Evaluation of the dynamics of nutrients and potentially toxic elements along a major river in Ethiopia using multivariate statistical techniques: Implications of possible co-occurrences.

This study utilized established field and laboratory methods and multivariate statistical tools to evaluate the nutrient and potentially toxic elements (PTEs) distribution, identify possible sources, and determine potential co-existence in the Awash River. The levels of soluble reactive phosphorus (SRP), total phosphorus (TP), NO 3 -N, Mn, Ni, Cr, and Cu generally increased downstream in the upper Awash, with the highest respective values of 0.70, 1.34, 1.19, 1.58, 1.03, 0.85, and 0.11 mg L⁻¹ at the inlet to Lake Koka. Sites found downstream of the inflow of Lake Beseka and Metehara town showed the highest levels of Fe, B, Zn, and dissolved silica. Principal components and correlation analysis findings revealed strong associations (r ≥ 0.80, p < 0.05) between nutrient parameters (SRP, TP, and NO 3 -N) and PTEs (Cu, Ni, Mn, and Cr), implying common origins and potential co-occurrences. The potential co-occurrences of these parameters may strengthen their potential individual impacts due to complex interactions. • The study evaluated nutrients and PTEs distribution, sources, and co-occurrences. • Nutrients and PTEs generally rise downstream in the upper Awash. • Urban and agriculture impacted sites showed elevated levels of nutrients and PTEs. • Fe, Pb, Ni, Mn, B, and Cr levels exceeded WHO drinking water safe limits. • Potential co-occurrence of SRP, TP, NO 3 -N, Mn, Ni, Cr, and Cu was observed. [ABSTRACT FROM AUTHOR]