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.

在缔约方会议第26届会议上，各国同意减少二氧化碳(CO2)和甲烷(CH4)排放，重点是减少化石燃料的使用。这将留下一个能源缺口，许多国家计划用氢(H2)作为能源载体来取代这个缺口。氢是一种小分子，在从生产到最终用户的所有运输阶段都容易发生泄漏。不可避免的是，这将增加大气中氢的浓度，过去20年来，大气中的氢浓度一直保持相对稳定。大气中氢的主要去除机制是通过扩散到土壤中，在土壤中被微生物消耗。这约占其移除总量的三分之二。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，氢气浓度的增加会导致水的增加，从而导致保护性臭氧的耗尽。占主导地位的H2土壤汇约束较差，目前尚不清楚它将如何应对不断变化的气候中大气H2的增加，这使得对未来H2大气影响的预测变得不确定。需要对土壤氢汇强度之谜进行调查，以便大气模型师对未来氢气水平的影响做出可靠的预测。为了解决这一知识差距，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模型师组成的团队。埃尔加项目将研究土壤吸氢率的控制和变化，并开发用于全球模型的数值算法。土壤对H2的吸收是一个被动扩散过程，因此，疏松土壤比压实土壤或淹水土壤具有更强的汇，扩散速率较低。许多土壤微生物利用氢气作为能源。吸收H2的速率受土壤温度、pH和碳的控制。在这些知识的基础上，我们将根据土壤参数、气候和植被覆盖范围来量化一系列土壤的氢汇速率：(I)使用来自英国(8个地点)和热带(Min.2个站点)将提供模型所需的土壤水分、温度、H2浓度、pH和CO2、CH4、N2O通量的响应数据。(2)我们将提供为期1年的土壤H2吸收的空间和时间的真实世界观测：(A)静态小室提供关于土地管理的领域内的时空变异性和影响的信息。(B)用空气动力学通量梯度法直接测量氢气通量，将研究在英国环境保护中心的复活节灌木丛监测点吸收氢气与气象、土壤中氢气浓度和CO2、CH4、N2O、CO通量之间的关系，以及(C)间接测量大气中氢气的通量，结合在另一个更干燥的站点测量臭氧沉积和氡累积。埃尔加将在最近发表的氢气建模工作的基础上，开发一个吸收氢气的土壤模型。该模型将在现场、国家和全球范围内运行，并适用于连接大气化学和传输模型。它将建立在成熟的土壤有机质建模方法上，并使用埃尔加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性质、气候和植被类型对H2吸收和释放的影响。ELGAR将与大气模型师合作，包括在本次呼吁下根据主题A和C资助的那些模型师，以确保新的过程理解有助于在项目生存期内和之后改进大气预测。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接触，了解在H2经济中最大限度地减少土壤压实和维护田间排水的重要性。