Sediments in the Tema Harbour (Ghana): chemical pollution and sedimentation rates

Benjamin Osei Botwe

Research output: Thesisinternal PhD, Joint degree

Abstract

The Tema Harbour in Ghana has been in operation for nearly six decades and is subject to large influxes of sediments and sediment pollution due to the intense human activities in the harbour area. This thesis assessed sediment pollution in the Tema Harbour by using the standard 10-day Corophium volutator and 28-day Hediste diversicolor whole-sediment toxicity bioassays as well as chemical contaminant (DDTs, HCHs, PAHs and metal - Cd, Pb, Cr, Ni, Cu, Zn and As) data. The bioassay results showed significant C. volutator and H. diversicolor mortalities, indicating that the Tema Harbour sediments are polluted and toxic. Biota-sediment accumulation factors further revealed a high potential for bioaccumulation of the sediment-associated metals, which can have adverse implications for the food chain. Thus, the Tema Harbour sediments are unsuitable for disposal at sea without remediation.

The thesis further investigated sediment accumulation rates in the Tema Harbour by the combined analyses of sediment trap and sediment core data. The sediment cores exhibited variable bulk density profiles, indicating highly dynamic and non-steady sedimentation conditions. 7Be-derived gross-estimates of very recent sediment accumulation rates using the constant flux-constant sedimentation (CF-CS) model were in the range of 2.5-9.0 g.cm-2.y-1. These values were much lower than the estimated average settling fluxes from the sediment trap data (15.2-53.8 g.cm-2.y-1), indicating sediment resuspension plays an important role in the sedimentation process. Conventional 210Pb sediment dating models did not allow any estimation of SARs in the Tema Harbour. The 210Pb-based TERESA model, on the other hand, proved to be a good tool for quantifying sediment accumulation rates in the Tema Harbour with time-averaged values in the range of 1.4-3.0 g.cm-2.y-1 and sediment accretion rates of 1.7-3 cm.y-1.

In conclusion, this study has shown that the Tema Harbour has been severely affected by anthropogenic activities, resulting in pollution of the sediments, especially those from the Fishing Harbour and the Canoe Basin. Moreover, the sediment accretion rates in the harbour may pose moderate problems for sustainable use of the harbour. There is, therefore, a need to improve sediment and environmental management in the Tema Harbour and regulate the disposal of the dredged material originating from this tropical coastal harbour.  

Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
  • Wageningen University
Supervisors/Advisors
  • Lens, P.N.L., Promotor
  • Nyarko, E., Co-promotor, External person
Award date29 Jun 2018
Place of PublicationLeiden
Publisher
Print ISBNs9781138323513, 9789463438384
DOIs
Publication statusPublished - 2018

Fingerprint

sedimentation rate
harbor
sediment
accumulation rate
sediment pollution
chemical pollution
sedimentation
sediment trap
sediment core
bioassay
human activity
accretion
metal
HCH
resuspension
DDT
food chain
environmental management
bioaccumulation
bulk density

Cite this

Botwe, Benjamin Osei. / Sediments in the Tema Harbour (Ghana): chemical pollution and sedimentation rates. Leiden : CRC Press/Balkema, 2018. 270 p.
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title = "Sediments in the Tema Harbour (Ghana): chemical pollution and sedimentation rates",
abstract = "The Tema Harbour in Ghana has been in operation for nearly six decades and is subject to large influxes of sediments and sediment pollution due to the intense human activities in the harbour area. This thesis assessed sediment pollution in the Tema Harbour by using the standard 10-day Corophium volutator and 28-day Hediste diversicolor whole-sediment toxicity bioassays as well as chemical contaminant (DDTs, HCHs, PAHs and metal - Cd, Pb, Cr, Ni, Cu, Zn and As) data. The bioassay results showed significant C. volutator and H. diversicolor mortalities, indicating that the Tema Harbour sediments are polluted and toxic. Biota-sediment accumulation factors further revealed a high potential for bioaccumulation of the sediment-associated metals, which can have adverse implications for the food chain. Thus, the Tema Harbour sediments are unsuitable for disposal at sea without remediation. The thesis further investigated sediment accumulation rates in the Tema Harbour by the combined analyses of sediment trap and sediment core data. The sediment cores exhibited variable bulk density profiles, indicating highly dynamic and non-steady sedimentation conditions. 7Be-derived gross-estimates of very recent sediment accumulation rates using the constant flux-constant sedimentation (CF-CS) model were in the range of 2.5-9.0 g.cm-2.y-1. These values were much lower than the estimated average settling fluxes from the sediment trap data (15.2-53.8 g.cm-2.y-1), indicating sediment resuspension plays an important role in the sedimentation process. Conventional 210Pb sediment dating models did not allow any estimation of SARs in the Tema Harbour. The 210Pb-based TERESA model, on the other hand, proved to be a good tool for quantifying sediment accumulation rates in the Tema Harbour with time-averaged values in the range of 1.4-3.0 g.cm-2.y-1 and sediment accretion rates of 1.7-3 cm.y-1. In conclusion, this study has shown that the Tema Harbour has been severely affected by anthropogenic activities, resulting in pollution of the sediments, especially those from the Fishing Harbour and the Canoe Basin. Moreover, the sediment accretion rates in the harbour may pose moderate problems for sustainable use of the harbour. There is, therefore, a need to improve sediment and environmental management in the Tema Harbour and regulate the disposal of the dredged material originating from this tropical coastal harbour.  ",
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Sediments in the Tema Harbour (Ghana): chemical pollution and sedimentation rates. / Botwe, Benjamin Osei.

Leiden : CRC Press/Balkema, 2018. 270 p.

Research output: Thesisinternal PhD, Joint degree

TY - THES

T1 - Sediments in the Tema Harbour (Ghana): chemical pollution and sedimentation rates

AU - Botwe, Benjamin Osei

N1 - WU thesis 6984 CRC Press/Balkema is an imprint of the Taylor & Francis Group, an informa business Ph.D. thesis UNESCO-IHE Institute for Water Education, 2018 Includes bibliographical references. - With summaries in English and Dutch

PY - 2018

Y1 - 2018

N2 - The Tema Harbour in Ghana has been in operation for nearly six decades and is subject to large influxes of sediments and sediment pollution due to the intense human activities in the harbour area. This thesis assessed sediment pollution in the Tema Harbour by using the standard 10-day Corophium volutator and 28-day Hediste diversicolor whole-sediment toxicity bioassays as well as chemical contaminant (DDTs, HCHs, PAHs and metal - Cd, Pb, Cr, Ni, Cu, Zn and As) data. The bioassay results showed significant C. volutator and H. diversicolor mortalities, indicating that the Tema Harbour sediments are polluted and toxic. Biota-sediment accumulation factors further revealed a high potential for bioaccumulation of the sediment-associated metals, which can have adverse implications for the food chain. Thus, the Tema Harbour sediments are unsuitable for disposal at sea without remediation. The thesis further investigated sediment accumulation rates in the Tema Harbour by the combined analyses of sediment trap and sediment core data. The sediment cores exhibited variable bulk density profiles, indicating highly dynamic and non-steady sedimentation conditions. 7Be-derived gross-estimates of very recent sediment accumulation rates using the constant flux-constant sedimentation (CF-CS) model were in the range of 2.5-9.0 g.cm-2.y-1. These values were much lower than the estimated average settling fluxes from the sediment trap data (15.2-53.8 g.cm-2.y-1), indicating sediment resuspension plays an important role in the sedimentation process. Conventional 210Pb sediment dating models did not allow any estimation of SARs in the Tema Harbour. The 210Pb-based TERESA model, on the other hand, proved to be a good tool for quantifying sediment accumulation rates in the Tema Harbour with time-averaged values in the range of 1.4-3.0 g.cm-2.y-1 and sediment accretion rates of 1.7-3 cm.y-1. In conclusion, this study has shown that the Tema Harbour has been severely affected by anthropogenic activities, resulting in pollution of the sediments, especially those from the Fishing Harbour and the Canoe Basin. Moreover, the sediment accretion rates in the harbour may pose moderate problems for sustainable use of the harbour. There is, therefore, a need to improve sediment and environmental management in the Tema Harbour and regulate the disposal of the dredged material originating from this tropical coastal harbour.  

AB - The Tema Harbour in Ghana has been in operation for nearly six decades and is subject to large influxes of sediments and sediment pollution due to the intense human activities in the harbour area. This thesis assessed sediment pollution in the Tema Harbour by using the standard 10-day Corophium volutator and 28-day Hediste diversicolor whole-sediment toxicity bioassays as well as chemical contaminant (DDTs, HCHs, PAHs and metal - Cd, Pb, Cr, Ni, Cu, Zn and As) data. The bioassay results showed significant C. volutator and H. diversicolor mortalities, indicating that the Tema Harbour sediments are polluted and toxic. Biota-sediment accumulation factors further revealed a high potential for bioaccumulation of the sediment-associated metals, which can have adverse implications for the food chain. Thus, the Tema Harbour sediments are unsuitable for disposal at sea without remediation. The thesis further investigated sediment accumulation rates in the Tema Harbour by the combined analyses of sediment trap and sediment core data. The sediment cores exhibited variable bulk density profiles, indicating highly dynamic and non-steady sedimentation conditions. 7Be-derived gross-estimates of very recent sediment accumulation rates using the constant flux-constant sedimentation (CF-CS) model were in the range of 2.5-9.0 g.cm-2.y-1. These values were much lower than the estimated average settling fluxes from the sediment trap data (15.2-53.8 g.cm-2.y-1), indicating sediment resuspension plays an important role in the sedimentation process. Conventional 210Pb sediment dating models did not allow any estimation of SARs in the Tema Harbour. The 210Pb-based TERESA model, on the other hand, proved to be a good tool for quantifying sediment accumulation rates in the Tema Harbour with time-averaged values in the range of 1.4-3.0 g.cm-2.y-1 and sediment accretion rates of 1.7-3 cm.y-1. In conclusion, this study has shown that the Tema Harbour has been severely affected by anthropogenic activities, resulting in pollution of the sediments, especially those from the Fishing Harbour and the Canoe Basin. Moreover, the sediment accretion rates in the harbour may pose moderate problems for sustainable use of the harbour. There is, therefore, a need to improve sediment and environmental management in the Tema Harbour and regulate the disposal of the dredged material originating from this tropical coastal harbour.  

U2 - 10.18174/443802

DO - 10.18174/443802

M3 - internal PhD, Joint degree

SN - 9781138323513

SN - 9789463438384

PB - CRC Press/Balkema

CY - Leiden

ER -