Assessments of heavy metals distribution, contamination and health risk in Dagilfani flood plains along River Hadejia

Abstract

This study assessed the distribution, contamination status, source characteristics, and health risks of heavy metals in soils from artisanal potash extraction sites within the Dagilfani section of River Hadejia floodplain, Northern Nigeria. The aim of the study is to evaluate heavy metals pollution in an artisan potash extraction site using pollution analysis and to evaluate the impact of heavy metals to public health. Twenty-five topsoil samples were collected and analyzed using Energy Dispersive X-Ray Fluorescence (ED-XRF). Descriptive statistics, Multivariate statistics, pollution Assessment and health risk models were applied for interpretation. The mean concentrations of Al, K, Fe, Mg, Zr, and La exceeded crustal background values, whereas Ca, Ti, Mn, Ce, Zn, and Cr remained below background levels. High coefficients of variation for Ca, Mg, La, Cr, and As indicated strong anthropogenic influence. Correlation analysis (CA), Principal Component Analysis (PCA), and Hierarchical Cluster Analysis (HCA) revealed that Al, K, Fe, Ca, Mg, Ti, Ce, Mn, and Zr were mainly controlled by lithogenic sources. The study also showed that Cr, As, Zn, and La originated from mixed anthropogenic and natural sources linked to agriculture, vehicular emissions, and artisanal activities. Geo-accumulation results showed that the soils were generally unpolluted, although La, Zr, K, and Al exhibited slight to moderate enrichment, with EF values of 2.04 and 1.66 recorded for La and Zr, respectively. Non-carcinogenic risk assessment indicated no significant risk for both adults and children (HI < 1). However, carcinogenic risk values for As and Cr ranged from 2.03 × 10⁻⁴ to 2.76 × 10⁻⁴, exceeding the USEPA acceptable limit and indicating potential long-term cancer risk.