Evaluation of the source, distribution and risk of metal contaminated stream sediment.

Background: The objective of the study is to determine the nature and the anthropogenic sources of the detected metal pollutant in the sediment of the Ikpoba River. Also, to study the distribution trend and the ecological and health risks of the analyzed metals. The metals were extracted from the sediment through aqua regia digestion and analyzed with an atomic absorption spectrometer. A total of six metals was quantified. Results: The distribution of the average concentration of metals showed that Cd < Cu < Co < Pb < Ni < Fe. The ecological risk assessment showed the values of geo-accumulation (igeo) and contamination indices of the metals to be zero except for Fe. This is an indication of zero pollution of the aquatic system by all detected metals except Fe. However, the enrichment factor (EF) of the metals has values greater than 1.5 in some sampling areas and less than that in others. Furthermore, the values of the ecological risk index (ERI), pollution load index (PLI), and potential ecological risk (PER) of the detected metals were all less than one. The sediment quality guidelines (SQGs) were all low for the tested metals. The human health risk assessment revealed the hazard quotient (HQ) and hazard index (HI) of the analyzed metals to be less than 1, while the carcinogenic risk was also noted to be less than 10 -6. Conclusions: Children's ADD values were higher than adults' through dermal and ingestion exposure routes, indicating that children are more vulnerable to metals risk than adults. Furthermore, the values of the EF and multivariate statistics showed the sources of the metals to be a mixture of anthropogenic and natural, with anthropogenic activities leading. However, despite the low ecological and human health risk posed by the various metals, Cd was discovered to be a potential carcinogen and ecological risk to children, and the biota of the studied stream, if released, persisted unabated