Toxicologia Ambiental e Analítica

Assessment of Metals Concentration in Water, Sediment and Macrophyte Plant Collected from Lake Hawassa, Ethiopia

Abstract

Tigist Ashagre Amare, Girma Tilahun Yimer and Kassaye Balkew Workagegn

This study was aimed to assess the concentration of metals (Hg, Cr, Zn Cd and Pb) in water, sediment, and S. corymbosus macrophyte plant samples collected from six different sites (S1 to S6) of Lake Hawassa. The results revealed that there was significant difference (p<0.05) in metals concentration among different sampling sites as well as within the site. Generally, significantly higher values (p<0.05) of metals concentration were recorded at sites S2, S4 and S5, which received industrial effluents, urban wastes and agrochemicals respectively. and were the most contaminated sites. The concentration of metals both in sediment and macrophyte plant followed similar pattern, viz., Zn>Cr>Pb>Cd>Hg, while the concentration of metals in water followed the order of Zn>Pb>Cr>Cd>Hg. High to very high correlations were recorded within some metal pairs and with some physico-chemical parameters. - Although metals concentration in water and sediment of the lake are generally in non-polluted to moderately polluted range according to international standards based on numerical sediment quality guidelines (SQGs), almost all values at different sampling sites along the shoreline are much higher than the reference site as well as the background metals concentration of the lake. This is a clear indication that Lake Hawassa is exposed to different pollutants from all directions and the problem can easily go out of hand unless a special attention to be properly monitored for better protection of the lake and the surrounding catchment areas is given. as different human activities are increasing around the lake. Therefore, strategies to control point and non-point sources of all over the shorelines should be developed for better protection of the lake as well as the surrounding catchment areas.