Topic B: The Enigma of the Soil Hydrogen Sink Variability [ELGAR]

主题 B：土壤氢汇变异之谜 [ELGAR]

• 批准号: NE/X013464/1
• 负责人: J.U. Smith
• 金额: $ 29.83万
• 依托单位: University of Aberdeen
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2022
• 资助国家: 英国
• 起止时间: 2022 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FX013464%2F1
• 关键词: Topic; Enigma; Soil; Hydrogen; Sink

At COP 26, countries agreed to reduce their carbon dioxide (CO2) and methane (CH4) emissions, with a focus on reducing fossil fuel use. This will leave an energy gap, which many countries plan to replace using hydrogen (H2) as an energy carrier. Hydrogen is a small molecule, and susceptible to leakage at all stages of delivery from production to the end-user. Inevitably, this will increase atmospheric H2 concentrations that have remained relatively stable for the last two decades. The primary removal mechanism for atmospheric H2 is via its diffusion into soils where it is consumed by microbes. This accounts for circa two-thirds of its removal. The other sink is through its atmospheric reaction with the hydroxyl radical, and increases in atmospheric H2 will extend the lifetimes of CH4 and ozone (O3). Both are important greenhouse gases, and tropospheric O3 is also an air pollutant that impacts human health and ecosystems. In the stratosphere, increased H2 concentrations can lead to increased water, leading to depletion of protective O3.The dominant H2 soil sink is poorly constrained and it is not clear how it will respond to increasing atmospheric H2 in a changing climate, making predictions of future H2 atmospheric impacts uncertain. The enigma of the soil H2 sink strength needs to be investigated for atmospheric modellers to develop robust forecasts of the impact of future H2 levels. To address this knowledge gap we created a team of atmospheric scientists, biogeochemists and biogeochemical modellers.Project ELGAR will study controls and variations of soil H2 uptake rates and develop numerical algorithms for implementation into global models. Soil H2 uptake is a passive diffusion process, hence, porous soils are stronger sinks than compacted or waterlogged soil, with low diffusion rates. Many soil microbes utilise H2 as an energy source. H2 uptake rates are controlled by i.e. soil temperature, pH and carbon. Building on this knowledge, we will quantify soil H2 sink rates from a range of soil in response to soil parameters, climates, and vegetation cover: (i) Laboratory manipulations using soils from the UK (8 sites), and the tropics (min. 2 sites) will provide data on the response to soil moisture, temperature, H2 concentrations, pH, and fluxes of CO2, CH4, N2O, required for the models. (ii) We will deliver 1-year real-world observations of spatial and temporal soil H2 uptake: (a) Static chambers inform on within-field spatial and temporal variability and effects of land management. (b) Direct H2 flux measurements by the aerodynamic flux gradient method will study the relationship between H2 uptake and meteorology, and in-soil H2 concentrations and fluxes of CO2, CH4, N2O, CO at UKCEH's Easter Bush monitoring site, and (c) indirect flux measurements, derived from atmospheric H2 decay in conjunction with measurements of ozone deposition and radon accumulation, at a second, drier site.ELGAR will develop a soil model of H2 uptake, drawing on recently published H2 modelling work. The model will run at the site, national and global scale, and be suitable to link to atmospheric chemistry and transport models. It will be constructed on well-established soil organic matter modelling approaches and use ELGAR measurement data to derive response functions and constrain model parameters. Simulations run at the global scale will investigate the impacts of soil properties, climate and vegetation types on H2 uptake and release. ELGAR will collaborate with atmospheric modellers, including those funded under Topics A and C under this call to ensure the new process understanding feeds into improved atmospheric predictions during and beyond the project lifetime. Data will be stored at a NERC data centre and we will educate the public on the importance of soils as a sink for atmospheric H2 and engage with policymakers and farmers regarding the importance of minimising soil compaction and maintaining field drains in the H2 economy.

在COP26上，各国同意减少二氧化碳（CO2）和甲烷（CH4）的排放，重点是减少化石燃料的使用。这将留下一个能源缺口，许多国家计划使用氢（H2）作为能源载体来取代。氢气是一种小分子，在从生产到最终用户的所有输送阶段都容易泄漏。这将不可避免地增加过去二十年来保持相对稳定的大气H2浓度。大气中H2的主要去除机制是通过其扩散到土壤中，在土壤中被微生物消耗。这大约占其清除量的三分之二。另一个汇是通过其与羟基自由基的大气反应，大气中H2的增加将延长CH4和臭氧（O3）的寿命。两者都是重要的温室气体，对流层O3也是影响人类健康和生态系统的空气污染物。在平流层中，H2浓度的增加会导致水分的增加，从而导致保护性O3的耗竭。H2主要的土壤汇受到的约束很差，目前尚不清楚它将如何在气候变化中对大气H2的增加做出反应，这使得未来H2大气影响的预测不确定。土壤H2汇强度之谜需要进行调查，为大气建模，以制定强大的预测未来H2水平的影响。为了解决这一知识缺口，我们创建了一个由大气科学家、地球化学家和地球化学建模师组成的团队。ELGAR项目将研究土壤H2吸收率的控制和变化，并开发用于全球模型的数值算法。土壤吸收H2是一个被动扩散过程，因此，多孔土壤比压实或淹水土壤更强，扩散速率低。许多土壤微生物利用H2作为能源。H2吸收速率受土壤温度、pH和碳的控制。在此基础上，我们将量化土壤H2汇率从一系列土壤响应土壤参数，气候和植被覆盖：（一）实验室操作使用土壤从英国（8个网站），热带（至少2个网站）将提供数据的响应土壤水分，温度，H2浓度，pH值，和通量的CO2，CH4，N2O，所需的模型。(ii)我们将提供为期1年的空间和时间土壤H2吸收的真实世界观测：（a）静态室提供田间空间和时间变化以及土地管理影响的信息。(b)通过空气动力学通量梯度法直接测量氢气通量，将研究氢气吸收与气象学之间的关系，以及UKCEH复活节灌木监测点土壤中氢气浓度和CO2、CH4、N2O、CO通量之间的关系，以及（c）间接通量测量，来自大气中氢气衰减，并结合臭氧沉积和氡积累的测量，第二，ELGAR将利用最近发表的H2建模工作，开发H2吸收的土壤模型。该模型将在国家和全球范围内运行，并适合与大气化学和运输模型相联系。它将建立在完善的土壤有机质建模方法上，并使用ELGAR测量数据来推导响应函数和约束模型参数。在全球范围内运行的模拟将调查土壤特性、气候和植被类型对H2吸收和释放的影响。ELGAR将与大气建模者合作，包括在本呼吁下在主题A和C下资助的大气建模者，以确保新的过程理解在项目生命周期内和之后改善大气预测。数据将存储在NERC数据中心，我们将教育公众土壤作为大气H2汇的重要性，并与政策制定者和农民就最大限度地减少土壤压实和维护H2经济中的田间排水沟的重要性进行接触。