contamination levels, source apportionments, and health risks evaluation of heavy metals from the surface water of the riruwai mining area, north-western nigeria

Mining is one of the most environmentally damaging human activities, having long-term health effects on humans. in this research, the levels of contamination, source distribution, and health risks of heavy metals to residents from drinking surface water near riruwai mining sites were investigated. the findings of the study indicated that the heavy metal levels ranged from as (0.00–0.04 mg/l), cd (0.00–0.04 mg/l), cr (0.02–0.06 mg/l), mn (0.02–0.07 mg/l), and pb (0.00–0.05 mg/l), with mean levels of 0.02, 0.013, 0.03, 0.02, and 0.04 mg/l, respectively. the concentrations of all metals, with the exception of mn and cr, are higher than acceptable limits. the values of the heavy metal pollution index (hpi) for all the metals, with the exception of mn, exceed the threshold limit of 100, indicating serious pollution of the surface water. this was confirmed by the results of nemerow’s pollution index (npi). multivariable analysis revealed anthropogenic and natural sources as the main sources of heavy metal contamination, with cd, as, cr, and pb originating from mining activities and mn possibly coming from parent materials. the total hazard index (hi) and non-cancer risk (hq) values in children and adults are within acceptable limits. however, the total life cancer risks (tlcr) of as and cd were higher than the tolerable limit of 1.00e-06. therefore, heavy metals in surface water, particularly as, cd, and pb, should be properly monitored and a treatment program implemented to safeguard the health of local residents, especially children.