Potential risk assessment and spatial distribution of elemental concentrations in sediment

Sediments are carrier and a sink of elements in the hydrological cycle. Monitoring of contaminated soil and sediment with metallic elements is of interest due to their influence on groundwater, surface water, plants, animals and humans. In this study, different sediment samples from five various places were taken, and the elemental concentration along with some physiochemical parameters were determined. The elemental concentrations were determined with proton-induced X-ray emission, while the physiochemical parameters were determined using a conductivity meter, pH meter and thermometer. This study showed that silicon had highest mean concentration and lead had the lowest mean concentration. Cadmium had the highest contamination values in all the locations. Okitipupa had the highest pollution load index, and the lowest pollution index was recorded in Irele. The overall risk index (RI) in all the locations in the sediment indicated very high ecological risk index. Pollution load index (PLI) also categorized ecological risk which ranged from 8.812 to 28.42. Mean PLI value (17.7) recorded in this study was far higher than the threshold (< 1), indicating the presence of heavy pollutant levels. Such high-level PLI values signified danger and measures are needed in order to reduce the sources of pollutants in the sediment. From enrichment value and Igeo-accumulation values, Sn was severely polluted. Si, Zr, Ag and Cd were extremely polluted. The physiochemical parameters correlated with the elemental concentrations both negatively and positively.