Free Amino Acids Content in Some Halophytes under Salinity Stress in Arid Environment,Jordan

The variation in free amino acids concentration was examined in halophytes under salt stress conditions during spring and autumn in an arid environment, Jordan. The experiment was conducted in the southern region of the Jordan valley, using four different halophytes namely: Atriplex halimus, Atriplex nummularia, Tamarix aphylla L., and Portulaca oleracea L. Free amino acid concentrations showed changeable patterns under salinity stress conditions compared to the non‐stress (control) with respect to plant species and seasonal variation. In general, the amino acid pool during the spring experienced increases in A. halimus with increasing salinity; and decreased in A. nummularia, P. oleracea L., and T. aphylla L., respectively. Whereas, during the autumn, the overall amino acids decreased in A. halimus and A. nummularia, and increased in T. aphylla L. and P. oleracea with increasing salinity. The amino acid pool concentrations of A. halimus L. during the autumn was similar to that in spring under stress condition. Similarly, T. aphylla L. and P. oleracea showed higher rates in the autumn. In contrast, A. nummularia L. exhibited a slight increase in amino acid composition in the autumn under stress conditions. The plantation of salt tolerant plants such as halophytes in saline sodic soils showed an effective decline in soil salinity and can be recommended to be used as a bioreclamation method instead of the traditional leaching method, which requires large amount of fresh water.     

Consequences of linseed oil spills in salt marsh sediments

In a simulated spill in a salt marsh, linseed oil penetrated rapidly into the sediments at a rate of 10(-7) cm2 s(-1). The oil concentration remained unchanged for the first month after the spill, but 60% of the oil disappeared from the top 30 cm after a further month. The oil adsorbed to and accumulated in the muddy sediments (top 15 cm) leading to decreased sediment permeability, pH, Eh, abundance of plant roots and infauna and to the establishment of anoxic conditions. These changes accompanied transformations in the original fatty acid composition of the linseed oil, mainly associated with a decrease in 18 : 3omega3, an increase in the other fatty acids and the presence of 'new' fatty acids. A rapid increase in the abundance of heterotrophic aerobic and anaerobic bacteria and aerobic oil degrading bacteria, suggested that these micro-organisms degraded the oil. The role of the bacteria in oil degradation was confirmed in laboratory experiments where the fatty acids composition of the linseed oil underwent identical transformations to those obtained in the field. The degradation of linseed oil appears to be a sequential process initiated by aerobic and/or anaerobic bacteria and continued by sulphate reducing bacteria, which were unable to degrade the raw oil.     

Petrological characteristics and volatile content of magma from the 2000 eruption of Miyakejima Volcano, Japan

Among the series of eruptions at Miyakejima volcano in 2000, the largest summit explosion occurred on 18 August 2000. During this explosion, vesiculated bombs and lapilli having cauliflower-like shapes were ejected as essential products. Petrological observation and chemical analyses of the essential ejecta and melt inclusions were carried out in order to investigate magma ascent and eruption processes. SEM images indicate that the essential bombs and lapilli have similar textures, which have many tiny bubbles, crystal-rich and glass-poor groundmass and microphenocrysts of plagioclase, augite and olivine. Black ash particles, which compose 40% of the air-fall ash from the explosion, also have similar textures to the essential bombs. Whole-rock analyses show that the chemical composition of all essential ejecta is basaltic (SiO₂=51–52 wt%). Chemical analyses of melt inclusions in plagioclase and olivine phenocrysts indicate that melt in the magma had 0.9–1.9 wt% H₂O, <0.011 wt% CO₂, 0.04–0.17 wt% S and 0.06–0.1 wt% Cl. The variation in volatile content suggests degassing of the magma during ascent up to a depth of about 1 km. The ratio of H₂O and S content of melt inclusions is similar to that of volcanic gas, which has been intensely and continuously emitted from the summit since the end of August 2000, indicating that the 18 August magma is the source of the gas emission. Based on the volatile content of the melt inclusions and the volcanic gas composition, the initial bulk volatile content of the magma was estimated to be 1.6–1.9 wt% H₂O, 0.08–0.1 wt% CO₂, 0.11–0.17 wt% S and 0.06–0.07 wt% Cl. The basaltic magma ascended from a deeper chamber (10 km) due to decrease in magma density caused by volatile exsolution with pressure decrease. The highly vesiculated magma, which had at least 30 vol% bubbles, may have come into contact with ground water at sea level causing the large explosion of 18 August 2000.Editorial responsibility: S. Nakada, T. DuittAn erratum to this article can be found at     

高升油田莲花油层主要砂体稠油中的酸性化合物

酸性化合物是辽河稠油的主要化学组成部分。对辽河盆地高升油田莲花油层沙三段４个主要砂体（４、５、６、７砂体）稠油样品的分子地球化学研究表明,其酸性化合在型包括饱和的直链脂肪酸、单甲基支链（异构－和反异构）脂肪酸、类型戊二稀酸、五环三萜类羧酸、甾烷类羧酸、单环芳构有机酸和酚、多环羧酸和少量的氮流化合物。饱和烃和酸性倾合物在各砂体中的存在和分布特征对比分析的结果表明,有机质的分布在各砂体中的变化不能简单     

A study of the formation of high molecular weight compounds during the decomposition of a field diatom population

This work has investigated the possible formation of humic and fulvic acids, particularly high molecular weight moieties, in degrading diatom debris. The diatom debris was collected, freshly sedimented, from a well characterized natural field diatom population and allowed to degrade under conditions similar to those found at the sediment-water interface of many marine, organic-rich sediments.Samples of the detritus and overlying water were taken regularly over a period of 4 months and analysed for the presence of humic compounds. In the case of the detrital material, a sequential series of extractions were used. Molecular weight fractionation of the extracted humic material was carried out using Diaflow Ultrafiltration Membranes and two different fractionation methods have been compared. It appears that the choice of method may have an important effect on the determined distribution of the humic material, particularly when humic acid concentrations are low.High molecular weight (> 300 000- > 100 000) humic and fulvic acids were found in all the detrital samples, the content increasing with the period of decomposition. No evidence of any humic material was found in extracts of the living diatoms, the conclusion being that this material had been formed in situ during the degradation of the diatom debris. Most (65–90%) of the humic material was extracted from the detritus using a mild 0·05 m NaOH extraction at room temperature. Fulvic acids comprised approximately 90% of the total 0·05 m NaOH extraction, being composed mainly of either low molecular weight compounds (40–50% < 10000) or high molecular weight compounds (38–48% > 100000). Levels of humic acids were much lower and included a wide range of molecular weight fractions.The relevance of these findings to the possible origin of humic material in certain marine sediments is discussed.     

The relationship between fatty acid distributions and bacterial respiratory types in contemporary marine sediments

Bacterial communities of different respiratory types were isolated from a marine sediment in a multiple chemostat system in an attempt to obtain bacterial cultures representative of the sediment. The fatty acid distribution of a mixed culture of sulphate-reducing bacteria isolated from this system showed a good correlation with the lipid distribution of the zone of maximum sulphate-reduction activity within the sediment. Both distributions had significant concentrations of C14 : 0, iso and anteiso C15 : 0, C16 : 0, C16 : 1ω7 and C18 : 1ω7. This was in contrast to the lipid profile of Desulfovibrio desulfuricans obtained by batch enrichment, which was dominated by iso C17 : 1ω7 fatty acids and correlated poorly with the sediment. The bacterial community cultured from the sediment was further differentiated according to respiratory types (aerobic, facultative aerobic and facultative anaerobic) by growth in a chemostat under defined conditions. The fatty acid distributions of these communities were sufficiently different to enable the various respiratory types to be recognized by their particular fatty acid composition. Cyclopropyl fatty acids (?17 and ?19) were present in significant levels only in the aerobic bacteria, while the facultative aerobes had significantly higher C18 : 1ω7 than the other cultures and the facultative anaerobic community was the only culture to have significant amounts of C12 : 0. The fatty acid distribution of Loch Eil sediment over the range C12-19 seemed to be predominantly of bacterial origin and were relatively abundant to a depth of 6 cm. The concentration of cyclopropyl fatty acids was highest in the oxidized surface sediments and decreased with depth as anaerobic conditions began to dominate, indicating that these fatty acids may only be indicative of aerobic sedimentary bacteria. In contrast to the fatty acids characteristic of bacteria, those fatty acids in the range C20-30 attributed to a terrestrial input were found in relatively constant concentrations over the whole 0–12 cm depth profile.     

Gas-Phase OH Oxidation of Monoterpenes: Gaseous and Particulate Products

Smog chamber experiments have beenconducted in which cyclic monoterpenes were oxidisedin the gas phase by OH. The evolved secondary organicaerosol (SOA) was analysed by LC-MSⁿ and thegas-phase products were analysed by FT-IR. Theconcentrations of the identified compoundscorresponded to carbon mass balances in the range of40%–90%. The identified compounds in the particularphase corresponded to 0.5%–4.2% of the reactedcarbon. The most abundant compounds in SOA fromterpenes with an endocyclic C=C double bond wereC₁₀-keto-aldehydes, C₁₀-keto-carboxylicacids, C₁₀-hydroxy-keto-carboxylic acids, andC₁₀-hydroxy-keto-aldehydes (pinonaldehyde,pinonic acid, hydroxy-pinonic acid isomers, andhydroxy-pinonaldehyde isomers from -pinene;3-caronaldehyde, 3-caronic acid, hydroxy-3-caronicacid isomers, and hydroxy-3-caronaldehyde isomers from3-carene). The most abundant compounds in SOA fromterpenes with an exocyclic C=C double bond wereC₉-ketones, C₉-dicarboxylic acids, andC₁₀-hydroxy-keto-carboxylic acids (nopinone,pinic acid, and hydroxy-pinonic acid isomers from-pinene; sabinaketone, sabinic acid andhydroxy-sabinonic acid isomers from sabinene).Decarboxylated analogues of most of the compounds werepresent in SOA in minor concentrations, such asC₉-keto-carboxylic acids (norpinonic acid,nor-3-caronic acid) and C₈-dicarboxylic acids(norpinic acid, nor-3-caric acid, norsabinic acid). InSOA from limonene, which contains an endocyclic aswell as an exocyclic C=C double bond, the mostabundant compounds were a C₁₀-keto-aldehyde andits oxo-derivative (limononaldehyde and keto-limononaldehyde) together with hydroxy-derivatives of aC₁₀-keto-carboxylic acid (isomers ofhydroxy-limononic acid). Also aC₁₀-keto-carboxylic acid (limononic acid) waspresent together with minor concentrations of aC₉-dicarboxylic acids (limonic acid), itsoxo-derivative (keto-limonic acid), and itsdecarboxylated analogue (norlimonic acid). Mechanisticpathways for the formation of these products, some ofwhich are identified here for the first time, areproposed.     

Improvement of kerogen structural interpretations based on oxidation products isolated from aqueous solutions

A detailed investigation of kerogen oxidation products remaining in aqueous solutions after the usual isolation of degradation products by extraction with ether or precipitation, was carried out for the first time in kerogen structural studies. Three shale samples were investigated: Green River shale (type I kerogen), Toarcian shale, Paris Basin (type II), and Mannville shale, Canada (type III). The yields of acids from aqueous solutions were noticeable: 12.98, 15.32 and 22.32%, respectively, based on initial kerogens. Qualitative and quantitative capillary GC/MS analysis showed that the ratios of different kinds of identified acids depended much on the type of precursor kerogen. Some of the acids identified in aqueous solutions have not been found earlier among the degradation products of the same kerogen samples, or were obtained in different ranges and yields. Consequently, slight modifications were suggested of the image on the nature of various types of kerogens based on examination of ether-soluble acids only. Namely, slightly higher proportions of aromatic and alkane-polycarboxylic acids in the total oxidation products of both type I and type II kerogens indicated larger participation of aromatic and alicyclic and/or heterocyclic structures in these two kerogens. On the other hand, for type III Mannville shale kerogen, a somewhat larger share of aliphatic type structures was demonstrated.     

The occurrence of bisulfite-aldehyde addition products in fog- and cloudwater

Elevated concentrations of S(IV) and formaldehyde were observed in fog- and cloudwater at sites in California. The highest concentrations (up to 3 mM S(IV) and 0.7 mM CH₂O) were measured at Bakersfield, during a prolonged period of repeated fog. In Bakersfield [S(IV)] generally exceeded [CH₂O], while in the Los Angeles area the reverse was observed. The lowest concentrations of both species were observed at marine and high altitude sites away from local emissions. Equilibrium computations indicate that high concentrations of S(IV) cannot be achieved without the formation of S(IV)-RCHO adducts.     

实验室模拟研究大气二次有机气溶胶的形成

二次有机气溶胶（SOA）是大气中重要的气溶胶组分,主要由挥发性有机物（VOCs）经化学转化形成,对天气、气候、大气环境和人体健康有重要影响,但至今其确切的化学成分和形成机制还十分不清楚。研究SOA的方法主要采用实验室单个物种或多物种的化学过程的模拟研究,野外实际大气的SOA化学成分、源汇和多尺度分析的观测研究,以及大气中SOA形成的数值模拟的回报和预报研究。实验室研究是对SOA形成过程中获取基础数据和推究SOA生成机制的最主要手段。在过去的几十年中,特别是近五年,SOA的研究取得了较大的进展,其中包括SOA前体物、SOA形成机制及影响因子的进一步理解。本文就这些方面展开了概要性的综述,重点强调了我国研究人员所做的研究工作。在采用实验室烟雾箱系统模拟研究SOA方面,首先简述了烟雾系统的发展以及表征,讨论了跟烟雾箱箱体相关的壁效应问题,重点综述了萜烯类、芳香烃类、小分子类等化学物种转化形成SOA的研究进展。在采用流动管和其他反应器类模拟研究SOA方面,重点讨论了挥发性有机物在颗粒物表面或在液相中所形成的SOA的主要化学成分及其可能的作用。