Assessment of Heavy Metal Concentrations in Parts of Meme River Distributaries Lokoja, North Central Nigeria

Abstract

The level and mobility of heavy and trace metals in sediments within parts of Meme River tributaries, Northwest of Lokoja. Heavy metal concentrations were delineated in fifteen (15) downstream sediment samples domicile within the study area, using Atomic Absorption Spectrometry (AAS). Mean value results showed that the degree of heavy metals decreased in order of Mo>As>Co>Hg>Mn>Pb>Cr>Cd>Cu>Fe. However, Cd, As, and Hg debut as metals with the highest concentration in sediments, when compared with the World Health Organization (WHO), World Surface Rock Average (WSRA) and other standards. The mapped area is not located within mining of Cd-bearing ore minerals, which suggests that anthropogenic sources of elemental enrichment of Cd, Pb, and Hg are more likely than bedrock geochemical dissolution (weathering). Each sample elemental concentrations were subjected to environmental indices evaluation using different equations. Cadmium (Cd) fall within the high degree of contamination in all the sample analyzed. Index of geo-accumulation (Igeo) was determined and the results indicate that elements such as Pb, As, Cr, Cu, Hg, Mo, Fe and Mn are unpolluted. Nonetheless, Cd shows enrichment that range between the class of moderately polluted to strongly polluted. The ecological risk factors revealed that only Cd shows very high ecological risk. The correlation analysis shows several significant relationships among the elements, suggesting potential co-occurrence patterns or shared sources in the sampled locations. Lead (Pb) has a strong positive correlation with cadmium (Cd) and mercury (Hg), which may indicate a common origin or similar environmental factors affecting their concentrations. This trend is echoed with Cd, which also correlates positively with Hg, further strengthening the hypothesis of a shared source for these elements, possibly from anthropogenic activities. The factor analysis reveals three main components explaining about 69.5% of the total variance in the heavy metal concentrations across the sampled locations. The first factor accounts for 34.5% of the variance, indicating a significant underlying influence common to multiple elements. This factor likely represents metals that co-occur due to similar environmental or anthropogenic sources, as suggested by the high communalities for lead (Pb: 0.854), cadmium (Cd: 0.753), mercury (Hg: 0.800), and iron (Fe: 0.796). This call for immediate attention by the environmental protection agencies in the study area for urgent remediation exercise.