Heavy Metal Contamination and Ecological Risk Assessment in Soils and Sediments of an Industrial Area in Southwestern Nigeria

摘要

Background. Increased growth of industrial activities, especially in urban centers, is one of themain sources of toxic substances in Nigeria. The level of these impacts is not well known. Soiland sediment samples from one such industrial area were examined for their mineralogicalcomposition and heavy metals contents in order to assess the level of contamination andpotential ecological risk status.Methods. Mineralogical composition of the media and their heavy metals concentrations weredetermined using X-ray diffractometry and inductively coupled plasma-mass spectrometrymethods, respectively. Ecological risk assessment was carried out using single (contaminationfactor, geo-accumulation index, enrichment factor) and multi-elemental (contamination degree,pollution index and modified pollution index) standard indices.Results. The average heavy metal concentrations in soils and sediments followed the ordermagnesium (Mn) chromium (Cr) lead (Pb) copper (Cu) cadmium (Cd) cobalt (Co) nickel (Ni), with corresponding values for soils and sediments of 324.3, 79.9, 66.1, 40.7, 14.3, 9.1,6.8 mg kg-1 and 266.8, 78.6, 40.6, 39.8, 12.9, 8.4, 4.6 mg kg-1, respectively. Principal component(PC) analysis of the results indicated three main sources of metals (industrial, vehicular activitiesand geogenic input). Evaluated contamination factor (Cf), enrichment factor (Ef) and geoaccumulation index (Igeo) revealed very high contamination for Pb, Cd and Cu in all of thesamples, with calculated pollution index (PI) and modified pollution index (MPI) revealing thatall the samples were severely polluted. Calculated potential ecological risk factor (ERi) within theindustrial area demonstrated a strong potential ecological risk for Cd, Pb and Cu.Conclusions. Activities in the industrial area have affected the quality of the analyzedenvironmental media, with possible detrimental health consequences. Regular environmentalmonitoring of the industrial area and the formulation of appropriate policies that supportreduction of contamination are strongly recommended. However, due to the limitations ofcomparing site samples with a single control sample in this work, further study is recommendedto compliment this preliminary study.Competing Interests: The authors declare no competing financial interests.