| 鄱阳湖平原直播稻CH4通量及其与CO2通量的综合温室效应 |
| 摘要点击 2943 全文点击 885 投稿时间：2022-04-11 修订日期：2022-06-14 |
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| 中文关键词 碳排放 甲烷通量 二氧化碳通量 综合温室效应 涡度相关 (EC) 直播稻 |
| 英文关键词 carbon emission CH4 flux CO2 flux comprehensive greenhouse effects eddy covariance (EC) direct-seeded rice |
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| 中文摘要 |
| 稻田是一个既排放CH4又吸收CO2的复杂生态系统，在全球水碳循环和碳收支中发挥着重要作用.利用涡度相关法得到2020年鄱阳湖平原双季直播稻田的CH4和CO2通量，定量揭示了稻田碳通量变化特征、累积量和2种温室气体的综合温室效应.结果表明，双季直播稻田为CH4排放源，全生育期排放量为52.6 g ·m-2，日均排放0.208 g ·（m2 ·d）-1.CH4通量具有明显的季节变化特征，强排放期（排放峰）集中在早稻生长中期和晚稻生长前期，早稻85.5%和晚稻92.1%的CH4在强排放期被释放，日尺度峰值分别为0.638 g ·（m2 ·d）-1和1.282 g ·（m2 ·d）-1.CH4通量日变化呈显著单峰型、不显著单峰型和无规律型，强排放期主要为单峰型，该型式下早稻季峰值0.453 μmol ·（m2 ·s）-1和晚稻季峰值0.977 μmol ·（m2 ·s）-1均出现在14：00~15：00，且在12：30~16：00维持较高排放速率.早稻和晚稻全生育期CO2累积量分别为-990.4 g ·m-2和-1156.6 g ·m-2，合计为-2147.0 g ·m-2.双季稻田CH4排放和CO2交换的综合温室效应（以CO2当量计）为-673.6 g ·m-2，表现为降温效应.当评价稻田温室效应时若不考虑CH4排放，将低估1473.4 g ·m-2的CO2当量排放，占净CO2吸收量的68.6%. |
| 英文摘要 |
| Paddy fields are complex ecosystems that both emit CH4 and absorb CO2, which plays an important role in the global water-carbon cycle and carbon budget. In this study, the CH4 fluxes and CO2 fluxes of double-cropping direct-seeded rice fields in 2020 in the Poyang Lake Plain were obtained using the eddy covariance method, and the variation characteristics, accumulation in the whole growth period, and comprehensive greenhouse effects of two greenhouse gases were quantitatively revealed. The results showed that, the double-cropping direct-seeded rice field in Poyang Lake Plain was the source of CH4 emission, and the emission during the whole growth period was 52.6 g·m-2, with an average daily emission of 0.208 g·(m2·d)-1. CH4 emission and daily average emission in the early rice season were 20.7 g·m-2 and 0.188 g·(m2·d)-1, respectively, which were lower than the emissions of 31.9 g·m-2 and 0.255 g·(m2·d)-1 in the late rice season. CH4 flux had significant seasonal variation characteristics. The strong emission period (emission peak) of CH4 was concentrated in the middle growth stage of early rice and the early growth stage of late rice. A total of 85.5% of CH4 in the early rice season and 92.1% of CH4 in the late rice season were released during the strong emission periods, and seasonal peak values were 0.638 g·(m2·d)-1 and 1.282 g·(m2·d)-1, respectively. The diurnal variation characteristics of CH4 flux showed three types:obvious unimodal type, non-obvious unimodal type, and irregular type. The strong emission period was mainly the unimodal type, and the peak values of 0.453 μmol·(m2·s)-1 in the early rice season and 0.977 μmol·(m2·s)-1 in the late rice season appeared at 14:00-15:00 and maintained a high emission rate at 12:30-16:00. The CO2 accumulation in the whole growth period of early rice and late rice was -990.4 g·m-2 and -1156.6 g·m-2, respectively, and the total was -2147.0 g·m-2. The comprehensive greenhouse effect of CH4 emission and CO2 exchange in the double-cropping paddy field was -673.6 g·m-2 (calculated using the CO2 equivalent), which showed a cooling effect. Excluding CH4 emissions when evaluating the greenhouse effect of the paddy field, the CO2 equivalent emission of 1473.4 g·m-2 would be underestimated, accounting for 68.6% of the net CO2 absorption. Considering CH4 emissions, CO2 exchanges, and carbon emissions caused by rice harvest, the two-season direct seeding paddy field in Poyang Lake Plain was the source of greenhouse gas emissions. |
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