Determination of heavy metal contamination in well water from selected locations within Kaduna metropolis

Abstract

This study aimed to measure heavy metal (Pb, Cr, Cd, Co, Hg, Ni, Fe, Mn, Zn and Cu) levels in well water from five locations in Kaduna: Unguwan Sarki, Kawo, Barakallahu, Mando, and Mahuta Estate. It also compared these levels with WHO standards and evaluated potential health risks to residents. The hand-dug well water samples were collected, acidified to a pH below 2 for preservation, and analysed using atomic absorption spectrophotometry (AAS). Results showed that 70% of the heavy metals such as lead (Pb), cadmium (Cd), chromium (Cr), nickel (Ni), copper (Cu), manganese (Mn), and zinc (Zn)—were within WHO safety limits. However, notably high iron (Fe) levels were found in Unguwan Sarki (0.412 mg/L) and Mahuta Estate (0.728 mg/L), both surpassing the WHO limit of 0.3 mg/L. In conclusion, while most metals are within safe levels, the elevated iron levels at two locations indicate a need for targeted measures to protect public health, as it causes significant aesthetic issues such as altering the water taste and can also cause staining.  The Hazard index for Ungwan Sarki, Barkallahu, and Kawo is on the high side, indicating that these locations are prone to hazards from these heavy metals. The CDI showed Barakallahu leading in the intake of Cr, Ni, Mn, and Copper; Kawo and Mando showed more consistent levels of the toxic heavy metals, while Ungwan Sarki showed the highest Cd intake overall. Variations across sites suggest local geology or pollution sources affect water quality. Recommendations involve further investigation into iron sources, health awareness campaigns, water treatment options, and regulatory enforcement to maintain water safety.