Diurnal and Seasonal Variation of CO₂ and CH₄ Fluxes in Tomago Wetland

Author(s): David Safari, Grant C Edwards, Faustina Gyabaah

The measurement of greenhouse gas (GHG) fluxes in estuaries is crucial in expressing the impacts of these GHGs on global warming, and hence climate change. In this study, we investigated the effect of various environmental and micrometeorological factors on diurnal and seasonal variations of methane (CH4) and carbon dioxide (CO2) in a tidal inundated saltmarsh. Measurements of GHG fluxes were taken by using eddy covariance technique from August 2015 to July 2016 in Tomago wetland, Newcastle, NSW, Australia. In this paper, a positive flux is defined as the one directing into the atmosphere. The highest average diurnal emissions were 2.54 µg m-2 s-1 CH4 during the day and 0.45 mg m-2 s-1 CO2 at night. Monthly average fluxes peaked in February (0.365 µg m-2 s-1 CH4 and 0.137 mg m-2 s-1 CO2). There was a significant negative relationship between CO2 flux and water level (p < 0.001), tidal height (p = 0.02) and positive relationship with water temperature (p = 0.002). CH4 flux showed positive correlation with water level and negative correlation with EC although not statistically significant. Although tidal flooding did not demonstrate clearly carbon sequestration before and after tidal reinstatement, freshwater events (rainfall) were seen to influence the wetland carbon balance.

GHG Flux, Water Level, Tidal Inundation, Salinization, Rainfall

1. Altor, A. E., & Mitsch, W. J. (2008). Pulsing hydrology, methane emissions and carbon dioxide fluxes in created marshes: a 2-year ecosystem study. Wetlands, 28(2), 423-438. doi:10.1672/07-98.1
2. Armentano, T., & Menges, E. (1986). Patterns of change in the carbon balance of organic soil-wetlands of the temperate zone. The Journal of Ecology, 755-774.
3. Bridgham, S. D., Cadillo‐Quiroz, H., Keller, J. K., & Zhuang, Q. (2013). Methane emissions from wetlands: biogeochemical, microbial, and modeling perspectives from local to global scales. Global Change Biology, 19(5), 1325-1346.
4. Bridgham, S. D., Megonigal, J. P., Keller, J. K., Bliss, N. B., & Trettin, C. (2006). The carbon balance of North American wetlands. Wetlands, 26(4), 889-916.
5. Bu, N.-S., Qu, J.-F., Li, G., Zhao, B., Zhang, R.-J., & Fang, C.-M. (2015). Reclamation of coastal salt marshes promoted carbon loss from previously-sequestered soil carbon pool. Ecological Engineering, 81, 335-339.
6. Caldwell, S. L., Laidler, J. R., Brewer, E. A., Eberly, J. O., Sandborgh, S. C., & Colwell, F. S. (2008). Anaerobic oxidation of methane: mechanisms, bioenergetics, and the ecology of associated microorganisms. Environmental science & technology, 42(18), 6791-6799.
7. Chambers, L. G., Reddy, K. R., & Osborne, T. Z. (2011). Short-Term Response of Carbon Cycling to Salinity Pulses in a Freshwater Wetland. Soil Science Society of America Journal, 75, 2000-2007. doi:10.2136/sssaj2011.0026
8. D'Angelo, E. M., & Reddy, K. R. (1999). Regulators of heterotrophic microbial potentials in wetland soils. Soil Biology and Biochemistry, 31(6), 815-830. doi:http://doi.org/10.1016/S0038-0717(98)00181-3
9. Deegan, L. A., Johnson, D. S., Warren, R. S., Peterson, B. J., Fleeger, J. W., Fagherazzi, S., & Wollheim, W. M. (2012). Coastal eutrophication as a driver of salt marsh loss. Nature, 490(7420), 388-392.
10. Del Grosso, S., Parton, W., Mosier, A., Ojima, D., Potter, C., Borken, W., . . . Dobbie, K. (2000). General CH4 oxidation model and comparisons of CH4 oxidation in natural and managed systems. Global Biogeochemical Cycles, 14(4), 999-1019.
11. Dengel, S., Levy, P. E., Grace, J., Jones, S. K., & Skiba, U. M. (2011). Methane emissions from sheep pasture, measured with an open-path eddy covariance system. Global Change Biology, 17(12), 3524-3533. doi:10.1111/j.1365-2486.2011.02466.x
12. Dick, T. M., & Osunkoya, O. O. (2000). Influence of tidal restriction floodgates on decomposition of mangrove litter. Aquatic Botany, 68(3), 273-280. doi:http://dx.doi.org/10.1016/S0304-3770(00)00119-4
13. Foken, T. (2008). Micrometeorology: Springer Science & Business Media.
14. Glamore, W. C. (2003). Evaluation and analysis of acid sulphate soil remediation via tidal restoration.
15. Herbst, M., Friborg, T., Ringgaard, R., & Soegaard, H. (2011). Interpreting the variations in atmospheric methane fluxes observed above a restored wetland. Agricultural and Forest Meteorology, 151(7), 841-853. doi:http://doi.org/10.1016/j.agrformet.2011.02.002
16. Howe, A., Rodriguez, J., & Saco, P. (2009). Surface evolution and carbon sequestration in disturbed and undisturbed wetland soils of the Hunter estuary, southeast Australia. Estuarine, Coastal and Shelf Science, 84(1), 75-83.
17. Indraratna, B., Blunden, B., & Nethery, A. (1999). Nature and properties of acid sulphate soils in drained coastal lowlands in New South Wales.
18. Indraratna, B., Glamore, W. C., & Tularam, G. A. (2002). The effects of tidal buffering on acid sulphate soil environments in coastal areas of New South Wales. Geotechnical & Geological Engineering, 20(3), 181-199.
19. Indraratna, B., Golab, A., Glamore, W., & Blunden, B. (2005). Acid sulphate soil remediation techniques on the Shoalhaven River Floodplain, Australia. Quarterly journal of engineering geology and hydrogeology, 38(2), 129-142.
20. Inglett, K., Inglett, P., Reddy, K., & Osborne, T. (2012). Temperature sensitivity of greenhouse gas production in wetland soils of different vegetation. Biogeochemistry, 108(1-3), 77-90.
21. Khalil, M., & Baggs, E. (2005). CH4 oxidation and N2O emissions at varied soil water-filled pore spaces and headspace CH4 concentrations. Soil Biology and Biochemistry, 37(10), 1785-1794.
22. Le Mer, J., & Roger, P. (2001). Production, oxidation, emission and consumption of methane by soils: A review. European Journal of Soil Biology, 37(1), 25-50. doi:http://dx.doi.org/10.1016/S1164-5563(01)01067-6
23. Macreadie, P. I., Hughes, A. R., & Kimbro, D. L. (2013). Loss of ‘blue carbon’from coastal salt marshes following habitat disturbance. PloS one, 8(7), e69244.
24. Mcleod, E., Chmura, G. L., Bouillon, S., Salm, R., Björk, M., Duarte, C. M., . . . Silliman, B. R. (2011). A blueprint for blue carbon: toward an improved understanding of the role of vegetated coastal habitats in sequestering CO2. Frontiers in Ecology and the Environment, 9(10), 552-560.
25. Mitsch, W. J., Bernal, B., Nahlik, A. M., Mander, Ü., Zhang, L., Anderson, C. J., . . . Brix, H. (2013). Wetlands, carbon, and climate change. Landscape Ecology, 28(4), 583-597. doi:10.1007/s10980-012-9758-8
26. Nachshon, U., Ireson, A., van der Kamp, G., Davies, S. R., & Wheater, H. S. (2014). Impacts of climate variability on wetland salinization in the North American prairies. Hydrology and Earth System Sciences, 18(4), 1251-1263. doi:10.5194/hess-18-1251-2014
27. Olsson, L., Ye, S., Yu, X., Wei, M., Krauss, K. W., & Brix, H. (2015). Factors influencing CO₂ and CH₄ emissions from coastal wetlands in the Liaohe Delta, Northeast China. Biogeosciences, 12(16), 4965-4977. doi:10.5194/bg-12-4965-2015
28. Pattey, E., Edwards, G., Strachan, I., Desjardins, R., Kaharabata, S., & Wagner Riddle, C. (2006). Towards standards for measuring greenhouse gas fluxes from agricultural fields using instrumented towers. Canadian journal of soil science, 86(3), 373-400.
29. Pulliam, W. M. (1993). Carbon Dioxide and Methane Exports from a Southeastern Floodplain Swamp. Ecological Monographs, 63(1), 29-53. doi:10.2307/2937122
30. Rogers, K., Saintilan, N., & Copeland, C. (2014). Managed Retreat of Saline Coastal Wetlands: Challenges and Opportunities Identified from the Hunter River Estuary, Australia. Estuaries and Coasts, 37(1), 67-78. doi:10.1007/s12237-013-9664-6
31. Saintilan, N. (2013). 3.5 Rehabilitation and management of saltmarsh habitats.
32. Streever, W. J. (1997). Trends in Australian wetland rehabilitation. Wetlands Ecology and Management, 5(1), 5-18. doi:10.1023/a:1008267102602
33. Wang, H., Liao, G., D’Souza, M., Yu, X., Yang, J., Yang, X., & Zheng, T. (2016). Temporal and spatial variations of greenhouse gas fluxes from a tidal mangrove wetland in Southeast China. Environmental Science and Pollution Research, 23(2), 1873-1885. doi:10.1007/s11356-015-5440-4
34. Xie, J., Li, Y., Zhai, C., Li, C., & Lan, Z. (2009). CO2 absorption by alkaline soils and its implication to the global carbon cycle. Environmental Geology, 56(5), 953-961. doi:10.1007/s00254-008-1197-0
35. Yamamoto, A., Hirota, M., Suzuki, S., Oe, Y., Zhang, P., & Mariko, S. (2009). Effects of tidal fluctuations on CO2 and CH4 fluxes in the littoral zone of a brackish-water lake. Limnology, 10(3), 229-237. doi:10.1007/s10201-009-0284-6