Characterizing Constituents of Sediment Phosphorus Fractionation in a Freshwater Shallow Lake System

[Objective] This study aimed to characterize constituents of phosphorus(P)fractionation as well as reciprocities among factors in sediments of a freshwater shallow lake. [Method] Surface sediment was discretely sampled at 24 sites through Van Veen grabs. Based on a modified sequential extraction scheme, P fractionation was determined as Fe/Al bound P(Fe/Al-P), Ca bound P(Ca-P), solute and reductive P(S/R-P) and organic P(OP). Curve estimation and Pearson product-moment correlation were employed for statistical analysis. [Result] Total P(TP) content ranged from 443 to 774 mg/kg. Inorganic P(IP) was the major component of TP,of which Ca-P was dominated with an average of 51%±9.7%. Average contents of P fractionation were in the following order: Ca-P(51%) OP(29%) S/R-P(8%) Fe/Al-P(7%). The molar ratio of Fe to P was 11- 20, close to the threshold value of P leaching. [Conclusion] In freshwater shallow lakes, IP and Ca-P were prone to be relatively high, whereas Fe/Al-P was low compared with deep lakes. Occurrence of spatially monotonic gradient indicated the primary causation of anthropogenic sources. Imminent sediment P liberation was also expected. Close associations among TP, Fe/Al-P and Ca-P, implying that anthropogenic P was mainly bound to metals in particulates. Significant correlations of TOC and P fractionation highlighted endogenous mechanism and authigenic origin in sediments.     

烟气中挥发性羰基化合物与卷烟味觉特性相关性研究

[目的]研究烟气中挥发性羰基化合物与卷烟味觉特性的相关性.[方法]通过简单相关分析、偏相关分析和通径分析方法分析了48个烟叶样本中8种挥发性羰基化合物释放量对卷烟味觉特征的影响.[结果]试验表明,甲醛、丙酮、丙烯醛与烟气味觉特征各指标基本都呈显著或极显著正相关,丁醛等与味觉特征没有显著相关性,其中甲醛与苦味,丙烯醛、丙酮与甜味呈良好线性相关,乙醛、丙醛与味觉特征相应显著性指标呈多元线性相关.[结论]研究确定了挥发性羰基化合物对烟气口感特征的影响规律,可为卷烟生产开发更适消费者喜好的产品提供参考依据.     

红葱化学成分与药理活性研究进展

鸢尾科红葱主要含有萘酚、萘醌及蒽醌类成分,具有血管舒张、抗细菌、抗真菌、抗病毒等多种药理作用。文章对国内外有关红葱化学成分及药理活性的最新研究进展进行了综述,为红葱的进一步开发及质量控制研究提供依据。     

异樟不同部位精油成分的气相色谱-质谱比较分析1）

采用气相色谱—质谱（ GC/MS）联用技术和保留指数比较法分析了精油成分,以面积归一化法进行定量分析。结果表明：从异樟叶、新枝、老枝、树干、主根和侧根6个不同部位精油中分别检测出了41、51、51、41、39、39种成分;共检测出了74种物质,包括醇类、烃类、醚类、酮类、酯类、醛类及氧化物类化合物,其中醇类20种、烃类40种、醚类6种、酮类1种、酯类3种、醛类1种及氧化物类3种。它们共有成分有20种,包括7种醇类、7种烃类、3种醚类、1种酮类、1种酯类及1种氧化物类。     

盐水鸭中挥发性风味物质研究进展

盐水鸭因具有独特的风味和较高的营养价值而深受消费者喜爱。挥发性化合物,如脂类及其降解产物,对盐水鸭特征风味的形成具有重要作用。从盐水鸭肉所含的主要挥发性风味成分、挥发性成分的测定方法、加工工艺对挥发性风味物质的影响3个方面综述了近年来盐水鸭特征香味物质的研究进展。     

神农香菊化学成分及药理作用研究进展

介绍了神农香菊主要化学成分的研究成果,比较了花、茎、全草和叶等不同组织中主要活性成分的异同,并综述了其抑菌能力、抗氧化能力以及药用价值的最新研究进展。     

败酱草挥发性化学成分研究

用水蒸气蒸馏法提取白花败酱草挥发油,并用气相色谱-质谱联用仪对白花败酱草挥发油的化学成分进行了分离和鉴定。结果分离并鉴定出51个组分,占峰面积的95.77%,并用峰面积归一化法测定了各成分的质量分数;其主要挥发性成分为:2-甲基-5-乙基呋喃(50.97%),其次是己二硫醚(9.47%)、1-己硫醇(6.97%)、紫苏醛(3.65%)、律草烷-1,6二烯-3-醇(2.65%)、(Z,E)-à-法呢烯(2.62%)、反-石竹烯(2.41%)、亚麻酸甲酯(2.03%)、紫苏醇(1.63%)、邻苯二甲酸二异丁酯(1.43%)、樟脑(1.21%)、à-雪松醇(1.16%)、邻苯二甲酸单-2-乙基酯(1.07%)、冰片(1.06%)、6-氨基异喹啉(1.03%)。     

Chemical Compositions of Volatile Oil from Fruiting Body of Armillaria luteo-virens

The chemical compositions of volatile oil from fruiting body of Armillaria luteo-virens in Qinghai Province were firstly analyzed with GC-MS and its relevant compositions were detected by calculating chromatographic peak area with normalized method.21 peaks were separated and 13 compositions were identified which were mainly unsaturated fatty acids,taking 97.1% of the total volatile oil.     

QTL mapping of volatile compounds in ripe apples detected by proton transfer reaction-mass spectrometry

The availability of genetic linkage maps enables the detection and analysis of QTLs contributing to quality traits of the genotype. Proton Transfer Reaction Mass Spectrometry (PTR-MS), a relatively novel spectrometric technique, has been applied to measure the headspace composition of the Volatile Organic Compounds (VOCs) emitted by apple fruit genotypes of the progeny ‘Fiesta’ × ‘Discovery’. Fruit samples were characterised by their PTR-MS spectra normalised to total area. QTL analysis for all PTR-MS peaks was carried out and 10 genomic regions associated with the peaks at m/z = 28, 43, 57, 61, 103, 115 and 145 were identified (LOD > 2.5). We show that it is possible to find quantitative trait loci (QTLs) related to PTR-MS characterisation of the headspace composition of single whole apple fruits indicating the presence of a link between molecular characterisation and PTR-MS data. We provide tentative information on the metabolites related to the detected QTLs based on available chemical information. A relation between apple skin colour and peaks related to carbonyl compounds was established. The two authors contributed equally to this work.     

Denitrification and fermentation in plant-residue-amended soil

Summary Nitrous oxide production (denitrification) during anaerobic incubation of ground-alfalfa-, red-clover-, wheat-straw-, and cornstover-amended soil was positively related to the initial water-soluble C content of the residue- amended soil. The water-soluble C concentration decreased in all treatments during the first 2 days, then increased in the alfalfa-, red-clover-, and wheat-straw-amended soil until the end of the experiment at 15 days. An accumulation of acetate, propionate, and butyrate was partly responsible for the increased water-soluble C concentration. Denitrification rates were much higher in the alfalfa-and red-clover-amended soil, but NO ₃ ^– was not fully recovered as N₂O in these treatments. Supported by earlier experiments in our laboratory, we conclude that some of the NO ₃ ^– was reduced to NH ₄ ⁺ through fermentative NO ₃ ^– reduction, otherwise known as dissimilatory NO ₃ ^– reduction to NH ₄ ⁺ . Acetate, the primary product of anaerobic fermentation, accumulated in the alfalfa- and red-clover-amended soil in the presence of NO ₃ ^– , supporting previous observations that the processes of denitrification and fermentation occur simultaneously in C-amended soil. The partitioning of NO ₃ ^– between denitrification and fermentative NO ₃ ^– reduction to NH ₄ ⁺ depends on the activity of the denitrifying and fermentative bacterial populations. NO₂ concentration may be a key in the partitioning of NO ₃ ^– between these two processes.