Establishing hydropyrolysis as an effective technique for the determination and isolation of pyrogenic carbon in samples from the natural environment

热原碳（PC）是一个通用术语，现在最常用来描述由自然和人为生物质和化石燃料的不完全燃烧产生的物质。它被称为各种其他术语，包括烟灰，炭，木炭，微炭，在黑碳的总标题下。所使用的名称范围不仅反映了其成分的复杂性，而且反映了它对几个学科的重要性，包括考古学、全球碳循环和古环境重建。对PC的传统理解是，它是高度顽固的，已知它可以在土壤中持续数千年，估计半衰期约为5000年。根据环境条件，PC对一系列化学氧化剂的高度抗性支持了长期保存的假设。相比之下，现在有相当多的证据表明，PC在某些环境中可以在相对较短的时间尺度上经历退化。例如，在十年的时间尺度上，经常燃烧的热带稀树草原土壤中的大部分PC已经退化。除了微生物降解外，还表明PC易受光氧化的影响，尽管速度比更不稳定的有机碳形式慢。因此，在基本层面上，PC研究人员的主要问题是如何量化这些材料在一系列环境中的稳定性，以及在自然环境中发生变化的机制是什么？显然，为了解决这些问题，需要普遍接受的方法来定量和纯化PC。不幸的是，目前主要基于化学/热氧化的方法得出的结果差异很大，因此，没有一种单一的方法得到了认可。然而，通过一种新的方法，即加氢热解（hypy），可以从土壤和沉积有机质中还原去除所有不稳定的有机物，并且在其他方法所需的一小部分时间内获得精确的结果。本提案的目标是开展必要的基础研究，以建立理论基础，证明hypy可以为PC定量和去除不稳定有机物以分离PC进行放射性碳，散装稳定同位素测量以及阐明和量化环境退化引起的PC结构变化提供通用方法。一旦hypy被证明是一种非常有效的PC定量和纯化方法，这将为全球数百家涉及PC研究方面的机构以及目前存在的150多个放射性碳实验室的研究人员采用该技术铺平道路。这将通过诺丁汉的合作伙伴公司Strata带来大量hypy反应堆系统的潜在销售。提出的hypy和现有氧化处理之间的比较将使许多文献能够重新评估，以确定实际的PC浓度已经报告的地方。此外，证明PC比整个泥炭/煤样品更能再现陆地稳定同位素记录，将为使用PC作为快速关联不同沉积记录和开发环境变化记录的手段提供令人兴奋的可能性，而不会受到有机物衰变的混淆影响。

Pyrogenic Carbon (PC) is the generic term now most commonly used to describe material arising from the incomplete combustion of natural and anthropogenic biomass and fossil fuels. It has been referred to by a variety of other terms, including soot, char, charcoal, microcharcoal, under the collective heading of black carbon. The range of names used reflects not only its compositional complexity but also its importance to several disciplines, encompassing archaeology, the global carbon cycle and palaeoenvironmental reconstruction. The traditional understanding of PC is that it is highly recalcitrant and it is known to persist for thousands of years in soils, with estimated half-lives being about 5,000 years. Dependant on environmental conditions, the presumption of long-term preservation is supported by the high degree of resistance of PC to a range of chemical oxidants. In contrast, there is now considerable evidence that PC can undergo degradation in some environments on comparatively short timescales. For example, most of the PC in a regularly-burned savanna soil has been degraded on decadal timescales. In addition to microbial degradation, it has also been shown that PC is susceptible to photo-oxidation, albeit at a slower rate than more labile forms of organic carbon. Thus, at a fundamental level, the major questions amongst PC researchers are how can the stability of these materials in a range of environments be quantified and what are the mechanisms by which alteration can occur in natural environments? Clearly, to address these questions, universally accepted procedures are needed for the quantification and purification of PC. Unfortunately, current methods based primarily on chemical/thermal oxidation give widely varying results and, consequently, no single procedure has gained acceptance. However, it is possible to remove all the labile organic matter from soils and sedimentary organic matter reductively via a new approach, hydropyrolysis (hypy) with precise results being obtained in a fraction of the time required for other procedures. The goal of this proposal is to carry out the fundamental research necessary to establish the theoretical basis for proving that hypy can provide a universal approach both for PC quantification and for the removal of labile organic matter to isolate PC for radiocarbon, bulk stable isotope measurements, as well as for elucidating and quantifying changes in PC structure arising from environmental degradation. Once hypy has been proven to be a highly effective method form PC quantification and purification, this will then pave the way for the technique being adopted by researchers in many hundreds of institutions worldwide that are involved in aspects of PC research, as well as by the 150+ radiocarbon laboratories that currently exist. This will lead to a number of potential sales of hypy reactor systems, through Nottingham's partner company, Strata. The proposed comparison between hypy and existing oxidation treatments will enable much of the literature to be re-evaluated in terms of identifying where realistic PC concentrations have been reported. Further, proving that PC is a more reproducible proxy for terrestrial stable isotope records than whole peat/coal samples will provide exciting possibilities of using PC as a means to rapidly correlate between disparate sedimentary records and develop records of environmental change, without the confounding influence of organic matter decay.