冻融过程不同粒径土壤N_2O排放特征

Effect of Soil Particle Sizes on N_2O Flux in Freezing and Thawing Processes

通过室内模拟的方法,研究了潮土两种粒径范围(≤1cm粒径,简称1cm粒径;≤0.25mm,简称0.25mm粒径)土壤在冻融过程中N2O排放的特征.结果表明,冻结前,0.25mm粒径土壤N2O排放通量比1cm粒径土壤平均高26.5%;冻结过程中,0.25mm粒径土壤比1cm粒径土壤较早达到稳定冻结状态(分别在冻结1410min和2610min时),并且在稳定冻结状态下,0.25mm粒径土壤N2O排放通量小于1cm粒径土壤;融化阶段,0.25mm粒径土壤比1cm粒径土壤较早出现N2O排放通量高峰(分别在融化2670min和2790min时),并且其峰值小于1cm粒径土样.1cm粒径土壤在冻结过程、融化过程和整个冻融过程中,土壤平均N2O排放量分别比0.25mm粒径土壤多3952.74、1512.51和5465.25μgm-2,相应增加76.83%、18.65%和41.23%.建议在土壤冻结前平整土地以减少N2O排放.

The lab-simulated freezing and thawing experiment was conducted to investigate the characteristics of different soil particle sizes（≤1 cm and ≤0.25 mm） affecting the N2O flux from fluvo-aquic soil.The results showed that the N2O flux of 0.25 mm soil increased by 26.5% compared with that of 1 cm soil before soil freezing;the stable frozen state of 0.25 mm soil was earlier than that of 1 cm soil（1 410 min and 2 610 min for freezing,respectively） at freezing stage,and the N2O flux of 0.25 mm was smaller than that of 1 cm soil at the state;the 0.25 mm soil could also reach N2O emission peaks earlier than 1 cm soil at the thawing stage,but the peak values of N2O were mostly smaller than those of 1 cm soil;in the 1 cm soil,the average cumulative soil N2O emissions increased by 3 952.74（76.83%）,1 512.51（18.65%） and 5 465.25 μg m-2（41.23%） compared with those in the 0.25 mm soil in the freezing and thawing processes,and the whole,respectively.It is suggested to level soil before soil freezing in order to reduce N2O emission.