Paddy soils are classified as wetlands which play a vital role in climatic change and food production. Soil carbon (C), especially soil organic C (SOC), in paddy soils has been received considerable attention as of recent. However, considerably less attention has been given to soil inorganic carbon (SIC) in paddy soils and the relationship between SOC and SIC at interface between soil and the atmosphere. The objective of this research was to investigate the utility of applying Fourier transform mid-infrared photoacoustic spectroscopy (FTIR-PAS) to explore SOC and SIC present near the surface (0–10 µm) of paddy soils. The FTIR-PAS spectra revealed an unique absorption region in the wavenumber range of 1,350–1,500 cm−1 that was dominated by C-O (carbonate) and C-H bending vibrations (organic materials), and these vibrations were used to represented SIC and SOC, respectively. A circular distribution between SIC and SOC on the surface of paddy soils was determined using principal component analysis (PCA), and the distribution showed no significant relationship with the age of paddy soil. However, SIC and SOC were negatively correlated, and higher SIC content was observed near the soil surface. This relationship suggests that SIC in soil surface plays important roles in the soil C dynamics.
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机译：稻田土壤被归类为湿地，在气候变化和粮食生产中起着至关重要的作用。近年来，水稻土中的土壤碳（C），特别是土壤有机碳（SOC）受到了相当大的关注。但是，对水稻土中土壤无机碳（SIC）以及土壤与大气之间的界面上SOC与SIC之间关系的关注却很少。这项研究的目的是研究应用傅里叶变换中红外光声光谱法（FTIR-PAS）来研究稻田表面（0-10 µm）附近的SOC和SIC。 FTIR-PAS光谱显示在1,350–1,500 cm -1 的波数范围内有一个独特的吸收区域，该区域主要受CO（碳酸盐）和CH弯曲振动（有机材料）的影响，并且使用了这些振动分别代表SIC和SOC。利用主成分分析法（PCA）确定了水稻土表面SIC和SOC之间的圆形分布，且该分布与水稻土年龄没有显着关系。但是，SIC和SOC呈负相关，并且在土壤表面附近观察到更高的SIC含量。这种关系表明土壤表面的SIC在土壤碳动力学中起重要作用。
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