[Effect of Nitrification on NO Emissions and Their Environmental Factors in Saline-alkali Wetlands].

Wetlands are important sources and sinks for NO. Exploring the role of NO emissions in saline-alkali wetlands has great significance in understanding the nitrification mechanism of NO production and assessing the role of saline-alkali wetlands in the greenhouse effect. The present study examined the NO fluxes and environmental factors of a typical Zhalong reed wetland during the growing season. The results suggested that the NO fluxes tended to decrease in volatility, with the highest value in mid-July. The mean flux of NO was (37.49±15.75) μg·(m·h), indicating that the typical Zhalong reed wetland was a source of NO. The NO fluxes exhibited a significantly positive correlation with soil temperature at different depths (<0.05), and the impact of the upper soil temperature on NO flux was higher than that of deep soil. In the flooding period, the relationship between NO fluxes and water table depth was negatively correlated (<0.05). Meanwhile, the TOC and TN contents were lower, and the NO flux was significantly positively correlated with the NH-N content in the 0-40 cm soil layer (<0.05), but it was not related to NO-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 (<0.01). Additionally, the activity of ammonia-oxidizing bacteria also presented significantly positive linear correlation with the NO fluxes (<0.001), which indicated that the release of NO in saline-alkali wetlands was greatly affected by nitrification.