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The Fate of Methanotrophically Fixed Carbon in Terrestrial Environments

陆地环境中甲烷氧化固定碳的命运

基本信息

批准号：
NE/E018351/1
负责人：
Richard Evershed
金额：
$ 56.94万
依托单位：
University of Bristol
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2007
资助国家：
英国
起止时间：
2007 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FE018351%2F1
关键词：
Fate Methanotrophically Fixed Carbon Terrestrial

项目摘要

The major cause of climate change is the atmospheric reintroduction via fossil fuel burning of large amounts of carbon that has been buried underground for millions of years. Once back in the atmosphere, the carbon-containing compounds absorb infrared radiation, which contributes to global warming. An effective way to limit the effects of global warming is through the removal of carbon containing compounds, such as carbon dioxide (CO2) and methane (CH4) from the atmosphere. The removal of atmospheric carbon and its storage in terrestrial environments, such as soils, is known as carbon sequestration. There are many natural processes that sequester carbon including the removal of atmospheric CO2 by terrestrial vegetation and marine organisms. Carbon from methane can also be sequestered in a similar way to carbon from CO2. Methanotrophs are bacteria that can utilise methane as their only source of carbon and are the major terrestrial methane sink. Methanotrophic bacteria remove a large proportion of methane formed in terrestrial environments and prevent it from reaching the atmosphere. In these circumstances they form a vital barrier that prevents the release of methane from natural wetlands, rice paddies, marine sediments and landfill sites. Whilst the amount of methane oxidised by methanotrophs in soils has been widely studied little is known about the fate of carbon from methane in soils and how much of this carbon is sequestered. To work out what happens to the carbon following methane oxidation in soils we are going to apply CH4 containing a tracer (13C-labelled methane) to a range of different soils. We will then track the fate of the label in the soil, to calculate what proportion of the carbon from CH4 is retained in the soil. We can also link the 13C-labelled CH4 to other soil microorganisms that utilise the carbon from methane as a source of food, and build up a picture of the wider soil microbial food web. Three different soil environments are going to be studied in this work. The initial development work will study a landfill cover soil and focus on establishing a range of new analytical techniques. The soil that overlays a landfill site contains extremely high concentrations of methane because as the organic waste in the landfill site degrades, it releases large amounts of methane. The methane permeates out to the atmosphere through the soil that covers the site. It is well known that bacteria in the landfill cover soils oxidise a large proportion of this methane but the ultimate fate of this carbon they consume is unknown. The fate of methane carbon in natural wetlands will also be studied. Natural wetlands include environments such as peat bogs, fens, salt marshes and tropical swamps. Natural wetlands have organic rich soils that release methane in a similar way to landfill sites when the soil organic matter degrades. We are going to study the fate of carbon from this methane following consumption by methanotrophic bacteria in the soil. The final type of soils that will be used to assess the fate of carbon from methane in soils are a range of soil chronosequences. A soil chronosequence is a related set of soils that formed under similar conditions of vegetation, topography and climate. The length of time over which the soils have developed is the only difference between the soils in the chronosequence. This will allow us to assess the relationship between soil development and the soil processes involved in carbon sequestration. Overall, the research will add a new dimension our understanding of the fate of carbon from one of the major green house gases as it is utilised and dispersed by the soil microbial community.

气候变化的主要原因是通过化石燃料燃烧大量埋藏在地下数百万年的碳重新进入大气。一旦回到大气中，含碳化合物吸收红外辐射，这有助于全球变暖。限制全球变暖影响的一种有效方法是通过从大气中去除含碳化合物，如二氧化碳（CO2）和甲烷（CH4）。将大气中的碳去除并将其储存在陆地环境中，例如土壤中，被称为碳封存。有许多自然过程可以固碳，包括陆地植被和海洋生物去除大气中的二氧化碳。甲烷中的碳也可以以类似于二氧化碳中的碳的方式被隔离。甲烷氧化菌是可以利用甲烷作为其唯一碳源的细菌，并且是主要的陆地甲烷汇。甲烷营养菌可以去除陆地环境中形成的大部分甲烷，并防止其到达大气层。在这种情况下，它们形成了一个重要的屏障，防止甲烷从自然湿地、稻田、海洋沉积物和垃圾填埋场释放出来。虽然土壤中甲烷氧化菌氧化的甲烷量已被广泛研究，但对土壤中甲烷中碳的命运以及有多少碳被隔离却知之甚少。为了弄清楚土壤中甲烷氧化后碳的变化，我们将把含有示踪剂（13C标记的甲烷）的CH4应用于一系列不同的土壤。然后，我们将跟踪标签在土壤中的命运，以计算CH4中的碳在土壤中保留的比例。我们还可以将13C标记的CH4与其他利用甲烷中的碳作为食物来源的土壤微生物联系起来，并建立更广泛的土壤微生物食物网。在这项工作中将研究三种不同的土壤环境。初步开发工作将研究垃圾填埋场覆盖土壤，重点是建立一系列新的分析技术。覆盖在垃圾填埋场上的土壤含有极高浓度的甲烷，因为随着垃圾填埋场中的有机废物降解，它会释放出大量的甲烷。甲烷通过覆盖现场的土壤渗透到大气中。众所周知，垃圾填埋场覆盖土壤中的细菌氧化了大部分甲烷，但它们消耗的碳的最终命运尚不清楚。还将研究天然湿地中甲烷碳的命运。自然湿地包括泥炭沼泽、沼泽、盐沼和热带沼泽等环境。天然湿地有丰富的有机土壤，当土壤有机质降解时，以类似于垃圾填埋场的方式释放甲烷。我们将研究土壤中的甲烷氧化细菌消耗甲烷后，甲烷中碳的去向。最后一种用于评估土壤中甲烷碳去向的土壤类型是一系列土壤年代序列。土壤年表是在相似的植被、地形和气候条件下形成的一组相关的土壤。土壤发育的时间长短是年代序列中土壤之间的唯一区别。这将使我们能够评估土壤发育与碳固存所涉及的土壤过程之间的关系。总的来说，这项研究将增加一个新的层面，我们的理解碳的命运，从一个主要的绿色家庭气体，因为它是利用和分散的土壤微生物群落。