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/X013448/1
• 负责人: Grant Forster
• 金额: $ 28.55万
• 依托单位: University of East Anglia
• 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%2FX013448%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.

在第26次缔约方会议上，各国同意减少二氧化碳和甲烷的排放，重点是减少化石燃料的使用。这将留下能源缺口，许多国家计划用氢（H2）作为能源载体来替代。氢是一种小分子，在从生产到最终用户的所有阶段都容易泄漏。不可避免地，这将增加过去二十年来保持相对稳定的大气H2浓度。大气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。这约占其移除量的三分之二。另一个汇是通过与羟基自由基的大气反应，大气中H2的增加将延长CH4和臭氧的寿命。两者都是重要的温室气体，对流层中的臭氧也是一种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的消耗。主要的H2土壤汇受到的约束很差，并且不清楚它将如何响应气候变化中大气H2的增加，这使得对未来H2大气影响的预测不确定。大气建模人员需要研究土壤H2汇强度的谜题，以便对未来H2水平的影响进行可靠的预测。为了解决这一知识缺口，我们创建了一个由大气科学家、生物地球化学家和生物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H2的吸收是一个被动扩散过程，因此多孔土壤比压实或浸水土壤具有更强的吸收能力，扩散速率低。许多土壤微生物利用氢气作为能量来源。H2的吸收速率受土壤温度、pH值和碳的控制。基于这些知识，我们将根据土壤参数、气候和植被覆盖，量化一系列土壤的土壤H2汇率：(i)使用来自英国（8个站点）和热带（最少）的土壤进行实验室操作。2个站点)将提供模型所需的对土壤湿度、温度、H2浓度、pH值和CO2、CH4、N2O通量的响应数据。（ii）我们将提供1年的真实世界土壤H2吸收时空观测结果：(a)静态室提供田间时空变化和土地管理影响的信息。(b)在UKCEH的easterbush监测点，采用空气动力通量梯度法进行的直接H2通量测量将研究H2吸收与气象学之间的关系，以及土壤中H2浓度与CO2、CH4、N2O、CO通量之间的关系；(c)在第二个较干燥的地点，通过大气H2衰变与臭氧沉积和氡积累测量相结合进行的间接通量测量。ELGAR将开发H2吸收的土壤模型，借鉴最近发表的H2建模工作。该模型将在现场、国家和全球范围内运行，并适合与大气化学和运输模型联系起来。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。在全球范围内进行的模拟将研究土壤性质、气候和植被类型对H2吸收和释放的影响。ELGAR将与大气建模人员合作，包括本次项目A和C主题下的资助人员，以确保在项目生命周期内和之后，对新过程的理解将用于改进的大气预测。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氢气经济中减少土壤压实和保持农田排水的重要性进行接触。