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本实验旨在研究稻田土壤中甲烷产生率对稻田CH_4排放的影响.观测结果表明:土壤各深度的甲烷产生率有很大的变化范围(1—4639ng·h~(-1)·g~(-1)d.w.).主要的甲烷产生区域是7—17cm深的土壤层,其中以13cm深的土壤层上的生成速率最大.土壤中甲烷产生率与稻田CH_4排放率在水稻生长的某些阶段有较好的相关性,但它的季节变化却不能与排放的季节变化完全耦合.在水稻生长期,土壤中甲烷产生率随时间而增大,并在8月份水稻收割前达到最大,其日平均值在38—767 ng·h~(-1)·g~(-1)d.w.间变动.稻田土壤中甲烷产生率也存在日变化,一般在下午达到最大值,但却没有发现它与土壤温度有明显的相关关系.在不同施肥及水稻品种的稻田土壤中也观测到不同的甲烷产生率.在土壤中产生的甲烷最多只有28.8％被排放到大气中,而其余多于71.2％的则被氧化在土壤中. 相似文献
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主要介绍了近 2 0年来稻田甲烷排放的模式研究和排放量的估算以及减少稻田甲烷排放的措施。数值模式是估算稻田甲烷排放量的一条有效途径 ,模式的研究现在正处于发展阶段。介绍了几个主要的模型 ,既有物理过程模型也有经验模型。年排放量的估算范围为 6 79～ 4 1 4Tg ,随着技术的发展和大量实验的进行估算值的精度正得到不断的提高。减排措施是减少稻田甲烷排放的必要手段 ,但是目前的减排技术均处于研究阶段 ,应用还不成熟 相似文献
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稻田甲烷排放及产生、转化、输送机理 总被引：65，自引：1，他引：64
通过对中国五大水稻产区稻田甲烷排放的多年观测实验,描述了稻田甲烷排放的时空变化规律及特征并分析研究了其形成机理。稻田甲烷排放的日变化有四种类型,甲烷的传输效率是日变化形成的主要因素。稻田甲烷土壤中排放率的季节变化型式在不同的地区是不同的,这取决于气温变化、水稻品种、施肥及水管理等不同因素。甲烷产生主要发生在稻田土壤耕作还原层（2～20 cm）,氧化主要发生在水土交界面的氧化层和根部氧化膜,并受多种因子的影响。土壤中的甲烷通过三个路径向大气排放,不同时期三个路径在甲烷传输中的相对重要性不同。施用化肥和沼渣肥可以降低土壤中甲烷的产生和排放,而有机肥会增加土壤中甲烷的产生和排放。中国的稻田每年向大气中排放9.67～12.66百万吨甲烷,全球稻田甲烷的总排放量约为35～56 Tg/a。 相似文献
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介绍了１９９０年和１９９４年我国甲烷排放源估算工作。首先,对１９９０年的甲烷排放源进行了收集和完善,尤其是对１９９０年城市垃圾甲烷排放源重新做了计算;其次,根据最新研究资料,对１９９４年的甲烷排放源重新作了计算;最后把１９９４年甲烷排放与１９９０年进行了对比。研究表明,中国１９９０年和１９９４年甲烷排放分别为３０９２×１０６ｔ和３２９１×１０６ｔ,分别约占当年全球总排放的５９％和６１％,其中,采煤、油气领域泄漏、反刍动物与动物粪便、垃圾填埋等甲烷排放有所增大,而生物质燃烧、稻田甲烷的排放有所减少,农村堆肥中的甲烷排放变化不大。 相似文献
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水稻田甲烷的减排方法研究及评价 总被引：26，自引：1，他引：25
通过对稻田甲烷排放多年的野外实验观测和对稻田甲烷排放控制因子的研究,总结出减少稻田甲烷排放的主要方法,对各种减排方法的减排效果和经济效益做了研究,并利用层次分析法对各种减排方法做了进一步的评价分析。现有的稻田甲烷减排方法主要有其他肥料代替传统的有机肥、种植低甲烷排放的水稻品种,以及稻田的灌水管理。适合中国国情的方法主要有杂交稻替代常规稻,沼渣肥替代纯有机肥。杂交稻替代常规稻的经济效益很显著,减少甲烷排放的同时能增加水稻的产量。沼渣肥替代有机肥的减排效果较好,社会效益和环境效益明显优于杂交稻替代常规稻。 相似文献
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减少温室气体排放以减缓全球变暖是当前全球变化研究的主要关注点。制定区域适应性的减排措施,有赖于对不同环境条件下温室气体排放空间差异性的进一步研究。广东是我国主要的双季稻种植区,其气候条件及稻田耕作方式都有别于我国其他稻区的。为估算广东省区域稻甲烷(CH_4)排放情况,利用IPCC2006清单指南中的稻田甲烷模型——CH_4MOD,模拟计算了2010年广东省21个地市双季早(晚)稻CH_4排放量及其排放因子。结果显示:1) 2010年稻田CH_4排放量为60. 74万t,其中双季晚稻CH_4排放量35. 01万t,双季早稻CH_4排放量25. 73万t。2)稻田CH_4排放量空间分布不均,区域稻田甲烷排放量为粤西的粤北的珠江三角洲的粤东的,排放量分别为21. 22万t、17. 02万t、15. 14万t、7. 36万t。3)双季早稻CH_4排放因子明显小于晚稻的,双季早稻CH_4排放因子为261. 18 kg CH_4/hm~2,双季晚稻为358. 53 kg CH_4/hm~2。4)空间上,粤西地区稻田CH_4排放因子水平较高,粤北、粤东的处于中等水平,珠江三角洲稻田CH_4排放水平最低。 相似文献
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我国杭州地区秋和稻田的甲烷排放 总被引：10，自引：1，他引：10
1987年秋季在杭州郊区采用一套全自动的观测系统,对稻田的甲烷排放进行了观测。在整个晚稻灌溉期内,稻田是大气甲烷的一个源地,其甲烷释放率最高可达240mg/m~2·h。甲烷释放率具有很强的季节性变化,在水稻成熟期之前,甲烷释放率一般在40-60mg·CH_4/m~2·h的水平上波动,在成熟期间则降为10mg·CH_4/m~2·h的水平。除移栽期外的整个水稻生长期间的甲烷平均释放率为39mg/m~2·h。甲烷释放率具有明显的日变化,一般在午夜至凌晨3—4点达最大值,白天较低,变化也较小。这可能与水稻植物体由于其生理上的日变化引起的甲烷气体传输能力的日变化有关。实验没有观测到不同施肥(K_2SO_4和菜饼)对甲烷释放率的明显影响。阴雨天的降温一般在2—3天后引起甲烷释放率的迅速下降,这可能是因土壤中发酵细菌如产甲烷菌数量的减少造成的。尽管甲烷释放率和土壤温度在整个生长期间基本上是逐步下降的,但两者之间并没有简单的正相关性。土壤中产生的甲烷气体只有一小部分释放到大气中,从土壤中冒出来的气泡往往可引起释放率的急剧上升。1985年全球稻田的甲烷释放量估计为134±3lTg(1Tg=10~(12)g),其中12±26Tg和30±6Tg分别来自亚太地区和中国稻田。 相似文献
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Methane Production, Emission and Possible Control Measures in the Rice Agriculture 总被引：19，自引：0，他引：19
Wang Mingxing Shangguan Xingjian Shen Renxing Wassmann Reiner Seiler Wolfgang 《大气科学进展》1993,10(3):307-314
In the rice field methane is produced in the soil layer with depths of 2-25 cm. The vertical profile of methane production rate in the paddy soil during the water covering period differs from that in the paddy soil in dry phase. Only a small part, about 30%. of the produced methane is emitted to the atmosphere through rice plant, air bubbles, and molecular diffusion. Therefore, the methane emission rate from the rice field depends not only on the methane production rate in the soil, but also on the transport efficiency of the rice plant, air bubble formation that in turn depends on the production rate, and molecular diffusion.Field measurements show that methane emission rates from a particular rice field have very large diurnal, seasonal and interannual variations, which are related to soil characteristics, water regime, farming procedure, local climate, and rice growing activities. The relationship between the methane emission rate and the above mentioned factors is very complicated. The emission rate 相似文献
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Methane and Nitrous Oxide Emissions from Three Paddy Rice Based Cultivation Systems in Southwest China 总被引：4，自引：0，他引：4
To understand methane (CH4) and nitrous oxide (N2O) emissions from permanently flooded rice paddy fields and to develop mitigation options, a field experiment was conducted in situ for two years (from late 2002 to early 2005) in three rice-based cultivation systems, which are a permanently flooded rice field cultivated with a single time and followed by a non-rice season (PF), a rice-wheat rotation system (RW) and a rice-rapeseed rotation system (RR) in a hilly area in Southwest China. The results showed that the total CH4 emissions from PF were 646.3±52.1 and 215.0±45.4 kg CH4 hm-2 during the rice-growing period and non-rice period, respectively. Both values were much lower than many previous reports from similar regions in Southwest China. The CH4 emissions in the rice-growing season were more intensive in PF, as compared to RW and RR. Only 33% of the total annual CH4 emission in PF occurred in the non-rice season, though the duration of this season is two times longer than the rice season. The annual mean N2O flux in PF was 4.5±0.6 kg N2O hm-2 yr-1. The N2O emission in the rice-growing season was also more intensive than in the non-rice season, with only 16% of the total annual emission occurring in the non-rice season. The amounts of N2O emission in PF were ignorable compared to the CH4 emission in terms of the global warming potential (GWP). Changing PF to RW or RR not only eliminated CH4 emissions in the non-rice season, but also substantially reduced the CH4 emission during the following rice-growing period (ca. 58%, P<0.05). However, this change in cultivation system substantially increased N2O emissions, especially in the non-rice season, by a factor of 3.7 to 4.5. On the 100-year horizon, the integrated GWP of total annual CH4 and N2O emissions satisfies PF>>RR≈RW. The GWP of PF is higher than that of RW and RR by a factor of 2.6 and 2.7, respectively. Of the total GWP of CH4 and N2O emissions, CH4 emission contributed to 93%, 65% and 59% in PF, RW and RR, respectively. These results suggest that changing PF to RW and RR can substantially reduce not only CH4 emission but also the total GWP of the CH4 and N2O emissions. 相似文献
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采用静态箱-气相色谱法在江汉平原开展早稻、晚稻、中稻、虾稻和再生稻5种稻作类型温室气体排放监测试验,研究不同稻作模式下稻田CH4和N2O排放特征、总增温潜势及温室气体排放强度,为准确评估稻田生态系统温室气体排放提供参考依据。结果表明:CH4排放集中在水稻前期淹水阶段,排放峰值最高为虾稻（85.7 mg·m-2·h-1）,较其他稻作模式高71.7%~191.5%。N2O排放峰值主要出现于中期晒田和施肥阶段,排放峰值最高为再生稻（1100.7 μg·m-2·h-1）,较其他稻作模式高16.8%~654.9%。CH4累积排放量从大到小依次为虾稻、再生稻、早稻、晚稻、中稻;N2O累积排放量从大到小依次为再生稻、早稻、晚稻、中稻、虾稻;总增温潜势从大到小依次为虾稻、再生稻、早稻、晚稻、中稻;温室气体排放强度从大到小依次为虾稻、早稻、再生稻、晚稻、中稻。CH4排放占比为82.9%~99.0%,稻虾田高排放主要原因为持续淹水时间长、秸秆还田和饲料投入,探究该模式CH4减排举措最为关键;中稻由于水旱轮作,稻田温室气体排放最低,可作为低碳减排的主要稻作类型。 相似文献
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l.Intr0ductionWiththedevelopmentofeconomy,theenvironmentalproblemsarebec0mingincreasinglyserious.Am0ngthem,theenhancementofgreenh0useeffectsandglobalwarm-ingaretwoimPOrtantonesthathavear0usedwideattention.Nitrousoxide(N,O)isanim-POrtantgreenhousegasandplayingagreatroleinthesetwoprocesses.SincetheIndustrialRevolution,theatmosphericN2Oconcentrationhasincreasedbyaboutl5%(IPCC,l995).Inthelast4Oyears,itincreasedrapidlyatarateof0.2%ro.3%yr-'(IPCC,l99O).Ifitin-creasesatthisrate,theatmospheri… 相似文献
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This assessment of the atmospheric methane budget for the African Continent is based on a set of experimental data obtained in tropical Africa including methane emission from various biogenic sources, and biomass burning, and methane consumption in savanna and forest soils. Emission rates from the various sources, uptake rates of soils, and complementary data from the litterature allow calculation of regional methane fluxes by means of different data bases. Biomass burning, animals and natural wetlands are the three dominant sources of methane in Africa while rice paddy fields and termites appear as minor sources. The total methane emission is estimated to be in the range 20–40 MT of CH4 per year, methane uptake by soils being less than 2 MT per year. Net methane emission from the African continent accounts for less than 10% of global emissions from terrestrial ecosystems. 相似文献
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Modeling Methane Emissions from Paddy Rice Fields under Elevated Atmospheric Carbon Dioxide Conditions 总被引：1，自引：0，他引：1
Methane(CH4 ) emissions from paddy rice fields substantially contribute to the dramatic increase of this greenhouse gas in the atmosphere.Due to great concern about climate change,it is necessary to predict the effects of the dramatic increase in atmospheric carbon dioxide(CO2 ) on CH4 emissions from paddy rice fields.CH4MOD 1.0 is the most widely validated model for simulating CH4 emissions from paddy rice fields exposed to ambient CO2(hereinafter referred to as aCO2 ).We upgraded the model to CH4MOD 2.0 b... 相似文献
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DNDC, a rainfall-driven and process-oriented model of soil carbon and nitrogen biogeochemistry, is applied to simulate the nitrous oxide emissions from agricultural ecosystem in Southeast China. We simulated the soil N2O emission during a whole rice-wheat rotation cycle (from Nov. 1, 1996 to Oct. 31, 1997) under three different conditions, which are A) no fertilizer, B) both chemical fertilizer and manure and, C) chemical fertilizer only. The processes of N2O emission were discussed in detail by comparing the model outputs with the results from field measurement. The comparison shows that the model is good at simulating most of the N2O emission pulses and trends. Although the simulated N2O emission fluxes are generally less than the measured ones, the model outputs during the dryland period, especially during the wheat reviving and maturing stages in spring, are much better than those during the paddy field period. Some sensitive experiments were made by simulating the N2O emissions in spring, when there is a smallest gap between the simulated fluxes and the measured ones. Meanwhile, the effects of some important regulating factors, such as the rainfall, N deposition by rainfall, temperature, tillage, nitrogen fertilizer and manure application on N2O emission during this period were analyzed. From the analysis, we draw a conclusion that soil moisture and fertilization are the most important regulating factors while the N2O emission is sensitive to some other factors, such as temperature, manure, tillage and the wet deposition of atmospheric nitrate. 相似文献
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Carbon dioxide, methane, and nitrous oxide emissions from a rice-wheat rotation as affected by crop residue incorporation and temperature 总被引：10，自引：0，他引：10
Field measurements were made from June 2001 to May 2002 to evaluate the effect of crop residue application and temperature on CO2, CH4, and N2O emissions within an entire rice-wheat rotation season.Rapeseed cake and wheat straw were incorporated into the soil at a rate of 2.25 t hm-2 when the rice crop was transplanted in June 2001. Compared with the control, the incorporation of rapeseed cake enhanced the emissions of CO2, CH4, and N2O in the rice-growing season by 12.3%, 252.3%, and 17.5%,respectively, while no further effect was held on the emissions of CO2 and N2O in the following wheatgrowing season. The incorporation of wheat straw enhanced the emissions of CO2 and CH4 by 7.1%and 249.6%, respectively, but reduced the N2O emission by 18.8% in the rice-growing season. Significant reductions of 17.8% for the CO2 and of 12.9% for the N2O emission were observed in the following wheatgrowing season. A positive correlation existed between the emissions of N2O and CO2 (R2 = 0.445, n =73, p ＜ 0.001) from the rice-growing season when N2O was emitted. A trade-off relationship between the emissions of CH4 and N2O was found in the rice-growing season. The CH4 emission was significantly correlated with the CO2 emission for the period from rice transplantation to field drainage, but not for the entire rice-growing season. In addition, air temperature was found to regulate the CO2 emissions from the non-waterlogged period over the entire rice-wheat rotation season and the N2O emissions from the nonwaterlogged period of the rice-growing season, which can be quantitatively described by an exponential function. The temperature coefficient (Q10) was then evaluated to be 2.3±0.2 for the CO2 emission and 3.9±0.4 for the N2O emission, respectively. 相似文献
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太湖地区冬小麦田与蔬菜地N2O排放对比观测研究 总被引：10，自引：0，他引：10
2003年11月8日至2004年6月5日对太湖地区相邻的蔬菜地和稻麦轮作生态系统的冬小麦田,在当季不施肥情况下的N2O排放进行了田间同步对比观测,分析了N2O排放时间变化以及土壤湿度、土壤温度、土壤速效氮含量和农业管理措施对N2O排放的影响。研究结果表明,小麦播种前的耕翻(表层大约7cm土壤旋耕)处理不会明显改变稻麦轮作农田整个旱地阶段的N2O排放总量,但却使小麦生长季初期的N2O排放明显减弱69%(p<0.01,p为相关概率),使小麦生长季后期的N2O排放明显偏高2.6倍(p<0.05),而对其余时间段的N2O排放作用不明显。与长期实行稻麦轮作的旱地阶段农田相比,由稻田改种蔬菜20多年的蔬菜地,其整个观测期的N2O排放总量比免耕处理小麦田同期的排放高85%(p<0.05),比耕翻处理小麦田同期的排放高99%(p<0.01)。蔬菜地N2O排放偏高的原因是土壤速效氮,特别是铵态氮含量明显偏高(p<0.01)。 相似文献