Pollution assessment of light rare earth metals in sediments of the Ogun River

This research was aimed at determining the concentrations of light earth metals in sediments of the Ogun River as well as their pollution and contamination status. Sediment samples collected using a graduated hand held sediment grab were stored in polythene bags and transported to the laboratory in an ice chested cooler. At the laboratory, the sediment samples were air dried, pulverized and sieved. Induced Couple Plasma Mass Spectrometry (ICP/MS) was used to determine the concentrations of light rare earth metals in the samples. Results obtained showed that the Cs values obtained which ranged from 21.10 to 121.40 mg kg-1 were higher than the Average Shale Value (ASV) of 5.00 mg kg-1. Similarly, La ranged from 47.60 to 56.20 mg kg-1; a value which exceeded the ASV value of 43.00 mg kg-1. Values obtained were subjected to Geochemical Pollution Intensity (Igeo) and Contamination Factor (CF) analyses where all Cs values were seen to be very strongly contaminated while Igeo values for Cs which ranged from 3.20 to 4.00 showed highly polluted status. Cs is of great concern to sediment quality in areas surveyed. Likewise, light rare earth metals from Arakanga New Scheme (dam area) and Lafenwa (residential area) should be closely monitored to avoid adverse effects on aquatic or human lives due to high values observed.   Key words: Light rare earth metals, sediment, river, concentration, contamination.