土壤pH影响氧化亚氮（N2O）排放的研究进展

潘亚男　王娅静　曹文超

摘 要：氧化亚氮（N2O）是第三大温室气体，也是21世纪内平流层臭氧（O3）的首要分解者。在过去约150年间，大气中N2O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N2O的大量排放。因此，理解土壤中N2O的排放机制与影响因素，已经成为估算N2O排放清单和制定N2O减排政策的关键科学问题。土壤pH是影响N2O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N2O排放之间的统计结果，发现多数研究中N2O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N2O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。

关键词：氧化亚氮；土壤pH；反硝化；硝化；非生物转化

中图分类号 S154.1 文献标识码 A 文章编号 1007-7731（2017）15-0019-7

Abstract：Nitrous oxide（N2O）is the third most important anthropogenic greenhouse gas，with a global warming potential 298 times that of CO2 over a 100-y time period. It is also the largest anthropogenic contributor to stratospheric ozone decomposition for the remainder of this century. Redox processes involving nitrogen（N）in soils contribute more than half of the global anthropogenic N2O emission，primarily fueled by reactive N from synthetic fertilizers and animal 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 policy. Though soil pH has been found as the important environmental factor influencing N2O emission，its relative importance and operation mechanisms are not understood well. Based on the analysis of previous literatures，this review summarized the statistic relationship between N2O emission and soil pH in field and laboratory researches. Most studies showed that N2O emissions were negatively correlated with soil pH. In addition，this review probed the influencing mechanisms of soil pH and N2O emission，involving biological nitrification，biological denitrification and abiotic mechanism. Some prospects were also proposed and highlighted for the future related works. In future studies，more attentions should be paid to the influencing mechanisms of soil pH on N2O emission，considering both magnitude and gas product stoichiometry.

Key words：Nitrous oxide；Soil pH；Denitrification；Nitrification；Abiotic transformation

氧化亚氮（N2O）是大气中的痕量组分，其对地球环境具有重要的影响[1]，是仅次于二氧化碳（CO2）和甲烷（CH4）的第三大温室气体，其增温潜势是CO2的298倍[2，3]。在氟里昂排放得到有效控制后，N2O已成为消耗平流层臭氧的最主要物质[4-7]。大气中N2O的来源包括自然源和人为源，其中自然源包括海洋、湖泊、草地、森林等，人为源包括农田土壤、工业排放等[8]。工业革命以后，大气中N2O的浓度已经从0.27μL/L上升至0.319μL/L[5，10-11]。其中，化学氮肥和有机肥的施用是土壤N2O排放的主要原因[8-9，12-14]。因此，在深入理解排放机制的基础上，实现土壤N2O科学减排，对缓解全球气候变化具有重要的现实和科学意义。……