Contamination of Heavy Metals and Physicochemical Parameters of Water and Sediment in Haramaya Lake, Ethiopia

Abstract

To evaluate specific heavy metal contamination and physicochemical parameters in water and sediment samples, across sectional laboratory investigation was carried out. A flame atomic absorption spectrophotometer was used to analyze the heavy metals that were selected from samples taken from three purposively chosen sites. Furthermore, measurements were made of physicochemical parameters such as pH, total dissolved solids, temperature and electric conductivity. In water samples, the overall mean levels of heavy metals were: copper 0.96±0.004 mgL-1, cadmium (Cd) 0.02±0.003 mgL-1, lead (Pb) 0.007±0.001 mgL-1, and manganese 0.99±0.001 mgL-1. In sediment samples, the mean concentrations were higher: Cu 2.0±0.004 mgkg-1, Cd 0.8±0.001 mgkg-1, Pb 1.7±0.003 mgkg-1, and Mn 1.22±0.004 mgkg-1. These results indicate that the seasonal concentrations of Cu, Cd, Pb, and Mn in water (mg/L) and sediment (mg/kg) samples across three sites, compared to the WHO permissible limits. In water, Cu, Cd, and Pb levels remained within safe limits, while Mn concentrations were significantly above the WHO threshold, with an overall mean of 0.99 mg/L. In sediments, Cu and Pb were also within permissible limits, but Cd and Mn exceeded WHO standards, indicating contamination. Seasonal variations showed generally higher concentrations in the wet season, especially for Mn and Pb, likely due to runoff and leaching. The results indicate that Mn and Cd are the primary contaminants of concern, emphasizing the need for regular monitoring and mitigation strategies to protect environmental and human health.