Variation of Heavy Metal Concentration in Otofure, Edo State, Southern Nigeria

Abstract

This study provides a critical assessment of heavy metal contamination at the Otofure dumpsite in Ovia North East Local Government Area, Edo State. Utilizing Atomic Absorption Spectrometry, soil samples from five distinct points and two depths (0-15 cm and 15-30 cm) were analyzed to determine the distribution of nine key heavy metals. Nine heavy metals were analyzed and they are Cadmium (Cd), Lead (Pb), Arsenic (As), Nickel (Ni), Iron (Fe), Chromium (Cr), Manganese (Mn), Copper (Cu)and Vanadium (V).  The mean of the results includes Fe 96.08 - 65.88 Mg/kg, Cr 0.10 - 0.06 Mg/kg, Mn 15.34 - 11.82 Mg/kg, Ni 9.87 - 5.57 Mg/kg, Cd 0.05 - 0.01 Mg/kg, Cu 30.82 - 24. 36 Mg/kg, Pb 4.19 - 3.09 Mg/kg, V 31.06 - 20.13 Mg/kg and As 0.08 - 0.02 Mg/kg. Then the results obtained were compared with past research done on the dumpsite and national standards. The mean concentrations observed across the samples indicate varying levels for the heavy metals, with ranges such as 96.08 - 65.88 mg/kg for the most prevalent metal and considerably lower values like 0.05 - 0.01 mg/kg for others. Crucially, a comparative analysis of these findings against historical data for the dumpsite and relevant national environmental standards reveals a notable and encouraging trend: a significant reduction in heavy metal pollution. This positive environmental shift is directly attributable to two primary factors: a decreased influx of waste being deposited at the site and the ongoing efforts to reclaim the land for residential development. These results strongly suggest a future transformation of the Otofure dumpsite. The observed decline in contamination, coupled with the continued land reclamation initiatives, indicates a trajectory towards the eventual phasing out of the dumpsite, paving the way for its conversion into residential areas within the Otofure community. This development holds significant implications for local environmental health and land-use planning in Edo State.

Received: 20 May 2025 / Accepted: 20 July 2025 / Published: 01 August 2025