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ORIGINAL RESEARCH article

Front. Environ. Sci., 13 February 2023
Sec. Freshwater Science
Volume 11 - 2023 | https://doi.org/10.3389/fenvs.2023.1125541

Exploring plastic transport dynamics in the Odaw river, Ghana

 Rose Boahemaa Pinto1 Tom Barendse1  Tim van Emmerik1  Martine van der Ploeg1 Frank Ohene Annor2, 3 Kwame Duah3 Job Udo4 Remko Uijlenhoet1, 2
  • 1Hydrology and Quantitative Water Management Group, Netherlands
  • 2Department of Water Management, Netherlands
  • 3Trans-African Hydro-Meteorological Observatory (TAHMO), Ghana
  • 4HKV, Lijn in Water BV, Netherlands

Plastic pollution in rivers threatens ecosystems, increases flood risk due to its accumulations at hydraulic structures and its final emissions into the ocean threaten aquatic life, especially and probably most in coastal urbanized areas. Previous work suggests that plastic pollution in these urban rivers is influenced by hydrometeorological and anthropogenic factors. However, the transport dynamics of the plastics in such rivers are non-linear and complex and remain largely unresolved. Here, we show that tidal dynamics can be the main driver of plastic transport closest to the river mouth. Outside the tidal zone, rainfall and river discharge were identified to be more important drivers. We monitored plastic transport in the Odaw river, Ghana during the dry season. The Odaw drains the densely populated city of Accra and discharges into the Gulf of Guinea. Data were collected between March and May 2021 (dry season), using visual counting at four bridges along the river, of which two were located within the tidal zone. We explored the correlations between river plastic transport, and rainfall, tidal dynamics, and river discharge. Finally, we estimated the total plastic mass transport by using item-to-mass conversion data from previously published literature. We observed a peak in plastic transport at the upstream bridge within the tidal zone after an increase in rainfall (7.3 times larger). We found a gradient of the hydrometeorological factors driving plastic transport. Closer to the river mouth, tidal dynamics were more strongly correlated with plastic transport than upstream. The daily mass transport was estimated to be between 1.4–3.8 × 102 kg/d, which is lower than previous model estimates. These results add to the evidence of inconsistent correlations between plastic transport and hydrometeorological variables. Long-term monitoring data is required to further investigate this. The results also support the hypothesis that tidal dynamics are a crucial factor in controlling the emissions of plastics from rivers into the ocean. The findings provide a baseline for the Odaw river during the dry season and allow for comparison with the wet season. The approach adopted here also serves as a blueprint for similar urban river systems, regionally and globally.

Keywords: Macroplastic, Urban river, rainfall, tide, discharge

Citation: Pinto R, Barendse T, van Emmerik T, van der Ploeg M, Annor F, Duah K, Udo J and Uijlenhoet R (2023). Exploring plastic transport dynamics in the Odaw river, Ghana. Front. Environ. Sci. 11:183. doi: 10.3389/fenvs.2023.1125541

Received: 16 Dec 2022; Accepted: 31 Jan 2023;
Published online: 13 Feb 2023.

Edited by:

Peiyue Li, Chang’an University, China

Reviewed by:

Venkatramanan Senapathi, Alagappa University, India
Anish Kumar Warrier, Manipal Academy of Higher Education, India  

Copyright: © 2023 Pinto, Barendse, van Emmerik, van der Ploeg, Annor, Duah, Udo and Uijlenhoet. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence:

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