Abebe et al. 2023 — Heavy metals in Awash River and Lake Beseka, Ethiopia
This study assesses heavy metal concentrations and pollution sources in the Awash River basin (Ethiopia), one of the most populated and industrially developed river basins in the country. A total of 205 water samples from 21 stations were analysed by ICP-MS across surface water and groundwater. The findings reveal that 20 percent of the 20 measured parameters exceeded WHO drinking water limits, with Al, V, Fe, Mn, and Mo elevated at multiple stations. Arsenic exceeded WHO limits in 57 percent of water samples at many stations down the river system. The study documents both anthropogenic contamination sources in the upper Awash (industrial, agricultural, and domestic discharges from Addis Ababa and surrounding urban areas) and geogenic contributions in the middle Awash, particularly from Lake Beseka, whose high metal concentrations derive from geological processes.
Key numbers
Maximum concentrations across sampling stations: Al 1,257 µg/L; Fe 1,082.7 µg/L; Mn 626.8 µg/L; Ba 211.7 µg/L; V 100.5 µg/L; Mo 116.7 µg/L (at 103.8 µg/L at specific stations); As 61.2 µg/L. The WHO drinking water guideline for As is 10 µg/L; 57 percent of samples exceeded this. Al, V, Fe, Mn, and Mo exceeded WHO limits at stations along the river system. Lake Beseka (SW13) showed TDS of 2,482 mg/L (dry season), EC 3,650 µS/cm, and pH 9.5, rendering it unsuitable for drinking and irrigation. Twenty heavy metals were analyzed in total; 20 percent of measured parameters exceeded WHO limits.
Methods (brief)
ICP-MS using Perkin Elmer NexION 350D with Elemental Scientific prepFAST M5 autosampler. Internal standards Rn, In, Ir, Re used for instrument drift correction. Certified reference materials SLRS-6 (river water, NRC Canada) and SPS-SW2 (surface water, LGC UK) used for quality control. In situ measurements of pH, temperature, EC, and TDS at all stations. Sampling performed seasonally across 21 stations in upper and middle Awash basin.
Implications
Certification: Directly relevant to the supply-chain risk framing for agricultural irrigation water. Awash River water is used for both drinking and irrigation across the basin; elevated As and other metals in irrigation water represent a pathway to food-chain contamination for crops grown in the region.
Courses: Good case study for illustrating mixed geogenic-anthropogenic contamination sources and the challenge of distinguishing them in a developing-country context.
App: Not directly applicable to food concentration data; provides irrigation water exposure context relevant to Ethiopian agricultural supply chains.
Microbiome: Not addressed.