黄土的红外反射光谱与红外光声光谱特征及其差异研究

红外光谱法作为一种新的研究手段已经广泛应用于土壤分析,由其检测区域和手段的不同又可分为多种光谱类 型。本研究以第四纪黄土为例,系统地比较了近红外区和中红外区反射光谱和光声光谱的吸收特征及其差异。结果表明,中红外光谱比近红外光谱的信息更为丰富,且中红外光谱与样品中物质的特征吸收关系更加密切,从而更有利于土壤定性与定量分析。土壤的反射光谱和光声光谱表现出了明显不同的特征,在近红外区,反射光谱和光声光谱吸收明显不同,而在中红外区,反射光谱和光声光谱具有相对应的吸收,但相对吸收强度明显不同,且吸收峰的位置也发生改变,尤其在1 000 ~ 2 000 cm-1谱区,反射光谱相互干扰很强,而光声光谱的吸收特征更为明显。在黄土的分类鉴别上,反射光谱优于光声光谱。红外反射光谱和光声光谱在不同波段下具有不同的吸收灵敏度,在土壤定性与定量分析中各自都将具有其明显的优势。     

应用拉曼和中红外衰减全反射光谱测定溶液和土壤中的硝酸盐

为比较拉曼光谱和红外光谱在溶液和土壤中硝酸盐含量定量分析的适用性,采用两种光谱对溶液和土壤中的NO3–-N含量(0~200 mg/L)进行快速测定。结果表明,溶液中硝酸盐的拉曼特征峰在1 047 cm–1处,该特征峰强度与NO3–-N浓度成正比,对1 035~1 060 cm-1波段拉曼光谱峰面积和NO3–-N含量进行线性回归,决定系数R2为0.995 4;溶液中硝酸盐的中红外衰减全反射光谱特征吸收峰在1 350 cm–1,吸收峰与NO3–-N含量成正比,特征吸收区1 200~1 500 cm–1峰面积与NO3–-N含量的决定系数R2为0.991 1,表明两种光谱都可用于溶液中硝酸盐的测定。对于土壤样品,红外光谱在1 250~1 500 cm–1处有硝酸盐吸收峰,且吸收峰与NO3–-N含量成正比,峰面积与NO3–-N含量之间的决定系数R2为0.968 4;而对于拉曼光谱,硝酸盐的拉曼峰因受较强干扰导致吸收峰不明显,峰面积与NO3–-N含量之间的决定系数R2仅为0.000 9,表明中红外衰减全反射光谱可用于土壤中硝酸盐的测定,而拉曼光谱则很困难。因此,拉曼光谱和中红外衰减全反射光谱都可用于溶液中硝酸盐的测定,且前者灵敏度要高于后者;中红外衰减全反射光谱可用于土壤中硝酸盐的测定,而拉曼光谱难以用于土壤中硝酸盐定量分析,这为硝酸盐的快速测定提供理论依据和技术支持。     

Cd对小白菜萌发生理影响的FTIR-ATR研究

应用傅立叶变换-衰减全反射红外光谱（FTIR-ATR）分析方法,用在一定浓度（0.0、0.1、0.5、1.0、5.0mg·kg-1）Cd胁迫下萌发3d的小白菜做试验材料,揭示了小白菜幼芽和幼根中蛋白质、碳水化合物的含量以及蛋白质二级结构对Cd胁迫的不同响应。结果表明,Cd处理导致幼根和幼芽1632cm-1和1030cm-1吸收峰强度显著增强,且1632cm-1峰的波数降低,说明蛋白质、碳水化合物含量增高以及蛋白质二级结构保持稳定,是小白菜种子萌发过程中抵御Cd毒害的重要原因。幼根FTIR谱未出现1710cm-1峰,说明分泌有机酸螯合Cd并非种子萌发初期幼根抗Cd毒机制。幼根中碳水化合物吸收峰强度,随着Cd处理浓度的增加增大,而幼芽中则先减小后增大,说明幼芽（主要为子叶）中的糖类转运至根部,以提高对Cd的耐受性。FTIR谱主要吸收峰强度与生理指标之间的相关性分析结果表明,小白菜幼根FTIR谱中主要吸收峰的强度与根长、超氧化物歧化酶（Superoxide Dismutase,SOD）活性、丙二醛（Malondial dehyde,MDA）含量等指标之间显著相关。以上结果说明FTIR-ATR法可用于植物对Cd胁迫的...     

基于FTIR和聚类分析的白木香内生真菌鉴别

基于表型和基因型的真菌鉴定方法耗时又苛刻,应用傅里叶变换红外光谱(FTIR)建立一种真菌快速筛选、鉴别的方法。确定了白木香内生真菌红外谱图3000～2800 cm-1, 1800～1500 cm-1及1200～900 cm-1等3个分析灵敏区。根据分析灵敏区的差异性使菌株得到较准确的归类,聚类分析方法用于不同种间的分类鉴别,并与菌株ITS rDNA的亲缘性分析进行比对验证。结果表明,根据光谱峰值、峰位及吸收强度鉴别真菌,系统聚类分析方法能更科学合理地鉴别白木香内生真菌种间的相似度,但不适合反映真菌遗传亲缘关系。傅里叶红外变换光谱具有快速、准确、方便等优点,其结合多元分析方法可用于真菌的快速筛选研究。     

基于红外光谱特点的南五味子鉴别

为建立南五味子快速鉴别方法,用粉末直接压片法测定南五味子、五味子对照药材、市售药材及2种自采样品粉末的红外光谱,利用软件绘制红外光谱并进行分析比较,计算400～4000 cm-1范围内不同区域的红外光谱的相似性、观察吸收峰数量及峰形.结果表明,南五味子固体粉末在500～900 cm-1处的红外光谱相似性和1000～17...     

厌氧和好气条件下油菜秸秆腐解的红外光谱特征研究

采用尼龙网袋法,研究了油菜(Brassica campestris L.)秸秆在厌氧和好气条件下的腐解规律及其红外光谱特征。结果表明:油菜秸秆还田后,腐解速率表现为前期快、后期较慢的规律。在360 d培养时间内,厌氧和好气条件下的油菜秸秆腐解率分别为60.50%和68.20%,腐解速率常数(k)分别为0.004-d-1和0.010-d-1,腐解1/2时所需时间分别为229 d和117 d。在厌氧和好气条件下,油菜秸秆的碳释放率分别为70.33%和77.43%,厌氧条件下的释放速率常数(0.025-d-1)低于好气条件(0.026-d-1)。油菜秸秆中氮的释放率分别为82.20%和87.48%,油菜秸秆在厌氧条件下的氮残留量比其在好气条件下高38.25%,且达到显著性差异水平(P0.05)。厌氧条件下的氮残留率始终高于好气条件下,且在60~90 d培养期内差异最大。红外图谱分析显示,油菜秸秆腐解过程最明显的变化在波数为3 430~3 410 cm-1、2 930 cm-1处,吸收峰吸收强度降低,表明油菜秸秆的脂族性下降。在波数为1 740 cm-1、1 419~1 425 cm-1处的吸收峰吸收强度降低,表明油菜秸秆木质素含量下降,且厌氧条件下的吸收强度高于其在好气条件下,表明厌氧条件的木质素残留较多。结果表明,油菜秸秆中羟基、甲基、亚甲基含量随腐解时间延长而降低,碳水化合物减少,脂族性下降,芳构化程度增强。好气条件有利于秸秆中纤维素、半纤维素和脂肪族化合物的分解,提高其芳香性,对土壤碳、氮的补充作用更大。     

傅立叶变换中红外光谱估测水稻叶片氮素含量的研究

通过不同氮素水平的水稻田间试验,在分析测定了水稻叶片叶绿素、氮素等农学参数后,采用傅立叶中红外光谱仪测定了水稻孕穗期叶片干样的透射光谱,利用协同偏最小二乘算法（siPLS）分析选取了傅立叶变换红外光谱估测水稻氮素含量的敏感波段及其组合。结果表明,其最优主成分数是9个,最佳估测建模的波段组合分别为1350.89～1586.57, 1587.53～1822.40 和 3709.41～3943.72 cm-1;建立的水稻氮素预测模型的精度较高,交互验证均方根误差（RMSECV）和预测均方根误差（RMSEP）分别为0.1538和0.1933,预测值与化学分析获得的叶片总氮浓度之间的交互相关系数和独立检验相关系数分别为0.9393和0.6649,高于中红外光谱指数NFS和NFSA的预测精度。说明利用傅立叶红外光谱作为水稻氮含量的诊断技术是可能的,值得进一步验证和完善。     

不同傅里叶变换红外光谱法研究土壤光谱特征的比较与应用

为了将傅里叶变换红外光谱技术更好地应用于土壤中官能团的定量分析,通过比较3种不同傅里叶变换技术下土壤特征吸收峰的差异,来选取最佳的光谱技术应用于土壤的相关研究。采用透射(T-FTIR)、衰减全反射(ATR-FTIR)和漫反射(DR-FTIR)3种光谱技术分别对有机物(苯甲酸、硬脂酸)和土壤(辽东栎)进行了分析。并将辽东栎和草地土壤样品按不同比例混合,使用T-FTIR和DR-FTIR对混合土样进行光谱测定,用于定量分析研究。结果表明:(1)有机物样品在3种光谱技术中均出现特征吸收峰,苯甲酸在1 600～1 400 cm^-1出现苯环C=C骨架特征峰,硬脂酸在2 900～2 800 cm^-1显现甲基的特征峰。有机物中羧酸-COOH内羰基-C=O在1 720～1 680 cm^-1出现伸缩振动吸收峰,羟基-OH分别在1 430～1 410 cm^-1,940～930 cm^-1附近出现面内和面外弯曲振动吸收峰。有机物在T-FTIR技术中需要用溴化钾(KBr)对其稀释。(2)辽东栎土壤样品在T-FTIR和DR-FTIR技术测试中发现,其土壤谱图中有较多有效特征吸收峰,土壤样品在T-FTIR技术中也需要用KBr进行稀释并使样品均匀的分布在锭片中; 而ATR-FTIR技术测试中仅出现个别有效特征吸收峰,不利于对土壤谱图鉴别与进一步分析。(3)辽东栎和草地土壤样品按不同比例混合的测试结果表明:T-FTIR和DR-FTIR技术测试中质量分数与峰面积比呈正相关,线性拟合分别为R²=0.70和R²=0.88。土壤在3种不同红外技术中,DR-FTIR光谱具有较好的土壤特征吸收峰,对土壤样品可以不用KBr稀释。测试步骤简单易操作,可用于土壤样品定量分析研究。     

我国不同产地黑茶的FTIR指纹图谱分析

采用傅立叶变换红外光谱法,比较了我国6个不同产地来源的37个黑茶样品间红外吸收光谱的差异,并对所得的指纹图谱进行了特征峰的指认和对比分析。方法的精密度、重现性和稳定性良好。结果表明,37个黑茶样品有16个共有峰;不同产地的黑茶样品由于原料和具体加工工艺的差异,所含化学成分及相对含量不同,在1800 cm-1~700 cm-1波段范围中吸收峰的数目、强度等存在一定的差异,根据红外二阶导数谱的相似度和聚类分析可区分不同产地的黑茶样品。该研究为对我国不同产地黑茶的鉴别和质量控制提供了参考。     

基于中红外漫反射光谱法预测黄土碳酸钙含量

以黄土高原侵蚀严重的丘陵沟壑区7个小流域126个土壤样品和108个沉积泥沙样品为对象,分析了土壤的基本属性及其中红外漫反射光谱特征,将中红外漫反射光谱技术与化学计量法相结合,采用不同的光谱预处理方法,分别利用偏最小二乘回归法、主成分回归法和支持向量机回归法建立土壤碳酸钙的光谱估算模型,并对模型进行验证。结果显示:土壤光谱变量与碳酸钙含量的关系更接近线性相关,偏最小二乘回归法和主成分回归法要优于支持向量机回归法,其中PLSR(SG-Der1st)模型为最优,对土壤(决定系数R~2=0.948,相对分析误差RPD=4.426)和沉积泥沙(决定系数R~2=0.875,相对分析误差RPD=2.841)均能准确预测其碳酸钙含量。研究结果表明,基于中红外漫反射光谱的碳酸钙含量估算模型能准确定量土壤及沉积泥沙碳酸钙含量,实现了对黄土高原小流域土壤碳酸钙的快速无损测量。     

An attempt to differentiate Pseudomonas spp. and other soil bacteria by FT-IR spectroscopy

Pseudomonads are ubiquitous bacterial inhabitants of soil and surface water with a variety of metabolic capacities. The isolation and identification of these bacteria is often required. A variety of methods have been employed to confirm the presence of Pseudomonads in different environments. In our experiments we tested the usefulness of infrared signals which deliver fingerprint like patterns that could be used for probing the presence and perhaps also the identity of these bacteria. If cultivated in a minimum nutrient broth, Pseudomonas aeruginosa, Pseudomonas fluorescens, Pseudomonas putida, and Pseudomonas stutzeri delivered well differentiated IR spectra in the following waverange: 3300 cm^–1 for nucleic acids structures, 3000–2800 cm^–1 for cell membrane fatty acids, 1800–1500 cm^–1 for cell proteins, 1500–1400 cm^–1 for fatty acids, 1500–1200 cm^–1 for proteins and phospholipids, 1200–900 cm^–1 for glycopeptides and phosphate groups of nucleic acids constituents, 900–550 cm^–1 for less defined cell constituents. However, the spectra of the individual species resembled each other. Some differences in the intensity of the individual bands were observed between IR spectra obtained by either the absorption/transmission (A/T) or the attenuated total reflectance (ATR) scanning techniques. Alterations in the composition of nutrient broth resulted in changes of the absorption ratios between the 2925 cm^–1 and 1658 cm^–1 bands (fatty acids:proteins), and between the 1656 cm^–1 and 1080 cm^–1 bands (proteins:peptidoglycans/polysaccharides). Some minor differences were observed between freshly harvested and starved cell biomass. Although less laborious and time consuming the FT–IR spectroscopy seems not sensitive enough to become a useful  tool in a differentiation of Pseudomonas spp.     

红外光谱在土壤学中的应用

红外光谱技术在土壤学中已得到较广泛的应用,它能够综合地反映土壤体系的物质组成及其相互作用,为研究土壤中物质循环及其作用过程提供了新的手段。本文回顾了近年来红外光谱技术在土壤学中的应用,包括透射光谱在土壤定性分析中的应用,并重点介绍红外反射光谱与化学计量学相结合的光谱建模技术发展情况及其在土壤定量分析中的应用。同时本文探讨了基于光声效应的红外光声光谱技术,红外光声光谱非常适合用于土壤这种复杂、非透明体系的研究,能够克服传统透射和反射光谱中存在的缺陷,测定快速方便,并具有较高的灵敏度和测量精确度,具有很大的应用潜力。     

Identification of agricultural Mediterranean soils using mid-infrared photoacoustic spectroscopy

This study investigated the use of Fourier transform infrared photoacoustic spectroscopy (FTIR-PAS) for rapid identification of agricultural soil samples. The PAS spectra of 166 air-dried samples belonging to five Mediterranean soil types most common in Israeli agriculture were recorded. The various soil types exhibited distinctive mid-IR bands, especially around the 2900–3700 cm^? 1, 2500–2550 cm^? 1, 1800–2050 cm^? 1 and 900–1600 cm^? 1 regions. Following smoothing and normalization of the spectra, principal component analysis (PCA) was used to reduce the dimensionality of the data and the PCA scores were used in classifiers based either on linear discriminant analysis or on probabilistic neural networks. The two classifiers based on four PCA scores yielded very similar results and correctly identified over 96% of the 77 validation samples. Comparison with the attenuated total reflectance (ATR) spectra of similar soils used in a previous study showed that the PAS spectra contained more information than the ATR ones, both in terms of the number of soil-specific bands and in terms of the bands' distinctiveness. The results clearly show that FTIR-PAS can be used for rapid soil identification and the abundance of information in the PAS spectra indicates that this technique could be further developed to assess important soil features.     

基于近红外光谱的土壤全氮含量估算模型

土壤全氮是诊断土壤肥力水平和指导作物精确施肥所需的重要信息,建立土壤全氮的近红外光谱估测模型并对建模波段进行优化选择对于土壤养分信息快速获取和精确农业发展具有重要意义。该研究以中国中、东部地区5种主要类型土壤为研究对象,利用近红外光谱仪采集土壤样品的光谱信息,结合近红外区域分子振动特点选取全谱、合频、一倍频、二倍频和N-H基团及其组合的8个波段,采用多元散射校正等多种预处理方法组合进行处理,结合偏最小二乘法(PLS)对每个波谱区域进行定标建模。结果表明,利用4000～5500cm-1波谱区域结合附加散射校正处理过的原始光谱建立的模型精度表现最好,其内部互验证决定系数达到0.90,均方根误差为0.16。经不同类型土壤的观测资料检验,模型验证决定系数为0.91,均方根误差为0.15,相对分析误差RPD为3.40,表明模型具有极好的预测能力。因此,利用近红外光谱可以实现土壤全氮的快速估测,且以合频波段(4000～5500cm-1)为建模区域可以得到更好的预测效果。     

Description of Chemical Changes Implied During Bread Dough Mixing by FT‐ATR Mid‐Infrared Spectroscopy

The aim of the present study was to investigate the ability of mid‐infrared (MIR) spectroscopy to identify physicochemical changes in the French bread dough mixing process. An ATR FT‐MIR spectrometer at 4000–800 cm^–1 was used. The MIR spectra collections recorded during mixing were analyzed after standard normal variate using principal component analysis (PCA) and after second‐derivative treatment. The results were interpreted in terms of chemical changes involved in dough development and more particularly in terms of secondary structural protein changes (amide III). The loading spectrum associated with principal component 1 (PC1) allows three MIR wave number regions of variations (3500–3000, 1700–1200, and 1200–800 cm^–1) to be identified. The loading spectrum associated with PC1 describes an increase in the relative protein band intensities and a decrease in relative water and starch band intensities. The variation during bread dough mixing time of the different amide III bands identified after the second‐derivative show that α‐helical, β‐turn, and β‐sheet structures increase while random coil structure decreases, suggesting that the gluten structure is becoming a more ordered structure. The MIR mixing time identified as being the maximum scores value on the PC1 scores plots was associated with the time at which the dough apparent torque begin to collapse, suggesting that the MIR spectroscopy could monitor bread dough development.     

Interpretation of infrared spectra for OM characterization of soil structural surfaces of Bt‐horizons

The surfaces of macropores or aggregates can act as hot spots for biogeochemical processes and solute transport during preferential flow. For the characterization of organic matter (OM) at macropore surfaces non‐destructive methods have been applied such as diffuse reflectance infrared Fourier transform spectroscopy (DRIFT). However, effects of organic components on DRIFT signal intensities are often difficult to distinguish from those of mineral components. Here, DRIFT spectra from intact earthworm burrow walls and coated cracks were re‐evaluated to improve the interpretation of C–H and C=O bands. We compared DRIFT and transmission Fourier transform infrared (FTIR) spectra of entire samples that were from the same pedogenetic soil horizon (Bt) but different in mineral composition and texture (i.e., glacial till vs. loess). Spectra of incinerated samples were subtracted from the original spectra. Transmission FTIR and DRIFT spectra were almost identical for entire soil samples. However, the DRIFT spectra were affected by the bulk mode bands (i.e., wavenumbers 2000 to 1700 cm^?1). These bands affected spectral resolution and reproducibility. The ratios between C–H and C=O band intensities as indicator for OM quality obtained with DRIFT were smaller than those obtained from transmission FTIR. The results demonstrated that DRIFT and transmission FTIR data required separate interpretations. DRIFT spectroscopy as a non‐destructive method for analyzing OM composition at intact surfaces in structured soils could be calibrated with information obtained with the more detailed transmission FTIR and complementary methods. Spectral subtraction procedure was found useful to reduce effects of mineral absorption bands. The improved DRIFT data may be related to other soil properties (e.g., cation exchange capacity) of hot spots in structured soils.     

基于漫反射光谱的茶园土壤硝态氮检测

该文研究了充分利用土壤漫反射光谱在可见-近红外波段的有效信息,研究快速准确检测土壤硝态氮含量的新方法。试验选取89个风干土壤样本,经粉碎过直径1 mm筛孔后,使用 FieldSpec 3便携式光谱仪（光谱波长范围：400～2 500 nm）,获取其漫反射光谱。检查各土样的原始光谱的有效性并进行平均,经偏最小二乘法partial least squares（PLS）聚类分析后,选取其中的63个样本构成校正集建立模型,10个样本构成预测集进行模型验证。通过一阶微分与滑动平均滤波相结合的预处理方法,用15个主成分建立的主成分+神经网络模型为最好,其校正模型的回判相关系数为0.9908,均方根误差（RMSEC）为1.4528,预测模型的相关系数为0.7179。研究结果表明,利用可见-近红外光谱技术可以准确地检测茶园土壤硝态氮含量。     

反射光谱估算滨海土壤黏粒含量

探明反射光谱估算土壤黏粒含量的成因是实现黏粒含量测定、提高估算精度的基础。该文以江苏省滨海平原的150个土壤样品为研究对象,将测得的原始光谱数据进行平滑、一阶导数、连续统去除和倒数等数据变换,采用逐步多元线性回归(stepwise multiple linear regression,SMLR)和偏最小二乘回归(partial least squares regression,PLSR)方法估算黏粒含量,并在此基础上分析建模的影响波段,探讨反射光谱估算土壤黏粒含量的成因。结果表明,连续统去除光谱数据的SMLR分析估算精度最高,建模集和验证集决定系数分别为0.941和0.750。360~900、1 800~2 490 nm是黏粒含量的重要建模影响波段,该建模影响波段主要包括铁离子(410 nm附近)、土壤有机质(500~800 nm)、层状硅酸盐中的结晶水(1 900 nm附近)、绿泥石和蛭石等黏土矿物(2 325 nm)的吸收特征波段;PLSR分析表明,1 400 nm附近回归系数出现的双峰特征源于高岭石的双峰吸收。黏粒中的黏土矿物、黏粒对铁离子的吸附特性以及黏粒与有机质的高度相关性是实现反射光谱估算滨海土壤黏粒含量的原因。