Abstract Pyrogenic organic matter (Py-OM), generated via the incomplete combustion of biomass, is well studied due to the presence of slow-cycling, condensed aromatic compounds (ConAC) known to sequester in soils and sediments. Recently, dissolved Py-OM (Py-DOM) has received interest, due to its higher mobility and potential to be transferred through watersheds to aquatic systems. Py-DOM quantities, molecular identities and importance to global carbon budgets and cycles are only beginning to be understood. Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) analyses were performed on Py-DOM isolated from oak and grass biochars produced over a range of temperatures (250–650 °C), and the data are compared to complementary 1H NMR spectroscopic and benzenepolycarboxylic acid biomarker (BPCAs) analyses. Py-DOM is revealed to be a heterogeneous mixture of compounds ranging in relative aromaticity and oxygenation. FTICR-MS analyses demonstrate a decrease in Py-DOM relative oxygen content and a concurrent increase in aliphatic character and heteroatomic (N, Cl) content. 1H NMR and BPCAs analyses detail low O/C dissolved ConAC not observed by FTICR-MS, demonstrating the necessity for a multiple proxy approach to Py-DOM characterization. Heterogeneous Py-DOM is explained as resulting from pyrolysis-initiated and radical-mediated functional group cleavage, aromatic condensation and aromatic ring-opening reactions. Oak biomass progresses faster along a char maturity continuum for a given pyrolysis temperature, perhaps due to its greater lignin content or radical quenching by grass cuticular material. Biomass species and pyrolysis temperature likely result in different Py-DOM compositions and fates and must be considered when evaluating the impacts of wildfires and biochar applications.

中文翻译：

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来自一系列热学橡木和草炭的热解溶解有机物的分子异质性

摘要 通过生物质的不完全燃烧产生的热解有机质 (Py-OM) 由于存在已知会隔离在土壤和沉积物中的慢循环稠合芳香化合物 (ConAC)，因此得到了很好的研究。最近，溶解的 Py-OM (Py-DOM) 引起了人们的兴趣，因为它具有更高的流动性和通过流域转移到水生系统的潜力。Py-DOM 的数量、分子特性以及对全球碳预算和循环的重要性才刚刚开始被理解。傅里叶变换离子回旋共振质谱 (FTICR-MS) 分析是对从在一系列温度 (250–650 °C) 内产生的橡木和草生物炭中分离出来的 Py-DOM 进行的，并将数据与互补的 1H NMR 光谱和苯多羧酸生物标志物 (BPCA) 分析。Py-DOM 被证明是一种在相对芳香性和氧化性方面不等的化合物的异质混合物。FTICR-MS 分析表明 Py-DOM 相对氧含量降低，同时脂肪族特征和杂原子 (N, Cl) 含量增加。1H NMR 和 BPCA 分析了 FTICR-MS 未观察到的低 O/C 溶解 ConAC 的详细信息，证明了对 Py-DOM 表征的多重代理方法的必要性。多相 Py-DOM 被解释为由热解引发和自由基介导的官能团裂解、芳香缩合和芳香开环反应产生。对于给定的热解温度，橡木生物质沿着炭成熟连续体进展得更快，这可能是由于其木质素含量更高或被草表皮材料自由基淬灭。