中文摘要：

以往人们较多的研究了土壤有机碳与温室气体的源、汇关系问题,却很少研究温室气体对土壤有机碳本身分解转化和各组分性质的影响。为了探讨CO2浓度升高对腐殖物质形成转化的作用,本文通过室内人为高浓度CO2的培养试验,用腐殖质组成修改法研究了玉米秸秆分解期间（1~180d）土壤总有机碳（TOC）、水溶性物质（WSS）、碱提取腐殖物质（HE）、胡敏酸（HA）和胡敏素（HM）数量的动态变化规律及不同CO2浓度对有机碳各组分形成与转化的影响。结果表明：玉米秸秆分解期间,“新形成”的净TOC逐渐降低,净HE表现为先增加而后下降的趋势,HM的绝对数量逐渐下降。可提取腐殖物质中HA的比例（PQ）先增加后下降,最终趋于平稳,说明最初富里酸（FA）的形成速度大于HA,随培养时间的延长,FA和HA经历了一段相互转化的过程,最终达到动态平衡。30%CO2浓度（V/V）处理的TOC、WSS、HE和HM数量明显高于3%CO2浓度处理和正常CO2浓度（0.0375%）处理,其中WSS和HM反应更为敏感。但3%CO2浓度处理与正常CO2浓度处理的差异不明显。可提取腐殖物质的PQ的顺序是30%CO2浓度处理〉3%CO2浓度处理〉正常CO2浓度处理,说明CO2浓度增加更有利于FA而不利于HA的形成和稳定。

英文摘要：

People used to focus on the relationship between the greenhouse gases in the atmosphere and the soil organic carbon （SOC） as mutual source or sink, and little has been done on effect of greenhouse gases on decomposition and transformation of SOC per se, and properties of its fractions. SOC can be divided into humic acid （HA）, fulvic acid （FA）, humin （HM） and non-humic substances. Formation, decomposition and transformation of SOC （HA, FA and HM） are all known mainly to be soil biochemical processes, which, however, belong to the issue of thermodynamic stability, if they are addressed from the aspect of energy changes from the initial to the final states of SOC. There are a number of factors that affect SOC stability in soil. However, as long as thermodynamic stability is concerned, only the following three, i.e. water activity, partial pressures of oxygen and carbon dioxide, may do, when the temperature is set to be 25℃. This is based on the understanding that any kind of organic matter is made of water, oxygen and carbon dioxide and can be decomposed eventually to the three substances. In order to explore effect of CO2 concentration on formation and transformation of SOC, an indoor incubation experiment with organic material added the but no crop planted is conducted under controlled conditions varying in CO2 concentration. Dynamic changes in amounts of total organic carbon （TOC）, water soluble substances （WSS）, extracted humic substances （HE）, HA and HM in the soil were determined, and contents of water floating substances （WFS） and FA in the corn stalks under incubation for 180 days, calculated with the revised humus composition method. Results show that the ＂newly formed＂ net TOC decreased in amount gradually with corn stalk decomposing, and the net HE increased in the first 7 days, and then decreases. The absolute amount of HM, however,decreased gradually. The proportion of HA to HE （PO） exhibited an increasing trend in the beginning, and then leveled off, indica