Diurnal Variations of Carbon Dioxide, Methane, and Nitrous Oxide Vertical Fluxes in a Subtropical Estuarine Marsh on Neap and Spring Tide Days

• Published in: Estuaries and coasts 2013-05, Vol.36 (3), p.633-642
• Main Authors: Tong, Chuan, Huang, Jia F., Hu, Zhi Q., Jin, Yu F.
• Format: Article
• Language: English
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Atmosphere; Biological and medical sciences; Biological rhythms; Brackish water ecosystems; Carbon dioxide; Climate change; Coastal Sciences; Diurnal variations; Earth and Environmental Science; Ecology; Ecosystems; Emissions; Environment; Environmental changes; Environmental Management; Estuaries; Freshwater & Marine Ecology; Fundamental and applied biological sciences. Psychology; Global warming; Greenhouse gases; Marshes; Methane; Neap tides; Nitrous oxide; Ocean tides; Pollutant emissions; Redox potential; Soil air; Soil salinity; Soil temperature; Soil temperature regimes; Soil water; Spring; Spring tides; Synecology; Tidal marshes; Tidal waves; Tidewater; Water and Health; Wetlands
• ISSN: 1559-2723; 1559-2731
• DOI: 10.1007/s12237-013-9596-1

Measuring fluxes of greenhouse gases (GHGs) is fundamental to estimating their impact on global warming. We examined diurnal variations of carbon dioxide (CO 2 ), methane (CH 4 ), and nitrous oxide (N 2 O) vertical fluxes in a tidal marsh ecosystem. Measurements were recorded on neap and spring tide days in April and September 2010 in the Shanyutan wetland of the Min River estuary, southeast China. Here, we define a positive flux as directing into the atmosphere. CH 4 fluxes on the diurnal scale were positive throughout, and CH 4 emissions into the atmosphere on neap tide days were higher than on spring tide days. CH 4 releases from the marsh ecosystem on neap tide days were higher in the daytime; however, on spring tide days, daily variations of CH 4 emissions were more complex. The marsh ecosystem plays a twofold role in both releasing and assimilating CO 2 and N 2 O gases on the diurnal scale. Average CO 2 fluxes were positive on the daily scale both on neap and spring days and were greater on the neap tide days than on spring tide days. Diurnal variations of N 2 O fluxes fluctuated more. Over the diurnal period, soil temperature markedly controlled variations of CH 4 emissions compared to other soil factors, such as salinity and redox potential. Tidal water height was a key factor influencing GHGs fluxes at the water—air interface. Compared with N 2 O, the diurnal course of CO 2 and CH 4 fluxes in the marsh ecosystem appeared to be directly controlled by marsh plants. These results have implications for sampling and scaling strategies for estimating GHGs fluxes in tidal marsh ecosystems.