This study investigated the accumulation and ecological risk of heavy metals in soils surrounding a major open dumpsite adjacent to the New Abattoir in Akerebiata Harmony Estate, Ilorin, Southwestern Nigeria. Ten representative soil samples were collected at 9 m by 45 m intervals and analyzed using Atomic Absorption Spectroscopy (AAS) to determine concentrations of Copper (Cu), Zinc (Zn), Chromium (Cr), Iron (Fe), Cadmium (Cd), Cobalt (Co), Arsenic (As), Lead (Pb), Silver (Ag), and Mercury (Hg). Environmental impact was evaluated through the calculation of the Geo-accumulation Index (Igeo), Contamination Factor (CF), Pollution Index (PI), Enrichment Factor (EF), Hazard Quotient (HQ), Hazard Index (HI), and Cancer Risk (CR). Results indicated that while absolute concentrations remained below current regulatory limits, the site is moderately to strongly polluted (PI = 3.37) due to significant anthropogenic inputs. Igeo values showed that the area is uncontaminated regarding Cr, Hg, and Cd, but moderately contaminated with Co and As. The HQ and HI values for all metals were below 1.0 for both children (HI = 0.0016) and adults (HI = 0.0002), indicating no immediate non-carcinogenic risk via soil ingestion. Total cancer risk (CR = 2.08 × 10⁻8 for children) fell within the acceptable range (< 10⁻⁶). However, trends in As, Co, and Hg contamination factors warrant precautionary monitoring. Principal Component Analysis (PCA) attributed PC1 (34.73% variance) primarily to geogenic Fe–Cr inputs and PC2 (24.52%) to anthropogenic Cu-As loading. These findings suggest that the current open dumping system poses a growing risk to the local ecosystem and public health. The study recommends the implementation of engineered sanitary landfills, regular environmental monitoring, and remediation strategies to mitigate future heavy metal accumulation.
Durga Ruth Panchalingam, M. Adisa· Discover Environment· 0 citations
The continued reliance on energy-intensive hydraulic binders for soil stabilization presents a significant environmental challenge, prompting the need for sustainable, low-carbon alternatives. This study investigates the technical, microstructural, and environmental performance of Recycled Concrete Aggregate (RCA) as a stabilizer for brown lateritic soil. A multi-scale experimental program was conducted, integrating microstructural characterization (X-ray Diffraction [XRD] and Scanning Electron Microscopy [SEM]) with macroscopic geotechnical evaluations (compaction and California Bearing Ratio [CBR]) at RCA replacement levels of 0–25%. Mineralogical analysis revealed the laterite to be a quartz-dominant ferruginous soil, while the RCA introduced calcium-rich anorthite and fibrous anthophyllite phases. SEM imaging showed that RCA addition promoted a rigid granular skeleton with mechanical interlocking and partial void infilling by fine particles. Geotechnical testing indicated that soil performance peaked at 20% RCA replacement, where Maximum Dry Density increased from 1.98 to 2.11 g/cm³, Optimum Moisture Content decreased from 9.5% to 8.0%, and soaked CBR improved from 30% to 41%. Replacements exceeding 20% led to performance declines attributed to matrix disruption and high-water absorption of the residual mortar. Environmental and cost analyses suggested that the optimized 20% RCA mixture can achieve a substantial reduction in CO₂ emissions (approximately 93%) compared to traditional 5% cement stabilization within the system boundary considered in this study. These findings indicate that RCA offers a promising circular-economy approach for improving the short-term mechanical properties of this lateritic soil, contributing to more sustainable road infrastructure development.
M. Adisa, Kayode Elizabeth Omolara, Houatchueng Tadjuidje Maurel et al.· Discover Geoscience· 0 citations
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