摘要:土壤不仅能够产生、排放温室气体N₂O，还具有截留、吸收、转化N₂O的能力。土壤消耗N₂O已经成为很重要的一种降低大气N₂O浓度的途径，但目前关于土壤N₂O消耗过程及其微生物调控机制的系统研究较为缺乏。试验以浅表层水稻土柱（0-5 cm）为研究对象，通过外源添加N₂O气体研究N₂O迁移通过淹水土柱的动态过程，以及N₂O消耗能力与氧化亚氮还原酶基因丰度变化和其他土壤养分含量变化的联系，揭示浅表层水稻土N₂O消纳量与N₂O还原微生物之间的耦合关系。结果显示，淹水厌氧条件下5 cm土壤深度外源添加的N₂O迁移通过浅表层土柱后，仅有7.17-9.80%部分逸散出土表，表明0-5 cm淹水水稻土层具有极强的N₂O截留能力（90%以上）而减少N₂O净排放量。排放出土表的N₂O也可被淹水土柱继续吸收消耗，且吸收转化速率随N₂O浓度增加而大幅提高，最高可达到3896.75 μg N m^-2 h^-1。与此同时，土壤DOC含量大量消耗，含nosZI基因的反硝化微生物数量显著增长（P < 0.01），而nosZII基因丰度的无显著变化。说明高浓度N₂O添加能够促进淹水土壤N₂O吸收消耗能力，此刺激作用可能主要由含nosZI基因的N₂O还原微生物进行调控。浅表层土壤强大的N₂O吸收消耗功能可进一步深入系统研究，为实践温室气体减排提供理论基础。



Abstract:Soil could produce greenhouse gas N₂O and emit it to atmosphere; however, it could be retained, absorbed, and transformed. The N₂O consumption by soil has become a very important way to reduce atmospheric N₂O concentration, but the systematic research on the N₂O consumption process in soil and its microbial regulation mechanism is scarce at present. The surface paddy soil cores (0-5 cm) were incubated under laboratory conditions, by adding exogenous N₂O into the bottom of flooded soil cores, and the dynamics of N₂O diffusion through the soil cores and after transportation were monitored. The links between N₂O consumption ability and the variation of the nosZ gene abundance and other soil nutrient contents were explored to reveal the coupling relationship between N₂O consumption and N₂O reducing microorganisms. The results showed that only 7.17%-9.80% of the exogenous N₂O added in the 5 cm soil depth escaped the soil surface under anaerobic and submergence conditions, indicating that the flooded 0-5 cm paddy soil layer had a strong N₂O interception capacity (over 90%) and reduced N₂O net emissions. The N₂O escaped from the soil surface could also be absorbed and transformed by the submerged soil column, and the consumption rate increased significantly as N₂O increased in the headspace, with a maximum value of 3896.75 μg N m^-2 h^-1. At the same time, large quantities of soil DOC were consumed and the number of denitrifying microorganisms containing the nosZI gene increased significantly (P < 0.01), whereas the abundance of nosZII gene did not obviously change. This suggests that the N₂O consumption ability of surface paddy soil cores under anaerobic and flooded conditions could be promoted by high concentrations of N₂O addition, and this stimulation may be mainly regulated by N₂O reducing microorganisms containing the nosZI gene, not the nosZII gene. The strong ability of N₂O consumption of surface soil needs to be further studied to provide a theoretical basis for the practice of greenhouse gas reduction.





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