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应用室内冰柜模拟冻融过程,研究了不同氮素形态(铵态氮、硝态氮和酰胺态氮)和浓度(40、200和800 mg/L)对潮土N2O排放通量的影响.结果表明,随土壤冻结时间的延长N2O排放通量缓慢降低,土壤融化初期出现一个土壤N2O排放通量高峰,而后随土壤逐渐融化的进行N2O排放通量缓慢升高.3种氮素浓度条件下,铵态氮、硝态氮和酰胺态氮冻融过程中土壤平均N2O排放通量分别为119.01、205.28、693.95μg.(m2.h)-1,611.61、1 084.40、1 820.02μg.(m2.h)-1和148.22、106.13、49.74μg.(m2.h)-1,而对照处理仅为100.35μg.(m2.h)-1.随氮素浓度的增加,铵态氮、硝态氮源土壤N2O累积排放通量分别比对照增加17.49%、40.09%、425.67%和563.38%、915.28%、1458.6%,且施加的浓度越高累积排放量越大,但达到稳定N2O排放通量的时间向后推移.随浓度增加酰胺态氮处理土壤N2O排放通量随浓度增加而降低.建议潮土越冬水中铵态氮和硝态氮浓度应分别小于200 mg/L和40 mg/L,酰胺态氮的浓度不限,从而减少土壤N2O的排放.
The effects of different nitrogen forms (ammonium nitrogen, nitrate nitrogen and amido nitrogen) and concentrations (40, 200 and 800 mg / L) on the N2O flux in the alluvial soils were studied by simulating the freeze-thaw process in indoor freezers. The results showed that N2O emission flux decreased slowly with the prolongation of soil freezing time, a peak of N2O flux occurred in the early stage of soil thawing, and then the N2O emission flux increased slowly with soil thawing time.With three kinds of nitrogen concentration, The average fluxes of N2O in the soil during ammonium nitrogen, nitrate and amido nitrogen freezing and thawing were 119.01, 205.28 and 693.95 μg, respectively (m2.h) -1,611.61 and 1 084.40 and 1 820.02 μg. (M2.h) -1 and 148.22,106.13,49.74μg. (M2.h) -1, while the control treatment was only 100.35μg. (M2.h) -1. With the increase of nitrogen concentration, ammonium nitrogen, nitrate nitrogen source soil N2O cumulative flux increased by 17.49%, 40.09%, 425.67% and 563.38%, 915.28% and 1458.6% respectively compared with the control, and the higher the concentration, the larger the cumulative emissions, but the time to reach a stable N2O flux With increasing concentration of N, N2O fluxes decreased with increasing concentration.An ammonium nitrogen and nitrate The nitrogen concentration should be less than 200 mg / L and 40 mg / L respectively, and the concentration of amide nitrogen should not be limited, so as to reduce the soil N2O emission.