Tolla, Belachew (2006) Physico-Chemical Characteristics and Pollution Levels of Trace Metals in the Little Akaki and Big Akaki Rivers. Masters thesis, Addis Ababa University.
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Abstract
In the present work, physico-chemical variables (temperatures, pH, TDS, and conductivity) and some selected trace metals (Cd, Cu, Co, Ni, Pb, and Zn) analysis of the water and surface sediments from river Big Akaki and Little Akaki were conducted with a view to asses the quality of the rivers as well as to identify the potential contaminated areas. The results of physicochemical parameters revealed that the mean values of temperature reading, pH, conductivity, and TDS along LAR varied between 19 to 21 oC, 6.59 to 7.71, 661 to 1790 μS/cm and 317 to 881 mg/L, respectively and the ranges of these values along BAR are 17 to 21 oC, 369 to 749 μS/cm, 176 to 316 mg/L. Trends of these variables showed an intimate relation with anthropogenic activities along both rivers. Trace metals in sediment and water samples were determined by FAAS. The levels of dissolved trace metals in these rivers were found to be below the detections limit of the method except for Zn and indeed Ni and Co in some sampling sites of the rivers. The levels of dissolved metals in both rivers are below the South Africa guidelines fixed for irrigational, domestic and livestock watering purposes. In contrast to water samples significant amount of metals were found in both river sediment samples at all sampling stations. The concentration ranges of the metals in LAR sediments were: 0.43 to 1.45,30 to 89, 18.32 to 44.02, 119 to 73, 55.73 to 320, and 205 to 730 mg/L for Cd, Cu, Co, Ni, Pb, and Zn, respectively also the mean range of these metals in BAR sediments are 0.31 to 0.59, 30.5 to 89.41, 18.33 to 30.47, 119 to 62, 35.67 to 71.75, 172.89 to 288 mg/L, respectively. Levels of Cd and Co were found to be low in both river sediments and they are below EPA sediment quality guidelines (SQG). Cu in both river sediments was found to be below SQG except at one site along LAR. Both rivers sediments were found to be enriched with Ni and all sampling sites of LAR and 80% of BAR sites surpassed SQG for Ni. The levels of Zn and Pb along BAR sediments are below SQG while 30% of sites along LAR contain Pb above SQG and one site along LAR surpassed the SQG for Zn content. Pair wise comparison of the two rivers revealed that generally the levels of trace metals and the values of physico-chemical variables in LAR are higher than that of BAR. The levels of Cd, Pb and Zn in the sediments of LAR showed a significant positive correlation with each other.
| Item Type: | Thesis (Masters) |
|---|---|
| Uncontrolled Keywords: | Little Akaki River, Big Akaki River, Water pollution, Sediment, Trace metals, Flame atomic absorption spectroscopy |
| Subjects: | G Geography. Anthropology. Recreation > GE Environmental Sciences Q Science > Q Science (General) Q Science > QD Chemistry |
| Divisions: | Africana |
| Depositing User: | Selom Ghislain |
| Date Deposited: | 12 Sep 2018 08:59 |
| Last Modified: | 12 Sep 2018 08:59 |
| URI: | http://thesisbank.jhia.ac.ke/id/eprint/5169 |
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