UV-B辐射增强对陆地生态系统温室气体排放影响的研究进展

地表太阳紫外线-B（UV-B，波长：280~320 nm）辐射增强和气候变化均是当今重要的全球性环境问题。平流层臭氧层损耗以及大气CO₂、CH₄和N₂O等温室气体排放的增加，是驱动这两大全球性问题的主要因素。UV-B辐射增强会通过一系列的生物地球化学进程影响陆地生态系统碳氮平衡，改变CO₂、CH₄、N₂O等温室气体的排放，进一步对气候变化产生作用。笔者对UV-B辐射增强对陆地生态系统CO₂排放的影响途径（凋落物和土壤）和影响机制（有机物中难降解分子转化为可溶性有机碳、有机物非生物光化学降解以及光引发产生的微生物降解）进行了总结，阐述了UV-B辐射增强对CH₄和N₂O排放的影响途径（植株组织化学结构变化和根系分泌物组分变化），及其在不同生态系统中与环境要素相互作用下的排放规律。此外，气候变化背景下，一定范围内的温度升高和降水量减少可促进UV-B辐射增强产生的有机物光降解作用，进而促进温室气体的排放。目前，UV-B辐射增强对陆地生态系统的影响研究相对较缺乏，大都集中在干旱生态系统，且定量研究较少。今后需更多长期、大规模的野外实地研究，并结合模型来准确估计UV-B辐射增强对陆地生态系统温室气体排放的贡献。本论文可为全球变化背景下精准预测温室气体排放提供参考。

Effects of Enhanced UV-B Radiation on Greenhouse Gas Emissions in Terrestrial Ecosystem: Research Progress

Ultraviolet-B (UV-B, 280-320 nm) radiation enhancement and climate change are critical global environmental issues. The depletion of the stratospheric ozone layer and the increase of greenhouse gases (GHGs, e.g. CO₂, CH₄ and N₂O) emissions are major factors driving these issues. Enhanced UV-B radiation would affect carbon and nitrogen balance of terrestrial ecosystem through a series of biogeochemical processes, and influence the emission of GHGs to the atmosphere, further impact the global climate change. In this paper, we systematically reviewed the effect of enhanced UV-B radiation on CO₂ emissions in terrestrial ecosystems through litter or soil and the mechanisms involved in these processes (photochemical degradation of recalcitrant organic molecules into soluble organic carbon, abiotic photo-mineralization of organic compounds and photo-induced microbial degradation). Besides, the influence of enhanced UV-B radiation on CH₄ and N₂O emissions (through changes in the chemical structure of plant tissue and the composition of root exudate) were summarized. The emission patterns of CH₄ and N₂O under the interaction of UV-B radiation enhancement and other environmental factors in different ecosystems were also discussed. In addition, the elevated temperature and reduced precipitation could promote photodegradation of organic matter induced by UV-B radiation enhancement, and further increase GHGs emissions. At present, studies regarding the effects of UV-B radiation enhancement on terrestrial ecosystem are still limited, while most of which focus on arid ecosystems and there are few quantitative studies. In the future, more long-term and large-scale field studies combining with models are needed to quantify the contribution of enhanced UV-B radiation to greenhouse gas emissions in terrestrial ecosystem. The study will provide theoretical reference for the accurate prediction of GHGs emissions under global environment change scenario.