【作者】 高程达；

【导师】 孙向阳；

【作者基本信息】 北京林业大学 ， 生态环境工程， 2008， 博士

【摘要】 全球变暖影响人类生存和可持续发展,是世界性重大课题,已经超越科学技术范畴,渗透到政治、经济、外交以及文化教育等社会领域。然而,对地球系统各个圈层之间温室气体的“源”与“汇”研究还存在不足,“碳失汇”之迷尚未揭开;人类对大气温室气体观测记录的历史与地球系统的形成、演化历史相比,时间太短;观测研究的方法和仪器设备有待于完善;陆地生态系统存在区域差异;人类正积极寻求各种减缓和适应的应对措施。因此,深入研究区域性温室气体的变化特征十分迫切和重要。本研究自2005年设计和研制了土壤表面（水平）和剖面（垂直）二氧化碳原位观测方法和装置,在我国温带干旱地区选定两个观测地点（宁夏和内蒙古）,进行了典型草原、荒漠草原、榆树林和油松林四种植被类型,对应于栗钙土、灰钙土、粗骨土和灰褐土四种土壤类型的近地层空气二氧化碳浓度、地-气界面（土壤表面）和土壤剖面二氧化碳通量的原位观测研究。38个观测样点,为期近3年的工作,主要研究成果如下:1.土壤表面二氧化碳通量的原位观测方法及装置本研究研制了一套土壤表面CO₂通量原位观测的方法和装置。该方法和装置可用于近地层空气二氧化碳浓度和土壤表面（地-气界面）二氧化碳通量两个观测指标的原位测定,具有花费小、便于携带、易操作、多样点以及测定数据可靠、直接、快速等特点。2.土壤剖面二氧化碳通量的原位观测方法及装置本研究研制了一套土壤剖面CO₂通量的原位观测的方法和装置,该方法和装置可用于不同深度（0-200cm）土壤CO₂通量的观测、不同深度土壤层CO₂存储量的估测、土地利用变化拟引起土壤CO₂释放量变化的测算和估计,以及植被或地力恢复速率的评价等。3.近地层空气二氧化碳浓度的变化特征以典型草原、荒漠草原、榆树林和油松林四种植被类型的下垫面为对象,观测研究了近地层空气二氧化碳浓度的变化特征。近地层空气二氧化碳本底浓度为323.49±21.36×10^-6;随植被类型不同存在差异:榆树林最低(297.92±15.56×10^-6),荒漠草原最高(331.82±19.17×10^-6)。植被控制着近地层空气二氧化碳浓度的大小。近地层空气二氧化碳浓度存在明显的季节变化和日变化:十一月份浓度最高(336.54±27.12×10^-6),七月份最低(305.05±15.45×10^-6);趋势呈“S”型曲线变化;日变化中,下午四点最低(318.2×10^-6),夜间零点最高(329.0×10^-6);变化趋势呈“沟谷”状,与气温日变化趋势相反。影响因子有植被覆盖类型、气象因子等。4.土壤表面（地-气界面）二氧化碳通量的变化特征对干旱地区栗钙土、灰钙土、粗骨土和灰褐土四种土壤类型表面二氧化碳的通量进行了观测研究,得出以下结论:这四种土壤类型表面二氧化碳通量的平均值为230.05μmol/m².h,变化范围为-147.27—2319.55μmol/m².h,由大到小依次为粗骨土（351.82μmol/m².h）＞灰褐土（347.33μmol/m².h）＞栗钙土（193.36μmol/m².h）＞灰钙土（162.37μmol/m².h）,森林土壤（粗骨土和灰褐土）的通量显著大于草原土壤（栗钙土和灰钙土）。土壤表面二氧化碳的通量存在明显的季节变化和日变化:其中季节变化走势呈“S”型,九月份最高（516.79μmol/m².h）,以土壤向大气释放为主;一月份最低（-7.09μmol/m².h）,以大气进入土壤,以土壤吸收为主,变化趋势与当地气候变化基本一致,土壤表面二氧化碳通量稍有后置。冬季,在栗钙土、灰钙土、粗骨土和灰褐土四种土壤类型上的土壤表面二氧化碳通量观测中均出现吸收二氧化碳的现象,元月份平均土壤二氧化碳通量为负值（-7.09μmol/m².h）,这将对减少和调节大气二氧化碳浓度具有重要意义。在日变化中,全天土壤表面二氧化碳通量呈“山峰”形变化,凌晨四点最小为154.13μmol/m².h,中午十二点最大为349.65μmol/m².h,日变化趋势随气候的日变化改变,具有昼夜交替规律,比气候因子变化同样稍有置后;也与0-10cm土壤温度的日变化相关,而且,0-10cm土壤温度的日变化置后更多。环境因子影响着土壤表面二氧化碳通量大小:地表空气温度、土壤温度（0-10cm、10-20cm和20-30cm）和土壤含水量（0-10cm）分别与土壤表面二氧化碳通量呈正相关关系,而10-20cm和20-30cm深度的土壤含水量与土壤表面二氧化碳通量呈负相关关系,地表空气相对湿度与土壤表面二氧化碳通量关系不显著;冬季下雪期间,雪对二氧化碳没有明显的吸收。5.土壤剖面二氧化碳通量的变化特征对干旱地区栗钙土、灰钙土、粗骨土和灰褐土四种土壤类型进行了土壤剖面二氧化碳通量的观测研究,主要结论是:土壤剖面二氧化碳通量的变化总趋势随土壤深度增加而增加;土壤种类不同,二氧化碳溢出速率存在不同:并且随季节变化而变化,生长季节明显高于其他季节。干旱地区0-70cm深度的土壤剖面二氧化碳通量平均值为660.43μmol/m².h,变化范围为-9076.25-16988.00μmol/m².h。即由于土地利用方式的改变,使0-70cm深度土壤剖面暴露在空气中,将可能有每年、每平方公里254.6 T（254.6t CO₂/km².a）的二氧化碳气体从土壤里向大气释放,这一数据,将用于土地利用改变温室气体排放的预测和估计。土壤种类不同,土壤剖面二氧化碳通量明显不同,四种土壤类型剖面二氧化碳通量由大到小排列为灰褐土（1271.92μmol/m².h）＞粗骨土（1234.01μmol/m².h）＞灰钙土（590.20μmol/m²）＞栗钙土（498.92μmol/m².h）,即森林土壤（粗骨土和灰褐土）释放总量要大于草原土壤（栗钙土和灰钙土）;在剖面通量-深度曲线中,均存在两个拐点,但是栗钙土、灰钙土和灰褐土呈一小一大峰,粗骨土为骆驼峰。这种变化的原因与土壤剖面结构和根系分布有关,钙积层的有无、厚度起决定作用。土壤质地决定土壤剖面二氧化碳通量的变化和大小,土壤剖面二氧化碳通量与空气温度、空气相对湿度的相关关系不显著。总之,本研究设计和研制了两套观测方法及其装置（水平和垂直）,用于野外观测近地层空气二氧化碳浓度、土壤表面（地-气界面）和土壤剖面二氧化碳通量,填补了国内空白,其中土壤剖面二氧化碳通量为国内外首次报道;本研究采用所研制装置和方法,对我国温带干旱地区四种典型植被类型:草原植被（典型草原、荒漠草原）和森林植被（榆树林、油松林）下垫面的近地层空气二氧化碳浓度作了观测和研究,同时对我国温带干旱地区四种干旱土壤类型质地（栗钙土、灰钙土、粗骨土和灰褐土）的土壤表面（地-气界面）和土壤剖面二氧化碳通量进行了观测和比较研究,除典型草原（栗钙土）以外,均为国内首次报道,其中土壤剖面二氧化碳通量的观测研究,给出单位面积、时间内改变土地利用方式,或使0-70cm深度土壤剖面暴露在空气中,将会给大气增加温室气体“源”254.6t CO₂/km².a,二氧化碳气体从土壤里向大气释放,这一数据为首次报道,可用于土地利用改变而引起温室气体排放的预测和估算。必须指出:本研究存在一些未尽事宜。冬季,在栗钙土、灰钙土、粗骨土和灰褐土四种土壤类型上的土壤表面二氧化碳通量观测中均出现吸收二氧化碳的现象,元月份平均土壤二氧化碳通量为负值（-7.09μmol/m².h）,这将对减少和调节大气二氧化碳浓度具有重要意义,但是其吸收机制还没能阐述清楚。近地层二氧化碳浓度、土壤表面和剖面二氧化碳的通量观测研究比较复杂,相关影响因素较多,包括植被、土壤种类、土壤质地、气象等,涉及大气圈、生物圈、土壤圈、岩石圈、水圈之间的物质、能量、信息交流,是长期的、历史的综合演变过程,揭示其中的规律,将需要更长时间的观测研究和反复验证。观测仪器装置具有广阔的应用前景,更多的地-气碳通量基础数据需要观测和获取,如农田、湿地等各种土地利用类型,都需要做碳通量的定量测定和科学评估,也需要将仪器装置自动化及版本升级;仪器装置在极端气候环境条件下使用,如0到-40℃低温环境、35-45℃高温环境、降雨天气等情况下,需要采取防护措施,这些将有待于今后进一步完善。更多还原

【Abstract】 The impact of golbal warming on human survival and sustainable development is a global major issue,which goes beyond science and technology and penetrates into political, economic,diplomatic,cultural educational and other areas of society.However,there are some things unknown in greenhouse gases "sources" or "sinks" in circles of the Earth.The "missing carbon sink" mystery has not yet been answered.Compared top to the historical formation and evolution of the Earth,the history of observations research of atmospheric greenhouse gas is very short.The observation and research methods and equipment need to be improved.Human beings are actively seeking various mitigation and adaptation measures to deal with them. Therefore,in-depth study of regional characteristics of greenhouse gases is very urgent and important.A design and development of the soil surface（horizontal） and profile（vertical） of carbon dioxide in situ observation methods and devices have been carried out of the temperate,arid areas in China.Two observation sites were selected with a typical grassland in chestnut soil,desert grassland in sierozem,Elm stand in fragmental soil and chinese pine stand in gray-cinnamonic soil.The concentration in surface layers and the flux of carbon dioxide between soil surface and atmosphere with 38-point of sample have been measured and researched in situ since 2005.The main results are as follows:1.An in situ method and apparatus for measuring CO₂ flux at soil surfaceAn in situ method and apparatus for measuring carbon dioxide flux at soil surface have been carried out.The methods and devices can be used for the concentration observations of carbon dioxide at surface layer of atmosphere and the flux measurment of carbon dioxide between soil and atmosphere in situ,with spending of small,portable and easy to operate devices,and diverse points of reliable data,directly and rapid obtained.2.An In Situ Method and Apparatus for Measuring CO₂ Flux at Various Depths of Arid Soil An in situ method and apparatus for measuring carbon dioxide flux at various depths of arid soil have been carried out.The methods and devices can be used for soil CO₂ flux of observation at different depths（0-200 cm）.Other values are the CO₂ storage Estimation at different soil depth,the value Estimation of CO₂ emissions caused by change of land-use and land-cover,as well as restoration of vegetation or soil fertility rate of evaluation.3.The characteristics of the carbon dioxide concentration in the surface layer of the atmosphereThis research focus on the concentration of carbon dioxide from the surface layer of atmosphere in 4 vegetations:typical grassland in chestnut soil,desert grassland in sierozem, Elm stand in fragmental soil and chinese pine stand in gray-cinnamonic soil.The background concentration of carbon dioxide is 323.49±21.36×10^-6.There are differences of the carbon dioxide concentration as the different types of vegetation:Elm stand in fragmental soil for minimum 297.92±15.56×10^-6,and the desert grassland in sierozem for maximum 331.82±19.17×10^-6.Vegetation controls the changes of carbon dioxide concentration in the surface layer of atmosphere.It is found that there are some seasonal and diurnal variations.In the seasonal variation with a trend of "S",the CO₂ concentration of 336.54±27.12×10^-6reaches a summit in November and that of 305.05±15.45×10^-6 falls to the minimum.In the diurnal variation with a trend of "valley" shape,the CO₂ concentration of 318.2×10^-6 touches the minimum at 16:00 and that of 329.0×10^-6 is up to the maximum at 24:00 or 0:00.The changes in the trend of CO₂ concentration in diurnal is opposite the changes in the trend of temperature.The key factors that influenced the the CO₂ concentration are the types of vegetation coverage,and other meteorological factors.4.The characteristics of the carbon dioxide flux from the interface of Soil - the atmosphereThis research focus on the flux of carbon dioxide from the interface of soil -atmosphere in 4 soils:chestnut soil in typical grassland,sierozem in desert grassland, fragmental soil in Elm stand and gray-cinnamonic soil in Chinese pine stand.The the average of carbon dioxide flux in four types of soil surface is 230.05μmol/m².h.The range of changes is from -147.27μmol/m².h to 2319.55μmol/m².h.The order of the flux as soil types is 351.82μmol/m².h in fragmental soil＞347.33μmol/m².h in gray-cinnamonic soil＞193.36μmol/m².h in chestnut soil＞162.37μmol/m².h in sierozem.The flux of carbon dioxide from forest soils（fragmental soil and gray-cinnamonic soil） is significantly higher than that from grassland soil（Chestnut soil and sierozem）.It is found that there are some seasonal and diurnal variations in carbon dioxide.In the seasonal variation with a trend of "S" shape,the CO₂ flux of 516.79μmol/m².h comes to a summit with the release from soil into the atmosphere mainly in September,and that of -7.09μmol/m².h falls to the minimum with soil absorption from the atmosphere to the soil. The trend of carbon dioxide flux in season is basically the same with the trend of climate change in local,and the trend of the carbon dioxide flux is slight later then the trend of climate change.In winter,a phenomenon of absorption（-7.09μmol/m².h）,appears in each soils in January.This change will reduce and regulate the cabon dioxide concentration of atmosphere.In the diurnal variation with "mountain" shape,the CO₂ flux of 154.13μmol/m².h is smallest at 4:00 and that of 154.13μmol/m².h is the maximum at 12:00.The changes trend of CO₂ flux in diurnal is as follows,as the climate change with turn of day and night,and the trend of the carbon dioxide flux is significant later then the trend of climate change.It is found that environmental factors affect the flux of carbon dioxide.Air temperature in soil surface,soil temperature（0-10 cm,10-20cm and 20-30 cm） and soil moisture（0-10 cm） is positively related to the carbon dioxide flux in soil surface.And the soil moisture in 10-20 cm and 20-30 cm depth is negatively related to the flux of carbon dioxide in soil surface.There is not significantly different between the air relative humidity in the soil surface and the carbon dioxide flux.During the winter,it is not found that the snow absorbs carbon dioxide in the atmosphere.5.The characteristics of the carbon dioxide flux from the Soil profileThe carbon dioxide flux from the soil profile is observed and researched in 4 soils: chestnut soil,sierozem,fragmental soil and gray-cinnamonic soil.It is found that the carbon dioxide flux from Soil profiles change with the general trend of increased depth of soil.There are different rates of carbon dioxide in different soil types.In chestnut soil on the typical grassland soil,there is a downturn when soil calcium plot of the encounter occurred.In gray-cinnamonic soil on Chinese pine stand,there are two downturns,not only in the soil calcium plot,but in the mother layer of the soil.It is also found that soil texture takes part in the change and size of the carbon dioxide flux in soil profiles.There is not significant correlation between the flux of carbon dioxide and the air humidity.In summary,there is a complexity in researching carbon dioxide concentration,flux of carbon dioxide.And there are other more relative factors,including vegetation,soil type, soil texture,and weather involving the biosphere,pedosphere,lithosphere,hydrosphere between the material,energy and information exchange.The research of concentration and flux of carbon dioxide is a long-term, comprehensive history of the evolution process,which revealed the need for a longer period of time of the observation and research and repeated verification.Observation equipment also needs automated devices,as these will be further research and improvement.更多还原