GEO-ACCUMULATION INDEX OF SOME HEAVY METALS IN THE WASTE DUMPSITE AT AGU AWKA ANAMBRA STATE, NIGERIA

Abstract

Uncontrolled disposal of municipal solid waste continues to pose serious environmental challenges in many developing countries, particularly through the release of toxic heavy metals into soil systems. This study evaluates the concentration, distribution, and contamination status of selected heavy metals (Pb, Cd, Ni, Cr, and As) in soils from the Agu-Awka dumpsite, Nigeria, using the Geo-accumulation Index (Igeo). Soil samples were collected at three depths (0–5, 15, and 30 cm) from two active dumpsites and a control site. Physicochemical properties were analyzed using standard procedures, while metal concentrations were determined via atomic absorption spectrophotometry following aqua regia digestion. The results show clear enrichment of heavy metals in dumpsite soils compared to the control, with the highest concentrations observed in surface layers. Igeo classification indicates moderate to moderately strong contamination, particularly for lead and arsenic. Although concentrations were generally below international guideline limits, the index-based approach reveals notable anthropogenic influence. The vertical distribution pattern suggests gradual leaching, raising concerns about potential groundwater contamination. Overall, the findings highlight the need for improved waste management strategies and consistent environmental monitoring to reduce long-term risks.