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Conversion of coastal wetland to aquaculture ponds decreased N2O emission: Evidence from a multi-year field study
Ping Yang , Kam Tang , Chuan Tong, Derrick Y.F. Lai , Linhai Zhang, Xiao Lin, Hong Yang, Lishan Tan, Yifei Zhang, Yan Hong, Chen Tang, Yongxin Lin
Water Research, Volume: 227, Start page: 119326
Swansea University Author: Kam Tang
Accepted Manuscript under embargo until: 6th November 2023
DOI (Published version): 10.1016/j.watres.2022.119326
Land reclamation is a major threat to the world's coastal wetlands, and it may influence the biogeochemical cycling of nitrogen in coastal regions. Conversion of coastal marshes into aquaculture ponds is common in the Asian Pacific region, but its impacts on the production and emission of nitro...
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Land reclamation is a major threat to the world's coastal wetlands, and it may influence the biogeochemical cycling of nitrogen in coastal regions. Conversion of coastal marshes into aquaculture ponds is common in the Asian Pacific region, but its impacts on the production and emission of nitrogen greenhouse gases remain poorly understood. In this study, we compared N2O emission from a brackish marsh and converted shrimp aquaculture ponds in the Shanyutan wetland, the Min River Estuary in Southeast China over a three-year period. We also measured sediment and porewater properties, relevant functional gene abundance, sediment N2O production potential and denitrification potential in the two habitats. Results indicated that the pond sediment had lower N-substrate availability, lower ammonia oxidation (AOA and comammox Nitrospira amoA), nitrite reduction (nirK and nirS) and nitrous oxide reduction (nosZ Ⅰ and nosZ Ⅱ) gene abundance and lower N2O production and denitrification potentials than in marsh sediments. Consequently, N2O emission fluxes from the aquaculture ponds (range 5.4–251.8 μg m–2 h–1) were significantly lower than those from the marsh (12.6–570.7 μg m–2 h–1). Overall, our results show that conversion from marsh to shrimp aquaculture ponds in the Shanyutan wetland may have diminished nutrient input from the catchment, impacted the N-cycling microbial community and lowered N2O production capacity of the sediment, leading to lower N2O emissions. Better post-harvesting management of pond water and sediment may further mitigate N2O emissions caused by the aquaculture operation.
Nitrogen substrate; Nitrification and denitrification; Nitrous oxide (N2O) production; N2O fluxes; Coastal wetlands; Aquaculture reclamation
Faculty of Science and Engineering
This research was supported by the National Natural Science Foundation of China (NSFC) (Grant No. 41801070, and No. 41671088), the National Natural Science Foundation of Fujian Province (Grant No. 2020J01136), the Minjiang Scholar Programme, the Research Grants Council of Hong Kong (CUHK 14122521, 14302420) and CUHK Direct Grant (145489489).