Assessment of chromium contamination in the surface water and soil at the riparian of Abbay River caused by the nearby industries in Bahir Dar city, Ethiopia Agegnehu Alemu a, * and Nigus Gabbiye b a Department of Chemistry, College of Science, Bahir Dar University, P.O. Box 79, Bahir Dar, Ethiopia *Corresponding author. E-mail: agegnehua@gmail.com b Faculty of Chemical and Food Engineering, Bahir Dar Institute of Technology, Bahir Dar University, P.O. Box 26, Bahir Dar, Ethiopia Abstract Chromium and its compounds are among the most well known strategic and critical materials in the world having a wide range of uses in the metals and chemical industries accompanied with chromium containing byproducts resulted in pollution of the environment. Chromium exists in the environment commonly in two oxidation states; Chromium (III) and chromium (VI), the later with the most toxic. The level of chromium contamination of water and soil samples in the peripheral of Abbay River were analyzed using inductively coupled plasma optical emis- sion spectroscopy (ICP-OES), Horiba Scientific Ultima 2. The level of total chromium at the riparian of upper Abbay River both in the water and soil samples indicated higher concentrations near the wastewater discharge points from industries compared to the control site (above the industries). A sample taken near the discharge point of Habesha Tannery wastewater (S7), an average of 8.420 + 5.409 mg/L total chromium was analysed, which is beyond the permissible limit to the surface water discharge set by WHO. It was also at this point, maximum chro- mium contamination in the soil was identified with an average of 232.465 + 56.219 mg/kg. This was much higher than the control 7.60 + 0.47 mg/kg. This study showed that the two tanneries discharge high chromium contain- ing wastewater resulted from low treatment potential of the existing treatment plants established by the industries. Key words: contamination, riparian, soil, surface water, tannery, total chromium INTRODUCTION Chromium is an element occurring naturally in the earth’s crust in the form of compounds or as ions in water and is a common contaminant of surface water and groundwater (Bartlett & James 1988). Chromium is also released to the environment from anthropogenic sources and it is the major contri- butors of chromium contamination in the environment (ATSDR 2008). Chromium can enter the atmosphere as a result of fossil fuel burning, steel production, stainless steel welding, and Cr manu- facturing, whereas, discharges into water and soil can result from industrial processes such as electroplating, tanning, dyeing, water treatment, or disposal of coal ash (USEPA 1995). Chromium exists in the environment in two most stable oxidation states, Cr (III) and Cr (VI), which are likely to be interconvertible in natural waters and in soils (Schroeder & Lee 1975; Handerson 1994). However, these two forms of chromium are mainly different in their physicochemical and toxi- cological properties. Cr 3þ is soluble in acidic solutions and it precipitates as the hydroxide in alkaline solutions (Rai et al. 1987). Chromium (III) is less toxic, but in higher concentrations it is likely to pro- duce genotoxic DNA effects in the cell nucleus (ATSDR 2012). Cr (VI) mainly exists in water as © IWA Publishing 2017 Water Practice & Technology Vol 12 No 1 72 doi: 10.2166/wpt.2017.012