigeria

Petroleum hydrocarbons (PHCs) are long-lasting contaminants that pose substantial environmental and public health risks, particularly in aquatic ecosystems affected by oil pollution. This study assessed the levels, spatial distribution, and potential health risks of PHCs in dry-season water samples collected from Alau Dam in Konduga Local Government Area, Borno State, Nigeria. Samples from ten locations (S1–S10) were analyzed using gas chromatography–mass spectrometry (GC–MS). PHC concentrations ranged between 0.001 and 0.457 mg/L, with higher concentrations detected near zones influenced by agricultural runoff and wastewater discharge. The predominant compounds were n-alkanes, notably n-C16, n-C23, and n-C33. Chronic daily intake (CDI) values varied from 1.12 × 10⁻⁵ to 8.43 × 10⁻³ mg/kg/day. Although Health Quotient values (0.01–0.92) indicated low risk from individual compounds, cumulative Health Index values exceeded acceptable thresholds at several sites, particularly for children (0.87–3.46). Estimated carcinogenic risks surpassed USEPA recommended limits, with the highest risks observed at sampling points S4, S6, and S9. These findings indicate that PHCs contamination in the study area represents a significant health concern, highlighting the need for immediate monitoring and remediation effort.