Diffuse-Reflectance Fourier-Transform Mid-Infrared Spectroscopy as a Method of Characterizing Changes in Soil Organic Matter
Diffuse-Reflectance Fourier-Transform Mid-Infrared Spectroscopy as a Method of Characterizing Changes in Soil Organic Matter
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DOI：
10.2136/sssaj2013.04.0131
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发表时间：
2013-09-01
影响因子：
2.9
通讯作者：
Paul, Eldor
中科院分区：
文献类型：
--
作者：
Calderon, Francisco;Haddix, Michelle;Paul, Eldor
漫反射傅里叶变换中红外光谱（MidIR）可以识别土壤有机质（SOM）中重要的有机官能团的存在;然而，光谱解释需要验证，以正确评估SOM质量和数量的变化。我们用已知的标准对土壤进行了修正，将样品中的总C增加了50%，并测量了MidIR光谱的变化。使用腺嘌呤、酪蛋白、纤维素、麦角固醇、葡糖胺、甘氨酸、鸟嘌呤、吲哚、甲硫氨酸、棕榈酸、卵蛋白、叶绿酸、单宁酸、木糖、尿素酶和香草醛标准品。此外，玉米（Zea mays L.）对秸秆原料和两种不同温度下制备的半焦进行了研究。使用两种土壤：Hoytville，OH土壤（2.5% C和36%粘土）和Akron，CO土壤（1.5% C和14%粘土）。添加N含量>10%的标准品导致在1670、1588和1513 cm（-1）处的酰胺样吸光度增加。在2970 - 2800、2200 - 2000和1030 - 1160 cm（-1）处的谱带对加入的多糖敏感。蛋白质的加入增加了2970 - 2800 cm（-1）的吸收，但也增加了1691和1547 cm（-1）的酰胺带。香草醛的加入导致在1592、1515和1295 cm（-1）芳香族C=C谱带处的较高吸光度。在300摄氏度下产生的生物炭导致羰基和脂肪族谱带处的吸光度增加，而添加500摄氏度的生物炭增加芳香族吸光度。我们的研究结果表明，MidIR是敏感的SOM相对较小的变化。如果满足有关土壤矿物学的假设，则可以使用特定的光谱带来跟踪SOM化学的变化。
Diffuse-reflectance Fourier-transform mid-infrared spectroscopy (MidIR) can identify the presence of important organic functional groups in soil organic matter (SOM); however, spectral interpretation needs to be validated to correctly assess changes in SOM quality and quantity. We amended soils with known standards, increasing the total C in the sample by 50%, and measured changes in MidIR spectra. Adenine, casein, cellulose, ergosterol, glucosamine, glycine, guanine, indole, methionine, palmitic acid, egg protein, chlorophyllin, tannic acid, xylose, urease, and vanillin standards were used. In addition, corn (Zea mays L.) stalk feedstock and two chars produced at different temperatures were studied. Two soils were used: a Hoytville, OH, soil (2.5% C and 36% clay) and an Akron, CO, soil (1.5% C and 14% clay). The addition of standards with >10% N content resulted in increased amide-like absorbance at 1670, 1588, and 1513 cm(-1). Bands at 2970 to 2800, 2200 to 2000, and 1030 to 1160 cm(-1) were sensitive to added polysaccharide. Protein addition increased absorption at 2970 to 2800 cm(-1) but also increased the 1691 and 1547 cm(-1) amide bands. Vanillin addition resulted in higher absorbance at the 1592, 1515, and 1295 cm(-1) aromatic C=C bands. Biochars produced at 300 degrees C resulted in increased absorbance at carbonyl and aliphatic bands, while addition of 500 degrees C biochar increased aromatic absorbance. Our results showed that MidIR is sensitive to relatively small changes in SOM. If assumptions about the soil mineralogy are met, specific spectral bands can be used to follow changes in SOM chemistry.