Permanganate oxidizable carbon (POXC) is a sub-pool of labile soil organic carbon (SOC) and is defined as the carbon (C) that can be oxidized by potassium permanganate (KMnO₄). Determination of the content of POXC has been used as a way to measure labile C and may be related to soil microbial biomass and particulate organic C. Fourier transform mid-infrared photoacoustic spectroscopy (FTIR-PAS) has been used for characterizing the chemical composition of soil organic matter. The objective of the current study was to identify the chemical information in the FTIR-PAS spectra that is unique to POXC and therefore associated with labile C. FTIR-PAS was used for characterizing SOC using a set of soil samples collected in four different countries (Laos, Malaysia, Peru and Thailand, n = 575). Partial least squares (PLS) regression was used to correlate the collected FTIR-PAS spectra with both POXC and total SOC. The FTIR-PAS spectra combined with the PLS method was useful for predicting both SOC and POXC. However, SOC and POXC were also highly correlated (R² = 0.84), and because POXC can be seen as a fraction of total SOC, a method for extracting the FTIR-PAS fingerprint of the POXC model that is independent of SOC was applied for the first time. The results showed that the POXC prediction was mainly based on its strong correlation with SOC and there was little information unique to POXC. However, the results do indicate four dominant peaks at 1,574, 1,495, 1,138 and 1,041 cm⁻¹ to be specific for POXC. These peaks can be ascribed to amide II, aromatics, polysaccharides and carbohydrates, respectively.

中文翻译：

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使用傅里叶变换中红外光声光谱识别高锰酸盐可氧化碳的指纹作为不稳定土壤有机碳的量度

高锰酸盐可氧化碳 (POXC) 是不稳定土壤有机碳 (SOC) 的子库，定义为可被高锰酸钾 (KMnO ₄ )氧化的碳 (C )。POXC 含量的测定已被用作测量不稳定 C 的方法，可能与土壤微生物生物量和颗粒有机 C 相关。傅立叶变换中红外光声光谱 (FTIR-PAS) 已用于表征化学成分土壤有机质。当前研究的目的是确定 FTIR-PAS 光谱中 POXC 独有的化学信息，因此与不稳定 C 相关。 FTIR-PAS 用于使用在四个不同国家收集的一组土壤样品表征 SOC（老挝、马来西亚、秘鲁和泰国，n = 575）。偏最小二乘 (PLS) 回归用于将收集的 FTIR-PAS 光谱与 POXC 和总 SOC 相关联。FTIR-PAS 光谱结合 PLS 方法可用于预测 SOC 和 POXC。然而，SOC 和 POXC 也高度相关（R ²  = 0.84），并且由于 POXC 可以被视为总 SOC 的一小部分，因此应用了一种提取与 SOC 无关的 POXC 模型的 FTIR-PAS 指纹的方法。第一次。结果表明，POXC的预测主要是基于其与SOC的强相关性，POXC特有的信息很少。然而，结果确实表明在 1,574、1,495、1,138 和 1,041 cm ^-1处有四个主要峰特定于 POXC。这些峰可分别归因于酰胺 II、芳烃、多糖和碳水化合物。