盐碱区不同开发年限水田温室气体排放规律及影响因素

以吉林省前郭盐碱水田区为研究对象,采用野外采样和小区试验相结合的方法,监测水稻生长期土壤温室气体(CH4和N2O)排放、土壤p H和土壤有机碳(SOC)变化,分析水田温室气体排放规律及其影响因素.结果表明,水田N2O排放季节变化特征明显并呈现3个峰值,肥料的施入提供了更多的反应底物,对水田N2O的排放量影响显著.在淹水条件下,N2O的主要来源于反硝化过程,而排水后,硝化作用则占据了主导地位.CH4排放呈现单峰,在水稻生长旺盛的分蘖期,稻田较深水层以还原环境为主,为产生CH4的微生物提供了适宜的条件,进而导致CH4排放呈高峰值;土壤p H对N2O和CH4排放的影响不明显,但土壤SOC含量与CH4的排放规律呈现显著正相关.

Rules and Impact Factors of Greenhouse Gases Emission in the Saline-Alkali Paddy Fields in Different Years

With the method of combining field sampling and plot test, we took saline-alkali paddy field of Qianguo county, Jilin province as an investigation object. According to the nature of soil in the area, we monitored CH₄ and N₂O which released from soil during rice growth period and tested the soil pH and soil organic carbon to analyze the law and reasons of greenhouse gas emission in the paddy fields. The results showed that N₂O emission from paddy fields presented three peaks with distinct seasonal patterns. Application of fertilizer provided additional reactive substrate, which affected N₂O emission significantly. Under flooding conditions, the main source of N₂O is a denitrification process, while after drainage, nitrification was the predominance. CH₄ emission showed a single peak at rice tillering stage when rice grew vigorously. That deoxidation condition dominated in the deep water layer in the paddy fields provided suitable conditions for CH₄ producing microorganisms, which result in the emergence of CH₄ emission peak. The pH doesn't have an obvious influence on CH₄ and N₂O, while SOC content in soil and pattern of CH₄ emission showed a significantly positive correlation.