Sun Minmin, Zhang Yuan, Ma Jing, Yuan Wenping, Li Xianglan, Cheng Xiao
State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing, China.
College of Global Change and Earth System Science, Beijing Normal University, Beijing, China.
PLoS One. 2017 Jun 6;12(6):e0176765. doi: 10.1371/journal.pone.0176765. eCollection 2017.
The Sanjiang Plain (SJP), one of the major rice producing regions in China, is an important source of methane (CH4) emissions. However, there have been large uncertainties in the estimates of CH4 emissions from this area during the past few years. In this study, we estimated CH4 emissions using a process-based model derived by rice area, CH4 flux, land surface temperature (LST), and the ratio of precipitation (P) and evapotranspiration (ET) in rice paddies in the SJP during the rice growing seasons in 2000, 2006, and 2010, respectively. The results showed that the total area of rice fields was 1.64 million ha in 2010, which was approximately 35 and 13% higher than in 2000 and 2006, respectively. The average LST was 22.1°C in 2000 which was higher than in 2006 (21.6°C) and 2010 (21.5°C). Monthly ET and P displayed similar seasonal and annual variability. The monthly ET was 61.7, 66.5, and 63.0 mm month-1 and P was 85.1, 80.6 and 85.9 mm month-1 during the rice growing seasons in 2000, 2006, and 2010, respectively. The averaged CH4 flux rates were 24.83, 24.63, and 24.59 ton km-2, and the estimated mean annual CH4 emissions from rice paddies were 0.30, 0.36, and 0. 40 Tg yr-1 in 2000, 2006, and 2010, respectively. The CH4 emissions displayed obvious spatial variations that decreased from east to west in the SJP, and were mainly affected by temperature. The results will improve our understanding of the inter-annual and spatial variations of CH4 emissions and provide a more accurate regional budget of CH4 emissions from rice paddies in the Sanjiang Plain.
三江平原是中国主要的水稻产区之一，也是甲烷（CH₄）排放的重要来源。然而，过去几年该地区CH₄排放量的估算存在很大的不确定性。在本研究中，我们分别利用基于水稻种植面积、CH₄通量、地表温度（LST）以及三江平原水稻田降水（P）与蒸散量（ET）之比的过程模型，估算了2000年、2006年和2010年水稻生长季的CH₄排放量。结果表明，2010年稻田总面积为164万公顷，分别比2000年和2006年高出约35%和13%。2000年平均LST为22.1℃，高于2006年（21.6℃）和2010年（21.5℃）。月ET和P呈现出相似的季节和年际变化。2000年、2006年和2010年水稻生长季的月ET分别为61.7、66.5和63.0毫米/月，P分别为85.1、80.6和85.9毫米/月。平均CH₄通量率分别为24.83、24.63和24.59吨/平方公里，2000年、2006年和2010年稻田CH₄年平均排放量估算值分别为0.30、0.36和0.40太克/年。CH₄排放在三江平原呈现出明显的空间变化，从东向西递减，且主要受温度影响。这些结果将增进我们对CH₄排放年际和空间变化的理解，并为三江平原稻田CH₄排放提供更准确的区域预算。
