我国东部典型内源和外源性静态水体N_(2)O排放与生态系统呼吸的关系初探

Preliminary study of the relationship between N_(2)O emission and ecosystem respiration in typical endogenous and exogenous static water bodies in eastern China

内陆水体是大气中N_(2)O的重要排放源,受到国内外广泛关注,为了探讨水生生态系统中水体N_(2)O排放通量与生态系统呼吸的响应关系,本研究以我国东部典型外源性和内源性静态水体为研究对象,在2022年4月29日-5月4日对10个表层水体N_(2)O排放通量和生态系统呼吸指标进行测定,结合贝叶斯方法初步探讨了水体N_(2)O排放通量和生态系统呼吸之间的关系。结果表明:外源性水体N_(2)O排放通量和生态系统呼吸均显著高于内源性水体(P<0.05),水体N_(2)O排放通量与CO_(2)排放通量和BOD5均呈显著正相关关系(P<0.05)。通过贝叶斯方法构建了水体N_(2)O排放通量与生态系统呼吸(CO_(2)和BOD_(5))之间的数学模型,可解释水体N_(2)O排放通量变异性的61%~71%,并且明确了模拟结果的不确定性。此外,本研究进一步区分了内源性水体与外源性水体N_(2)O排放通量和生态系统呼吸的关系,在内源性水体中,N_(2)O的产生受碳源限制的影响大于氮源限制,而在外源性水体中N_(2)O排放通量与CO_(2)排放通量的耦合关系大于内源性水体。研究表明,生态系统呼吸与水体N_(2)O排放通量间有很强的响应关系,本研究为区域水体N_(2)O排放通量估算方法和生态系统呼吸耦合机制研究提供了基础。

Inland waters emit large amounts of nitrous oxide(N_(2)O)to the atmosphere,which has attracted extensive attention worldwide.The goal of this study was to investigate the relationship between N_(2)O flux and ecosystem respiration(ER)in aquatic ecosystems.We measured N_(2)O and ER in 10 typical exogenous and endogenous static water bodies in eastern China and identified the relationship between N_(2)O flux and ER in the aquatic environments using a Bayesian method from April 29 to May 4,in 2022.The results showed that N_(2)O flux and ER were significantly higher in exogenous water bodies than in endogenous water bodies.There was a significant positive correlation between N_(2)O flux and carbon dioxide(CO_(2))flux and BOD_(5) in the water.The Bayesian model explained 61%to 71%of the variability of N_(2)O flux and clarified the uncertainty of the model.We also distinguished the relationship between N_(2)O flux and ER in endogenous and exogenous water bodies.In endogenous water bodies,the effect of carbon source limitation on N_(2)O flux is greater than the effect of nitrogen source limitation.However,the coupling relationship between N_(2)O and CO_(2) is stronger in exogenous water bodies than in endogenous water bodies.In summary,ER indirectly promotes N_(2)O emission,which provides a basis for an estimation method of N_(2)O flux from water bodies and the coupling mechanism of ER.