Assessment of Physicochemical Properties of Water and Associated Human Health Risk Factors from Gitata River, Nasarawa State, Nigeria
Adamu Usman
Peter Godiya Nmagbo
Samson Likita Jawo
Onyeakazi Cynthia Chimobi
Agwadu Ezekiel Kunza
Abstract
Water in regions affected by mining can be laden with toxic metals, posing a risk to nearby populations. Physicochemical characteristics, heavy metal concentration and the associated human health risks were examined in the surface water of Gitata River located in Nasarawa State, Nigeria. Water from five sites of the river were sampled, during the dry season and analysed using standard analytical procedures. Physicochemical parameters including pH 7.05-7.25; electrical conductivity 228-240 μS/cm; total dissolved solids 141-152 mg/L; turbidity 2.73-3.1 NTU; dissolved oxygen 6.2-6.8 mg/L; biochemical oxygen demand 2.1 to 2.4 mg/L; hardness 91.8-97 mg/L; chloride 17.9-20.3 mg/L; and nitrate 6.5-7.24, which all lie within the permissible limit of the World Health Organisation (WHO). Heavy metal concentration at different sites ranges from 0.000-0.803 mg/L for chromium, from 0.036-0.151 mg/L for cadmium, and from 0.001-0.321 mg/L for arsenic, with a 0.056-0.385 mg/L range for lead.Cadmium and arsenic exceeded the WHO and National Environmental Standard Regulation Agency (NESREA) limits at several locations. Exposure risk to humans was assessed using models provided by the United States Environmental Protection Agency (USEPA). Chronic daily intake (CDI) values were between 0.00 and 2.49×10-4 mg/kg/day for adults, and from 0.00 to 6.77×10-4 mg/kg/day for children, while hazard index (HI) ranged from 0.070 to 0.431 for adults and 0.189-1.170 for children, with the value greater than unity for children at Site E, mostly from cadmium and arsenic. The estimated risk of cancer associated with arsenic was 2.27×10-4-1.12×10-3 higher than tolerable levels. The findings recommend risk-based water management practices, regulatory control of artisanal mining activities and continuous surface water quality monitoring in the study area.
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