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1.
依据政府间气候变化专门委员会(IPCC)对农田N2O排放因子的定义,将气候和种植制度等N2O排放的主控因素引入到估算方法中,结合GIS技术估计了中国农田化肥氮导致的N2O直接排放量的空间分布和年际变异.结果表明,在1991—2000年间由于化肥投入量的增加,中国农田化学氮源N2O排放呈上升趋势.20世纪90年代的平均年排放量为204 Gg N2O-N,变幅为159~269 Gg N2O-N,排放量最高的年份出现在1998年,而1992年排放量为最低.估算结果的不确定性约为23%.受施氮量和降水的影响,N2O排放通量表现出明显的地区差异,东部较高,西北偏低.  相似文献   

2.
采用静态箱-气相色谱法对菜地、旱地、林地、果园、水改旱土壤N2O排放特征及其相关影响因子进行研究.结果表明:不同土地利用方式下土壤N2O的排放通量在-21~435 μg·m-2·h-1之间变化,N2O年排放总量为菜地>果园>旱地>水改旱>林地,分别为447.14、313.57、167.00、124.87和7.24 mg·m-2.土壤N2O排放通量呈现明显的季节性变化,以春夏季最高,秋季次之,冬季最低,并与对应的大气及土壤温度的变化趋势基本一致.N2O排放通量与5 cm土壤温度及土壤硝态氮含量呈显著或极显著正相关,与土壤水分及土壤铵态氮含量无明显相关关系.  相似文献   

3.
施氮和玉米生长对土壤氧化亚氮排放的影响   总被引:13,自引:2,他引:11  
运用土壤盆栽试验、静态箱法采样和气相色谱分析技术研究了种植玉米土壤和裸土在两种土壤施氮水平 (低氮:150 mg·kg-1土,和高氮:300 mg·kg-1土) 下对土壤排放N2O的影响.结果表明,在种植玉米的土壤中,N2O排放率的峰值出现在苗期,且氮肥施用量的影响显著,土壤N2O排放率与温度没有显著的相关性.在裸土中,土壤N2O排放率的峰值出现在试验后期,土壤N2O排放率与温度呈极显著指数相关.土壤施氮量增加,土壤N2O排放总量增加,裸土N2O增加尤其显著,种植玉米比裸土减少87%~92%的N2O排放量.这一结果表明种植作物与否,不仅改变了土壤N2O排放的季节变化和排放量,而且改变了温度与土壤N2O排放之间的关系.  相似文献   

4.
成都平原水稻-油菜轮作系统氧化亚氮排放   总被引:16,自引:0,他引:16  
2005年6月—2006年6月利用静态箱/气相色谱法对成都平原水稻 油菜轮作系统氧化亚氮(N2O)排放进行定位观测, 研究了该系统N2O排放特征及土壤水热状况、氮肥施用、作物参与对N2O排放的影响. 结果表明: 成都平原水稻-油菜轮作系统N2O排放总量为(8.3±2.8)kg·hm-2·a-1, 水稻季、油菜季和休闲期对整个轮作周期N2O排放总量的贡献分别为30%、65%和5%. 水稻季N2O平均排放速率表现为排灌交替期最大, 持续淹水期和排水晒田期相当;氮肥施用是N2O排放高峰出现的主要驱动力;土壤表层含水量偏低是旱季出现土壤N2O吸收现象的主要原因. 土壤水分、土壤温度、施用氮肥和作物参与均在不同程度上影响N2O排放, 土壤水分是影响N2O排放的关键因子, 避免水稻季土壤频繁干湿交替或控制旱季土壤水分(表层土壤含水孔隙率介于50%~70%)可有效抑制N2O排放.  相似文献   

5.
百菌清对土壤氧化亚氮和二氧化碳排放的影响   总被引:1,自引:0,他引:1  
郎漫  蔡祖聪 《应用生态学报》2008,19(12):2745-2750
在25 ℃、60%WHC(最大持水量)的好氧条件下进行14 d的培养试验,研究杀菌剂百菌清在添加水平为0 mg·kg-1(CK)、5.5 mg·kg-1(田间施用量,FR)及110 mg·kg-1(20FR)和220 mg·kg-1(40FR)时对酸性、中性和碱性土壤中N2O和CO2排放的影响.结果表明:百菌清对N2O和CO2排放的影响取决于土壤类型和施用浓度.与对照相比,百菌清在20FR和40FR时显著抑制了酸性土壤N2O的产生与排放;3种施用量均显著促进了中性土壤N2O的排放,其中FR水平的促进效果最显著;高浓度(20FR和40FR)的百菌清在培养初期抑制了碱性土壤N2O的排放,而在培养后期显著促进了N2O的排放.田间用量的百菌清对土壤CO2排放量没有明显影响;高浓度(20FR和40FR)时显著促进了酸性土壤CO2的排放,显著抑制了中性和碱性土壤CO2的排放.  相似文献   

6.
华南丘陵区冬闲稻田二氧化碳、甲烷和氧化亚氮的排放特征   总被引:11,自引:0,他引:11  
采用静态箱 气相色谱法对收获后冬闲稻田CO2、CH4和N2O排放进行了田间原位测定,探讨了越冬稻田3种温室气体的排放规律.结果表明,残茬稻田和裸田的CO2的排放峰值分别出现在18:00和16:00左右.日间CH4排放为净值,夜间表现为弱吸收.残茬稻田和裸田N2O夜间排放分别为日间平均的1.79和1.58倍.残茬稻田的昼夜CO2平均排放通量显著高于裸田(P<0.05).在测定期间,残茬稻田CO2排放随温度升高而增高.相关分析表明,CO2排放与土温、地表温度和气温均呈显著相关,表明温度是影响收获后稻田CO2排放的主要因素.在11月10日至翌年1月18日测定期间,残茬稻田的CO2和CH4平均排放通量分别为(180.69±21.21) mg·m-2·h-1和(-0.04±0.01) mg·m-2·h-1,CO2排放通量较裸田高13.06%,CH4吸收增高50%.残茬稻田的N2O排放通量为(21.26±19.31) μg·m-2·h-1,较裸田低60.75%.由此说明华南丘陵区冬闲稻田是大气CO2和N2O的源,CH4的汇.  相似文献   

7.
四种温带森林土壤氧化亚氮通量及其影响因子   总被引:9,自引:0,他引:9  
以中国东北东部4种典型森林生态系统(人工红松林、落叶松林、天然次生蒙古栎林和硬阔叶林)为研究对象,采用静态暗箱-气相色谱法,比较其土壤N2O通量的季节动态及其影响因子.结果表明:在生长季, 4种森林生态系统土壤总体上表现为大气N2O的排放源, 其N2O通量大小顺序为:硬阔叶林(21.0±4.9 μg·m-2·h-1)> 红松林(17.6±4.6 μg·m-2·h-1)>落叶松林(9.8±5.9 μg·m-2·h-1)>蒙古栎林(1.6±12.6 μg·m-2·h-1).各生态系统的N2O通量没有明显的季节动态,只在夏初出现排放峰值(蒙古栎林为吸收峰).4种生态系统N2O通量均与10 cm深土壤含水量呈极显著正相关,与NO3--N呈显著负相关;N2O通量对土壤温度和NH4+-N的响应出现分异:针叶林N2O 通量与NH4+-N呈显著正相关,而与5 cm深土壤温度呈不相关;阔叶林与针叶林正相反.在较为干旱的2007年,土壤水分是影响4种林型土壤N2O通量的关键因子.植被类型与环境因子及氮素有效性对N2O通量的相互作用将是未来研究的重点.  相似文献   

8.
鼎湖山主要森林土壤N2O排放及其对模拟N沉降的响应   总被引:8,自引:0,他引:8       下载免费PDF全文
 研究了鼎湖山生物圈保护区马尾松(Pinus massoniana)林、混交林和季风常绿阔叶林(季风林)土壤N2O排放特 征及其对氮沉降增加的响应。在1999~2002年期间,3种森林土壤N2O排放速率均 表现明显的季节性变化特点, 但这种季节性变化因年份和森林类型不同而异,总的来说,3种森林土壤N2O排放速率呈现夏秋季较高而冬春季较 低的变化。土壤N2O排放速率在3年观测期间的平均值分别为(g•hm-2•d-1):14.2±3.1(季风林),5.8± 0.9 (混交林)和5.1±0.9(马尾松林)。土壤N2O排放速率与土壤温度之间在季风林呈现显著的指数正相关关 系,但在混交林和马尾松林中它们之间的关系则均不明显。经3个月的模拟氮沉降试验后, 氮沉降增加对季风林 和马尾松林土壤N2O的排放均具有明显的促进作用,且这种促进作用随氮沉降水平的升高而增强,但对混交林土 壤N2O排放的影响则不明显。  相似文献   

9.
三江平原典型沼泽湿地氧化亚氮通量   总被引:16,自引:2,他引:14  
2002~2004年利用静态箱-气相色谱法对三江平原3种具有代表性的湿地类型(常年积水的毛果苔草沼泽、季节性积水的小叶章湿草甸和常年土壤过湿的灌丛湿地)进行了为期两年半的N2O现场观测研究.结果表明,三江平原3种类型湿地N2O通量均有明显的季节变化和年际变化,一般在非冰冻期表现为排放,冰雪覆盖期表现为微弱的吸收.生长季的N2O通量以灌丛湿地N2O排放通量最大,毛果苔草沼泽最小.全年平均N2O交换通量: 毛果苔草沼泽为53.928 mg·m-2·yr-1,小叶章湿地为21.408 mg·m-2·yr-1,灌丛湿地为657.120 mg·m-2·yr-1,证明沼泽湿地是大气N2O的源.3种类型湿地生长季N2O通量无明显的日变化,与温度的相关性不大.  相似文献   

10.
采用预设取样器和静态箱气相色谱法,对渗滤液灌溉条件下,土柱土壤不同深度剖面 N2O的浓度以及N2O和CO2的表面释放通量进行了监测.结果表明: 渗滤液灌溉可促进N2O的生成和释放,灌溉后24 h内土柱N2O的释放通量与表土下10 cm(r=0.944,P< 0.01)、20 cm(r=0.799,P<0.01)、30 cm(r=0.666,P<0.01)和40 cm(r=0.482,P<0.05)处所生成的N2O浓度呈显著相关,且相关程度依次递减.渗滤液灌溉还促进了CO2的释放,但N2O与CO2释放通量之间无显著相关性(P>0.05).渗滤液的灌溉负荷主要决定温室气体释放总量的强弱(N2O和CO2,以CO2当量计),灌溉负荷为6 mm·d-1条件下温室气体释放总量为灌溉负荷2 mm·d-1的3倍多.采用表土下20 cm处灌溉方式可比表土下10 cm处灌溉方式削减47%的温室气体释放总量.渗滤液灌溉土壤14 d内,N2O释放量约占温室气体释放总量的57.0%~91.0%.  相似文献   

11.
The emission of nitrous oxide (N2O) from streams draining agricultural landscapes is estimated by the Intergovernmental Panel on Climate Change (IPCC) to constitute a globally significant source of this gas to the atmosphere, although there is considerable uncertainty in the magnitude of this source. We measured N2O emission rates and potential controlling variables in 12 headwater streams draining a predominantly agricultural basin on glacial terrain in southwestern Michigan. The study sites were nearly always supersaturated with N2O and emission rates ranged from ?8.9 to 266.8 μg N2O‐N m?2 h?1 with an overall mean of 35.2 μg N2O‐N m?2 h?1. Stream water NO3? concentrations best‐predicted N2O emission rates. Although streams and agricultural soils in the basin had similar areal emission rates, emissions from streams were equivalent to 6% of the anthropogenic emissions from soils because of the vastly greater surface area of soils. We found that the default value of the N2O emission factor for streams and groundwater as defined by the IPCC (EF5‐g) was similar to the value observed in this study lending support to the recent downward revision to EF5‐g. However, the EF5‐g spanned four orders of magnitude across our study sites suggesting that the IPCC's methodology of applying one emission factor to all streams may be inappropriate.  相似文献   

12.
Agriculture in developing countries has attracted increasing attention in international negotiations within the United Nations Framework Convention on Climate Change for both adaptation to climate change and greenhouse gas mitigation. However, there is limited understanding about potential complementarity between management practices that promote adaptation and mitigation, and limited basis to account for greenhouse gas emission reductions in this sector. The good news is that the global research community could provide the support needed to address these issues through further research linking adaptation and mitigation. In addition, a small shift in strategy by the Intergovernmental Panel on Climate Change (IPCC) and ongoing assistance from agricultural organizations could produce a framework to move the research and development from concept to reality. In turn, significant progress is possible in the near term providing the basis for UNFCCC negotiations to move beyond discussion to action for the agricultural sector in developing countries.  相似文献   

13.
The Kyoto protocol requires countries to provide national inventories for a list of greenhouse gases including N2O. A standard methodology proposed by the Intergovernmental Panel on Climate Change (IPCC) estimates direct N2O emissions from soils as a constant fraction (1.25%) of the nitrogen input. This approach is insensitive to environmental variability. A more dynamic approach is needed to establish reliable N2O emission inventories and to propose efficient mitigation strategies. The objective of this paper is to develop a model that allows the spatial and temporal variation in environmental conditions to be taken into account in national inventories of direct N2O emissions. Observed annual N2O emission rates are used to establish statistical relationships between N2O emissions, seasonal climate and nitrogen‐fertilization rate. Two empirical models, MCROPS and MGRASS, were developed for croplands and grasslands. Validated with an independent data set, MCROPS shows that spring temperature and summer precipitation explain 35% of the variance in annual N2O emissions from croplands. In MGRASS, nitrogen‐fertilization rate and winter temperature explain 48% of the variance in annual N2O emissions from grasslands. Using long‐term climate observations (1900–2000), the sensitivity of the models with climate variability is estimated by comparing the year‐to‐year prediction of the model to the precision obtained during the validation process. MCROPS is able to capture interannual variability of N2O emissions from croplands. However, grassland emissions show very small interannual variations, which are too small to be detectable by MGRASS. MCROPS and MGRASS improve the statistical reliability of direct N2O emissions compared with the IPCC default methodology. Furthermore, the models can be used to estimate the effects of interannual variation in climate, climate change on direct N2O emissions from soils at the regional scale.  相似文献   

14.
Global Circulation Models (GCMs) contributed to the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4) and are widely used in global change research. This paper assesses the performance of the AR4 GCMs in simulating precipitation and temperature in China from 1960 to 1999 by comparison with observed data, using system bias (B), root-mean-square error (RMSE), Pearson correlation coefficient (R) and Nash-Sutcliffe model efficiency (E) metrics. Probability density functions (PDFs) are also fitted to the outputs of each model. It is shown that the performance of each GCM varies to different degrees across China. Based on the skill score derived from the four metrics, it is suggested that GCM 15 (ipsl_cm4) and GCM 3 (cccma_cgcm_t63) provide the best representations of temperature and precipitation, respectively, in terms of spatial distribution and trend over 10 years. The results also indicate that users should apply carefully the results of annual precipitation and annual temperature generated by AR4 GCMs in China due to poor performance. At a finer scale, the four metrics are also used to obtain best fit scores for ten river basins covering mainland China. Further research is proposed to improve the simulation accuracy of the AR4 GCMs regarding China.  相似文献   

15.
Soil organic carbon (SOC) represents a significant pool of carbon within the biosphere. Climatic shifts in temperature and precipitation have a major influence on the decomposition and amount of SOC stored within an ecosystem. We have linked net primary production algorithms, which include the impact of enhanced atmospheric CO2 on plant growth, to the Soil Organic Carbon Resources And Transformations in EcoSystems (SOCRATES) model to develop a SOC map for the North Central Region of the United States between the years 1850 and 2100 in response to agricultural activity and climate conditions generated by the CSIRO Mk2 Global Circulation Model (GCM) and based on the Intergovernmental Panel for Climate Change (IPCC) IS92a emission scenario. We estimate that the current day (1990) stocks of SOC in the top 10 cm of the North Central Region to be 4692 Mt, and 8090 Mt in the top 20 cm of soil. This is 19% lower than the pre-settlement steady state value predicted by the SOCRATES model. By the year 2100, with temperature and precipitation increasing across the North Central Region by an average of 3.9°C and 8.1 cm, respectively, SOCRATES predicts SOC stores of the North Central Region to decline by 11.5 and 2% (in relation to 1990 values) for conventional and conservation tillage scenarios, respectively.  相似文献   

16.
Soil erosion and contamination are two main desertification indices or land degradation agents in agricultural areas. Global climate change consequence is a priority to predict global environmental change impacts on these degradation risks. This agro-ecological approach can be especially useful when formulating soil specific agricultural practices based on the spatial variability of soils and related resources to reverse environmental degradation. Raizal and Pantanal models within the new MicroLEIS framework, the Ero&Con package, are database/expert system evaluation approach for assessing limitations to land use, or vulnerability of the land to specified agricultural degradation risks. This study was performed in Souma area with approximately 4100 ha extension in the North-West of Iran (west Azarbaijan). Based on 35 sampling soils, Typic Xerofluvents, Typic Calcixerepts, Fluventic Haploxerepts and Fluventic Endaquepts were classified as main subgroups. Climatological data, referred to temperature and precipitation of more than 36 consecutive years were collected from Urmieh station reports and stored in monthly Climate Database CDBm, as a major component of MicroLEIS DSS (CDBm) program. Climate data for a hypothetical future scenario were collected from the Intergovernmental Panel on Climate Change (IPCC) reports for the 2080s period. The evaluation approach predicts that attainable water erosion vulnerability classes were none (V1) very low (V2) and moderately low (V4) in the total of 72%, 13% and 15% of the Souma area, respectively and they will not affected by climate change. On contrary, attainable wind erosion vulnerability classes will increase. Also, phosphorous and heavy metal contamination vulnerability risks will not differ in two compared scenarios while nitrogen and pesticides vulnerability classes will be improved.  相似文献   

17.
两种温室气体排放方案下我国水稻产量变化模拟   总被引:23,自引:1,他引:22  
利用最新的温室气体和SO2排放方案,即政府间气候变化委员会(IPCC)排放情景特别报告(SRES)的A2和B2方案,通过区域气候模式PRECIS和作物模型CERES-Rice相嵌套,在50 km×50 km网格尺度下,模拟了未来2080年我国水稻产量的变化.结果表明,两种温室气体排放方案下,我国水稻的年平均单产水平各地有增有减,增产地区主要集中在长江及长江流域以南地区,其中四川和湖北交界的山区增产幅度最大,减产地区主要集中在华北平原和东北平原;由于CO2的肥效作用,A2温室气体排放方案对我国水稻单产的正面影响大于B2方案,A2排放方案下,我国水稻总产呈现一定程度的上升趋势,B2排放方案下,水稻总产表现为少量下降.  相似文献   

18.
In order to contribute to the improvement of the national greenhouse gas emission inventory, this work aimed at estimating a country-specific enteric methane (CH4) emission factor for the Italian Mediterranean buffalo. For this purpose, national agriculture statistics, and information on animal production and farming conditions were analysed, and the emission factor was estimated using the Tier 2 model of the Intergovernmental Panel on Climate Change. Country-specific CH4 emission factors for buffalo cows (630 kg body weight, BW) and other buffalo (313 kg BW) categories were estimated for the period 1990-2004. In 2004, the estimated enteric CH4 emission factor for the buffalo cows was 73 kg/head per year, whereas that for other buffalo categories it was 56 kg/head per year. Research in order to determine specific CH4 conversion rates at the predominant production system is suggested.  相似文献   

19.
The current Intergovernmental Panel on Climate Change (IPCC) default methodology (tier 1) for calculating nitrous oxide (N2O) emissions from nitrogen applied to agricultural soils takes no account of either crop type or climatic conditions. As a result, the methodology omits factors that are crucial in determining current emissions, and has no mechanism to assess the potential impact of future climate and land‐use change. Scotland is used as a case study to illustrate the development of a new methodology, which retains the simple structure of the IPCC tier 1 methodology, but incorporates crop‐ and climate‐dependent emission factors (EFs). It also includes a factor to account for the effect of soil compaction because of trampling by grazing animals. These factors are based on recent field studies in Scotland and elsewhere in the UK. Under current conditions, the new methodology produces significantly higher estimates of annual N2O emissions than the IPCC default methodology, almost entirely because of the increased contribution of grazed pasture. Total emissions from applied fertilizer and N deposited by grazing animals are estimated at 10 662 t N2O‐N yr?1 using the newly derived EFs, as opposed to 6 796 t N2O‐N yr?1 using the IPCC default EFs. On a spatial basis, emission levels are closer to those calculated using field observations and detailed soil modelling than to estimates made using the IPCC default methodology. This can be illustrated by parts of the western Ayrshire basin, which have previously been calculated to emit 8–9 kg N2O‐N ha?1 yr?1 and are estimated here as 6.25–8.75 kg N2O‐N ha?1 yr?1, while the IPCC default methodology gives a maximum emission level of only 3.75 kg N2O‐N ha?1 yr?1 for the whole area. The new methodology is also applied in conjunction with scenarios for future climate‐ and land‐use patterns, to assess how these emissions may change in the future. The results suggest that by 2080, Scottish N2O emissions may increase by up to 14%, depending on the climate scenario, if fertilizer and land management practices remain unchanged. Reductions in agricultural land use, however, have the potential to mitigate these increases and, depending on the replacement land use, may even reduce emissions to below current levels.  相似文献   

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