水位波动下微生物介导的鄱阳湖南荻湿地CH4排放机制

Concentration increasing of greenhouse gases induce the climate warming and the effects of global climate change have become the major environmental problems all over the world. Now, CH4 is one of the most important kinds of greenhouse gases in the atmosphere, and they had important influences on global climate change. Wetland of Poyang Lake is an important place for greenhouse gas emissions. Because of its water level fluctuation, it has become an important regional to study the greenhouse gas emissions. Therefore, this project intends to choose the wetland of Nanji mountain in poyang lake as the study object, using the liquid chromatography technology analysis of soil low molecular organic matter structure, using high-throughput sequencing and RT-PCR technologies to analyze microbial functional groups, and using the gas chromatography technology analysis of CH4, to clarify the wetland soil low molecular organic matter, functional group of microorganisms, to demonstrate the relationship between the low molecular organic matter structure, soil microorganism functional group, and the CH4 release. Then under the lab study with three water level treatments and three elector acceptor addition (Fe3+、NO3-、SO42+) , we try to reveal the key factors of CH4 release and impact mechanism of the wetland soil low molecular organic matter under the action of soil microorganism on CH4 releasing under the water level fluctuation and variation of soil environment. These results will help us to understand the geochemical process of CH4 and the true resources of CH4 releasing, and also help to optimize the wetland ecological environment of the poyang lake, to provide some theoretical guidance and decision-making basis to settle the problem of climate warming.

温室气体浓度增加导致全球气温升高已成为全球关注的重大环境问题。CH4是大气中最重要的温室气体之一，对全球气候变化有着重要影响。鄱阳湖湿地是温室气体排放的重要来源，因具有典型的水位变化成为研究CH4排放的重要区域。本项目拟选取鄱阳湖南矶山湿地为研究对象，利用液相色谱学技术分析土壤低分子量有机质结构组成，利用高通量测序和荧光定量PCR技术分析产甲烷菌和甲烷氧化菌群落结构和丰度，利用气相色谱技术测定CH4通量，调查和分析原位土壤低分子量有机质结构组成对产甲烷菌和甲烷氧化菌群落结构和丰度、及CH4排放的影响，再利用模拟实验分析水位和土壤Fe3+、NO3-、SO42+等电子受体对CH4排放的影响，力图揭示水位波动下CH4排放的微生物驱动机制。研究结果对于了解CH4的排放过程，认识CH4排放真正的源具有非常重要的意义，为丰富优化鄱阳湖湿地生态环境、应对气候变暖问题提供一定的理论参考资料。

在全球变暖这个严峻的形势下，鄱阳湖湿地对区域碳平衡和气候变化中起着极其重要的作用。本项目通过野外和室内模拟分析不同水位下土壤CH4排放特征、土壤有机质组成、及产甲烷菌和甲烷氧化菌群落等，结果如下：.退水期-淹水土壤与涨水期-淹水条件下CH4排放通量都在15点达到最大值，这可能是由于下午15点气温较高的原因；涨水期和退水期的淹水甲烷排放（均值1.5032 mg/m2h；1.4240mg/m2h）分别显著高于非淹水（均值0.0211 mg/m2h；0.0476 mg/m2h）（P<0.05）。土壤含水量和pH影响甲烷排放的程度高于土壤有机质含量。产甲烷菌（mcrA）丰度的变化为：涨水期-非淹水（2.86×106 copies/g） > 涨水期-淹水（1.25×106 copies/g），退水期-淹水（1.99×106 copies/g）> 退水期-非淹水（1.24×106 copies/g）（P<0.05），甲烷氧化菌（pmoA）的丰度变化趋势也类似。大部分产甲烷菌和CH4排放呈正相关，大部分甲烷氧化菌和CH4排放呈负相关。.和非淹水、间歇淹水相比，淹水条件下土壤古菌以及产甲烷菌群落多样性最高。甲烷八叠球菌目（55.27%）和Methanoregula（5.93%）为优势产甲烷菌。pH、Eh、土壤含水量等因子直接影响CH4排放及土壤古菌以及产甲烷菌群落结构。.除Fe3+处理组外，NO3-、SO42-和对照（CK）组在光照条件下的甲烷排放显著低于黑暗条件下。mcrA、硫酸盐还原菌Dsr、固碳菌CbbL基因丰度均在Fe3+组中光照条件下显著上调，而pmoA、铁还原菌Geo、反硝化细菌nosZ基因丰度分别在光照条件下NO3-和CK组及黑暗条件下CK组中显著上调。黑暗条件下甲烷排放浓度与古菌、pmoA基因丰度呈正相关，与其他功能基因均呈负相关。光照条件下甲烷排放浓度与微生物及功能基因丰度均呈负相关。