大气颗粒物稳定同位素组成的研究进展

大气颗粒物成分复杂,容易对环境和人体健康产生较大影响,是雾霾的主要来源。如何对大气颗粒物及其成分的来源、形成和迁移转化过程进行表征一直是大气环境科学研究中的重要课题。近年来,稳定同位素技术被广泛应用到环境污染物的来源示踪研究中。本文综述了大气颗粒物的研究进展,重点围绕大气颗粒物中的轻稳定同位素组成(主要包括碳、氮、硫和氧的稳定同位素),结合大气颗粒物的时空变化特征及特定的同位素数学模型,对大气颗粒物中物质的来源、形成过程和贡献等研究进行分析总结,并对稳定同位素技术在未来大气颗粒物研究中的应用发展趋势进行探讨。     

水同位素分析与生态系统过程示踪:技术、应用以及未来挑战

水分是生态系统的重要因子,水同位素自然示踪和人工标记是研究生态系统水循环过程的重要方法,利用水同位素所具有的示踪、整合和指示等功能特征,通过测量和分析生态系统中不同组分所含水分的氢氧同位素比值的变化情况,可实现生态系统蒸散发的拆分、植物水分来源判定和叶片水同位素富集机理研究,是研究生态系统水循环过程机理和生态学效应不可或缺的技术手段。该文首先简要回顾了生态系统水同位素发展和应用的历史,在此基础上阐述了水同位素技术和方法在生态学研究热点领域应用的基本原理,概述了水同位素在植物水分来源判定、蒸散发拆分、露水来源拆分、降水的水汽来源拆分以及~(17)O-excess的研究进展,并介绍了植物叶片水富集机理及基于稳定同位素的碳水耦合研究。最后,指出了水同位素研究亟待解决的问题,展望了水同位素应用的前沿方向,旨在利用水同位素分析加深对生态系统的水分动态、植被格局和生理过程的理解。     

Water isotope analysis for tracing ecosystem processes: measurement techniques,ecological applications,and future challenges

水分是生态系统的重要因子, 水同位素自然示踪和人工标记是研究生态系统水循环过程的重要方法, 利用水同位素所具有的示踪、整合和指示等功能特征, 通过测量和分析生态系统中不同组分所含水分的氢氧同位素比值的变化情况, 可实现生态系统蒸散发的拆分、植物水分来源判定和叶片水同位素富集机理研究, 是研究生态系统水循环过程机理和生态学效应不可或缺的技术手段。该文首先简要回顾了生态系统水同位素发展和应用的历史, 在此基础上阐述了水同位素技术和方法在生态学研究热点领域应用的基本原理, 概述了水同位素在植物水分来源判定、蒸散发拆分、露水来源拆分、降水的水汽来源拆分以及 ¹⁷O-excess的研究进展, 并介绍了植物叶片水富集机理及基于稳定同位素的碳水耦合研究。最后, 指出了水同位素研究亟待解决的问题, 展望了水同位素应用的前沿方向, 旨在利用水同位素分析加深对生态系统的水分动态、植被格局和生理过程的理解。     

氮稳定同位素技术在陆地生态系统氮循环研究中的应用

在过去几十年中, 氮(N)稳定同位素技术的发展提高了人们对于陆地生态系统氮循环的认识。该文回顾了氮稳定同位素技术在研究生态系统氮循环中的历史, 综述了最近十多年来氮稳定同位素技术在陆地生态系统氮循环研究中的典型案例, 包括利用氮同位素自然丰度鉴定植物氮来源、指示生态系统氮状态和量化过程速率, 利用¹⁵N标记技术示踪氮的去向和再分布等。该文同时指出这些应用中存在的问题, 以及在陆地生态系统上氮稳定同位素技术今后研究的重点发展方向。     

氮稳定同位素技术在陆地生态系统氮循环研究中的应用

在过去几十年中,氮(N)稳定同位素技术的发展提高了人们对于陆地生态系统氮循环的认识。该文回顾了氮稳定同位素技术在研究生态系统氮循环中的历史,综述了最近十多年来氮稳定同位素技术在陆地生态系统氮循环研究中的典型案例,包括利用氮同位素自然丰度鉴定植物氮来源、指示生态系统氮状态和量化过程速率,利用~(15)N标记技术示踪氮的去向和再分布等。该文同时指出这些应用中存在的问题,以及在陆地生态系统上氮稳定同位素技术今后研究的重点发展方向。     

稳定同位素技术在植物水分利用研究中的应用

近20a稳定同位素技术在植物生态学研究中的应用得到了长足发展,使得对植物与水分关系也有了更深一步的了解。介绍稳定同位素性碳、氢、氧同位素在研究植物水分关系中的应用及进展,以期能为国内植物水分利用研究提供参考。由于植物根系从土壤中吸收水分时并不发生同位素分馏,对木质部水分同位素分析有助于对植物利用水分来源,生态系统中植物对水分的竞争和利用策略的研究,更好地了解生态系统结构与功能。稳定碳同位素作为植物水分利用效率的一个间接指标,在不同水分梯度环境中,及植物不同代谢产物与水分关系中有着广泛的应用。同位素在土壤-植被-大气连续体水分中的应用,有助于了解生态系统的水分平衡。随着稳定同位素方法的使用,植物与水分关系的研究将取得更大的进展。     

水域生态学中生物稳定同位素样品采集、处理与保存

稳定同位素分析技术由于能够刻画复杂的食物网结构并追踪食物网中的能量流而成为水域生态学研究中的重要手段。但是当水生生物样品采集、处理和保存过程中存在不确定性时, 营养关系分析中的同位素结果可能会产生误导性解释。文章采用数据模拟分析和文献总结的方法, 研究了水域生态系统中样品采集、处理和保存对于稳定同位素的影响, 概括性地建议了水域生态系统中适合应用稳定同位素分析技术开展生态学研究的样品采集、处理和保存的注意事项。但今后仍需进一步评估样品采集、处理和保存对稳定同位素比值的影响效果, 确定化学动力学在水生生物样品采集、处理和保存中的作用, 以进一步完善水生生物样品的采集、处理和保存稳定同位素生态学研究规范。     

碳同位素技术在森林生态系统碳循环研究中的应用

碳同位素技术对碳素在生态系统中的迁移动态具有很好的示踪作用,在生态学各领域研究中应用广泛。土壤、大气、植物是森林生态系统的重要碳库,植物是大气和土壤交换碳元素的重要介质。本文简要总结了碳同位素技术在研究碳元素在植物体内以及植物、土壤、大气碳库之间的迁移规律和生态学过程中的应用,展望了该技术在森林界面学中的应用前景。     

有机硫对生物脱硫过程的抑制机理及其研究进展

作为一种绿色、经济的新兴技术,生物脱硫技术正逐渐受到人们的青睐。然而,处理气体中的有机硫对生物脱硫过程的抑制是一个不容忽视的问题。文中总结了近年来国际上对生物脱硫过程中有机硫影响的相关研究,主要包括有机硫的种类及理化特征、有机硫对脱硫过程的影响、有机硫的作用机理、操作条件与有机硫的相互关系以及耐受有机硫微生物的种类,并据此归纳了缓解有机硫对脱硫过程影响的一些方法,为生物脱硫工艺在实际应用中稳定、高效地运行提供一定的指导。     

稳定同位素技术在鲨鱼摄食和洄游行为研究中的应用

随着稳定同位素分析技术的不断成熟,其在生态学领域中的应用也增长迅速,并成为动物摄食生态学的重要研究工具.鲨鱼因其在生物系统进化过程中的独特地位和海洋生态系统中的重要作用已成为海洋食物网研究的重点,然而国内针对鲨鱼摄食习性和洄游行为等方面的研究仍处于起步阶段.本文在总结了国内外鲨鱼稳定同位素分析组织样品选取和样品预处理方法的基础上,系统归纳了稳定同位素技术在鲨鱼摄食生态学,尤其在其摄食和洄游行为研究领域中的应用,着重分析稳定同位素技术在鲨鱼稳定同位素判别值和更新速率、食性分析、营养级评估、洄游路径分析和生态位分布等核心问题上的应用现状和发展前景,以期为国内学者开展鲨鱼类基础生物、生态学研究提供有益参考.     

Isotope effects associated with the anaerobic oxidation of sulfite and thiosulfate by the photosynthetic bacterium, Chromatium vinosum

Abstract The purple photosynthetic bacterium Chromatium vinosum , strain D, catalyzes several oxidations of reduced sulfur compounds under anaerobic conditions in the light: e.g., sulfide → sulfur → sulfate, sulfite → sulfate, and thiosulfate → sulfur + sulfate. Here it is shown that no sulfur isotope effect is associated with the last of these processes; isotopic compositions of the sulfur and sulfate produced can differ, however, if the sulfane and sulfonate positions within the thiosulfate have different isotopic compositions. In the second process, an observed change from an inverse to a normal isotope effect during oxidation of sulfite may indicate the operation of 2 enzymatic pathways. In contrast to heterotrophic anaerobic reduction of oxidized sulfur compounds, anaerobic oxidations of inorganic sulfur compounds by photosynthetic bacteria are characterized by relatively small isotope effects.     

Isotope dilution mass spectrometry for the quantification of sulfane sulfurs

Sulfane sulfurs are one type of important reactive sulfur species. These molecules have unique reactivity that allows them to attach reversibly to other sulfur atoms and exhibit regulatory effects in diverse biological systems. Recent studies have suggested that sulfane sulfurs are involved in signal transduction processes regulated by hydrogen sulfide (H₂S). Accurate and reliable measurements of sulfane sulfurs in biological samples are thus needed to reveal their production and mechanisms of actions. Herein we report a convenient and accurate method for the determination of sulfane sulfur concentrations. The method employs a triphenylphosphine derivative (P2) to capture sulfane sulfurs as a stable phosphine sulfide product, PS2. The concentration of PS2 was then determined by isotope dilution mass spectrometry, using a ¹³C₃-labeled phosphine sulfide, PS1, as the internal standard. The specificity and efficiency of the method were proven by model reactions. It was also applied to the measurement of sulfane sulfurs in mouse tissues including brain, kidney, lung, liver, heart, spleen, and blood.     

34S/32S and 18O/16O Fractionation During Sulfur Disproportionation by Desulfobulbus propionicus

In the present study, coupled stable sulfur and oxygen isotope fractionation during elemental sulfur disproportionation according to the overall reaction: 4H₂O + 4S^? → 3H₂S + SO₄ ^{2 ?} + 2H⁺, was experimentally investigated for the first time using a pure culture of the sulfate reducer Desulfobulbus propionicus at 35^?C. Bacterial disproportionation of elemental sulfur is an important process in the sulfur cycle of natural surface sediments and leads to the simultaneous formation of sulfide and sulfate. A dual-isotope approach considering both sulfur and oxygen isotope discrimination has been shown to be most effective in evaluating specific microbial reactions. The influence of iron- and manganese bearing-solids (Fe(II)CO₃, Fe(III)OOH, Mn(IV)O₂) acting in natural sediments as scavengers for hydrogen sulfide, was considered, too. Disproportionation of elemental sulfur was observed in the presence of iron solids at a cell-specific sulfur disproportionation rate of about 10^{? 9.5± 0.4} μ mol S^? cell^{? 1} h^{? 1}. No disproportionation, however, was observed with MnO₂. In the presence of iron solids, newly formed sulfate was enriched in ¹⁸ O compared to water by about +21‰ (≡ ? _H2O ), in agreement with a suggested oxygen isotope exchange via traces of intra- or extracellular sulfite that is formed as a disproportionation intermediate. Dissolved sulfate was also enriched in ³⁴S compared to elemental sulfur by up to +35%. Isotope fractionation by Desulfobulbus propionicusis highest for all disproportionating bacteria investigated, so far, and may impact on the development of isotope signals at the redox boundary of surface sediments.     

Speciation of sulfur from filamentous microbial mats from sulfidic cave springs using X-ray absorption near-edge spectroscopy

Most transformations within the sulfur cycle are controlled by the biosphere, and deciphering the abiotic and biotic nature and turnover of sulfur is critical to understand the geochemical and ecological changes that have occurred throughout the Earth's history. Here, synchrotron radiation-based sulfur K-edge X-ray absorption near-edge structure (XANES) spectroscopy is used to examine sulfur speciation in natural microbial mats from two aphotic (cave) settings. Habitat geochemistry, microbial community compositions, and sulfur isotope systematics were also evaluated. Microorganisms associated with sulfur metabolism dominated the mats, including members of the Epsilonproteobacteria and Gammaproteobacteria. These groups have not been examined previously by sulfur K-edge XANES. All of the mats consisted of elemental sulfur, with greater contributions of cyclo-octasulfur (S8) compared with polymeric sulfur (Smicro). While this could be a biological fingerprint for some bacteria, the signature may also indicate preferential oxidation of Smicro and S8 accumulation. Higher sulfate content correlated to less S8 in the presence of Epsilonproteobacteria. Sulfur isotope compositions confirmed that sulfur content and sulfur speciation may not correlate to microbial metabolic processes in natural samples, thereby complicating the interpretation of modern and ancient sulfur records.     

嗜热古菌异化型硫氧化途径的研究进展

微生物参与的还原性无机硫化合物的氧化过程是硫地球化学循环的重要组成部分,也可应用于生物冶金工业及酸性矿水治理等方面。嗜热古菌是高温环境中存在的一群特殊的微生物,其所参与的异化型硫氧化途径复杂多样,涉及众多氧化还原酶以及硫转运蛋白。本文将结合我们的研究工作,就参与异化型硫氧化代谢过程的嗜热古菌的种类,以及它们所参与的硫氧化过程进行系统的介绍。     

15N自然丰度法在生态系统氮素循环研究中的应用

稳定性同位素技术是现代生态学研究中的一门新兴技术,在生态学研究的诸多领域都展示了广阔的应用前景,其中,稳定性同位素＾１５Ｎ自然丰度法近年来在生态系统氮素循环研究中发挥了正在发挥着极为重要的作用,首先简述了自然生态系统氮素循环诸过程中的＾１５Ｎ同位素分馏机制,然后,在此基础上,综述了＾１５Ｎ自然丰度法的基本原理与方法,列举了近年 来此法在生物固氮及氮素转化过程研究中的一些应用实例,并预测了该方法在国     

Isotope exchange reactions with radiolabeled sulfur compounds in anoxic seawater

The isotope exchange between³⁵S-labeled sulfur compounds of sulfate (SO₄ ^2–), elemental sulfur (S⁰), polysulfide (S_n ^2–), hydrogen sulfide (HS^–: H₂S + HS^– + S^2–), iron sulfide (FeS), and pyrite (FeS₂) was studied at pH 7.6 and 20 °C in anoxic, sterile seawater. Isotope exchange was observed between S⁰, S₂ ^2– HS^–, and FeS, but not between³⁵S labeled SO₄ ^2– or FeS₂ and the other sulfur compounds. Polysulfide mediated the isotope exchange between S⁰ and bisulfide (HS^–). The isotope exchange between S⁰ and S_n ^2–) reached 50% of equilibrium within < 2 min while exchange between S₂ ^2– and HS^– approached equilibrium within 0.5-1 h. In all the experiments HS^–, revealed a fraction exchange from 0.79 to 1.00. Isotope exchange between S^2– and FeS took place only via S₂ ^2– and/or HS^–. The isotope exchange between iron sulfide and the other sulfur compounds was not complete within 24 h as shown by a fraction exchange of 0.07–0.83. This lack of equilibrium (fraction exchange < 1) was due to the isotope exchange between dissolved compounds and surfaces of sulfur particles. The isotopic exchange reactions limit the usefulness of radiotracers in process studies of the inorganic sulfur species. Exchange reactions will also affect the stable isotope distribution among the sulfur species. The kinetics of the isotopic exchange reactions, however, depend on both pH and temperature.     

Stable isotope ecology in insects: a review

1. The use of stable isotope analysis (SIA) in ecological research has dramatically increased in recent years largely because it allows researchers to investigate ecological questions that have been previously difficult to address. 2. Ecological applications of SIA include estimating fundamental niche space and overlap, evaluating trophic or species level interactions, and investigating food web structure. Increasingly, researchers have been incorporating SIA in studies of animal migration, disease transmission, diet composition, nutrient assimilation, and body condition among others. 3. Studies using SIA to evaluate the ecology of terrestrial insects have lagged behind other taxonomic groups. This poor representation of stable isotope studies in publications likely stems from a lack of familiarity of entomologists with this technique. 4. An improved understanding of SIA, as well as the advantages and disadvantages specifically related to insect research, will benefit the field of entomology. In addition, insect-model systems provide unique opportunities for entomologists to incorporate SIA in their research to advance our knowledge of insect biology and the stable isotope ecology of insects. 5. We provide background information on stable isotopes, explain sources of isotopic variation, describe the processes of how isotopes are differentially routed and incorporated into an individual's tissues, explain the principles that influence isotopic fractionation and discrimination, highlight different methods and advancements in SIA, review innovative stable isotope studies, and provide an overview of common mistakes, considerations, and future directions entomologists can explore.     

Feeding habits may explain the morphological uniqueness of brown bears on Etorofu Island,Southern Kuril Islands in East Asia

The brown bear (Ursus arctos) population on Etorofu Island, Southern Kuril Islands, has several unique morphological features: (1) the presence of white‐pelage bears within the population and (2) a larger body size than bears on a larger neighbour island, Hokkaido Island. Nevertheless, little ecological information is available about Etorofu brown bears. In the present study, we reveal the unique feeding habits of Etorofu brown bears and suggest that their unique morphological features and diet are related. The feeding habits of brown bears on Etorofu Island were assessed using carbon, nitrogen, and sulfur stable isotope analysis, and their feeding habits were compared with those of bears on the eastern side of Hokkaido Island. According to the stable isotope analysis, the dependence on salmon is great for bears on Etorofu but only slight for bears on Hokkaido. Our results suggest that the feeding habits of Etorofu brown bears may explain their unique morphological features because a white pelage colour confers an advantage when catching salmon, and a carnivorous diet can make their body size larger. The variation in feeding habits can be an important driver of the speciation and evolution of animals.     

15N自然丰度法在生态系统氮素循环研究中的应用

稳定性同位素技术是现代生态学研究中的一门新兴技术,在生态学研究的诸多领域都展示了广阔的应用前景。其中,稳定性同位素