Abstract
Agricultural activities involving irrigation has been intensively practiced along the banks of River Kaduna. This river is contaminated with domestic and industrial wastes. This action may expose the soil to heavy metals, which could have negative ecological effects. A total of 45 surface soil samples were taken from five sampling locations along the banks of River Kaduna within the period January to March, 2021 which represents the peak period for dry season irrigation farming and the highest dilution ratio of contaminants in the irrigation water. The experimental design was random-blocked design. Soil samples were analyzed for cadmium, lead, nickel, zinc and copper using atomic absorption spectrometer and in order to evaluate the scale of pollution in the study area, the background values were employed to estimate the values for the Enrichment factor (EF), Geoaccumulation index (Igeo), Contamination factor (CF), Contamination degree (CD), Pollution Load Index (PLI), Ecological Risk Index (ERI), and Integrated Ecological Risk Index (IERI). Data were subjected to ANOVA using SPSS version 26 software. According to the contamination indicators (EF, Igeo, CF, CD, ERI, and IERI), Cd was the main source of the heavy metal contamination, but Pb and Ni were responsible for the minor scale of pollution. However, the Pollution Load Index of all stations was within the baseline level. Irrigation of agricultural land with water contaminated with industrial effluent and sewage could be responsible for heavy metal pollution of the soil. These findings suggest that remediation techniques are necessary especially for Cd to protect the soil ecosystem due to its detrimental effects on human health.

Key words: Geoaccumulation index; Enrichment factor; contamination factor; ecological risk; River Kaduna