温度对东北平原水稻田甲烷排放的影响

Effect of Temperature on Methane Emission over Paddy Fields in Northeast Plain

水稻(Oryza sativa)田是农业环境中甲烷(CH4)排放的重要来源。在东北水稻主产区三江平原和辽河平原开展典型水稻田CH4排放监测、分析CH4排放与温度之间的关系,对制定合理的减排措施来降低水稻田温室气体CH4排放具有的一定参考意义。该研究将两地2017-2018年水稻田CH4的高频通量、温度、水稻生育期数据相结合,研究CH4的排放过程、不同时间尺度的排放特性及其在不同生育阶段对温度变化响应的敏感性。结果表明,2017年三江平原和辽河平原CH4的年排放量分别是26.77 g·m^−2和16.17 g·m^−2。两地2018年CH4的排放量均比2017年明显增加,年际变化差异显著。三江平原6月和7月排放量最大,分蘖期是CH4排放高峰,最大排放速率为0.127μmol·m^−2·s^−1,非生长季基本无CH4排放。辽河平原拔节抽穗期和成熟期是CH4排放高峰,7月CH4月排放量最高,拔节—抽穗期的排放速率增加至0.102μmol·m^−2·s^−1,然后逐渐减少,生长季末出现第三个峰值,在非生长季存在CH4排放弱日变化。2018年与2017年的气温持平,但5—9月土壤温度比2017年略有升高。三江平原生长季夜间CH4排放与土壤温度符合指数相关关系,孕穗到排水前CH4排放对温度变化最敏感(温度敏感性系数Q10=11.336),辽河平原只有泡田到返青期CH4排放与土壤温度符合指数相关关系(温度敏感性系数Q10=2.846)。三江平原和辽河平原典型水稻田的灌溉制度、淹水条件、种植方式基本相同,而辽河平原水稻田CH4排放比三江平原水稻田低。土壤温度变化对三江平原水稻田CH4排放速率的影响比辽河平原强。

Paddy fields are important emission sources for methane(CH4),one major greenhouse gas,in agricultural environment.SanJiang Plain and Liaohe Plain are the dominant rice-producing areas in northeast China.Monitoring CH4 emissions and analyzing its relationship with environment temperature in typical paddy fields of the two plains are significant for developing reasonable measures to reduce CH4 emissions from paddy fields.In this study,observational data of high-frequency CH4 fluxes,temperature,and plant growth periods in paddy fields in Sanjiang Plain and Liaohe Plain from 2017 to 2018 were used to analyze the emission processes of CH4,particularly the emission characteristics on different time scales,and the sensitivity of rice to temperature changes during different plant growth stages.The results showed that the annual emissions of CH4 in Sanjiang Plain and Liaohe Plain in 2017 were 26.77 g·m−2 and 16.17 g·m^−2,respectively.In comparison,the annual CH4 emissions in both regions in 2018 increased significantly,showing an obvious inter-annual variation.In Sanjiang Plain,the largest CH4 monthly emission occurred in June and July,with an emission peak rate of 0.127μmol·m^−2·s^−1 from turning green to booting stage.CH4 emissions during the non-growing season were almost zero.In Liaohe Plain,CH4 emissions remained high in the jointing heading stage and the maturity stage,reached the highest emission in July,with the emission rate increasing up to 0.102μmol·m^−2·s^−1.Thereafter,CH4 emissions decreased gradually,and the third peak occurred in the end of growth season.During in the non-growth season,CH4 emission exhibited a weak diurnal variation.In terms of environment temperature,air temperature in 2018 was close to that in 2017,while soil temperature from May to September in 2018 was slightly higher than that in 2017.In Sanjiang Plain,the nighttime CH4 emission during the growing season had an index correlation with soil temperature.CH4 emission from booting to drainage was the most sensitive to temperature change(temperature sensitivity coefficient Q10=11.336).In Liaohe Plain,CH4 emission had an index correlation with soil temperature only during the period from the soaking stage to the green stage(Q10=2.846).In Sanjiang Plain and Liaohe Plain,the irrigation system,flooding conditions,and planting methods of typical paddy fields were basically the same.The CH4 emission of paddy field in Liaohe Plain was lower than that in Sanjiang Plain,which was probably because the variation of soil temperature had a stronger impact on CH4 emission rate in Sanjiang Plain than that in Liaohe Plain.