受外界环境因素的影响,自然湿地氮循环过程中排放的氮氧化物气体正在全球范围内不断累积,全球气候也正在经历着前所未有的变化,因此,氮氧化物排放和全球气候变化关系成为了近年来国际上重点关心的环境问题。为了厘清两者关系,该文从以下几个方面进行了综述研究,(1)对Web of Science核心数据库和中国知网有关氮排放和气候变化的关键词进行检索,结果表明:近年来关于自然湿地氮排放和气候变化关系的文献数量逐年增多,说明氮排放和气候变化关系已经引起相关学者的重视。(2)自然湿地氮排放对气候变化的影响有直接影响和间接影响。直接影响是通过湿地氮循环过程中排放的温室气体(以N_2O为主)产生的,N_2O的大量排放加速了气候变暖的趋势;间接影响是通过发生氮排放的氮循环与碳循环耦合关系影响产生的,自然湿地系统中不断增加的活性氮使得两大温室气体二氧化碳和甲烷的吸收和排放发生了变化,从而对气候变化产生了影响。(3)气候变化主要包括温度、降雨、辐射、光照和风速等气候因子的变化,这些变化对湿地的主要氮循环过程硝化和反硝化过程产生影响,使得氮排放的程度和速率发生变化。文章最后对湿地氮排放和气候变化关系的研究进行了展望,为更好地理解自然湿地氮排放和气候变化关系提供了一定的研究思路。
英文摘要:
The relationships between nitrogen emission of natural wetlands and climate change are becoming environmental hotspots of international attention. In order to clear the relationships, literature review was conducted from the following aspects, (1) Key words about nitrogen emission and climate change were searched from web of science and China National Knowledge Infrastructure (CNKI), the results implied that papers about relationships of nitrogen emission and climate change are increasing year by year, indicating that the relationships have brought about awareness of relevant scholars. (2) The impacts of nitrogen emission on climate change, analysis and summarization showed that the impacts of nitrogen emission on climate change are divided into direct impacts through greenhouse gases emission and indirect impacts through the coupled cycle of nitrogen and carbon. And (3) the impacts of climate change on nitrogen emission of natural wetlands are imposed by temperature, precipitation, radiative forcing, light, wind and other factors. In detail, when the ambient temperature is above or below the appropriate temperature, it will affect a certain part of the nitrogen cycle, and even inhibit the occurrence of a certain link, which will disrupt the wetland nitrogen cycle and break the nitrogen balance within the wetland system. Precipitation can cause changes in soil water content, which in turn, affects air permeability, redox potential (Eh), pH, microbial activities and the diffusion rate of N_2O, so the wetland nitrogen cycle is affected. Other factors of climate change have an important impact on the wetland nitrogen cycle by affecting the growth of wetland vegetation, which is the source, sink and transformer of wetland nitrogen emission. The results provided theoretical basis for the mitigation of climate change and management of ecological water environment of wetlands. Finally, research perspectives are provided, including enhance the study on the relationship between wetland nitrogen cycle and climate change, detailing the impacts of wetland nitrogen cycle on climate change and emphasize the impacts of other factors of climate change on wetland nitrogen cycle. These perspectives will shed lights on a better understanding of the relationships between nitrogen cycle of wetlands and climate change.