Nitrous Oxide Production Processes and Associated Mechanisms in Estuarine and Coastal Ecosystems

Over the past five decades, human activities have doubled the nitrogen (N) loading on the Earth system. The extensive N loading not only deteriorates water quality and also triggers high nitrous oxide (N2O) emissions. Atmosphere N2O concentration has increased from 270 ppb to 325 ppb since the industrial revolution. In addition, N pollution and sources show diversification characteristics under climate changes and human activities, which can alter N cycling and made the pathways of N2O production more complicated. Recently, more and more studies have been concerned about N2O production processes, contributing to the improvement of the N cycling mechanism, and promoting the understanding of the importance of N conversion in N2O production. Estuarine and coastal environments are important ecosystems on earth, playing a critical role in global biogeochemical cycling. Most studies reported that estuarine and coastal environments are important sources of N2O emissions. N2O is the intermediate and by-product of the N transformation, and exploring the pathways of N2O production is increasingly concerned. Traditionally, nitrification and denitrification are the main processes of N2O production), however, the coupled nitrification-denitrification and nitrifier denitrification can also generate N2O. The contributions of these processes to N2O emissions differ strongly in estuarine and coastal environments, depending on the environmental factors. Therefore, more studies on understanding N2O production processes and associated mechanisms in estuarine and coastal ecosystems are required.

Up to date, most studies are concerned with nitrification and denitrification responsible for N2O emissions, however, the importance of coupled nitrification–denitrification, fungal denitrification, and nitrifier denitrification to N2O emissions remain poorly understood. The topic can highlight the mechanisms of N2O production.

The focus of this Research Topic is on studies that use isotopic and molecular biology methods, to explore the main processes of N2O processes and associated contributions to N2O emissions. It calls for original and novel papers related to N2O production processes and microbial community in any of the following research topics:

• The impacts of N loading and climate change and other environmental stressors on N2O emissions.
• The main processes of N2O production and associated contributions to N2O emissions in estuarine and coastal environments.
• Isotopic fractionation effects of N2O production in estuarine and coastal environments.
• Microbial communities of the N2O production processes and in response to environmental changes.

Keywords: nitrous oxide, mechanism, isotopic fractionation, microbial community, coastal ecosystem

Important note: All contributions to this Research Topic must be within the scope of the section and journal to which they are submitted, as defined in their mission statements. Frontiers reserves the right to guide an out-of-scope manuscript to a more suitable section or journal at any stage of peer review.