Cluster analysis of elemental concentrations of cored Nigerian river sediments

Abstract

Cored samples of the Kubanni River sediments were analysed for their elemental composition using Neutron Activation Analysis(HAA). Long‐lived reactor irradiation of the samples at thermal and epithermal neutron fluxes of 2.15 × 10¹⁰ n cm^‐2 s^‐1 and 1.78 × 10¹¹ n cm^‐2 s^‐1 respectively revealed the presence of 18 elements (Sc, Cr, Fe, As, Co, Rb, Y. Cs, Ba, Ce, Nd, Eu, Tb, Lu, Hf, Ta, U and Th) with varying concentrations for each core level.

The CLUSTAN statistical package was used in studying the relative clustering of these elements for all the core levels. The resulting dendrograms from Vard's nethod is suggestive of segregation and possible enrichments at some of the cores, due to contamination of the river bed.

It is suspected that the contamination of some of the cores of the the river bed by primordial elements like uranium and thorium could be attributed to the high use of phosphate fertilizers by farmers cultivating the river banks. Data from this work strongly shows a disparity between the multi‐elemental composition of aquifer sediments when compared to contaminated sediments of river beds.

Key words:

• Clusters
• Ward's method
• dendrograms
• aquifer
• enrichments
• segregation and contamination