矿物流体包裹体中的羧酸     

曾贻善  刘家齐 《矿物岩石地球化学通报》1997,(1)

矿物流体包裹体中的羧酸曾贻善刘家齐（北京大学地质系，北京１００８７１）（地矿部宜昌地质矿产研究所，宜昌４４３００３）关键词矿物包裹体浸取液羧酸离子色谱分析分子中含有羧基官能团（—ＣＯＯＨ）的物质称为羧酸。Ｆｅｉｎ［１］和Ｓｈｏｃｋ［２］曾概述羧酸在自...  相似文献   

沉积盆地流体—岩石相互作用研究的现状   总被引：17，自引：0，他引：17  

蔡春芳 《地球科学进展》1996,11(6):575-579

沉积盆地流体－岩石相互作用研究主要是通过实验地球化学和岩石学，地球化学模拟方法开展的，综述了这一领域的研究现状，主要包括有机酸来源和分布及期 对矿物稳定性的影响，地层水成因与演化、烃类与岩石间的氧化还原反应、以及储层润湿性的变化等，并展望了其 发展趋势。  相似文献   

Characterisation of brown coal humic acids and modified humic acids using pyrolysis gcms and other techniques     

W. R. Jackson  G. D. Bongers  P. J. Redlich  G. Favas  Y. Fei  A. F. Patti  R. B. Johns 《International Journal of Coal Geology》1996,32(1-4)

It has been proposed that Victorian brown coal can be considered as a two-component structure — a lignocellulosic “host”, containing various amounts of weakly bound or entrapped “guest” material together with very small amounts of inorganic and/or mineral matter. The latter predominantly consists of wax esters and/or terpenoid material. In this paper we describe attempts to gain structural information regarding the more complex, “host” component of the coal. Our initial model compound has been humic acid that can be readily obtained from the coal by alkaline extraction. It has been found that “pure” humic acid, free from material associated with the “guest” components of the coal, can be obtained by a highly selective, low-yielding alkaline extraction. This humic acid has been studied by nmr spectroscopy and pyrolysis gas chromatography-mass spectroscopy (py-gc/ms). The products arising from py-gc/ms have been compared with those obtained from similar pyrolysis of whole coals. Alkylation of humic acids using alkyl halides in the presence of base has been successfully carried out and reactivity of the resulting materials compared with those of the parent coal and humic acid.  相似文献   

Effect of vegetation with different evolution degree on soil organic matter in a semi-arid environment (Cabo de Gata-Níjar Natural Park, SE Spain)     

V. Aranda  C. Oyonarte 《Journal of Arid Environments》2005,62(4):631-647

The organic matter of the surface horizons of soils developed below scrub vegetation in a Mediterranean semi-arid area of great environmental interest (Cabo de Gata-Níjar Natural Park, SE Spain) has been studied. The study mainly concentrates on examining the influence of two vegetation types, one evolved (according to its successional stage), and the other clearly degraded as a result of prior removal of vegetation. In spite of the homogeneity in the results obtained from the analysis of the organic matter from the soils studied, a relationship may be established between vegetation biotype and characteristics and evolution of the soil organic matter. The evolved vegetation results in the presence in the soil of a somewhat more evolved and stable organic matter (demonstrated by certain chemical and microbiological aspects), resulting in a greater degree of humification, thus favouring the protection of the soil and the ecosystem as a whole. Hence, the presence of degraded vegetation might lead to soil degradation, something that is unsustainable in semi-arid areas that are particularly fragile in nature.  相似文献   

Transformation of arsenic compounds in modern intertidal sediments of Iriomote Island, Japan   总被引：1，自引：0，他引：1  

Harue Masuda  Yoshito Yamatani  Mitsuru Okai   《Journal of Geochemical Exploration》2005,87(2):587-81

The arsenic accumulation process in intertidal sediments of Iriomote Island, Japan, is analyzed as a naturally balanced arsenic-fixation system. Major and minor element chemistry is analyzed by X-ray fluorescence photometry, mineralogy is investigated by X-ray diffractometry, and four arsenic compounds are characterized by hydrogen-generated atomic absorption photometry. It is found that arsenic is accumulated by iron hydroxides/oxides precipitated following the decomposition of humic acids in the shallower sediment, and is subsequently incorporated into iron sulfide minerals at depth. The arsenic is immobile during incorporation into arsenic-bearing phases, suggesting that arsenic is unlikely to be released into the porewater under natural conditions in early diagenesis. The formation and decomposition of arsenic-bearing organic compounds appear to be associated with the formation and decomposition of arsenic in oxyhydroxides/oxides, suggesting that microbial activity may play an important role in controlling the behavior of arsenic and arsenic-bearing phases in the sediment column.  相似文献   

Changes in dissolved organic matter (DOM) amount and composition along nested headwater stream locations during baseflow and stormflow          下载免费PDF全文

Shatrughan Singh  Shreeram Inamdar  Myron Mitchell 《水文研究》2015,29(6):1505-1520

Amount and composition of dissolved organic matter (DOM) were evaluated for multiple, nested stream locations in a forested watershed to investigate the role of hydrologic flow paths, wetlands and drainage scale. Sampling was performed over a 4‐year period (2008–2011) for five locations with drainage areas of 0.62, 3.5, 4.5, 12 and 79 ha. Hydrologic flow paths were characterized using an end‐member mixing model. DOM composition was determined using a suite of spectrofluorometric indices and a site‐specific parallel factor analysis model. Dissolved organic carbon (DOC), humic‐like DOM and fluorescence index were most sensitive to changes with drainage scale, whereas dissolved organic nitrogen, specific UV absorbance, Sr and protein‐like DOM were least sensitive. DOM concentrations and humic‐like DOM constituents were highest during both baseflow and stormflow for a 3.5‐ha catchment with a wetland near the catchment outlet. Whereas storm‐event concentrations of DOC and humic DOM constituents declined, the mass exports of DOC increased with increasing catchment scale. A pronounced dilution in storm‐event DOC concentration was observed at peak stream discharge for the 12‐ha drainage location, which was not as apparent at the 79‐ha scale, suggesting key differences in supply and transport of DOM. Our observations indicate that hydrologic flow paths, especially during storms, and the location and extent of wetlands in the catchment are key determinants of DOM concentration and composition. This study furthers our understanding of changes in DOM with drainage scale and the controls on DOM in headwater, forested catchments. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

沙虫干呈味及功能性成分研究     

章超桦  铃木健  吉江由美子 《广东海洋大学学报》2000,20(2):24-27

对沙虫干抽提物成分的组成进行的研究结果表明 :游离氨基酸含量 w为 10 .3% ,占抽提物含氮物质的 77.9%。抽提物组成中 ,呈甘味的 Gly(3.2 % )、Ala(2 .5% )和呈鲜味的 IMP(0 .2 7% )、Glu(0 .2 5% )、琥珀酸 (0 .35% )等成分同沙虫干独特的风味有关 ,Na 、Cl-等无机离子也同其呈味相关。此外 ,牛磺酸含量 w高达 3.2 % ,是富含牛磺酸的一种海洋生物 ;精氨酸的含量 w亦较高 ,为 1.2 %。  相似文献   

The molecular composition of ambers     

J.O. Grimalt  B.R.T. Simoneit  P.G. Hatcher  A. Nissenbaum 《Organic Geochemistry》1988,13(4-6)

Bulk (elemental composition, IR, CP/MAS ¹³C NMR) and molecular (GC-MS) analyses have been performed on a series of ambers and resins derived from different locations (Dominican Republic, Philippines, Canada, Israel, New Zealand, Chile) having diverse botanical affinities (Araucariaceae, Hymenaea) and variable age (from Holocene to Early Cretaceous). No major differences have been observed from the elemental composition and the spectroscopic data; however, the molecular analyses of the solvent extractable fraction show that a specific mixture of components is present in each sample. These are mainly diterpenoid products that in general are also found abundantly in the higher plants from which the ambers and resins originate. Nevertheless, a direct relationship between major terpenoid constituents in fossil resins and precursor plant materials can only be established for the younger samples.Irrespective of the geographical or botanical origin of the ambers and resins, several common age-dependent molecular transformation trends can be recognized: (1) progressive loss of olefinic bonds (especially those located in exocyclic positions), (2) decrease of functionalized products, and (3) increasing proportion of aromatized components. However, even in the samples of older age (Cretaceous) the degree of aromatization is very low when compared with that of other higher-plant related materials such as fossilized woods or low rank coals. This indicates that maturation must involve essentially olefin polymerization processes instead of extensive aromatization.  相似文献   

Computational methods for fitting statistical distribution models of multi-site binding equilibria     

Rudolph S. Parrish  E. Michael Perdue 《Mathematical Geology》1989,21(2):199-219

Statistical distribution models of multi-site binding equilibria have potential applicability in the study of acid-base and metal complexation chemistry of humic substances in soils, sediments, and natural waters. A mathematical derivation is presented for the general continuous model for the case of proton binding; computational methods are described for fitting numerically the parameters in such models. Among models considered are those based on nontruncated, truncated, and bimodal (mixed) distributions. Specific emphasis is placed on Gaussian distribution models.  相似文献   

Amino acid nitrogen in atmospheric aerosols: Occurrence,sources and photochemical modification   总被引：2，自引：0，他引：2  

Peter J. Milne  Rod G. Zika 《Journal of Atmospheric Chemistry》1993,16(4):361-398

The presence of amino acids in atmospheric precipitation and aerosols has been noted for many years, yet relatively little is known about these or other nitrogen containing organic compounds in the atmosphere. Marine and continental rainwater analyses indicate that atmospheric aerosols, and subsequently atmospheric precipitation, may contain substantial levels of free and combined amino acids. The most likely source of amino N in the remote marine atmosphere appears to be the injection of proteinaceous material through the action of bursting bubbles at the sea-air interface or the long range transport from terrestrial sources. The capacity of these substrates to undergo photooxidation and photodegradation in the atmosphere to simpler species, such as ammonium ions, carboxylic acids, and for the S containing amino acids, oxidized forms of sulfur, has received little attention from atmospheric chemists. The photochemistry of covalently bound amino groups, particularly as found in peptides and amino acids, is discussed here with the purpose of summarizing what is known of their occurrence and their possible importance to atmospheric chemistry.  相似文献