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Determination of Persistent Organic Pollutants and Trace Metals In Sediment and Fish Samples from Akaki River Catchment and Aba Samuel Reservoir, Central Ethiopia

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dc.contributor.advisor Leta, Seyoum (PhD)
dc.contributor.advisor Berhanu, Tarekegn (PhD)
dc.contributor.author Berhanu, Alemnew
dc.date.accessioned 2020-11-17T06:41:39Z
dc.date.available 2020-11-17T06:41:39Z
dc.date.issued 2019-06-06
dc.identifier.uri http://etd.aau.edu.et/handle/123456789/23330
dc.description.abstract This Ph.D. thesis describes the occurrence and distribution of selected persistent organic pollutants (organochlorine pesticides (OCPs) and polychlorinated byphenyls (PCBs)) and trace metals (Hg, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn) in sediment and fish samples from Akaki River catchment and Aba Samuel Reservoir, Central Ethiopia between 2016-2017. The implications of the levels of OCPs, PCBs and trace metals were also evaluated based on national and/or international guidelines. Eight representative OCPs namely DDT and its metabolites (p, p‘-DDE and p, p‘-DDD), α,-endosulfan, endosulfan sulfate, heptachlor epoxide (B), lindane and dieldrin and indicator PCBs (PCB-28, PCB-52, PCB-101, PCB-118, PCB-138, PCB-153, and PCB- 180) in sediment and fish were determined using gas chromatography-mass spectroscopy (GC-MS), while trace metals were determined using inductively coupled plasma-optical emission spectroscopy (ICP-OES) and cold vapor-atomic absorption spectroscopy (CV-AAS). Analyzed sediment samples showed the presence of lindane in the dry and p, p‘-DDT, p, p‘-DDE, p, p‘-DDD, , -endosulfan, heptachlor epoxide (B), and dieldrin in the rainy seasons. Lindane and DDTs were the predominant OCPs in the studied regions. Among the indicator PCBs, the analyzed sediment samples showed the presence of PCB-52, PCB-101 and PCB-118 in the dry and all indicator PCBs (PCB-28, PCB-52, PCB-101, PCB-118, PCB-138, PCB-153 and PCB-180) in the rainy seasons. The distribution of PCB congeners in the sediment from Akaki river catchment and Aba Samuel Reservoir showed a predominance of lower chlorinated PCB congeners in the dry and highly chlorinated PCB congeners in the rainy season. A low level of higher chlorinated PCB congeners accumulation suggests a point source contamination. Ecological risk assessment of the analyzed OCPs and PCBs using sediment quality guidelines indicated that total DDTs, p, p‘-DDT, p, p‘-DDE and p, p‘-DDD were higher than the maximum residue limit in most of the sampling sites in the rainy season. Then it is possible to conclude that a greater possibility of higher ecological hazards in DDT residues. However, the levels of total PCB concentrations at all sites were below the limit except one site in the dry season. Analyzed fish muscle and liver showed the presence of metabolites of DDT (p, p‘-DDE and p, p‘-DDD), lindane and dieldrin. Among PCBs, only PCB-118 in muscle and PCB-153 in the liver were detected in the dry season. Comparing the concentrations of the present study with international existing limits indicated that 83% of fish muscle samples in both dry and rainy seasons from Aba Samuel Reservoir exceeded the permissible limits with respect to DDTs (14.4 g/kg ww, USEPA (2000)). Similarly, 100% of our fish samples in the dry and 17% of fish samples in the rainy seasons were found to be overloaded with lindane (10 g/kg ww, European Union). However, indicators PCBs were within the permissible limits. The concentration of THg found in all the sediment samples were below the US EPA guideline value of 200 g/kg dry wt. The THg concentrations found in Clarias gariepinus were within the acceptable guidelines of the FAO/WHO. Therefore, the muscle of Clarias gariepinus from the study area is not hazardous to human health with respect to mercury. However, the average value of THg seems to be slightly higher than results reported from other Ethiopian freshwater bodies. Thus, monitoring of mercury species in sediment and different organs of fish are strongly recommended. The trace metals analyzed in surface sediments occurred in varying concentrations along the course of the sampling stations. Ecological risk assessment using USEPA sediment guidelines, geo-accumulation index, contamination factor and pollution load index revealed the widespread pollution by Cd and Pb. These were followed by Mn, Ni and Zn. On the other hand, the levels of trace metals in the muscle of Clarias gariepinus were above the permissible limits for Cr, Fe, Mn, Ni and Pb. en_US
dc.language.iso en en_US
dc.publisher Addis Ababa University en_US
dc.subject Determination en_US
dc.subject Persistent Organic Pollutants en_US
dc.subject Trace Metals en_US
dc.subject Sediment en_US
dc.subject Fish Samples from Akaki River Catchment en_US
dc.subject Aba Samuel Reservoir en_US
dc.subject Central Ethiopia en_US
dc.title Determination of Persistent Organic Pollutants and Trace Metals In Sediment and Fish Samples from Akaki River Catchment and Aba Samuel Reservoir, Central Ethiopia en_US
dc.type Thesis en_US

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