ABSTRACT
An ecosystem's anthropogenic effects constitute an ecological risk that might have a negative influence on human health. Heavy metal pollution has gained a lot of attention recently and has turned into a major environmental problem due to its toxicity, persistence, and bioaccumulation in the environment. This study aimed to determine the toxicity profiling, source identification, and ecological risks of sediment in the Polobubo River, Delta State. The study was conducted at seven locations throughout the Polobubo (Tsekelewu) River in Warri North Local Government Area. Prior to collecting samples, a recognisance visit was conducted to guarantee that logistics and community-related issues would be kept to a minimum. In the study area, top sediments were collected using a stainless-steel scoop. The samples were kept in a chiller at 4 °C in the laboratory after being put in polyethylene plastic bags, labelled appropriately, and carried in an ice chest. Standard methods were used in the determination of the heavy metals and physicochemical characteristics of the sediment. The results of the physicochemical characteristics of sediment in the Polobubo river showed that electrical conductivity, total organic matter, phosphorus, iron, nickel, chromium, zinc, cadmium and lead contents were significant (p < 0.05) across locations; while pH, total organic carbon, total organic nitrate and copper which were not significant. The spatial and monthly variations of the physicochemical characteristics of sediment fluctuated across the stations and the sampling months. The result of the ecological risk assessment [contamination factor (CF), degree of contamination (DC), pollution load index (PLI), index of geoaccumulation (I-geo), and potential ecological risk index (PERI)] of selected heavy metals in the sediment of Polobubo River indicated that the CF, PLI and I-geo were < 1. However, the values obtained in station 2, 3, and 7 showed that the PERI (RI) was >1 (1.98, 1.98, and 2.34) respectively; as cadmium was the main comprehensive RI indicator with value of 2.25. The findings from this study showed that the selected stations were slightly polluted with the influx of organic materials like sewage and suspended particles. The ecological characterization of the sediment revealed that the sediment pollution is from geogenic and human activities. It is advisable to reduce the use of chemicals like herbicides in farming activities which could be washed into the river during rainfall. More so, there is a need for the remediation of the water to reduce the heavy metal presence in the river. Future research on the river is necessary. Finally, public sensitization is highly needed to enlighten the pond users of the potential health impact of the consumption of water
