测定时间对黑土区CO_2和N2_O排放通量的影响

Effect of Measurement Time on Emission Flux of CO_2 and N2_O in Black Soil Region

[目的]探讨测定时间对黑土区CO2和N2O排放通量的影响,确定排放通量的最佳测定时间,以期为黑土区农田温室气体减排提供科学依据。[方法]以黑土区长期肥料定位试验为平台,采用静态箱式法研究了小麦3个关键生育期(抽穗期、灌浆期和成熟期)CO2和N2O排放的日变化动态,揭示不同测定时段黑土区CO2和N2O排放通量的差异。[结果]土壤CO2和N2O排放通量日变化较大,变化范围分别为CO2 206～552 mg/(m2.h)和N2O 51～295μg/(m2.h)。在不同生育期CO2呈单峰曲线变化,峰值出现在中午12:00,峰谷出现在凌晨3:00;N2O排放通量在抽穗期白天较小,而夜间排放量大。如果不考虑小麦生育期对CO2和N2O排放通量的影响,测定CO2排放代表性时间段在6:00～8:00或16:00～21:00;测定N2O时间段在8:00～10:00或16:00～21:00;若同时测定CO2和N2O排放通量,最佳测定时间在16:00～18:00。若在通常的观测时间9:00～12:00进行观测,CO2和N2O的较正系数分别为0.81和0.90。[结论]该研究结果为黑土区农田温室气体减排提供了科学依据。

[Objective]The aim was to investigate and discuss effect of measurement time on emission flux of CO2 and N2O to ensure the optimum time of emission flux,in order to provide scientific reference for emission reduction of greenhouse gas in black soil region.[Method]Based on experiment of long-term fertilizer location in black soil region,the paper studied on daily dynamic variation of CO2 and N2O discharge in 3 key growth periods（booting stage,grain-filling stage and mature stage） to reveal differences of CO2 and N2O emission flux in different times.[Result]Daily variations of CO2 and N2O emission flux were large,from 205 mg/（m2.h） to 552 mg/（m2.h） h for CO2 and from 51 μg/（m2.h） to 295 μg/（m2.h） for N2O.Trend of CO2 discharge in different growth times showed a unimodal curve,and the peak was at noon of 12： 00 and the peak valley was at 3： 00 am;discharge of N2O was small in day time at booting stage and large at night.Regardless of rice growth period effect on CO2 and N2O emission flux,representative time of CO2 discharge was 6： 00-8： 00 or 16： 00-21： 00;and time of N2O was 8： 00-10： 00 or 16： 00-21： 00;if CO2 and N2O emission fluxes were measured simultaneously,the optimum time was 16：00-18： 00;if the measurement was started during 9： 00-12： 00,correction coefficients of CO2 and N2O were 0.81 and 0.90,respectively.[Conclusion]The result provided scientific reference for reduction of greenhouse gas emission in black soil region.