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1.
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   

2.
种植不同作物对农田N2O和CH4排放的影响及其驱动因子   总被引:3,自引:0,他引:3  
以种植玉米(Zea mays)、大豆(Glycine max)和水稻(Oryza sativa)的农田生态系统为研究对象,于2003年6~10月系统观测了N2O和CH4的排放、土壤温度和湿度以及相关的生物学因子。玉米和水稻分别施化肥氮300 kg.hm-2,大豆未施氮肥。研究结果表明,作物类型对农田N2O和CH4排放具有显著的影响。土壤-玉米系统、土壤-大豆系统和土壤-水稻系统的N2O季节性平均排放通量分别为620.5±57.6、338.0±7.5和238.8±13.6μg.m-2.h-1(N2O)。种植作物促进了农田生态系统的N2O排放,玉米地土壤和裸地土壤的N2O平均排放通量分别为364.2±11.7和163.7±10.5μg.m-2.h-1(N2O)。土壤-玉米系统、土壤-水稻系统、玉米地土壤和裸地土壤N2O排放受土壤温度的影响,与土壤湿度无显著统计相关,但受土壤温度和水分的综合影响。土壤-大豆系统N2O排放随作物绿叶干重的增加而指数增加,与土壤温度和水分条件无统计相关,由大豆作物自身氮代谢所产生的N2O-N季节总量约为6.2 kg.hm-2(N)。土壤-水稻系统CH4平均排放通量为1.7±0.1 mg.m-2.h-1(CH4),烤田抑制了稻田CH4的排放。烤田前影响稻田CH4排放的主要因素是水稻生物量,烤田后的浅水灌溉及湿润灌溉阶段的CH4排放与土壤温度和水稻生物量无关。本研究未观测到旱作农田有吸收CH4的现象。  相似文献   

3.
准确定量施肥农田土壤的N_2排放仍然困难。本研究基于华北冬小麦季的一次基肥(尿素150 kg N ha~(–1))施用事件,采用氦培养-直接测定N_2法,在与田间土壤温度和氧气含量一致的条件下测定鲜土的N_2和N_2O排放。结果显示:施肥和灌溉/降雨事件共同促进N_2和N_2O出现峰值排放;施肥导致N_2O/(N_2O+N_2)摩尔比增加至0.25;基肥施用后的一个月内,土壤N_2和N_2+N_2O排放损失分别占肥料氮投入的1.6%和2.2%。我们的结果证实了广泛采用的乙炔抑制法极大的低估了冬小麦田石灰性土壤N_2排放造成的肥料氮素损失。  相似文献   

4.
华东稻田CH4和N2O排放   总被引:71,自引:1,他引:71       下载免费PDF全文
稻田CH4和N2O排放的季节变化规律完全不同,两者的排放通量随土壤水分条件变化而互为消长,但它们的日变化形式则比较一致。晴天时的CH4和N2O排放日变化规律明显,主要表现为下午单峰模态,有时CH4排放夜间出现一个次峰。CH4和N2O排放总量因肥料类型而不同,堆肥加尿素处理比NH4HCO3处理少排放N2O 30%,多排放CH4 12%。  相似文献   

5.
随着大气CO2浓度的逐渐升高,CO2的施肥效应很可能对陆地生态系统的N2O地气交换过程产生一定的影响。在江苏北部的中国稻麦轮作FACE (Free-Air Carbon Dioxide Enrichment) 实验平台上,采用静态箱暗箱-色谱法,研究了一个稻麦轮作周期(2005年6月中旬至2006年6月中旬)3种小麦秸秆还田水平处理(全还田、半还田和不还田)和CO2浓度升高200 μmol·mol-1对稻麦轮作农田N2O排放的影响。结果表明,就当地传统农田管理方式下的砂性土壤稻麦轮作农田N2O排放而言,所采用的观测方法未能检测到显著的秸秆还田效应和大气CO2浓度升高效应。  相似文献   

6.
半干旱草原温室气体排放/吸收与环境因子的关系研究   总被引:13,自引:3,他引:10  
静态箱一气相色谱法对内蒙古半干旱草原连续两年的实验观测研究结果表明,内蒙古草原是大气CO2和N2O的排放源,而是CH4的汇.在植物生长不同季节,草原生态系统排放/吸收温室气体CO2,CH4和N2O的日变化形式各有不同,其中在植物生长旺季日变化形式最具特征.3种温室气体的季节排放/吸收高峰主要出现在土壤湿度较大的春融和降雨较为集中时期.所有草原植物生长季节CO2净排放日变化形式均为白天出现排放低值,夜间出现排放高值.较高的温度有利于CO2排放,地上生物量决定着光合吸收CO2量值的高低.影响半干旱草原吸收CH4和排放N2O日变化形式的关键是土壤含水量和供氧状况,日温变化则主要影响日变化强度.吸收CH4和排放N2O的季节变化与土壤湿度季节变化分别呈线性反、正相关,相关系数均在0.4~0.6之间.自由放牧使CO2、N2O和CH4交换速率日较差降低,同时使N2O和CH4年度排放/吸收量减少和CO2年度排放量增加.  相似文献   

7.
CH4和N2O作为主要温室气体,自工业革命以来排放量急剧增加,已经被列入《京都议定书》要求控制它们的排放。本文利用高光谱分辨率的辐射传输模式,计算了CH4、N2O在晴空大气和有云大气条件下的瞬时辐射效率和平流层调整的辐射效率,以及它们的全球增温潜能(GWP)和全球温变潜能(GTP),并根据模式结果拟合了CH4和N2O的辐射强迫的简单计算公式。本文的研究表明:CH4和N2O在有云大气下的平流层调整的辐射效率分别为4.142×10-4 W m-2 ppb-1和3.125×10-3 W m-2 ppb-1 (1ppb=10-9),经大气寿命调整后的辐射效率分别为3.732×10-4 W m-2 ppb-1和2.987×10-3 W m-2 ppb-1,与IPCC(2007)的相应结果高度一致。CH4和N2O 100年的全球增温潜能GWP分别为16和266;100年的脉冲排放的全球温变潜能GTPP分别为0.24和233;持续排放的全球温变潜能GTPS分别为18和268。它们在未来全球变暖和气候变化中,影响仅次于CO2,仍然起着非常关键的作用。  相似文献   

8.
1999年在常熟农业生态站试验稻田于水稻主要生长季, 利用进口的条件采样装置对水稻低层大气N2O的垂直通量进行了观测, 并在2000年做了补充观测。结果如下:各生长季测定的N2O垂直通量值最多出现在0~2.0 mg·m-2·h-1之间;N2O垂直通量平均日变化最大值出现在下午;插秧期和收割后N2O垂直通量是各个生长季中最小的;观测到N2O负通量现象的出现;在稻田用条件采样技术观测到的低层大气N2O垂直通量大于国内用箱式法观测报道的土壤N2O排放通量。  相似文献   

9.
我国瓦里关山、兴隆温室气体CO2、CH4和N2O的背景浓度   总被引:14,自引:1,他引:13       下载免费PDF全文
为了研究中国大陆温室性气体CO2、CH4和N2O大气浓度的区域分布和变化特征以及与人类活动的关系,从1995~2000年,先后在青海瓦里关山全球大气基准站(36°18′N,100°54′E,3810 m)及河北中国科学院兴隆天文台(40°24′N,117°30′E, 940 m),利用不锈钢瓶取样和气相色谱法分析,观测了两地大气中温室气体CO2、CH4和N2O的浓度及其变化情况。结果表明:兴隆和瓦里关山站CO2、CH4和N2O的同期年平均浓度分别为376.7×10-6和373.5×10-6,1886×10-9和1831×10-9,316.7×10-9和314.9×10-9。从1995~2000年,兴隆站CO2、CH4和N2O的年增长率分别为1.95×10-6,9.02×10-9和0.75×10-9。而瓦里关山站从1997~2000年,CO2、CH4和N2O的年增长率分别为1.41×10-6,9.95×10-9和0.82×10-9。两地大气中三种气体的浓度与年增长率与全球同类台站的观测结果接近。同时也在一定程度上反映了各自不同的环境背景特征。  相似文献   

10.
半干旱草原温室气体排放/吸收与环境因子的关系研究   总被引:7,自引:0,他引:7  
静态箱—气相色谱法对内蒙古半干旱草原连续两年的实验观测研究结果表明,内蒙古草原是大气CO2和N2O的排放源,和CH4的汇。在植物生长不同季节,草原生态系统排放/吸收温室气体CO2、CH4和N2O的日变化形式各有不同,其中在植物生长旺季日变化形式最具特征。三种温室气体的季节排放/吸收高峰主要出现在土壤湿度较大的春融期和降雨较为集中时期。对所有草原植物生长季节,CO2净排放日变化形式均为白天出现排放低值,夜间出现排放高值。较高的温度有利于CO2排放,地上生物量决定着光合吸收CO2量值的高低。影响半干旱草原吸收CH4和排放N2O日变化形式的关键是土壤台水量和供氧状况,日温变化则主要影响日变化强度。吸收CH4和排放N2O的季节变化与土壤湿度季节变化分别呈线性反、正相关,相关系数均在0.4-0.6之间。自由放牧使CO2、N2O和CH4交换速率日较差降低,同时使N2O和CH4年度排放/吸收量减少和CO2年度排放量增加。  相似文献   

11.
Field measurements of N2O emission rates were carried out from August until October 1982 in a subtropical region in Europe, i.e. in Andalusia, Spain. The measurements were performed by using an automatic sampling and analysis technique allowing the semi-continuous determination of N2O emission rates. The N2O emission rates were positively correlated to the soil surface temperature and exhibited a diurnal rhythm with maximum rates in the afternoon and minimum rates in the early morning with average values of 1 g N2O–N/m2/h for the grass lawn and 15 g N2O–N/m2/h for cultivated land. Application of urea and ammonium nitrate resulted in elevated N2O emission rates when compared to the unfertilized control. The loss of fertilizer-nitrogen as N2O was 0.18% for urea and 0.04% for NH4NO3 which compares very well with data obtained in a temperate climate (Germany). The total source strength of fertilizer-derived N2O is estimated to be 0.01–2.2 Tg N2O–N per year. The N2O flux from unfertilized natural soils may be as high as 4.5 Tg N2O–N, indicating that the N2O emission from soils contributes significantly to the global N2O budget.  相似文献   

12.
Emissions of N2O, CH4, and CO2 from soils at two sites in the tropical savanna of central Venezuela were determined during the dry season in February 1987. Measured arithmetic mean fluxes of N2O, CH4, and CO2 from undisturbed soil plots to the atmosphere were 2.5×109, 4.3×1010, and 3.0×1013 molecules cm-2 s-1, respectively. These fluxes were not significantly affected by burning the grass layer. Emissions of N2O increased fourfold after simulated rainfall, suggesting that production of N2O in savanna soils during the rainy season may be an important source for atmospheric N2O. The CH4 flux measurements indicate that these savanna soils were not a sink, but a small source, for atmospheric methane. Fluxes of CO2 from savanna soils increased ninefold two hours after simulated rainfall, and remained three times higher than normal after 16 hours. More research is needed to clarify the significance of savannas in the global cycles of N2O, CH4, CO2, and other trace gases, especially during the rainy season.  相似文献   

13.
对临安大气本底站2003-2004年冬、夏季二氧化氮(NO2)、二氧化硫(SO2)、臭氧(O3)进行了分析.结果表明:冬季NO2和SO2平均体积分数分别为19.48×10-9和35.74 x10-9,而夏季的平均体积分数分别为4.81×10-9和8.12×10-9,冬季高于夏季;O3在夏季的平均体积分数为33.55×10-9,略高于冬季的25.44×10-9;夜间NO2和SO2体积分数比白天高,并且NO2呈明显的单峰单谷型分布,O3也呈单峰型但峰值出现在白天.NO2、SO2体积分数存在着明显的“假日效应”,假日比非假日低,周五高于假日和非假日;但O3体积分数没有明显的假日效应.降水对SO2有明显的清除作用,但对NO2的清除作用不明显.与风向对比发现,夏季高体积分数的NO2、SO2都受到NW、WNW风的影响,冬季则分别受NE和SW、SSW风的影响;而O3受风向的影响较复杂,与局地光化学反应有关.  相似文献   

14.
Field measurements of NO and NO2 emissions from soils have been performed in Finthen near Mainz (F.R.G.) and in Utrera near Seville (Spain). The applied method employed a flow box coupled with a chemiluminescent NO x detector allowing the determination of minimum flux rates of 2 g N m-2 h-1 for NO and 3 g m-2 h-1 for NO2.The NO and NO2 flux rates were found to be strongly dependent on soil surface temperatures and showed strong daily variations with maximum values during the early afternoon and minimum values during the early morning. Between the daily variation patterns of NO and NO2, there was a time lag of about 2 h which seem to be due to the different physico-chemical properties of NO and NO2. The apparent activation energy of NO emission calculated from the Arrhenius equation ranged between 44 and 103 kJ per mole. The NO and NO2 emission rates were positively correlated with soil moisture in the upper soil layer.The measurements carried out in August in Finthen clearly indicate the establishment of NO and NO2 equilibrium mixing ratios which appeared to be on the order of 20 ppbv for NO and 10 ppbv for NO2. The soil acted as a net sink for ambient air NO and NO2 mixing ratios higher than the equilibrium values and a net source for NO and NO2 mixing ratios lower than the equilibrium values. This behaviour as well as the observation of equilibrium mixing ratios clearly indicate that NO and NO2 are formed and destroyed concurrently in the soil.Average flux rates measured on bare unfertilized soils were about 10 g N m-2 h-1 for NO2 and 8 g N m-2 h-1 for NO. The NO and NO2 flux rates were significantly reduced on plant covered soil plots. In some cases, the flux rates of both gases became negative indicating that the vegetation may act as a sink for atmospheric NO and NO2.Application of mineral fertilizers increased the NO and NO2 emission rates. Highest emission rates were observed for urea followed by NH4Cl, NH4NO3 and NaNO3. The fertilizer loss rates ranged from 0.1% for NaNO3 to 5.4% for urea. Vegetation cover substantially reduced the fertilizer loss rate.The total NO x emission from soil is estimated to be 11 Tg N yr-1. This figure is an upper limit and includes the emission of 7 Tg N yr-1 from natural unfertilized soils, 2 Tg N yr-1 from fertilized soils as well as 2 Tg N yr-1 from animal excreta. Despite its speculative character, this estimation indicates that NO x emission by soil is important for tropospheric chemistry especially in remote areas where the NO x production by other sources is comparatively small.  相似文献   

15.
Emission of nitrous oxide from temperate forest soils into the atmosphere   总被引:5,自引:0,他引:5  
N2O emission rates were measured during a 13-month period from July 1981 till August 1982 with a frequency of once every two weeks at six different forest sites in the vicinity of Mainz, Germany. The sites were selected on the basis of soil types typical for many of the Central European forest ecosystems. The individual N2O emission rates showed a high degree of temporal and spatial variabilities which, however, were not significantly correlated to variabilities in soil moisture content or soil temperatures. However, the N2O emission rates followed a general seasonal trend with relatively high values during spring and fall. These maxima coincided with relatively high soil moisture contents, but may also have been influenced by the leaf fall in autumn. In addition, there was a brief episode of relatively high N2O emission rates immediately after thawing of the winter snow. The individual N2O emission rates measured during the whole season ranged between 1 and 92 g N2O-N m–2 h–1. The average values were in the range of 3–11 g N2O-N m–2 h–1 and those with a 50% probability were in the range of 2–8 g N2O-N m–2 h–1. The total source strength of temperate forest soils for atmospheric N2O may be in the range of 0.7–1.5 Tg N yr–1.  相似文献   

16.
We investigated the partitioning of trace substances during the phase transition from supercooled to mixed-phase cloud induced by artificial seeding. Simultaneous determination of the concentrations of H2O2, NH3 and black carbon (BC) in both condensed and interstitial phases with high time resolution showed that the three species undergo different behaviour in the presence of a mixture of ice crystals and supercooled droplets. Both H2O2 and NH3 are efficiently scavenged by growing ice crystals, whereas BC stayed predominantly in the interstitial phase. In addition, the scavenging of H2O2 is driven by co-condensation with water vapour onto ice crystals while NH3 uptake into the ice phase is more efficient than co-condensation alone. The high solubility of NH4+ in the ice could explain this result. Finally, it appears that the H2O2–SO2 reaction is very slow in the ice phase with respect to the liquid phase. Our results are directly applicable for clouds undergoing limited riming.  相似文献   

17.
中国部分清洁地区大气中N2O的浓度   总被引:11,自引:0,他引:11  
1993年4月—1995年8月对中国部分清洁地区大气的N2O浓度进行了现场观测,结果表明:农田(玉米田和麦田)大气的N2O平均浓度高达322.1-343.4ppbv,这是土壤排放N2O的结果;临安、龙风山和瓦里关山大气本底观测站(WMO/GAW)N2O的平均浓度分别为318.8±8.4ppbv,317.4±4.7ppbv和314.0±4.2ppbv。在此基础上,分析了大气N2O的分布及变化特征。另外,还对现场取样及N2O浓度测量技术作了初步分析和评价  相似文献   

18.
全球闪电活动与对流层上部NO及O3的相关性分析   总被引:1,自引:1,他引:0       下载免费PDF全文
为了解闪电对对流层上部微量气体的贡献,利用全球水资源和气候中心(GHRC)提供的1995年4月—2006年6月的闪电卫星格点资料,以及高层大气研究卫星(UARS)上的卤素掩星试验(HALOE)1991年10月—2005年11月的观测资料,分析了全球闪电与对流层上部NO和O3体积分数的时空分布特征及其相关性。结果表明:全球闪电12、1、2月集中在南半球,6—8月集中在北半球,全球闪电的季节分布与NO、O3类似;NO体积分数在350 h Pa附近达到最大,该高度的南半球NO体积分数变化范围为7×10-12~11×10-12、北半球为3×10-12~17×10-12;450~300 h Pa,北半球夏季O3体积分数呈明显增加趋势,且同一高度上夏季的值比年平均值大25%左右,南半球夏季O3体积分数高于冬季,但差异并不大。结论进一步证明了闪电与对流层上部NO及O3的密切关系,也为研究全球气候变化提供有力证据。  相似文献   

19.
In a nighttime system and under relatively dry conditions (about 15 ppm H2O), the reaction mixture of NO2, O3, and NH3 in purified air turns out to result in the formation of nitrous oxide (N2O). The experiments were performed in a continuous stirred flow reactor, in the concentration region of 0.02–2 ppm.N2O is thought to arise through the heterogeneous reaction of gaseous N2O5 and absorbed NH3 at the wall of the reaction vessel % MathType!MTEF!2!1!+-% feaafeart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqaqpepeea0xe9qqVa0l% b9peea0lb9sq-JfrVkFHe9peea0dXdarVe0Fb9pgea0xa9pue9Fve9% Ffc8meGabaqaciGacaGaaeqabaWaaeaaeaaakeaatCvAUfKttLeary% qr1ngBPrgaiuaacqWFOaakcqWFobGtcqWFibasdaWgaaWcbaGae83m% amdabeaakiab-LcaPmaaBaaaleaacqWFHbqyaeqaaOGaey4kaSIaai% ikaiab-5eaonaaBaaaleaacqWFYaGmaeqaaOGae83ta80aaSbaaSqa% aiab-vda1aqabaGccaGGPaWaaSbaaSqaaiaadEgaaeqaaOGaeyOKH4% Qae8Nta40aaSbaaSqaaiab-jdaYaqabaGccqWFpbWtcqGHRaWkcqWF% ibascqWFobGtcqWFpbWtdaWgaaWcbaGae83mamdabeaakiabgUcaRi% ab-HeainaaBaaaleaacqWFYaGmaeqaaOGae83ta8eaaa!59AC!\[(NH_3 )_a + (N_2 O_5 )_g \to N_2 O + HNO_3 + H_2 O\]In principle, there is competition between this reaction and that of adsorbed H2O with N2O5, resulting in the formation of HNO3. At high water concentrations (RH>75%), no formation of N2O was found. Although the rate constant of adsorbed NH3 with gaseous N2O5 is much larger than that of the reaction of adsorbed H2O with gaseous N2O5, the significance of the observed N2O formation for the outside atmosphere is thought to be dependent on the adsorption properties of H2O and NH3 on a surface. A number of NH3 and H2O adsorption measurements on several materials are discussed.  相似文献   

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