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Nitrous Oxide Emission from Deyeuxia angustifolia Freshwater Marsh in Northeast China
- Yu, Junbao, Liu, Jingshuang, Wang, Jinda, Sun, Weidong, Patrick, William H. Jr., Meixner, Franz X.
- Environmental management 2007 v.40 no.4 pp. 613-622
- Calamagrostis, air, biomass, ecology, freshwater, greenhouse gas emissions, growing season, humans, marshes, nitrous oxide, redox potential, soil, temperature, China
- Here we report N₂O emission results for freshwater marshes isolated from human activities at the Sanjiang Experimental Station of Marsh Wetland Ecology in northeastern China. These results are important for us to understand N₂O emission in natural processes in undisturbed freshwater marsh. Two adjacent plots of Deyeuxia angustifolia freshwater marsh with different water regimes, i.e., seasonally waterlogged (SW) and not- waterlogged (NW), were chosen for gas sampling, and soil and biomass studies. Emissions of N₂O from NW plots were obviously higher than from the SW plots. Daily maximum N₂O flux was observed at 13 o'clock and the seasonal maximum occurred in end July to early August. The annual average N₂O emissions from the NW marsh were 4.45 μg m-² h-¹ in 2002 and 6.85 μg m-² h-¹ in 2003 during growing season. The SW marsh was overall a sink for N₂O with corresponding annual emissions of -1.00 μg m-² h-¹ for 2002 and -0.76 μg m-² h-¹ for 2003. There were significant correlations between N₂O fluxes and temperatures of both air and 5-cm-depth soil. The range of soil redox potential 200-400 mV appeared to be optimum for N₂O flux. Besides temperature and plant biomass, the freeze-thaw process is also an important factor for N₂O emission burst. Our results show that the freshwater marsh isolated from human activity in northeastern China is not a major source of N₂O.