Quantification and risk assessment of trace metals in soils from selected solid waste dumpsites in Delta State, Nigeria.

Author:Emoyan et al., 2024

published date:2024-Aug-29

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Abstract

This study examined the concentration of heavy metals (HMs) in soil from selected open dumpsites in Delta State, Nigeria. The potential health and ecological risks from exposure to these metals were also evaluated. 27 soil samples were collected from 9 different dumpsites at soil depths of 0-15 cm, 15-30 cm and 30-45 cm. The soil samples were digested with aqua regia and analyzed for Pb, Cd, Cr, Cu, Ni, Mn and Co using atomic absorption spectrophotometry. The ecological risk of HMs was evaluated using soil pollution assessment models-geoaccumulation index, contamination factor and ecological risk index. Health risk was assessed using the carcinogenic and non-carcinogenic risk models. The concentration of HMs across the 9 locations and depths ranged as follows: 0.85 – 207 mg kg-1 for Cd, 2.08 – 33.5 mg kg-1 for Pb, 4.65 – 307 mg kg-1 for Ni, 1.05 – 69.5 mg kg-1for Cr, 4.20 – 436 mg kg-1 for Co, 3.50 – 405 mg kg-1 for Cu, 0.15 – 293 mg kg-1 for Mn, 7.36 – 47.7 mg kg-1 for Zn and 54.4 – 474 mg kg-1 for Fe. Cd, Co, Ni, Cu and Fe exceeded their respective regulatory limits at some soil depths. Cd showed very high geoaccumulation index values and contamination factors across depths. The non-carcinogenic risk exposures indicated significant risks in 2 locations, while the risk of developing cancer was high in all locations. The very high levels of Cd in soil call for concern, owing to its low biodegradation and associated health consequences.

Keywords: Dumpsite soil, Heavy metals, Pollution index, Non-carcinogenic risk, Carcinogenic risk

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