Applications of Raman and Surface-Enhanced Raman Scattering Techniques to Humic Substances

This paper highlights the use of Raman, FT-Raman and surface-enhanced Raman scattering (SERS) techniques for the study of humic substances. In contrast to other technologies which reveal information only about the average compositions and the kinds of functional groups present in humic substances, Raman and especially FT-Raman spectroscopies characterize the building blocks of humic substances and their changes in derivation and separation processes. Furthermore, surface-enhanced Raman scattering (SERS) techniques are able to readily detect humic substances and co-existing organic species at low concentrations typically found in natural environments and reveal definitive information about the specific groups in humic substances that bind on metal electrodes. Further applications of both Raman and SERS techniques can be extended to complicated systems as well as real environmental samples. Experiments have demonstrated: (1). the backbones of humic substances are structurally disordered carbon networks in most cases; (2). The backbones of humic substances from different sources and types are similar to each other; (3). Normal Raman spectroscopic study of humic substances should concentrate on the use of near-IR laser(s) resulting from strong fluorescence background and self-adsorption under the excitation with visible laser irradiation; (4). FT-Raman spectroscopy is the required analytical method to assess the effectivity of fractionation methods; (5). SERS spectra of humic substances on metal colloids and films are in most aces very similar to the corresponding Raman spectra of neutralized samples; (6). SERS techniques are very sensitive and highly selective, also both visible lasers and near-IR lasers can be used for SERS study; (7). SERS spectra on metal electrodes may provide additional information about the binding sites and adsorption mechanisms of humic substances on metal surfaces.     

猪粪堆肥过程中水溶性有机物结构演变特征

水溶性有机物(DOM)所在的固-液交界面是化学反应和微生物活动最活跃的部分。DOM中存在具有氧化还原作用的含氧芳香性官能团,使得DOM能影响有机污染物和重金属污染物迁移与转化。堆肥物料猪粪含有丰富且有利于微生物生长的氮元素,其DOM结构变化可能具有一定的独特性。本研究选取8个不同阶段的猪粪堆肥样品,提取其中的DOM,利用紫外-可见光光谱和三维荧光光谱等现代光谱学方法,并结合基础理化指标解析猪粪堆肥DOM的结构和组分演变特征。在堆肥过程中可溶性有机碳和总有机碳分别降低了58.88%和16.30%,说明可溶性有机碳的降解速率要高于不可溶性有机碳。紫外-可见光光谱特征值SUVA₂₅₄,SUVA₂₈₀和E₂₅₃/E₂₀₃均随着堆肥过程呈现出逐渐增加的趋势,表明堆肥过程DOM芳香性升高,大分子有机质含量增大,芳环取代基中含氧基团增多。基于三维荧光光谱体积积分中类酪氨酸、类色氨酸和微生物代谢产物的百分比分别从15.96%,18.14%和25.45%降低至5.53%,11.27%和17.96%,而类胡敏酸和类富里酸的百分比则分别从17.67%和22.77%增加至20.62%和44.62%,这一方面是由于DOM中各有机质组分中类蛋白物质降解速率比类腐殖质物质快,另一方面是由于随着堆肥进行一部分类蛋白物质会转化为类腐殖质物质。研究结果可为调控生产稳定化、无害化的堆肥产品提供科学依据。     

复合污染旱田黄土中还田秸秆动态腐解的光谱学特性

秸秆是农业生产的重要副产物,其资源化再利用一直是国内外学者关注的热点。目前,秸秆还田已成为秸秆资源化利用的主要途径之一。还田秸秆能在合适的土壤环境和土壤微生物的作用下腐烂分解,将腐殖质和矿质元素等组分释放进入土壤体系。这不仅能改变土壤固有的肥力属性,对于土壤重金属污染物的环境化学行为也将产生一定影响。实验土壤采集于西部典型黄土区,采用SEM-EDS、元素分析、FTIR和13C NMR等光谱联用技术,研究复合污染黄土中还田秸秆腐解残体的表面特性及生成胡敏酸性质差异。实验结果表明：在秸秆还田全程,秸秆腐解残体呈现出“结构致密→表面崩解→骨架破坏”的表面形貌动态变化特性,EDS检测结果揭示了腐解残体元素组成的变化行为。新生成的胡敏酸脂族性较高、芳香性较低,属于较“新鲜”和“年轻”的胡敏酸,有利于提高黄土有机质活性。秸秆腐解各阶段FTIR图谱具有很高的相似性,波峰的变化揭示了胡敏酸生成过程的复杂性。13C NMR结果说明胡敏酸芳香性逐渐降低、脂族性不断增加,证实了胡敏酸分子结构的简单化趋势。光谱联用技术对于揭示黄土区秸秆还田过程胡敏酸的性质差异是可行的。     

地表水总有机碳含量紫外-可见光谱检测方法

总有机碳是以碳含量评价水质有机污染的指标,可以反映水体受污染程度。目前地表水总有机碳检测多采用现场取样后实验室分析检测方法,该方法存在费时费力、操作复杂、二次化学污染等缺点。紫外-可见光谱法具有环保、操作简便、可实时在线原位检测等优点,在地表水总有机碳检测中具有很好的应用前景。针对总有机碳检测问题,采用了一种基于自适应增强学习的区间偏最小二乘回归方法,该方法将总有机碳吸收光谱波段分为若干子区间,初始化训练样本权重, 依次在各子区间建立偏最小二乘回归模型,根据子区间模型预测误差率计算该子区间预测结果的权重系数,并更新下一子区间训练样本权重,最后将各子区间模型预测结果线性加权得到总有机碳的检测结果。实验配制总有机碳标准溶液浓度25～150 mg·L-1共43个样品,第一时间段采集35个总有机碳标准样品光谱分为训练集和测试集,建立并验证总有机碳检测算法模型。为评价算法模型鲁棒性,在另一时间段采集剩余的8个标准样品光谱进行反测验证。实验结果表明,采用基于自适应增强学习的区间偏最小二乘回归法建立的总有机碳定量模型具有较高的精度和鲁棒性,分组验证和反测验证的预测均方根误差分别为1.304和1.533 mg·L-1,均优于偏最小二乘回归和极限学习机方法。为进一步验证该方法的有效性,使用该建模方法预测生活污水的总有机碳含量。实际地表水样本取样于河北石家庄藁城污水处理厂排污口污水及河北先河公司园区的生活污水,经稀释后共获得50组地表水样本,采用SPXY方法分为训练集33组水样,测试集17组水样。在实际水样检测中,采用净信号分析方法进行光谱预处理,降低总有机碳与其他水质参数间的交叉干扰;分组验证预测均方根误差为3.26 mg·L-1,平均绝对值百分比误差为3.46%。综上所述,基于自适应增强学习的区间偏最小二乘回归方法,可以快速准确地对地表水中总有机碳进行检测,为在线水质总有机碳检测提供了方法支撑。     

施加有机肥对农田有机质和氮素演化影响的光谱学分析

施用有机肥是改善土壤物理结构、提升土壤肥力、调控养分平衡的的有效手段之一，但目前有机肥施用对农田有机质和氮素演化的影响尚不清楚。研究了施入有机肥后土壤总有机碳(TOC)、可溶性有机碳(DOC)、无机氮含量的变化特征，并利用三维荧光光谱分析了施加有机肥后土壤DOM光谱学特性的变化规律，结合PARAFAC分析法分析了施加有机肥后不同时期土壤水溶性有机物(DOM)各组分相对含量的变化，利用2D-COS技术分析各荧光组分随时间的变化顺序，此外采用典型相关度分析法研究了DOM各组分相对含量与土壤氮素的响应关系，以探究施入有机肥对土壤有机质和氮素演变的影响。结果表明：①施加有机肥提高了土壤总有机碳、水溶性有机碳和硝态氮含量，降低了铵态氮含量；②土壤DOM三维荧光光谱图出现了A峰（UV类腐殖酸）、M峰（UVA类腐殖酸）、T峰（类色氨酸），PARAFAC分析结果显示试验土壤DOM主要由陆地源类腐殖酸（C1）、典型类腐殖酸(C2)、类色氨酸(C3)组成。结果还显示，施加有机肥能提高土壤C1，C2和C3组分的相对含量，试验期间，施加有机肥处理后土壤C1，C2和C3组分的相对含量均呈现先上升后下降的趋势，第30 d达到最大值，不同荧光组分随时间的变动顺序一般表现为C1和C2组分先增加，然后C1和C2组合降解促进C3形成，为简便起见，可用C1(C2)↑→C3来描述。类腐殖酸变动幅度较大，施加有机肥对类腐殖酸促进作用更为显著；③施加有机肥能提高土壤的生物可利用性，降低土壤腐殖化程度。试验期间，施加有机肥后BIX值呈先上升后下降的趋势，在第30 d达到最大值；HIX值呈先下降后上升的趋势，在第30 d达到最小值。BIX和HIX呈显著负相关（R2=0.732）；④C1，C2和C3相对含量与硝态氮呈正相关，与铵态氮呈负相关，且C1和C2组分的相对含量对硝态氮和铵态氮含量的影响较大。综上所述，合理施加有机肥可调控土壤有机质和氮素转化，减少农田面源污染。     

Isotopengeochemische Charakterisierung kohlenwasserstoffbildender organischer Substanzen

Within the framework of a larger research project on contributions of isotope investigations to natural gas and crude oil exploration, the following publication is a first part of research reports from the author's laboratory.

The isotopic composition of carbon in fossil organic matter is primarily determined by the type of biological precursors. The main constituents forming organic matter in sediments are higher plants and microorganisms (algae, bacteria). These precursors contain a great number of organic compounds with corresponding isotope signatures. Hydrocarbons and lignin e.g., are enriched in carbon 13, while lipids in most cases are depleted.

Semi-empirical calculations on a thermodynamic basis are used to precalculate isotopic compositions of components or single compounds, applying the so-called β-factor method. The results are compared with numerous data from references about isotopic compositions of higher plants, algae and plant components. Also environmental conditions of plant growing-including paleoenvironment-have been taken into consideration.

The δ¹³C values of more than 150 types of organic substances in sediments of several geological formations have been measured in our isotope geochemical department.

The results allow a characterization and classification of organic matter: humic and sapropelitic organic substances can in many cases be distinguished by their isotopic signatures taking into account exceptions of e.g., regional origins. Influences of maturity (characterized by vitrinite reflectance) and especially of macerale composition of organic matter on it's isotope values and on the formation of hydrocarbons including their isotopic compositions are elucidated. The interpretation concept is also assured using special examples of drilling sites in Germany. The obtained results and proposed interpretation concept can contribute to further development in the understanding of hydrocarbon formation and natural gas exploration.     

小麦秸秆堆肥水溶性有机物的结构和组成演变

堆肥是小麦秸秆资源化利用重要的途径之一,然而目前关于秸秆单一物料堆肥的研究较少。水溶性有机物（DOM）被普遍认为是堆肥中最活跃的有机组分,因此探讨DOM的演变特征可有效评价秸秆的腐熟过程。以小麦秸秆好氧堆肥过程中的DOM为研究对象,利用总有机碳、紫外-可见光光谱（UV-Vis）、三维荧光光谱（EEM）结合平行因子（PARAFAC）分析方法,阐明小麦秸秆堆肥过程中DOM的含量、结构和组成的演变特征。结果表明：堆肥过程中DOM的有机碳含量降低了23%,说明DOM是堆肥中活跃的有机质组分。值得注意的是,堆肥前期DOM微生物降解最为剧烈。UV-Vis谱图显示DOM光谱随堆肥进行不断降低,表明堆肥过程芳香族物质不断降解。EEM光谱显示出显著的荧光峰演变趋势,由堆肥前期较强的类蛋白荧光峰（D,E）演变为堆肥后期较强的类腐殖质荧光峰（H）,表明堆肥过程DOM的物质组成发生改变。通过光谱参数SUVA₂₅₄和HIX的观测,发现随着堆肥进行,DOM的芳香度和腐殖化程度呈现动态变化,整体呈增强趋势。由此可推测堆肥过程DOM降解的成分主要为非腐殖质,而腐殖质类物质的相对含量则不断提升、整体芳构化和腐殖化程度增加。EEM-PARAFAC进一步定量分析了DOM组分的演变特征。随着堆肥的进行,DOM中的类蛋白物质（C3）相对含量显著降低（~46%）,而类富里酸（C1）和类腐殖酸（C2）物质相对含量分别提高了45%和80%。DOM中的组成由堆肥初期的C1∶C2∶C3=41∶17∶42演变成堆肥后期的53∶27∶20。结果揭示出堆肥过程中类蛋白物质发生显著的降解,而类腐殖质则由于分子聚合生成作用和微生物降解速率较慢等因素逐渐演变成堆肥DOM的主要组分。相关性分析结果显示HIX与C1和C2均呈现极显著正相关（r=0.806~0.853）,表明腐殖化指数(HIX)可有效指示DOM的腐殖质物质组成。本研究结果可为进一步优化小麦秸秆堆肥条件,改善秸秆有机肥质量提供科学依据。     

Direct Fluorescence Monitoring of Coal Organic Matter Released in Seawater

Whenever immersed in seawater after a collier accident, a fossil fuel such as coal could become a source of pollution to the marine environment. To study the effect of such a contamination, four coal samples from different origins were used. A first analysis on those coals enabled us to determine the content of polycylic aromatic hydrocarbons. Seawater was then mixed with coal to study the organic matter released from coal into seawater. Fluorescence was used for its sensitivity to aromatic compounds, with the additional purpose of evaluating the relevance of using an immerse fluorescence probe to monitor water pollution. Excitation–emission matrices were recorded and the excitation–emission wavelength range corresponding to the highest fluorescence intensity was 230 nm/[370 nm; 420 nm]. The samples with coal happened to fluoresce more than the coal-free samples, the difference depending on the coal origin. The fluorescence intensity increased with coal mass, up to some limit. The particle size also influenced the fluorescence intensity, the finest particles releasing more fluorescing substances, due to their higher exchange surface. When seawater percolated through coal, the samples fluoresced highly at the beginning, and then the fluorescence intensity decreased and reached the seawater level. However, even with a 10 ns acquisition time shift, the fluorescence spectra were not specific enough to show the presence of PAHs in the samples, which were too diluted to be detected, whenever released from coal into seawater. The lifetimes of the seawater and of the coal samples were respectively 4.7 and 3.8 ns, indicating that the substances released from coal mainly consisted of short-lived fluorescing substances, such as natural humic or fulvic substances. Consequently, the presence of coal does not seem to be too detrimental to the marine environment, and a direct fluorescence probe could be used to monitor the seawater organic charge increase due to the immersion of coal in seawater.     

多光谱融合的海洋沉积物碳含量检测

海洋沉积物中碳的变化是衔接海洋生态系统的过去与未来的信息桥梁,揭示了海洋生态过程变化规律。因此开展海洋沉积物碳含量的研究,对掌握海洋生态系统碳循环规律,研究全球碳循环,研究对气候变化的响应和反馈有着重要的作用。光谱技术是一种快速、无损的测量方法,在定量分析中已有很成熟的应用。多光谱融合通过将多个光谱数据结合一起,获得比单一光谱更丰富的信息,有利于物质的分析研究。将多光谱融合应用于海洋沉积物碳含量的研究,以青岛海洋潮间161份沉积物为样品,分别采用海洋光学QE65000光谱仪（光谱仪1）和AVANTES光纤光谱仪AvaSpec-ULS2048（光谱仪2）采集沉积物可见-近红外光谱。将两种光谱仪的光谱进行多光谱融合,分别采用偏最小二乘回归算法（PLSR）和BP神经网络算法（BPNN）建立沉积物碳含量模型。在PLSR沉积物碳含量建模结果中,多融合光谱结果优于光谱仪2,略低于光谱仪1,RPD值为1.968;在BPNN沉积物碳含量建模结果中,多融合光谱结果优于两个单光谱仪,RPD值为2.235。将多光谱融合后的光谱划分多个波段,分别建立沉积物碳含量模型,寻找沉积物碳的特征波段。通过分析多光谱融合各波段模型结果,560～790 nm的建模效果最好,R2_c为0.949,RMSEC为0.550,R2_p为0.874,RMSEP为0.733,RPD值为2.823。预测效果相较于光谱仪1、光谱仪2、多光谱融合全波段都有了显著的提高。因此采用多融合光谱特征波段建立海洋沉积物碳含量模型,能够提高海洋沉积物碳含量的预测结果,建立准确度更高的沉积物碳模型,为沉积物碳的快速测定打下基础。     

Isotopengeochemische Untersuchungen an organischen Substanzen aus Sedimenten der Hilsmulde (Nordwestdeutschland)

Abstract

Model coalification experiments have been carried out using organic matter in sediments from the Hils syncline. In the experiments we wanted to elucidate, to what extent different facies situations can be observed in the investigated region and which conclusions can be drawn regarding the type of originating substances for hydrocarbons adsorbed in drilling cores. As a result of chemical and isotope analyses the organic substances should be characterized not only as pure sapropelites but show in different degree the participation of humic organic matter.

The obtained data of the several evaluation methods used for the characterization of organic matter are in good agreement for the particular samples.     

黑土腐殖酸的近红外光谱测定

研究了我国黑土腐殖酸碳含量及其光化学性质,并探索了利用近红外光谱分析法(near infrared spectroscopy, NIRS)对其进行预测的潜力。针对东北典型黑土带土壤样品,利用偏最小二乘法(PLSr)建立定量模型,并用独立样本对模型进行检验。结果表明,模型对腐殖酸碳、胡敏酸碳和富里酸碳含量的预测效果很好,NIRS对富里酸碳和胡敏酸碳的465 nm(E₄)和预测结果也较好,665 nm光密度(E₆)的预测达到可接受水平。胡敏酸碳和富里酸碳含量与SOC的相关性,高于其与NIRS模型预测值的相关性,二者光化学性质与SOC的相关性则低于其与模型预测值的相关性。NIRS在简化黑土腐殖酸碳、胡敏酸碳和富里酸碳含量和光密度测定领域具有很好的应用前景,且能够反映SOC性质方面的信息。     

不同辅料与生物沥浸深度脱水污泥混合堆肥中溶解性有机质的光谱特征研究

生物沥浸深度脱水污泥为主料,四种农林有机废物为辅料,设4个处理组（T1：污泥+甘蔗渣、T2：污泥+秸秆、T3：污泥+米糠、T4：污泥+木屑）进行混合堆肥,采用紫外-可见光谱(UV-Vis)、傅里叶变换红外光谱(FTIR)和三维荧光光谱(3D-EEM),研究不同辅料堆肥过程中溶解性有机质（DOM）结构特征和组分含量的演化规律。UV-Vis结果显示,四个处理组在堆肥过程中DOM的芳香度和不饱和度皆有所增加,其中T3处理组的增加幅度最大。四个处理组的紫外参数SUVA₂₅₄和SUVA₂₈₀均呈现递增趋势,其中T3处理组的变化幅度高于其他三个处理组,表明芳构化程度加深,DOM分子量逐渐加大;E₂₅₃/E₂₀₃和E₂₅₃/E₂₂₀在堆肥结束时显著增加,表明DOM中苯环上的脂肪链发生氧化分解,转化为羧基羰基等官能团,A_226～400随堆肥进行增加而E₂₅₀/E₃₆₅减小,表明共轭程度增加。FTIR结果表明堆肥过程中多糖类、脂肪族类物质含量在减少,包括带有苯环的芳香族等不饱和有机物在增加,其中T4处理组的转化程度优于其他三个处理组。发射荧光光谱显示荧光峰位置由334 nm红移至422 nm附近,说明共轭程度低的物质不断降解,芳香基团不断缩合,生成结构复杂的类腐殖质物质。同步荧光光谱中代表类蛋白物质的荧光峰随堆肥时间由强变弱,代表腐殖质的荧光峰由弱变强,A_250～308值降低,A_308～360和A_363～500值上升,说明了类蛋白质物质在不断降解而类胡敏酸物质和类富里酸物质含量在上升。结合平行因子（PARAFAC）模型分析四个处理组的三维荧光光谱,将DOM解析为三类荧光组分,根据每个组分所在的激发、发射波长位置分析判断,三类组分分别是类富里酸物质,类胡敏酸物质和类色氨酸物质,且C1（类富里酸物质）和C2（类胡敏酸物质）组分所占百分比呈现增加趋势,C3（类色氨酸物质）组分所占百分比呈现减少趋势,表明类蛋白物质减少而类腐殖质物质增加,其中T3和T4处理组的腐殖化程度较好。综合分析,米糠和木屑作为辅料时堆肥腐熟度更好。     

LASER FLUORESCENCE SPECTROSCOPY AS A METHOD FOR STUDYING HUMIC SUBSTANCE

This paper summarizes the results obtained by fluorescence spectroscopic techniques with conventional and laser light sources for the characterization of the spectral luminescent properties of aquatic humic substances (AHS). The band profiles of corrected absorption, fluorescence emission, and fluorescence excitation spectra are compared in graphical form with unique functions used for the axes. In order to calculate the quantum efficiency of fluorescence, we used the Raman signal from water molecules as an internal reference. The temperature dependence of the fluorescence spectra of humic matter has been recorded in solid (?160°C to 0°C) and in liquid (0°C to +300°C) aqueous solutions. The behavior of the fluorescence band shape is discussed. A new method of nonlinear fluorimetry is proposed to enhance the capabilities of fluorescence spectroscopy. This method is based on the fluorescence saturation effect manifesting itself under powerful laser pumping (excitation) conditions. The use of the technique allows one to determine certain photophysical properties of molecules, as a complement to the normal spectral data. Using three different samples of aquatic humic substances with very similar fluorescence band shapes, it is demonstrated that these compounds have distinct molecular luminescent parameters and therefore, can be identified. The similarity of the fluorescence band shapes of humic substances in natural water of different types; the absence of any noticeable effect of temperature across a wide range and the fluorescence saturation on the fluorescence band contour can be explained. This assumes that in all of the samples of aquatic humic substances studied, with different molecular weight fractions, that there is a single dominant fluorescent functionality present.     

抗酸化微生物复合菌系对餐厨垃圾堆肥腐殖质组分光谱学性质的影响

抗酸化微生物复合菌系（AAMC）通过多种耐酸、嗜酸微生物的协同作用,在克服由于酸化抑制导致的餐厨垃圾堆肥发酵崩溃问题方面效果显著,接种AAMC可明显加速有机物质降解。然而生物堆肥存在有机物彻底降解和碳重新固定（形成稳定的腐殖质类物质）两种途径,有机质降解与腐殖质形成具有互动关系,为腐殖质形成提供原材料。为探究接种AAMC对餐厨垃圾堆肥腐殖质品质的影响,采用树脂柱法进行腐殖质分组,分别研究接种AAMC对富里酸、亲水性组分和胡敏酸3个组分分子结构复杂度和稳定性的影响。设接种组（AAMC）、加碱组（MgO和K₂HPO₄）和自然堆肥组3个处理,采用三维荧光技术（EEM）结合两种定量表征方法区域体积积分（FRI）和平行因子分析（PARAFAC）,实现对富里酸、亲水性组分和胡敏酸3个组分光谱学性质定量表征的准确性和完整性。FRI结果显示,堆肥结束后3个腐殖质组分中表征简单分子结构组分例如羧基或蛋白源结构区域的P_{i, n}值均降低,接种组降低幅度显著大于对照组,降低幅度大小排序为：接种组＞加碱组＞对照组。表征高芳香度和缩聚程度的胡敏酸类物质区域的P_{i, n}值均上升,且接种组上升幅度显著高于其他两处理,上升幅度排序也为：接种组＞加碱组＞对照组。PARAFAC结果显示,富里酸和胡敏酸组分又可分成短波长胡敏酸、长波长胡敏酸和色氨酸或类蛋白类物质3个组分,亲水性组分又可分为短波长胡敏酸、色氨酸和酪氨酸3个组分。堆肥结束后,表征短波胡敏酸和长波胡敏酸组分的F_max升高,而表征色氨酸等类蛋白类物质组分的F_max降低,升高或降低的幅度接种组最高,显著高于加碱组和对照组。综上结果说明接种AAMC可明显促进腐殖质组分子结构复杂化、稳定化,提高腐殖质组分高芳香度和缩聚程度,改善餐厨垃圾堆肥腐殖质品质,利于施用堆肥土壤保水保肥。这可能与AAMC具有高的小分子有机酸降解、转化能力,可规避酸累积对堆肥微生物活性的抑制导致的堆肥腐殖化效率低的问题密切相关。添加化学缓冲剂也能一定程度促进腐殖质组分稳定化、结构复杂化和提高堆肥腐殖化程度。这可能与堆料pH的改善,使得小分子有机酸可被持续降解和转化,有利于堆肥腐殖化进程有关。     

褐煤添加对羊粪有机肥发酵过程中水溶性有机物光谱学变化特征的影响

研究添加褐煤对羊粪有机肥中水溶性有机物(DOM)光谱学特性的影响,为高腐殖酸有机肥的腐熟度评价提供依据。以内蒙古褐煤、羊粪为原料,添加10%褐煤进行羊粪有机肥发酵,对不同阶段有机肥样品的DOM进行紫外可见光谱、荧光光谱、FTIR的表征。紫外-可见吸收光谱分析显示,有机肥样品的E₄/E₆值随着有机肥发酵的进行呈现出先下降后上升的趋势,由有机肥开始时的9.110 4降至最低为4.647 7,再升为有机肥结束时的5.390 1;A₁呈现先减小后增大趋势,A₂和A₃均呈现先增大后减少的趋势,峰值出现在12 d。同步荧光光谱显示,荧光峰光强的比值(I₄₇₀/I₄₃₅) 由有机肥起始的0.452 8上升至有机肥结束的0.655 2;A_HLR/A_FLR呈现上升趋势,从有机肥开始的0.673 9上升至有机肥结束的1.040 8。经过18 d的有机肥发酵后,有机肥发酵结束后样品荧光强度小于有机肥起始时的荧光强度,而且10%褐煤添加的羊粪有机肥的相对荧光强度明显高于未添加褐煤的荧光强度。FTIR显示,18 d的有机肥发酵过程中DOM中的碳水化合物、蛋白质被逐渐分解,而羧基、含苯环的物质含量明显增加。随着发酵的进行,DOM中的非腐殖质物质转化为类腐殖质,不饱和结构的多聚化或联合程度变大,稳定度增加;添加褐煤可以有效促进羊粪中木质素类物质的分解,提高羊粪有机肥DOM的芳构化程度,促进羊粪有机肥腐熟。     

泾渭河交汇区域平水期水体和表层沉积物溶解性有机质的光谱性质

溶解性有机质是环境生态学者关注的典型对象,其对环境质量的指示作用以及修复策略的效果评价具有重要参考价值。现阶段,对于河流和沉积物DOM的研究略显不足,尤其考虑到目标组分的动态差异 (时空、水文、环境、尺度等),相关方面的精细化研究便显得尤为必要。以泾渭河交汇区域(陕西西安高陵段)水体和表层沉积物为研究对象,通过光谱联用技术(元素分析、UV、FTIR、Raman、3D-EEMs和NMR) 深度揭示其微观特征。研究表明：沉积物DOM的H/C和N/C比都高于水体DOM,说明沉积物DOM碳氢饱和度更高,同时含有更多含氮组分。DOM紫外吸光度随吸收波长的增加逐渐下降;水体DOM吸收平台极弱,但沉积物DOM发现较明显的吸收平台(240～310 nm)。DOM含有—OH,CC, C—O等基团,沉积物DOM官能团性质略为复杂,具体体现在峰形和峰强的局部差异上。水体和沉积物DOM的Raman图谱相似,基本无法给予有效的区别信息。水体DOM荧光峰归属为可见光区类色氨酸和紫外区类富里酸,以陆源有机质为主;沉积物DOM荧光峰均属于紫外区类富里酸荧光峰,没有发现类蛋白组分特征峰。水体和沉积物DOM具有类似的C骨架,但沉积物DOM的脂族特性更明显。1H NMR结果表明碳水化合物H含量较高,而芳香族H、γ-H等含量较低。总体认为水体DOM的陆源性更加明显,沉积物DOM组分更为复杂和“年轻”。相关结果有助于深度明晰典型环境体系DOM的微观性质和环境行为。     

内蒙古羊草草原不同管理措施对栗钙土胡敏酸光谱特性的影响

为了研究草原七壤退化与恢复机制,以锡林郭勒盟草原生态定位站长期定位实验为基础,采集了围栏禁牧、轻度放牧与过度放牧等放牧管理措施样地的土壤样品,提取其中的胡敏酸,综合应用元素分析、傅里叶变换红外光谱、固相魔角旋转13C核磁共振谱对放牧和围栏的羊草草原样地表层土胡敏酸的分子结构特征进行了比较分析.研究表明:在围栏禁牧和放牧条件下相比,土壤胡敏酸的分子结构特性存在明显的差异,围栏样地的胡敏酸结构其芳香度明显降低,显示出更高的脂肪族特性,羧酸官能团含量降低.经过围栏样地禁牧恢复的土壤胡敏酸结构中含有更多的来源多糖和蛋白质类母体的结构单元,而不同放牧强度之间胡敏酸的结构组成差异不大.     

长江河口不同分子量溶解有机质的三维荧光光谱特征

应用切向流超滤和三维荧光光谱技术研究长江河口丰水期和枯水期水体中不同分子量溶解有机质的荧光性质,探讨其来源与影响因素。结果表明：长江河口水体存在四种荧光峰,分别是陆源类腐殖酸荧光峰A和海洋来源类腐殖酸荧光峰C、酪氨酸和类蛋白荧光峰B及芳香蛋白荧光峰D。荧光物质主要存在于真溶解有机质(<1 kDa)中,其次是低、中分子量胶体有机质(1～500 kDa)。溶解有机质中蛋白质来源以污染排放的人为源为主,其次是生物活动的内源;在丰水期腐殖酸来源是陆源和内源,在枯水期主要为陆源。真溶解有机质中腐殖酸多来源于生物分解的内源,胶体有机质以陆源为主,可能同时受再悬浮作用影响。荧光峰强与各环境参数均有一定相关性,说明在环境参数对溶解有机质中的荧光物质产生的影响较为复杂多样。     

A new algorithm for NMR spectral normalization.

There is increasing use of high-resolution NMR spectroscopy to examine variations in cell metabolism and/or structure in response to numerous physical, chemical, and biological agents. In these types of studies, in order to obtain relative quantitative information, a comparison between signal intensities of control samples and treated or exposed ones is often conducted. The methods thus far developed for this purpose are not directly related to the overall intrinsic properties of the samples, but rather to the addition of external substances of known concentrations or to indirect measurement of internal substances. In this paper, a new method for quantitatively comparing the spectra of cell samples is presented. It depends on a normalization algorithm which takes into consideration all cell metabolites present in the sample. In particular, the algorithm is based on maximizing, by an opportune sign variable measure, the spectral region in which the two spectra are superimposed. The algorithm was tested by Monte Carlo simulations as well as experimentally by comparing two samples of known contents with the new method and with an older method using a standard. At the end, the algorithm was applied to real spectra of cell samples to show how it could be used to obtain qualitative and quantitative biological information.     

Evaluation of spectral pretreatments,spectral range,and regression methods for quantitative spectroscopic analysis of soil organic carbon composition

Although there is an increasing interest in using infrared spectroscopy for the simple, rapid, and inexpensive prediction of soil organic carbon content, few studies have used this technique to measure organic carbon chemistry. In this paper, based on both near-infrared and mid-infrared diffuse reflectance spectroscopy, we compared the use of instrumentation, spectral pretreatment, and regression method for the prediction of three parameters related to organic carbon content, one related to isotopic composition, and five related to organic carbon chemistry. A total of 140 soil samples collected from seven oriental oak forest sites across East China were used as the data set for the calibration-validation procedure. Calibrations using sample set partitioning based on joint x-y distances method significantly outperformed those using Kennard-Stone method. Compared to models using linear method (i.e., partial least squares), those using non-linear regression method (i.e., support vector machines) greatly improved the prediction precision of the alkyl-to-O-alkyl ratio and performed slightly better for the other organic carbon chemical compositions. Instrumentation had a large effect as mid-infrared models had higher average prediction accuracies than near-infrared models. We finally proposed a model using second derivative preprocessing, joint x-y distances based sample set partitioning, mid-infrared spectra, and support vector machines regression to quantify organic carbon chemistry in this study. The results are helpful for the further study of soil composition measurement.