Seasonal variations of heavy metals concentrations and pollution assessment of major dumpsites in Ilisan-Remo, Nigeria

Globally, natural and anthropogenic activities have led to soil pollution resulting in physiological and health challenges on environment, plants, animals, and humans. The present study was conducted to determine the total levels of heavy metals including cadmium (Cd), copper (Cu), chromium (Cr), lead (Pb), and nickel (Ni), in two major dumpsites in Ilisan-Remo, Ogun State, Nigeria.

Sixteen composite soil samples were collected from both dumpsites (Cargo and Ilisan) at depths of 0-15 cm. Samples were collected in the wet and dry seasons. After collecting samples, they were air-dried and sieved, and the concentrations of metals were evaluated using flame atomic absorption spectrometry (FAAS). The obtained data were used to determine the pollution indices including contamination factor (CF), geo-accumulation index (Igeo), and ecological risk index.

The concentrations of heavy metals in Cargo dumpsite followed this order: Cr > Pb > Cu > Ni > Cd, during wet and dry seasons. Conversely, the concentrations of heavy metals in Ilisan dumpsite followed this order: Pb > Cr > Cu > Cd > Ni, over both seasons. The measured CF levels for both Cargo and Ilisan dumpsites were low to very high for Cd over both seasons. The Igeo revealed that both dumpsites were moderately to heavily polluted by Cd and Ilisan dumpsite was moderately polluted by Pb. A low to considerable ecological risk was observed for both dumpsites.

The pollution indices suggest that both dumpsites were heavily polluted by Cd due to anthropogenic activities. Appropriate measures should be implemented to manage these dumpsites.