Engineering toolboxes to verify the fate mechanism and permanence of drawndown carbon

人为二氧化碳排放是地球气候变化紧急情况的最大贡献者。环境评估表明，为了缓解不可逆转的气候变化，并满足联合国气候变化框架公约《巴黎协定》，全球碳排放量需要在2018年的基础上减少95%以上。减排不足以实现这一目标，因此，必须广泛采用负排放技术来直接降低大气中的二氧化碳水平。负排放技术会导致现在所说的“碳减少”。随着这种方法的积极开发和实地试验，迫切需要开发更好的工程工具箱，以确定被封存和储存的碳的去向机制和持久性。土壤固碳有两种形式可以在减缓气候变化中发挥作用：无机碳和有机碳。科学证据表明，不仅被广泛研究的亚稳定土壤有机质可以捕获大气中的二氧化碳，而且地质稳定的成壤碳酸盐也可以捕获大气中的二氧化碳。现在，关键是要解决另一个重要的知识鸿沟，即如何容易地将土壤有机碳(SOC)分为更稳定和更不稳定的组分，以及这与土壤和底土中碳的长期储存和运输有何关系。该研究计划的目标是开发新的实验(表征)和数值(反应传输)工具箱，以准确估计SOC的封存速率、数量、稳定性和物种形成。将利用工程学、地球科学、农业和经济学的概念来开发用于监测、量化和预测土壤中的碳固存的工具。在短期内，光电催化传感器的进步和先进的高压热重分析技术将被用来利用光催化、气化、热解和热氧化来对有机碳组分进行定量分类，包括不稳定的(不稳定的)、腐殖质和抗性(更稳定的)。将收集和生成热力学、动力学和吸附数据，以使土壤碳运输的传统地球化学模拟能够解释一类不同稳定性的有机碳化合物，这些化合物在不同的土壤、作物和气候条件下老化或降解。从长远来看，这项研究的目标是：(I)具有直接的政策影响，特别是因为它涉及长期(10至100年，最好是更长时间)的可验证和可证明的碳信用；以及(Ii)为碳固定核查人员配备先进的方法，以确定土壤中所有形式的新固定碳的持久性。

Anthropogenic carbon dioxide emissions are the largest contributor to the Earth's climate change emergency. Environmental assessments show that to mitigate irreversible climate change and to meet the UNFCC Paris Agreement, a more than 95% reduction in the global carbon emissions from the 2018 level is required. Emissions reduction is insufficient to achieve this, hence negative emissions technologies, which result in what is now known as `carbon drawdown', must be widely adopted to reduce atmospheric CO2 levels directly. With such approaches being actively developed and field tested, there is urgent need to develop better engineering toolboxes for determining the fate mechanism and permanence of sequestered and stored carbon. There are two forms of soil carbon sequestration that can play a role in climate change mitigation: inorganic and organic carbon. Scientific evidence has shown that not only the widely researched meta-stable soil organic matter can trap atmospheric CO2, but also the geologically stable pedogenic carbonates. Now, it is crucial to tackle another important knowledge gap, which is on how soil organic carbon (SOC) can be readily classified into more stable and less stable fractions, and how this is related to the long-term storage and transport of carbon in soils and subsoils. The goal of this research program is to develop novel experimental (characterization) and numerical (reactive transport) toolboxes to accurately estimate SOC sequestration rates, amounts, stability, and speciation. Concepts from Engineering, Earth Sciences, Agriculture, and Economics will be leveraged to develop tools for monitoring, quantifying, and predicting carbon sequestration in soils. In the short term, advances in photoelectrocatalytic sensors and advanced high-pressure thermogravimetric analysis techniques will be leveraged to make use of photocatalysis, gasification, pyrolysis and thermal oxidation for the purpose of quantitatively classifying SOC fractions that include labile (less stable), humus, and resistant (more stable). Thermodynamic, kinetic and sorption data will be collected and generated to enable conventional geochemical modeling of soil carbon transport to be able to account for a family of SOC compounds of different stabilities that age or degrade under variable soil, crop and climate conditions. For the long term, this research aims: (i) to have direct policy implications, particularly as it pertains to verifiable and certifiable carbon credits for long-lasting (10 to 100 years, or ideally more) carbon removal; and (ii) to equip carbon sequestration verifiers with superior methods to determine the permanence of all forms of newly sequestered carbon in soils.