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Savanna Journal of Basic and Applied Sciences 3(1):43-52
Groundwater Heavy Metal Pollution and Human Health Risk Assessment in Shendam Area, North Central Nigeria
Abusu C. O.

ABSTRACT
Elevated heavy metal concentrations have been observed in fishes sampled from water sources in Shendam area, north-central Nigeria. Due to the close interaction between surface and groundwater, this study was carried out to appraise the heavy metal concentration to assess the human health risk associated with groundwater ingestion from the study area. Forty groundwater samples were collected from shallow wells in the area. pH, which affects heavy metal dissolution in groundwater, was measured in-situ while heavy metals in groundwater, rock and soil were analysed at the Central Instrumentation Laboratory, Centre of Dryland Agriculture, Bayero University Kano. Results showed heavy metal concentration of the order Sr > Se > Ba > As > Pb > Li > Zn > Cu > V > Ni > Cr > Cd > Co. Arsenic, Pb, and Se were the main heavy metal pollution sources in the area, with 40%, 17.7%, and 35% of their respective samples occurring within guideline limits. Computation of ingestion Chronic Daily Intake (CDI) and Health Risk Index (HRI) for adults indicated that use of groundwater from the study area additionally exposes users to the health risk from Cd, Cr, Pb, V, and Li, which have 97.5%, 95%, 85%, 97.5% and 95% within World Health Organization (WHO) guideline limits. HRI results maintained Se and As with only 50% and 40% respectively occurring within guideline limits, as the main sources of groundwater pollution. Observed HRI for children was similar to that of adults except that lower percentages of V and Li occurred within optimum limits (32.5% respectively). The study area's overall heavy metal hazard index revealed severe cumulative health hazard, with only 12.5% of the samples occurring within guideline limits. The main heavy metal pollutants As is thought to have originated from natural sources. However, Pb and Se are believed to be triggered by anthropogenic activities. A detailed appraisal of heavy metal sources is thus recommended, and the exploitation of groundwater from deeper bore wells to avoid contaminated groundwater.