Tropical artificial rural and urban ponds are net sources of carbon dioxide and methane in Rwanda, East Africa

Artificial ponds have been overlooked as sources of greenhouse gases (GHGs) despite their potential to be significant emission sources. We studied the concentration of dissolved organic carbon, [DOC], and the concentration and fluxes of CO2 and CH4 in five rural fishponds and five ornamental urban p...

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Main Authors: Mabano Amani, Esaie Dufitimana, Eric Ndagijwenimana, Egide Kalisa
Format: Article
Language:English
Published: Elsevier 2025-09-01
Series:Environmental and Sustainability Indicators
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Online Access:http://www.sciencedirect.com/science/article/pii/S2665972725002880
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author Mabano Amani
Esaie Dufitimana
Eric Ndagijwenimana
Egide Kalisa
author_facet Mabano Amani
Esaie Dufitimana
Eric Ndagijwenimana
Egide Kalisa
author_sort Mabano Amani
collection DOAJ
description Artificial ponds have been overlooked as sources of greenhouse gases (GHGs) despite their potential to be significant emission sources. We studied the concentration of dissolved organic carbon, [DOC], and the concentration and fluxes of CO2 and CH4 in five rural fishponds and five ornamental urban ponds with areas of 981 to 3676 m2 in the capital of Rwanda, Kigali. The mean concentration of DOC in rural ponds (60.12 ± 4.70 mg L−1) was lower than that in urban ponds (69.61 ± 5.97 mg L−1). The dissolved CO2 concentration in rural ponds (24.20 ± 2.40 μmol L−1) was also lower than that in urban ponds (30.40 ± 8.61 μmol L−1). However, the concentration of CH4 in rural ponds (3.31 ± 1.16 μmol L−1) was ∼6 times higher than that in urban ponds (0.59 ± 0.11 μmol L−1). Areal CO2 fluxes in rural ponds (8.07 ± 1.57 mmol m−2 d−1) were slightly higher than those in urban ponds (7.86 ± 3.33 mmol m−2 d−1). Areal CH4 fluxes in rural ponds (1.77 ± 0.62 mmol m−2 d−1), were 7 times higher than in urban ponds (0.25 ± 0.05 mmol m−2 d−1). The mean C flux in CO2 equivalents (CO2-eq) from all ponds was 275.53 g CO2-eq m−2 yr−1, of which 53 % was attributed to CH4. These findings highlight the need to include artificial ponds in national and global greenhouse gas inventories to their overall carbon footprint.
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spelling doaj-art-95a6c54b46714b6183b331ee5554f7df2025-08-23T04:49:10ZengElsevierEnvironmental and Sustainability Indicators2665-97272025-09-012710086710.1016/j.indic.2025.100867Tropical artificial rural and urban ponds are net sources of carbon dioxide and methane in Rwanda, East AfricaMabano Amani0Esaie Dufitimana1Eric Ndagijwenimana2Egide Kalisa3Departament de Biologia Evolutiva, Ecologia i Ciències Ambientals (BEECA), Universitat de Barcelona (UB), Av. Diagonal 643, 08028, Barcelona, Spain; Institut de Recerca de la Biodiversitat (IRBio), Universitat de Barcelona (UB), Av. Diagonal 643, 08028, Barcelona, Spain; The Albertine Rift Conservation Society (ARCOS), KN 14 Avenue, 1735, Kigali, RwandaQuantum Leap Africa Research Centre, African Institute for Mathematical Sciences (AIMS), Kigali, RwandaThe Albertine Rift Conservation Society (ARCOS), KN 14 Avenue, 1735, Kigali, RwandaDepartment of Epidemiology and Biostatistics, Schulich School of Medicine and Dentistry, Western University, London, Ontario, N6G 2M1, Canada; Corresponding author. Western University, London, Ontario, Canada.Artificial ponds have been overlooked as sources of greenhouse gases (GHGs) despite their potential to be significant emission sources. We studied the concentration of dissolved organic carbon, [DOC], and the concentration and fluxes of CO2 and CH4 in five rural fishponds and five ornamental urban ponds with areas of 981 to 3676 m2 in the capital of Rwanda, Kigali. The mean concentration of DOC in rural ponds (60.12 ± 4.70 mg L−1) was lower than that in urban ponds (69.61 ± 5.97 mg L−1). The dissolved CO2 concentration in rural ponds (24.20 ± 2.40 μmol L−1) was also lower than that in urban ponds (30.40 ± 8.61 μmol L−1). However, the concentration of CH4 in rural ponds (3.31 ± 1.16 μmol L−1) was ∼6 times higher than that in urban ponds (0.59 ± 0.11 μmol L−1). Areal CO2 fluxes in rural ponds (8.07 ± 1.57 mmol m−2 d−1) were slightly higher than those in urban ponds (7.86 ± 3.33 mmol m−2 d−1). Areal CH4 fluxes in rural ponds (1.77 ± 0.62 mmol m−2 d−1), were 7 times higher than in urban ponds (0.25 ± 0.05 mmol m−2 d−1). The mean C flux in CO2 equivalents (CO2-eq) from all ponds was 275.53 g CO2-eq m−2 yr−1, of which 53 % was attributed to CH4. These findings highlight the need to include artificial ponds in national and global greenhouse gas inventories to their overall carbon footprint.http://www.sciencedirect.com/science/article/pii/S2665972725002880Aquaculture pondsSmall tropical pondsRwandaOrnamental pondsshallow waterbodies
spellingShingle Mabano Amani
Esaie Dufitimana
Eric Ndagijwenimana
Egide Kalisa
Tropical artificial rural and urban ponds are net sources of carbon dioxide and methane in Rwanda, East Africa
Environmental and Sustainability Indicators
Aquaculture ponds
Small tropical ponds
Rwanda
Ornamental ponds
shallow waterbodies
title Tropical artificial rural and urban ponds are net sources of carbon dioxide and methane in Rwanda, East Africa
title_full Tropical artificial rural and urban ponds are net sources of carbon dioxide and methane in Rwanda, East Africa
title_fullStr Tropical artificial rural and urban ponds are net sources of carbon dioxide and methane in Rwanda, East Africa
title_full_unstemmed Tropical artificial rural and urban ponds are net sources of carbon dioxide and methane in Rwanda, East Africa
title_short Tropical artificial rural and urban ponds are net sources of carbon dioxide and methane in Rwanda, East Africa
title_sort tropical artificial rural and urban ponds are net sources of carbon dioxide and methane in rwanda east africa
topic Aquaculture ponds
Small tropical ponds
Rwanda
Ornamental ponds
shallow waterbodies
url http://www.sciencedirect.com/science/article/pii/S2665972725002880
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AT ericndagijwenimana tropicalartificialruralandurbanpondsarenetsourcesofcarbondioxideandmethaneinrwandaeastafrica
AT egidekalisa tropicalartificialruralandurbanpondsarenetsourcesofcarbondioxideandmethaneinrwandaeastafrica