[Effect of Nitrification on N₂O Emissions and Their Environmental Factors in Saline-alkali Wetlands]

Wetlands are important sources and sinks for N₂O. Exploring the role of N₂O emissions in saline-alkali wetlands has great significance in understanding the nitrification mechanism of N₂O production and assessing the role of saline-alkali wetlands in the greenhouse effect. The present study examined the N₂O fluxes and environmental factors of a typical Zhalong reed wetland during the growing season. The results suggested that the N₂O fluxes tended to decrease in volatility, with the highest value in mid-July. The mean flux of N₂O was (37.49±15.75) μg·(m²·h)^-1, indicating that the typical Zhalong reed wetland was a source of N₂O. The N₂O fluxes exhibited a significantly positive correlation with soil temperature at different depths (P<0.05), and the impact of the upper soil temperature on N₂O flux was higher than that of deep soil. In the flooding period, the relationship between N₂O fluxes and water table depth was negatively correlated (P<0.05). Meanwhile, the TOC and TN contents were lower, and the N₂O flux was significantly positively correlated with the NH₄⁺-N content in the 0-40 cm soil layer (P<0.05), but it was not related to NO₃^--N content. Nitrification was stronger than denitrification. There was a significant positive correlation between ammonia-oxidizing bacterial activity and soil temperature in 0-20 cm layer (P<0.01). Additionally, the activity of ammonia-oxidizing bacteria also presented significantly positive linear correlation with the N₂O fluxes (P<0.001), which indicated that the release of N₂O in saline-alkali wetlands was greatly affected by nitrification.