| 设施菜田土壤N2O产生对O2的响应 |
| 摘要点击 1519 全文点击 619 投稿时间：2018-01-02 修订日期：2018-02-09 |
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| 中文关键词 氧 N2O 反硝化 硝化细菌反硝化 亚硝酸盐 N2O/(N2O+NO+N2)指数 |
| 英文关键词 oxygen N2O denitrification nitrifier denitrification nitrite N2O/(N2O+NO+N2) index |
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| 中文摘要 |
| 以添加（DIS）/不添加（DI）玉米秸秆的常规设施菜田土壤为研究对象，通过室内培养试验，利用在线自动监测培养系统，在不同初始氧气体积分数下（0%、1%、3%、5%和10%）监测土壤N2O、NO、N2和CO2产生量的动态变化，并同步分析了土壤无机氮（NO2-、NO3-、NH4+）含量，同时设置添加NaClO3的处理抑制土壤NO2-的氧化，以期对比研究不同碳投入菜田土壤N2O产生量对O2的响应.结果表明，厌氧条件下土壤N2O产生量显著高于有氧条件下土壤N2O产生量（P<0.01）.当氧气体积分数≤ 1%时，添加秸秆的（DIS）土壤N2O产生量显著高于未添加秸秆的（DI）土壤（P<0.01）.土壤中氧耗竭时会观察到明显的N2O产生速率峰值，但N2产生速率峰值随着初始氧气体积分数的升高极显著降低（P<0.01），反之，土壤中如果没有出现氧耗竭的现象，则N2O和N2产生量随着初始氧气体积分数的升高显著降低（P<0.01）.初始氧气体积分数介于1%~5%时，培养过程中会观察到持续的NO2-累积，且在该氧梯度内N2O/（NO+N2O+N2）指数显著高于0%以及10%初始氧气体积分数的处理，此外，添加NaClO3后，当初始氧气体积分数为5%和10%时，持续增加的NO2-与N2O产生量两者之间线性相关（R2 ≥ 0.85）.本研究结果表明，低氧条件下不完全的反硝化和NO2-诱导的硝化细菌反硝化共同作用，显著增加了土壤N2O的产生量和N2O/（N2O+NO+N2）指数；但是，有氧条件下土壤N2O的产生量显著低于厌氧条件（P<0.01）. |
| 英文摘要 |
| To explore the sources of peak nitrous oxide (N2O) flushes in solar greenhouse vegetable field, an experiment was conducted with two conventional vegetable soils under different initial volume fractions of oxygen (O2) (0%, 1%, 3%, 5%, and 10%). A robotized incubation system was employed to analyze the gas kinetics[O2, N2O, nitric oxide (NO), nitrogen (N2), and carbon dioxide (CO2)] every 6 or 8 h and calculate the N2O/(NO+N2O+N2) index. Sodium chlorate (NaClO3) was used to inhibit the oxidation of NO2- to further explore the relationship between N2O and nitrite (NO2-). A parallel off-line incubation in triplicates was conducted under similar conditions to measure the dynamic changes in inorganic nitrogen content[ammonia (NH4+), nitrate (NO3-), and NO2-]. The results showed that N2O production under anaerobic condition was significantly higher than that under aerobic condition. The peak value of N2O in the soil collected from a straw-added plot (DIS) was significantly higher than that in the soil from non-straw added plot (DI) (P<0.01) when the volume fraction of oxygen was ≤ 1%. Oxygen can directly affect N2O production by delaying or inhibiting N2O reduction, with significant increase in N2O production rate under oxygen-depleted condition. However, the N2production rate decreased significantly with increase in initial oxygen volume fraction (P<0.01). When the initial volume fraction of oxygen was between 1% and 5%, a continuous accumulation of NO2- was observed during the incubation period, resulting in the significantly higher N2O/(NO+N2O+N2) index than that in either anaerobic or 10% of oxygen treatments. Furthermore, a linear correlation was observed between NO2- and N2O at 5% and 10% of oxygen with the addition of NaClO3 (R2 ≥ 0.85). Incomplete denitrification and nitrifier denitrification from NO2- induction co-occurred in the range of 1% and 5% volume fractions of oxygen, significantly increasing the soil N2O production and N2O/(NO+N2O+N2) index. In addition, N2O production under anaerobic condition was significantly higher than that under aerobic condition (P<0.01). |
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