THE PREVALENCE OF HEAVY METALS AND FLAME RETARDANTS IN OLUKU DUMPSITE LEACHATE, EDO STATE, NIGERIA

This study evaluated the physicochemical characteristics, heavy metal content, and flame retardant contamination of leachate from the Oluku dumpsite in Edo State, Nigeria, to assess its potential environmental impacts. The physicochemical analysis revealed that the leachate was highly polluted, with pH (8.01 ± 0.14) indicating slight alkalinity and temperature (30.68 ± 0.37°C) reflecting active microbial decomposition. Electrical conductivity (8333.33 ± 2117.65 µS/cm) and total dissolved solids (5500 ± 1278.1 mg/L) were significantly elevated, suggesting strong mineralisation and ionic concentration. Dissolved oxygen (0.74 ± 0.20 mg/L) was markedly low, whereas biochemical oxygen demand (74.33 ± 4.65 mg/L) and chemical oxygen demand (182.33 ± 13.32 mg/L) were high, indicating severe organic pollution and oxygen depletion. Heavy metal analysis revealed that chromium (3.57 ± 0.78 mg/L), zinc (9.89 ± 2.48 mg/L), lead (0.59 ± 0.15 mg/L), and cadmium (0.39 ± 0.10 mg/L) exceeded NESREA limits, while nickel (0.19 ± 0.04 mg/L), copper (0.93 ± 0.18 mg/L), and iron (9.47 ± 0.91 mg/L) were within permissible levels. Manganese (0.11 ± 0.02 mg/L) and arsenic (0.03 ± 0.01 mg/L) were low, and vanadium was undetected. Flame retardant analysis revealed severe contamination, with PBB-153 (31.0 ± 8.7 µg/L) and BDE-153 (12.1 ± 3.9 µg/L) far exceeding the EU Environmental Quality Standard (0.0005 µg/L). The results indicate that the Oluku dumpsite leachate is heavily contaminated with organic matter, heavy metals, and brominated flame retardants. These pollutants pose significant risks to surrounding soil and groundwater, underscoring the urgent need for proper leachate management, site remediation, and continuous environmental monitoring.