三江平原典型小叶章湿地土壤硝化反硝化作用与氧化亚氮排放

应用C₂H₂抑制原状土柱培育法研究了三江平原典型小叶章湿地土壤N₂O排放速率及反硝化速率的变化，分析了它们与环境因子的关系，并估算了N₂O排放量及反硝化损失量.结果表明：草甸沼泽土和腐殖质沼泽土N₂O排放速率的变化基本一致，其范围分别为0.020～0.089 kg N·hm^-2·d^-1和0.012～0.033 kg N·hm^-2·d^-1,前者的N₂O排放速率均明显高于后者(平均为1.79±1.07倍)，且其差异达到显著水平(P＜0.05)；二者反硝化速率的变化并不一致，其范围分别为0.024～0.127 kg N·hm^-2·d^-1和0.021～0.043 kg N·hm^-2·d^-1，前者的反硝化速率一般也要高于后者(平均为1.67±1.56倍)，但其差异并未达到显著水平(P＞0.05)；硝化作用在前者N₂O排放和氮素损失过程中发挥了重要作用，而反硝化作用则是导致后者N₂O排放和氮素损失的重要过程；氮素物质基础不是影响二者硝化-反硝化作用的重要因素；温度对前者硝化 反硝化作用的影响比后者更为明显，其反硝化速率与5、10和15 cm地温均呈显著正相关(P＜0.05)；二者所处湿地水分条件的差异是导致其N₂O排放速率及反硝化速率差异的重要原因.生长季内，前者的N₂O排放量和反硝化损失量分别为5.216 kg N·hm^-2和6.166 kg N·hm^-2，而后者分别为3.196 kg N·hm^-2和4.407 kg N·hm^-2；在二者的反硝化产物中，N₂O/N₂的比率最高，分别为5.49和3.76，表明N₂在后者反硝化产物中所占的比例明显高于前者，说明季节积水条件会导致N₂O/N₂比例降低.

Nitrification-denitrification and N2O emission of typical Calamagrostis angustifolia wetland soils in Sanjiang Plain

With intact soil core and by using acetylene inhibition method, this paper measured the N2O emission and denitrification rates of typical Calamagrostis angustifolia wetland soils in Sanjiang Plain, analyzed their relationships with environmental factors, and estimated the total amounts of N2O emission and denitrification loss. The results showed that meadow marsh soil and humus marsh soil had a similar change range of N2O emission rate (0.020-0.089 kg N x hm(2) x d(-1) and 0.012-0.033 kg N x hm(2) x d(-1), respectively), but the former had a much higher N2O emission rate than the latter, and the difference was significant (P < 0.05). As for denitrification rate, its change range was 0.024-0.127 kg N x hm(2) x d(-1) for meadow marsh soil and 0.021-0.043 kg N x hm(2) x d(-1) for humus marsh soil. Meadow marsh soil also had a higher denitrification rate than humus marsh soil, but the difference was not significant (P > 0.05). In meadow marsh soil, nitrification played an important role in N2O emission and nitrogen loss; while in humus marsh soil, denitrification was the main process inducing N2O emission and nitrogen loss. For these two soils, nitrogenous compounds were not the important factor affecting nitrification-denitrification. In meadow marsh soil, temperature had more evident effect, where nitrification-denitrification had a significant positive correlation with the soil temperature at the depths of 5 cm, 10 cm and 15 cm (P < 0.05). Soil moisture condition was another important factor inducing the difference of N2O emission and denitrification rates. In growth season, the amount of N2O emission and denitrification loss was 5.216 kg N x hm(-2) and 6.166 kg N x hm(-2) for meadow marsh soil, and 3.196 kg N x hm(-2) and 4.407 kg N x hm(-2) for humus marsh soil, respectively. In the denitrification productions of meadow marsh soil and humus marsh soil, the maximum value of N2O/N2 ratio was 5.49 and 3.76, respectively, indicating that the proportion of N2 in denitrification productions was higher in humus marsh soil than in meadow marsh soil, and the seasonal waterlogged condition could induce the decrease of N2O/N2 ratio.