Multivariate analysis of potentially toxic elements in surface waters in Ethiopia

Yilma Sileshi,Minbale Aschale,Mary Kelly-Quinn,Dereje Hailu

doi:10.1007/s13201-021-01412-6

Abstract

The Akaki River and its tributaries, in the city of Addis Ababa, are polluted by potentially toxic elements (PTEs) (Sb, Zn, Cd, As, Hg, Cu, Pb, Fe, V, Ni, Co, Mn, Cr, B, Sr and Ba) in varying degrees due to the significantly fast urban expansion and the industrial activities. The water samples collected from twenty-six different locations or sampling sites along the River and some of its tributaries were analyzed by ICP-MS to determine PTEs. The multivariate component analysis was used to evaluate the relationship and interdependency among the PTEs. The results showed that the mean concentrations for most of PTEs exceeded the recommended limits of drinking and irrigation water quality guidelines. A strong and positive relationship was observed among many of PTEs in the river water indicating common sources. The concentrations of many PTEs in the study area exceeded those previously reported and also varied with site or location, signifying localized contributions of the different contaminants associated with municipal, domestic, industrial, hospitals, garages and other activities. These findings of this study should help highlight and focus water quality management on key PTEs of concern and prioritize efforts to mitigate their release into surface waters in the city. Given the potential health implications of the PTEs mitigation measures should be sought as a matter of urgency by the relevant authorities in Ethiopia.

Highlights

Water pollution is a serious global environmental issue
The one-way ANOVA showed that the values of potentially toxic elements (PTEs) among sampling sites varied significantly depending on sampling locations (p < 0.05)
The pollution levels of the river were lowest in sites upstream of the city boundary where no factories are located, highest in Akaki-kalit industrial areas in the southern parts of Addis Ababa while concentrations declined with distance farther downstream

Summary

Introduction

Water pollution is a serious global environmental issue. Surface waters are the major recipient of contaminants from different point and non-point sources, for instance industrial activities, municipal, domestic, agricultural practices, urban runoff, leachate, mining of ore, and weathering (Zarazua et al 2006; Gupta et al 2009; Sekabira et al 2010). The physico-chemical properties of water bodies are influenced by a variety of factors including interaction with geology, topography, Toxic and PTEs could be present in higher amounts than the background levels or concentrations, and pollute aquatic ecosystems and affect aquatic living organisms (Akan et al 2013). They cause damage to the kidney, the nervous system, gastrointestinal, cancer, heart and even death due to their long half-life, non-biodegradable nature, and their accumulation in different parts of living organisms (Lohani et al 2008; Marta and Raul 2008). The toxicity, reactivity and bioavailability of a number of PTEs such as As and Cr are based on

Methods

Results

Conclusion