Spatial Distribution and Health Risk Assessment of Nitrate in some Groundwater of Lagos, SW Nigeria

Abstract

High concentrations of nitrate in groundwater caused by agricultural activities, prolonged leakages from sewage tanks, open defecation and industrial effluents have become a global concern. Many residents of Lagos do not have access to government-supplied water and source their water from groundwater. This study aims to assess the concentration of nitrate in groundwater and the risk it poses to human health within some parts of Lagos, southwest Nigeria. Ninety-seven groundwater samples were collected for this purpose, and nitrate analysis was performed using Dionex DX-600 Ion Chromatograph (Thermo Fisher). The nitrate concentration in the study area varied from 0.02–307 mg/L with a mean value of 61.3 mg/L, and approximately 57% (n = 55) of the samples exceeded the Nigerian and World Health Organization permissible threshold of 45 mg/L. The nitrate pollution index (NPI) revealed that 13%, 11%, and 37% of groundwater samples were moderately, significantly and very significantly polluted. In addition, human health risk assessment of nitrate revealed that the oral route significantly impacted the health of residents. Hazard Quotient (HQ) values for oral route ranged between 9.1E-04 - 13.94; 6.5E-04 - 9.97; 6.7E04 - 10.42; 5.0E-04 - 7.67; 4.8E-04 - 7.422 and 5.0E-04 - 7.67 for 0-6 months, 5-10 years, 10-15 years, 15-20 years, 20-60 years, and above 60 years, respectively. Alimosho, Mushin, Ikeja, Ogba, and Kosofe areas are more negatively disposed to nitrate health risks through the oral route, with infants and children most susceptible.

Publication Info:

Author: Akinwunmi, M.S.; Odukoya, A.M.; Oloruntola, M.O. and Aniekan, R.D.

Volume: 61

Issue: September

Published By: Journal of Mining and Geology Vol. 61(1) 2025. pp. 79 - 92, 2025-09-01