Jiapeng Wu
Xiaofei Li2*
Xiaoli Zhang
Wenli Wang- 1Institute of Environmental Research at Greater Bay Area, Key Laboratory for Water Quality and Conservation of the Pearl River Delta, Ministry of Education, Guangzhou University, Guangzhou, China
- 2State Key Laboratory of Estuarine and Coastal Research, Yangtze Delta Estuarine Wetland Ecosystem Observation and Research Station, Ministry of Education & Shanghai, East China Normal University, Shanghai, China
- 3Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China
- 4Department of Molecular Biosciences and The Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX, United States
Editorial on the Research Topic
Nitrous oxide production processes and associated mechanisms in estuarine and coastal ecosystems
Anthropogenic activities have doubled the nitrogen loading, resulting in high nitrous oxide (N2O) emissions (Murray et al., 2015). The atmospheric N2O concentrations increased significantly at a rate of roughly 0.8 ppb yr-1 (IPCC, 2014). N2O is a major substance depleting the stratospheric ozone layer. Increasing concerns have been raised regarding the N2O production. Recently, critical N2O emissions have been found in five subtropical estuaries located in southeast China (Li et al., 2022), the Pearl River Estuary (Tan et al., 2019; Xiang et al., 2023) and the Chesapeake Bay (Tang et al., 2022). Different pathways responsible for N2O production (Li et al., 2023) and related microbial communities (Hu et al., 2023) have been also investigated. Still, microbial mechanisms of N2O production and associated responses to environmental changes remain largely unknown.
Four articles in this Research Topic have reported interdisciplinary approaches (including isotopic tracing and molecular biology methods), seasonal investigations and historical data to investigated the mechanisms of N2O production in oceans, river network, aquaculture systems and blue mussel. The summaries are listed below.
Heo et al. investigated the distribution, production and control mechanism of N2O in the Subtropical Western North Pacific Ocean (STWNPO). Results showed that the STWNPO was the main source of atmospheric N2O with average air-sea flux of 2.0 ± 0.3 mmol m-2 d-1. The relationship between N2O and apparent oxygen utilization and nitrate in different water layers indicated that N2O was mainly produced from nitrification and denitrification. This study highlighted the overall N2O dynamics in understanding STWNPO and provided an important basis for further exploration of the relationship between environmental factors and N2O dynamics.
Wang et al. summarized the N2O emission data of the Changjiang River network (CRN) from 1986 to 2014 throughout the main area of this basin, emphasizing the control of N2O emissions by basin-scale. The N2O emission rates and flow rates of the headwater stream were higher than that of the mainstem and the estuary, indicating that the headwater stream was the hotspot of N2O emission in the whole aquatic continuum. The N2O discharge rate is negatively correlated with the Strahler river order and positively correlated with the nitrogen loading, suggesting that increased nitrogen loading induced by human activities would affect nitrogen cycling in CRN. This study provided a systematic analysis for the N2O budget source of large river networks in the world.
Niu et al. reported the microbial nitrogen cycling process in the zero-water exchange aquaculture system. The nitrification and denitrification rates varied from 149.77 to 1024.44 ng N g−1 h−1 and from 48.32 to 145.01 ng N g−1 h−1, respectively, indicating that the zero-water exchange pond had great potential nitrification and denitrification performance. Furthermore, the gene abundance of denitrifiers was higher than nitrifiers, which suggested that denitrification process was the main driver of nitrogen removal. In addition, Bacillus, Flavobacteria and Shewanella were the key nitrogen removal bacteria in the zero-water exchange pond, and their microbial communities were positively correlated with ammonia and nitrate concentrations. This study contributes to a better understanding of the relationship of nitrogen removal and microbial communities in zero-water exchange ponds.
Voet et al. quantified the contribution of blue mussel and its shell biofilm to marine N2O production by cultivating blue mussels and 15N isotopic tracing. Net 45N2O and 46N2O were both detected in the blue mussel and its shell membrane after incubation with 15N tracer. Nitrifier denitrification was the main pathway of N2O production of blue mussel and its shell biofilm. Closed-core incubation experiments showed that warmer condition would increase the N2O production of blue mussel and the shell biofilm. In contrast, the N2O production rate decreased under acidification conditions. This study refined the role of animal-related nitrogen cycling and climate change in the region where blue mussels are increasing.
Overall, this Research Topic brings progress, datasets, as well as novel methodologies for understanding N2O production processes and associated mechanisms in estuarine and coastal ecosystems.
Author contributions
JW: Writing – original draft, Writing – review & editing. XL: Conceptualization, Writing – original draft, Writing – review & editing. XZ: Conceptualization, Writing – review & editing. WW: Writing – review & editing.
Funding
The author(s) declare financial support was received for the research, authorship, and/or publication of this article. This study was supported by the National Natural Science Foundation of China (No. 42006122, 42071130).
Acknowledgments
We would like to thank the authors for their contributions, and the reviewers for their help in the review process.
Conflict of interest
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
Publisher’s note
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References
Hu Y., Wu J., Ye J., Liu X., Wang Y., Ye F., et al. (2023). The imbalance between N2O production and reduction by multi-microbial communities determines sedimentary N2O emission potential in the Pearl River Estuary. Mar. Environ. Res. 190, 106119. doi: 10.1016/j.marenvres.2023.106119
IPCC (2014). “Summary for policymakers. Climate change 2014: synthesis report. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change,” (Cambridge: Cambridge University Press). doi: 10.1017/CBO9781107415324
Li X., Gao D., Li Y., Zheng Y., Dong H., Liang X., et al. (2023). Increased nitrogen loading facilitates nitrous oxide production through fungal and chemodenitrification in estuarine and coastal sediments. Environ. Sci. Technol. 57, 2660–2671. doi: 10.1021/acs.est.2c06602
Li X., Qi M., Gao D., Liu M., Sardans J., Peñuelas J., et al. (2022). Nitrous oxide emissions from subtropical estuaries: Insights for environmental controls and implications. Water. Res. 212, 118110. doi: 10.1016/j.watres.2022.118110
Murray R. H., Erler D. V., Eyre B. D. (2015). Nitrous oxide fluxes in estuarine environments: response to global change. Glob. Change Biol. 21 (9), 3219–3245. doi: 10.1111/gcb.12923
Tan E., Zou W., Jiang X., Wan X., Hsu T., Zheng Z., et al. (2019). Organic matter decomposition sustains sedimentary nitrogen loss in the Pearl River Estuary. China. Sci. Total. Environ. 648, 508–517. doi: 10.1016/j.scitotenv.2018.08.109
Tang W., Tracey J., Carroll J., Wallace E., Lee J., Nathan L., et al. (2022). Nitrous oxide production in the Chesapeake Bay. Limnol. Oceanogr. 67, 2101–2116. doi: 10.1002/lno.12191
Keywords: nitrous oxide, mechanism, isotopic fractionation, microbial community, coastal ecosystem
Citation: Wu J, Li X, Zhang X and Wang W (2023) Editorial: Nitrous oxide production processes and associated mechanisms in estuarine and coastal ecosystems. Front. Mar. Sci. 10:1342548. doi: 10.3389/fmars.2023.1342548
Received: 22 November 2023; Accepted: 24 November 2023;
Published: 29 November 2023.
Edited and Reviewed by:
Marta Marcos, University of the Balearic Islands, SpainCopyright © 2023 Wu, Li, Zhang and Wang. 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) and the copyright owner(s) 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: Xiaofei Li, xfli@sklec.ecnu.edu.cn