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Advances in the aquatic sciences
RESEARCH ARTICLE

An unexpected source of CO2 and CH4 emissions: a case of littoral zones of small wetlands during the growing season

Gang Li https://orcid.org/0000-0001-9097-4105 A B # , Shengming Dong A C # , Hao Wang A , Xin Wang A , Linjiang Xie A , Lei Quan B D , Emily Kathryn Hosea E , Ying Chen D F and Wei Nie A *
+ Author Affiliations
- Author Affiliations

A School of Architecture and Urban Planning, Anhui Jianzhu University, Hefei, Anhui, 230022, PR China.

B Everglades Wetland Research Park, the Water School, Florida Gulf Coast University, Naples, FL 34112, USA.

C School of Landscape Architecture, Beijing Forestry University, Beijing, 100083, PR China.

D Key Laboratory of Agricultural Machinery Monitoring and Big Data Application, Ministry of Agriculture and Rural Affairs, Beijing, 100083, PR China.

E The Water School, Florida Gulf Coast University, Naples, FL 34112, USA.

F College of Information and Electrical Engineering, China Agricultural University, Beijing, 100083, PR China.

* Correspondence to: archway@qq.com

# Co-first authors

Handling Editor: Wan Zhanhong

Marine and Freshwater Research 76, MF24269 https://doi.org/10.1071/MF24269
Submitted: 27 November 2024  Accepted: 2 August 2025  Published: 5 September 2025

© 2025 The Author(s) (or their employer(s)). Published by CSIRO Publishing

Abstract

Context

Freshwater ecosystems significantly influence global carbon budgets from greenhouse gas (GHG) emissions. However, GHG emissions from littoral zones of small wetlands remain understudied.

Aims

Examining if carbon dioxide (CO2) and methane (CH4) emissions from littoral zones to the atmospheric of small wetlands can be an unexpected carbon source.

Methods

Carbon were measured during the growing season (from May to October) by a cavity-enhanced absorption technique. Water vapour (H2O), atmospheric pressure (AP), wind speed (WS), soil pH, air temperature (AT), and −5-cm soil temperature (ST) were also investigated.

Key results

The mean emission rate was 9.94 ± 0.27 g CO2 eq m−2 day−1, with 18.24 ± 0.40 and 0.26 ± 0.04 g CO2-eq m−2 day−1 of CO2 and CH4 respectively. The mean CO2:CH4 ratio was 1.84. Except for WS and soil pH, WS, AT and ST showed significant non-linear relationships with both CO2 and CH4 emissions.

Conclusion

This study demonstrated that littoral zones of small wetlands can play an unexpected major role in the C cycle budget and should be included in GHG inventories.

Implications

In the future, GHG emissions from small wetlands could be not neglected as a carbon source and should be included in GHG inventories.

Keywords: carbon balance, carbon emission, carbon source and sink, CO2:CH4 ratio, GHG inventories, greenhouse gases, micro wetlands, small wetlands.

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