Differential Nitrous oxide emission and microbiota succession in constructed wetlands induced by nitrogen forms

Jun-Feng Wang; Jia-Wei Huang; Ze-Xiang Cai; Qu-Sheng Li; Yun-Yun Sun; Huan-Zhan Zhou; Hui Zhu; Xin-Shan Song; Hai-Ming Wu

doi:10.1016/j.envint.2023.108369

Differential Nitrous oxide emission and microbiota succession in constructed wetlands induced by nitrogen forms

Environ Int. 2024 Jan:183:108369. doi: 10.1016/j.envint.2023.108369. Epub 2023 Dec 6.

Authors

Jun-Feng Wang¹, Jia-Wei Huang¹, Ze-Xiang Cai¹, Qu-Sheng Li¹, Yun-Yun Sun¹, Huan-Zhan Zhou¹, Hui Zhu², Xin-Shan Song³, Hai-Ming Wu⁴

Affiliations

¹ Guangdong Key Laboratory of Environmental Pollution and Health, School of Environment, Jinan University, Guangzhou 510632, China.
² Key Laboratory of Wetland Ecology and Environment, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun 130102, China. Electronic address: zhuhui@iga.ac.cn.
³ State Environmental Protection Engineering Center for Pollution Treatment and Control in Textile Industry, College of Environmental Science and Engineering, Donghua University, Shanghai 201600, China.
⁴ Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao 266237, China. Electronic address: haimingwu20@sdu.edu.cn.

PMID: 38070437
DOI: 10.1016/j.envint.2023.108369

Abstract

Nitrous oxide (N₂O) emission during the sewage treatment process is a serious environmental issue that requires attention. However, the N₂O emission in constructed wetlands (CWs) as affected by different nitrogen forms in influents remain largely unknown. This study investigated the N₂O emission profiles driven by microorganisms in CWs when exposed to two typical nitrogen sources (NH₄⁺-N or NO₃^--N) along with different carbon source supply (COD/N ratios: 3, 6, and 9). The results showed that CWs receiving NO₃^--N caused a slight increase in total nitrogen removal (by up to 11.8 %). This increase was accomplished by an enrichment of key bacteria groups, including denitrifiers, dissimilatory nitrate reducers, and assimilatory nitrate reducers, which enhanced the stability of microbial interaction. Additionally, it led to a greater abundance of denitrification genes (e.g., nirK, norB, norC, and nosZ) as inferred from the database. Consequently, this led to a gradual increase in N₂O emission from 66.51 to 486.77 ug-N/(m²·h) as the COD/N ratio increased in CWs. Conversely, in CWs receiving NH₄⁺-N, an increasing influent COD/N ratio had a negative impact on nitrogen biotransformation. This resulted in fluctuating trend of N₂O emissions, which decreased initially, followed by an increase at later stage (with values of 122.87, 44.00, and 148.59 ug-N/(m²·h)). Furthermore, NH₄⁺-N in the aquatic improved the nitrogen uptake by plants and promoted the production of more root exudates. As a result, it adjusted the nitrogen-transforming function, ultimately reducing N₂O emissions in CWs. This study highlights the divergence in microbiota succession and nitrogen transformation in CWs induced by nitrogen form and COD/N ratio, contributing to a better understanding of the microbial mechanisms of N₂O emission in CWs with NH₄⁺-N or NO₃^--N at different COD/N ratios.

Keywords: COD/N ratio; Constructed wetlands; Metabolomics and metagenomics; Nitrogen form; Nitrous oxide.

MeSH terms

Denitrification
Microbiota*
Nitrates
Nitrogen
Nitrous Oxide* / metabolism
Wetlands

Substances

Nitrous Oxide
Nitrogen
Nitrates