土壤pH影响氧化亚氮(N_2O)排放的研究进展

A Review of the Influence of Soil pH on Nitrous oxide(N_2O)Emission

氧化亚氮(N_2O)是第三大温室气体,也是21世纪内平流层臭氧(O_3)的首要分解者。在过去约150年间,大气中N_2O的浓度持续增加,其主要原因在于化肥和有机肥料刺激下土壤中N_2O的大量排放。因此,理解土壤中N_2O的排放机制与影响因素,已经成为估算N_2O排放清单和制定N_2O减排政策的关键科学问题。土壤pH是影响N_2O排放的重要环境因子之一,但目前对其相对重要性和影响机制尚不明确。该文基于已有文献的梳理,总结了原位观测和室内培养研究中土壤pH与N_2O排放之间的统计结果,发现多数研究中N_2O排放与土壤pH呈显著负相关关系;并且从生物硝化、生物反硝化和非生物过程3个方面探讨了土壤pH影响N_2O排放的微观机制。在此基础上,本文对今后的研究工作提出展望,以期为后续的研究提供参考和依据。

Nitrous oxide（N2O）is the third most important anthropogenic greenhouse gas,with a global warming poten-tial 298 times that of CO2 over a 100-y time period. It is also the largest anthropogenic contributor to stratosphericozone decomposition for the remainder of this century. Redox processes involving nitrogen（N）in soils contributemore than half of the global anthropogenic N2O emission,primarily fueled by reactive N from synthetic fertilizers andanimal manure,added to agricultural lands. Understanding on the mechanisms of soil N2O emission have,therefore,become an important perquisite to construct sound N2O emission inventory and to make scientific N2O mitigation poli-cy. Though soil pH has been found as the important environmental factor influencing N2O emission,its relative impor-tance and operation mechanisms are not understood well. Based on the analysis of previous literatures,this reviewsummarized the statistic relationship between N2O emission and soil pH in field and laboratory researches. Most stud-ies showed that N2O emissions were negatively correlated with soil pH. In addition,this review probed the influenc-ing mechanisms of soil pH and N2O emission,involving biological nitrification,biological denitrification and abioticmechanism. Some prospects were also proposed and highlighted for the future related works. In future studies,moreattentions should be paid to the influencing mechanisms of soil pH on N2O emission,considering both magnitude andgas product stoichiometry.