亚热带典型丘陵坡地马尾松林土壤N_2O的年通量特征

Annual Nitrous Oxide Fluxes from the Pinus massoniana Woodland in a Typical Hilly Region of the Southern Subtropical China

由人类活动所造成的大气中温室气体浓度急剧增加而引起的全球气候变暖和环境变化已引起全世界的广泛关注。氧化亚氮（N2O）是仅次于二氧化碳（CO2）和甲烷（CH4）的一种温室气体,在大气中含量较低却十分稳定,具有较大的增温潜能（其单分子的增温潜能是CO2的310倍）和较快的浓度增加速率（以每年0.25%的速率增加）（IPCC,2007）。N2O可吸收红外线,减少地球表面通过大气向外层空间的热辐射,导致地球表面温度增加。N2O能参与大气中许多光化学反应,破坏臭氧层（Crutzen,1970）,导致到达地球表面的紫外线明显增加,给人类健康和生态环境带来多方面的危害。

Nitrous oxide （N2O） emissions from the Pinus massoniana woodland were continuously measured using a static closed-chamber method for a year of 2010 and gas chromatography in the southern subtropical in China, and the relationship between N2O fluxes and main environmental factors were analyzed. The observation result showed that the mean daily N2O flux during the period was 3.89 g N·hm^-2d^-1 The N2O fluxes had seasonal variation with the higher fluxes occurring in summer and early autumn, and the lower fluxes in late autumn, winter and spring. The negative fluxes were also observed in winter. The Pearson＇s correlation analysis indicated that daily N2O fluxes showed positive and significant correlations with daily minimum air temperature, soil temperature at 5 cm depth and soil volumetric water content of the 0 -20 cm soil layer, and highly significant correlation with the cumulative precipitation over previous four days and soil mineral nitrogen content of the 0 - 20 cm soil layer. In addition, a model for predicting N2O emissions from the Pinus massoniana woodland was established using multiple linear regression analysis.