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Seyoum Leta Leta Asfaw
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ORCiD: https://orcid.org/0000-0003-3774-4663
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Background: The Addis Ababa City’s river ecosystem is under extreme pressure as a result of inappropriate practices of dumping domestic and industrial wastes; thus, threatening its ability to maintain basic ecological, social and economic functions. Little Akaki River which drains through Addis Ababa City receives inorganic and organic pollutants from various anthropogenic sources. Most of inorganic pollutants such as toxic heavy metals relased into the river are eventually adsorbed and settled in the sediment. The objective of this study was to evaluate the enrichment levels, pollution load and ecological risks of selected heavy metals ( Zn, Cr, Cd and Pb) using various indices .
Results: The mean concentrations of heavy metals in Little Akaki River sediment were: Zn (78.96±0.021 - 235.2 ±0.001mg / kg); Cr (2.19±0.014 - 440.8±0.003 mg / kg); Cd (2.09±0.001-4.16 ±0.0001mg / kg) and Pb (30.92±0.018 -596.4±0.066 mg / kg). Enrichment factor values indicated that sediments were moderate to significant enrichment with Zn and Cr; moderate to very high enrichment with Pb, and very high enrichment in all sampled sites with Cd. Geo-accumulation index and contamination factor values indicated that the sediments were moderate to very high contamination with toxic Cd and Pb. The decreasing order of pollution load index (PLI) in downstream was: (S9) > (S4) > (S8) > (S3)> (S6) > (S10) > (S5) > (S2)> (S7) > (S1). PLI and hierarchal cluster analysis revealed that highest pollution load occurred in the lower course of the river (S9) which may be due to metals inputs from anthropogenic sources; hence, its quality was deteriorated showing that the site is polluted. The ecological risk (RI =350.62) suggested that the contaminated Little Akaki River (LAR) sediment can pose considerable ecological risks of pollution.
Conclusions: The concentrations of Zn, Cr, Cd and Pb in Little Akaki River sediment surpassed eco-toxicological guideline limits of USEPA (threshold effect concentration) and CCME (Interim Sediment Quality Guidelines). Thus, the contaminated sediments can occasionally pose adverse biological effects on sediment dwelling organisms. Thus, measures must be taken to regulate discharge of untreated wastes into river and surrounding environment.
Keywords
Enrichment factor, Ecological risks index , Geo-accumulation index, Pollution load
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CURRENT STATUS: Published
View the published article at Environmental Systems Research.
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Editorial decision: Accept
On 18 Sep, 2020
Editor assigned
On 15 Sep, 2020
Submission checks complete
On 14 Sep, 2020
Editor invited
On 14 Sep, 2020
Version 2
Posted 31 Aug, 2020
No comments provided
Review #2 received
Received 03 Sep, 2020
Editorial decision: Minor Revision
On 03 Sep, 2020
Review #1 received
Received 29 Aug, 2020
Reviewer #2 agreed
On 28 Aug, 2020
Reviewers invited
Invitations sent on 27 Aug, 2020
Reviewer #1 agreed
On 27 Aug, 2020
Editor assigned
On 26 Aug, 2020
Submission checks complete
On 25 Aug, 2020
Editor invited
On 25 Aug, 2020
No comments provided
Review #2 received
Received 20 Jul, 2020
Editorial decision: Major Revision
On 20 Jul, 2020
Reviewer #4 agreed
On 01 Jul, 2020
Reviewer #2 agreed
On 29 Jun, 2020
Reviewer #3 agreed
On 29 Jun, 2020
Review #1 received
Received 29 Jun, 2020
Editor assigned
On 28 Jun, 2020
Reviewers invited
Invitations sent on 28 Jun, 2020
Reviewer #1 agreed
On 28 Jun, 2020
Submission checks complete
On 27 Jun, 2020
Editor invited
On 27 Jun, 2020
First submitted
On 22 Jun, 2020
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Subject Areas
Environmental Economics
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See the published version of this preprint at Environmental Systems Research.
This is a preprint, a preliminary version of a manuscript that has not completed peer review at a journal. Research Square does not conduct peer review prior to posting preprints. The posting of a preprint on this server should not be interpreted as an endorsement of its validity or suitability for dissemination as established information or for guiding clinical practice.
Learn more about In Review
Research
Seyoum Leta Leta Asfaw
Corresponding Author
ORCiD: https://orcid.org/0000-0003-3774-4663
Badges
Prescreen
This manuscript passed our Prescreen assessment
Complete author information
Appropriate declaration statements
Potential risks to human health
Prescreen
Peer Review Timeline
CURRENT STATUS: Published
View the published article at Environmental Systems Research.
No community comments so far
Editorial decision: Accept
On 18 Sep, 2020
Editor assigned
On 15 Sep, 2020
Submission checks complete
On 14 Sep, 2020
Editor invited
On 14 Sep, 2020
Version 2
Posted 31 Aug, 2020
No comments provided
Review #2 received
Received 03 Sep, 2020
Editorial decision: Minor Revision
On 03 Sep, 2020
Review #1 received
Received 29 Aug, 2020
Reviewer #2 agreed
On 28 Aug, 2020
Reviewers invited
Invitations sent on 27 Aug, 2020
Reviewer #1 agreed
On 27 Aug, 2020
Editor assigned
On 26 Aug, 2020
Submission checks complete
On 25 Aug, 2020
Editor invited
On 25 Aug, 2020
No comments provided
Review #2 received
Received 20 Jul, 2020
Editorial decision: Major Revision
On 20 Jul, 2020
Reviewer #4 agreed
On 01 Jul, 2020
Reviewer #2 agreed
On 29 Jun, 2020
Reviewer #3 agreed
On 29 Jun, 2020
Review #1 received
Received 29 Jun, 2020
Editor assigned
On 28 Jun, 2020
Reviewers invited
Invitations sent on 28 Jun, 2020
Reviewer #1 agreed
On 28 Jun, 2020
Submission checks complete
On 27 Jun, 2020
Editor invited
On 27 Jun, 2020
First submitted
On 22 Jun, 2020
Metrics
Comments: 0
PDF Downloads: ...
HTML Views: ...
Subject Areas
Environmental Economics
License:
This work is licensed under a CC BY 4.0 License. Read Full License
View the published article at Environmental Systems Research.
Background: The Addis Ababa City’s river ecosystem is under extreme pressure as a result of inappropriate practices of dumping domestic and industrial wastes; thus, threatening its ability to maintain basic ecological, social and economic functions. Little Akaki River which drains through Addis Ababa City receives inorganic and organic pollutants from various anthropogenic sources. Most of inorganic pollutants such as toxic heavy metals relased into the river are eventually adsorbed and settled in the sediment. The objective of this study was to evaluate the enrichment levels, pollution load and ecological risks of selected heavy metals ( Zn, Cr, Cd and Pb) using various indices .
Results: The mean concentrations of heavy metals in Little Akaki River sediment were: Zn (78.96±0.021 - 235.2 ±0.001mg / kg); Cr (2.19±0.014 - 440.8±0.003 mg / kg); Cd (2.09±0.001-4.16 ±0.0001mg / kg) and Pb (30.92±0.018 -596.4±0.066 mg / kg). Enrichment factor values indicated that sediments were moderate to significant enrichment with Zn and Cr; moderate to very high enrichment with Pb, and very high enrichment in all sampled sites with Cd. Geo-accumulation index and contamination factor values indicated that the sediments were moderate to very high contamination with toxic Cd and Pb. The decreasing order of pollution load index (PLI) in downstream was: (S9) > (S4) > (S8) > (S3)> (S6) > (S10) > (S5) > (S2)> (S7) > (S1). PLI and hierarchal cluster analysis revealed that highest pollution load occurred in the lower course of the river (S9) which may be due to metals inputs from anthropogenic sources; hence, its quality was deteriorated showing that the site is polluted. The ecological risk (RI =350.62) suggested that the contaminated Little Akaki River (LAR) sediment can pose considerable ecological risks of pollution.
Conclusions: The concentrations of Zn, Cr, Cd and Pb in Little Akaki River sediment surpassed eco-toxicological guideline limits of USEPA (threshold effect concentration) and CCME (Interim Sediment Quality Guidelines). Thus, the contaminated sediments can occasionally pose adverse biological effects on sediment dwelling organisms. Thus, measures must be taken to regulate discharge of untreated wastes into river and surrounding environment.
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
The full text of this article is available to read as a PDF.
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