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题名	水稻土碳、氮投入对甲烷产生及产甲烷古菌的影响
作者	保琼莉
学位类别	博士后
答辩日期	2014-05
授予单位	中国科学院研究生院
授予地点	北京
导师	朱永官
关键词	水稻土 稻秸 硝态氮 CH4 产甲烷古菌 rice paddy soil rice straw nitrate CH4 methanogenic community
学位专业	环境科学
中文摘要	CH4对全球变暖贡献仅次于CO2。稻田是CH4排放的重要源。CH4是厌氧产甲烷古菌的终产物。稻秸还田作为传统的农事操作改善土壤条件，而稻秸还田促进了稻田CH4的排放。稻田施氮主要以无机氨态氮肥为主，如尿素等。稻田土壤有氧区域的氨态氮经过硝化作用转化成硝态氮，而硝态氮在厌氧区域进行的反硝化作用往往对CH4产生有抑制作用。综合研究两种类型水稻土在添加不同量稻秸时的甲烷产生及产甲烷古菌的响应及水稻土在添加稻秸与否条件下研究NO3-对产CH4及产甲烷古菌在转录水平上的影响，为调控传统农事操作（稻秸还田及硝态氮肥施用）下稻田CH4的排放提供理论依据，为稻田CH4排放预测模型的研究提供数据支持，对评价稻田生态系统CH4排放措施的有效性具有重要意义。     本文通过微宇宙厌氧培养实验，以典型水稻土为实验材料，设置添加稻秸或硝态氮肥等不同处理，进行严格厌氧培养，并定期测定体系中CH4产生量、其他生物地球化学参数及产甲烷古菌的变化。分析了水稻土在不同碳氮投入条件下CH4产生量，探讨了不同条件下影响CH4产生的主要因素及微生物响应机制。主要结果如下： （1）稻秸添加显著促进了两种水稻土CH4的产生。相同秸秆量添加条件下江西鹰潭水稻土产生的CH4量高于广东雷州半岛水稻土。两种水稻土生物地球化学元素的变化及产甲烷古菌的响应对稻秸添加的响应存在差异。稻秸添加显著促进了古菌16S rRNA基因及mcrA基因的拷贝数的增加，以江西鹰潭水稻土尤为明显。多元回归分析显示H2、SO42-、Fe(II)、古菌16S rRNA 基因及mcrA基因的拷贝数、多样性指数以及Methanosarcinaceae 和Methanobacteriaceae丰度的变化共同影响了两种水稻土CH4的产生。表明水稻土甲烷的产生受生物及非生物因素的共同影响。RDA及偏RDA分析表明生物地球化学参数与产甲烷古菌之间的交互作用对CH4产生的解释量近达70%。 （2）NO3-添加抑制了水稻土CH4的产生，而在稻秸添加条件下，在培养后期NO3-对产CH4的抑制作用有所缓解。反硝化菌与产甲烷古菌之间的底物竞争及反硝化过程的中间产物（NO2-、NO及N2O）对产甲烷古菌的毒害可能是这种抑制效应的主要原因。生物地球化学参数的变化在不同处理中亦有较大差异。mcrA基因的T-RFLP图谱显示产甲烷古菌群落结构在RS与RS+N之间、Ctrl与N之间无明显差异，以甲烷八叠球菌科（Methanosarcinaceae）的产甲烷古菌为优势菌群。mcrA转录水平的T-RFLP分析表明不同处理及培养时间均影响了产甲烷古菌群落结构。在培养前期及培养末期，以T-RF为416 bp的未知产甲烷古菌和Methanocellaceae在N及RS+N处理中均有较高程度的转录。CH4产生量与mcrA基因及mcrA转录子拷贝数均显著相关，而CH4产生量与mcrA基因转录子拷贝数之间的相关性更高。表明通过提高mcrA基因的转录从而增强产甲烷古菌活性可能与水稻土产甲烷相关。偏冗余分析（偏RDA）结果表明CO2变化是本研究CH4产生的显著影响因子。
英文摘要	Methane (CH4) is a major contributor to global warming, second only to CO2. Rice paddy soils are a large source of CH4. CH4 is the final product of anaerobic methanogens. Returning rice straw to paddy soil is a common practice in agriculture for the amelioration of soil conditions. The intensive use of chemical nitrogen (N) fertilizer in rice fields has significantly increased to meet the growing food demands due to continued population growth. In paddy soils, most N is applied in the form of inorganic, ammonium-based fertilizers, such as urea. However, nitrate is produced from the oxidation of ammonium in the oxic surface soil and rhizosphere. The inhibitory effects of nitrate on CH4 production have been widely observed in paddy soils. Thus, we comparatively studied CH4 production in two types of paddy soil (silt loam soil and silty clay soil) amended with different amounts of rice straw, detected the temporal patterns of CH4 formation, the variations of the biogeochemical parameters, and the methanogenic archaeal communities involved. Additionally, we detected the CH4 production and the response of methanogenic communities transcription under the condition of nitrate added to soil with or without rice straw appliment. In-depth knowledge of this researches might be of particular importance for providing a theoretical basis for the control of CH4 production in paddy soil, further developing models to predict CH4 emission from paddy soils at regional and global scales. The main results are as follows: (1) Straw incorporation significantly stimulated CH4 production in two soil types. CH4 production in JX soil was higher than the GD soil with equal straw addition. Significant differences between biogeochemical parameters and methanogenic archaeal communities were observed between two soil types. Straw addition increased archaeal 16S rRNA genes and mcrA genes copy numbers, especially in JX soil. Multiple regression analysis indicated that variations in H2, sulfate, Fe (II) concentrations, archaeal 16S rRNA genes and mcrA genes copy numbers, methanogens diversity index, and the relative abundance of Methanosarcinaceae and Methanobacteriaceae together influenced CH4 production in two soil types.These results indicated that methane production was influenced by the comprehensive effects of biotic and abiotic factors in paddy soils. (2) Nitrate addition inhibited CH4 production throughout the incubation. However, under the condition of rice straw appliment, the inhibitory effect of nitrate on CH4 production was reduced at the later stage of incubation. Significant differences in biogeochemical parameters were observed between treatments. The T-RFLP analysis of mcrA genes compositions showed that the methanogenic community structures were almost similar between RS and RS+N treatments, and between Ctrl and N treatments, and with Methanosarcinaceae dominating the methanogenic community in all incubations. The composition of mcrA transcripts showed a substantial response to different treatments and incubation times. The correlation between methane production and mcrA transcripts copy numbers were more significant. These results suggested that the enhancement of mcrA transcription and hence methanogenic activity is probably more related to methanogenesis. The variations of the CO2 exhibited the great contributor to CH4 production.
公开日期	2015-06-12
内容类型	学位论文
源URL	[http://ir.rcees.ac.cn/handle/311016/13452]
专题	生态环境研究中心_土壤环境科学实验室
推荐引用方式 GB/T 7714	保琼莉. 水稻土碳、氮投入对甲烷产生及产甲烷古菌的影响[D]. 北京. 中国科学院研究生院. 2014.

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