Multivariate analysis of sediment quality in River Ogbere, Ibadan, South-West Nigeria

Heavy metals are pollutants of river sediments, and their concentration varies depending on parental material and anthropogenic inputs, thus it is important to distinguish between the natural and anthropogenic inputs. The objective of this study is to use different types of indexes to assess the current pollution status in Ogbere River sediment and select the best index to describe the sediment quality. The indexes used in this study were enrichment factor (EF), geoaccumulation index (Igeo) and principal component analysis (PCA). The PCA has an advantage over other index analyses as it reduces the dimensionality of the data set and thus used to support multivariate cluster analysis. From the study, a total of 12 sediment samples were collected in both seasons across six sampling location and pollution indexes indicated three things: firstly, the metal distribution profile in the sediment showed that the heavy metals analysed were lower than the maximum allowable limits stipulated by Department of Petroleum Resources (DPR); secondly, minor to extremely severe significant levels of enrichment and thirdly, practically uncontaminated to a moderately contaminated degree of contamination in Ogbere River during the study period. The PCA is considered more sensitive in the analysis of benthic changes as well as sediment quality. However, the heavy metal assessment indices are not only used for sediment quality. Biological testing and ecological analysis of existing community related to sediment contamination are further recommended in River Ogbere.