Geostatistical assessment of soils in Ibadan, Southwest Nigeria: Focus on agricultural lands

Abstract

Food production relies on agricultural fields, which can accumulate hazardous materials. This study examined multi-element concentration of agricultural soils in Ibadan, located in Southwest Nigeria. A systematic sampling approach was employed where 39 soil samples were collected and analysed for their elemental composition with plasma-mass spectrometry (ICP-MS) atomic fluorescence spectrometer (AFS). Pb (27.96 ppm), Ag (75.68 ppm), As (0.87 ppm), Ba (37.30 ppm) and Co (3.8 ppm) recorded average values below the recommended baseline values. While 20% of samples for Cr and all of the samples for Co reported values above the recommended baseline values of 80.74 ppm and 0.40 ppm respectively. The soils had a Relative Contamination and Cumulative Index (RCCI) greater than 75%–100%. This shows that some soils were highly contaminated with various elements. The Empirical Orthogonal function (EOF) analysis also indicated that the soils were loaded with Cu, Co, Mn, As, Cr, and Fe. This study provides valuable insight on the multi-element concentration in agricultural soils in Ibadan. These findings may help policymakers, agricultural stakeholders, and environmental authorities manage and remediate soil in the study area.