核磁共振技术在沉积物磷素组分及迁移转化规律研究中的应用

沉积物磷素释放是造成湖泊水体发生富营养化的主要原因之一,而磷的活性又取决于其在沉积物中的化学赋存形态.磷-31核磁共振(31PNMR)技术因可以增强研究者对环境中磷素组分信息的认识而广受关注.本文主要综述了该技术在沉积物磷素形态表征以及迁移转化规律方面的研究成果,对技术原理和分类、分析流程以及具体应用领域进行了全面阐述.目前,应用核磁共振技术分析沉积物磷素的研究主要集中于不同形态磷化合物表征、微生物对磷素迁移转化的影响和定量研究三方面,而关于提取剂和提取方法的研究也是热点之一.最后,对未来31PNMR技术在环境样品中应用研究的重点和发展趋势进行了展望.     

反硝化聚磷菌的脱氮除磷机制及其在废水处理中的应用

摘要:水体富营养化是当前水污染治理的重点关注对象,利用微生物脱氮除磷开展富营养化水体治理是一种重要的技术。基于反硝化细菌和聚磷菌的脱氮除磷功能,兼具反硝化和聚磷功能的微生物研究及其在污水工艺中的应用越来越广泛。在厌氧和好氧/缺氧环境中,反硝化聚磷菌的脱氮除磷机制有很大差别,且在化学和酶学方面都有所体现。其中,质子驱动力/电子受体理论能够很好地解释反硝化聚磷的化学过程,而反硝化酶系和多聚磷酸盐激酶是酶学过程的主要参与者。当前研究已明确在不同氧含量环境中氮素对磷去除的影响机制,但是否存在磷对除氮作用的影响仍有待进一步研究。在此基础上,本文以氮-磷的偶联过程为切入点,分别从反硝化聚磷的化学过程和酶学机制方面进行简要综述。此外,介绍了反硝化聚磷菌在实验室以及工厂化污水处理中的应用近况,并提出了今后的研究重点与方向,以期为反硝化聚磷菌在环境修复中的进一步开发应用提供理论依据。     

多环芳烃(PAHs)微生物降解的原位表征方法

多环芳烃(polycyclic aromatic hydrocarbons,PAHs)是一类在环境中广泛存在的持久性有机污染物,微生物降解是去除环境中多环芳烃污染的主要途径。传统的有关PAHs微生物降解的研究主要依靠分离培养技术,难以准确认识PAHs微生物降解的原位过程及机制。近年来发展起来的原位表征方法可以在基因及单细胞水平研究PAHs在复杂环境中的微生物降解过程,能够原位表征具有PAHs降解功能的微生物及其功能基因和代谢活性,是阐明PAHs原位降解过程及分子机制的强有力的手段。该文综述了宏基因组技术(meta-genomics)、稳定同位素探针技术(stable isotope probe,SIP)、荧光原位杂交技术(fluorescence in situ hybridization,FISH)、拉曼光谱技术(Raman spectra)以及二次离子质谱技术(secondary ion mass spectrometry,SIMS)等原位表征技术在PAHs微生物降解研究领域的应用及其存在的问题和发展趋势等。PAHs微生物降解过程及机制的原位表征将为缓解与修复PAHs污染提供科学基础。     

土壤胶体磷活化迁移的影响因素及分析技术

胶体在土壤磷素迁移中起重要作用.土壤胶体磷活化迁移对土壤磷库的变化和周围水环境质量产生影响.本文介绍了土壤胶体磷研究的相关进展,探讨了土壤理化性质、施肥、降雨、土壤改良剂等因素对胶体磷在土壤赋存迁移中的影响,分析了流场分离、电镜能谱、同步辐射X光近边吸收结构光谱和核磁共振等技术在胶体磷研究中的应用,以及降低胶体磷流失的方法,以期为胶体磷在土壤中赋存变化和迁移机制的研究提供重要信息.
     

基于同步辐射技术研究土壤铁氧化物固定重金属分子机制的进展

铁氧化物在土壤中广泛赋存,因其比表面积大,对重金属具有很强的吸附固定能力,深刻影响着土壤重金属的形态转化过程.因此,研究土壤铁氧化物对重金属的固定机制,对于深入理解重金属在土壤系统中的环境化学行为以及评估污染土壤重金属生物有效性具有重要意义.然而,采用传统的吸附模型和化学提取法研究土壤铁氧化物固定重金属的机制具有明显的局限性,无法从分子水平上阐明其固定机制.同步辐射技术在环境土壤学的应用显著推进了在分子水平上认识土壤铁氧化物吸附重金属及其受典型环境因子影响的分子机制.本文主要从同步辐射技术的发展历程、模拟系统和实际土壤系统中铁氧化物在多种因素影响下对重金属固定的分子机制等方面进行了综述,同时对同步辐射技术的未来发展趋势及其在该研究领域的应用进行了展望.     

植物氮磷化学计量特征及其在药用植物研究中的应用

氮、磷元素在生物体内的组成及分配是相互联系的整体,可与环境相互作用,调节植物营养水平与生长发育过程。本文综述了环境非生物、生物和人为因子对植物氮、磷元素化学计量特征的影响,氮、磷化学计量对植物生长发育和代谢产物的影响机制,及其对药用植物生长发育和代谢产物积累的作用,并对药用植物的氮磷化学计量研究趋势进行展望。指出氮磷元素化学计量特征为药用植物响应环境变化机制、限制性营养元素判断、探讨与菌根真菌的相互作用等研究提供新思路,为药用植物的资源评价与规范化种植提供理论依据。     

不同介质中多环芳烃光降解及与生物耦合降解研究现状

多环芳烃(PAHs)是环境中广泛存在的一类有机污染物。它的降解一直是人们关注的课题。光降解就是多环芳烃降解的一种重要形式。对在气相、液相和固相不同介质中的PAHs光降解研究进行了综合论述,重点对PAHs在液相介质的降解速率及影响因素、中间产物及降解机制和反应动力学进行了深入探讨,并介绍了光-生物耦合降解多环芳烃的研究进展。建立系统而有效的PAHs光降解研究技术与方法,是目前当务之急。进一步完善PAHs光降解研究的技术与方法,可更准确地研究PAHs光降解机制及影响因素。     

环境介质中铂族金属形态分析方法的研究进展

环境中铂族金属(PGMs)的赋存形态多样,形态分析对识别其生态风险具有十分重要的意义。本文综述了环境中3种主要铂族金属(铂、钯、铑)的形态分析方法,包括化学顺序提取、仪器联用技术及计算机模拟等,概述了这些方法的类型、特点及应用,同时阐述了它们存在的不足,并对未来发展方向进行了展望。化学顺序提取法普遍用于固相样品形态分析,当前研究中提出的提取条件和步骤多样,但不能很好地标准化;仪器联用技术在溶液元素形态分析上具有显著优势,毛细管电泳联用系统能够分离具有相同电泳能力的相似物质,但在分离能力和检出限方面不如液相色谱联用系统;计算机模拟则进一步拓展了形态分析的途径,能够实现复杂的形态计算。建议今后将多个方法进行结合,通过相互补充与完善,不断提高分析技术准确性。     

单细胞拉曼光谱在微生物研究中的应用

拉曼显微光谱是一种能够提供0.5–1.0μm空间分辨率的单个微生物细胞内化学结构信息的研究技术。近几年来,拉曼显微光谱被越来越多地应用于微生物单细胞的研究中,它可以快速无损地检测微生物细胞内的特征化学组分。典型的单个微生物细胞的拉曼光谱包含核酸、蛋白质、碳水化合物、脂质和色素(例如类胡萝卜素)等信息,这些信息能够表征微生物细胞的基因型、表型和生理状态。所以单细胞拉曼显微光谱是一种可用于区分微生物样品的"全生物指纹"技术,它可用于研究单个微生物细胞生命阶段的转变、鉴定微生物单细胞中的色素及其他化合物的含量变化等。本文综述了目前拉曼显微光谱在微生物单细胞研究上的应用,主要包括与稳定同位素标记(stable isotope probing,SIP)、拉曼成像、光谱分类和细胞分选技术结合来探究微生物单细胞对物质吸收后特征峰的变化、推导物质循环过程、进行微生物分类鉴定和探索基因型与表型的关系。拉曼显微光谱作为微生物单细胞研究的手段之一,在代谢过程的研究、活细胞分选和细胞对物质的利用上具有广泛的应用前景。     

利用导数光谱估算珠江河口水体悬浮泥沙浓度

悬浮泥沙不仅影响水体的生态状况,而且对河口地貌及岸线的演变起到重要作用。高光谱技术可用于船载、机载及星载的光学传感器上,被认为是监测光学复杂水体的有效工具。为研究高光谱技术在河口悬浮泥沙监测应用中的可行性,于2004年5月及2006年8月,在珠江口进行了两个航次的现场水质采样及同步光谱测量。测量的原始遥感反射率光谱的分辨率为0.38nm,处理成为10nm的带宽,并进一步处理成导数光谱。以悬浮颗粒物(SPM)表征悬浮泥沙,分析了SPM和各光谱间的相关性。结果显示,一阶导数光谱,特别是605nm,可用于河口水体的SPM估算。该研究结果可应用到光学复杂河口水体的悬浮泥沙现场监测,并且对Hyperion及环境1号等卫星成像高光谱数据有潜在的应用价值。     

Naturally-occurring pituitary growth hormone is phosphorylated

The results of this communication show that ovine growth hormone (oGH) contains organically-bound phosphorous. The phosphorous content of growth hormone, lot S-11, is 1:3 (mol/mol) and that of lot S-12 is 1:6 (mol/mol). Results of 31P NMR studies suggest that the phosphorous exists in two chemical forms: as a monophosphoryl ester and as a phosphodiester. Evidence is provided which demonstrates that growth hormone can be phosphorylated in vitro with the catalytic subunit of protein kinase.     

菜地土壤氮磷面源污染现状、机制及控制技术

为了提高蔬菜产量,菜农大量施用化肥,菜地氮磷肥用量在一些地区已超过蔬菜实际需求量的数倍;而大多数蔬菜是浅根系和没有庞大根系的作物,菜地土壤已出现明显的氮磷累积现象,从而导致蔬菜作物营养失调,硝酸盐含量严重超标、品质下降,并引起菜地土壤理化性状恶化、地下水硝酸盐污染及地表水富营养化等一系列环境问题.本文综述了菜地土壤氮磷面源污染现状(氮磷累积特征、对水环境及蔬菜污染现状)、污染机制(氮磷来源、转化特征及损失途径)及包括施肥控制技术、应用化学添加剂技术、填闲作物技术、种植制度优化技术、汇源景观组合和生态草带拦截技术等污染控制技术,旨在为菜地土壤氮磷面源污染的深入研究提供借鉴.     

Aluminium speciation in the Vienne river on its upstream catchment (Limousin region, France)

The aim of this study was to investigate the speciation of aluminium in the river Vienne on its upstream catchment (Limousin region, France) over a period of seven years (May 1998-September 2004) in order to assess harmful effects on aquatic life. Two sampling points were selected: the first at 4 km from the spring (Peyrelevade), and the second one at 89 km from the spring (Royères). The aluminium speciation was computed with Mineql+ 4.5 speciation software. Organic matter and phosphorous play a major role in aluminium speciation. If we consider the free aluminium ion (Al3+) as being the only toxic form of aluminium, the concentrations of toxic forms recorded at Peyrelevade and Royères were always below the toxic values for fish. However, if the sum of the concentrations of Al3+, Al(OH)2+, Al(OH)2+ and Al(OH)4- is taken into consideration, the concentration of aluminium recorded may have adverse effects on aquatic life in the upstream catchment of the river Vienne. Al(OH)4- is the major contributor to the concentration in toxic aluminium recorded. In general, Al(OH)4- forms appears in water during the summer with water alkalinisation due to an increase in photosynthetic activities.     

Chemical speciation of saliva containing remineralizing solutions and their predicted effectiveness for subsurface lesion remineralization

Abstract

A computer modelling approach to estimate the chemical speciation which occurs in saliva and in subsurface lesion remineralizing solutions has been used to correlate chemical speciation data with published findings related to remineralization of dental enamel. The work also provides a means of selecting improved carrier ligands for the ions involved in remineralization and for optimising tooth protection and repair.     

On the scent of speciation: the chemosensory system and its role in premating isolation

Chemosensory speciation is characterized by the evolution of barriers to genetic exchange that involve chemosensory systems and chemical signals. Here, we review some representative studies documenting chemosensory speciation in an attempt to evaluate the importance and the different aspects of the process in nature and to gain insights into the genetic basis and the evolutionary mechanisms of chemosensory trait divergence. Although most studies of chemosensory speciation concern sexual isolation mediated by pheromone divergence, especially in Drosophila and moth species, other chemically based behaviours (habitat choice, pollinator attraction) can also play an important role in speciation and are likely to do so in a wide range of invertebrate and vertebrate species. Adaptive divergence of chemosensory traits in response to factors such as pollinators, hosts and conspecifics commonly drives the evolution of chemical prezygotic barriers. Although the genetic basis of chemosensory speciation remains largely unknown, genomic approaches to chemosensory gene families and to enzymes involved in biosynthetic pathways of signal compounds now provide new opportunities to dissect the genetic basis of these complex traits and of their divergence among taxa.     

Methods and recent advances in speciation analysis of mercury chemical species in environmental samples: a review

Mercury (Hg) and its compounds are much concerned for their high toxicity and wide presence in the environment. Since the toxicity of Hg is species dependent, various methods have been developed for the speciation analysis of Hg. This review focus on the determination and speciation analysis of Hg chemical species in water, sediment, and soil samples. Recent developments on sample pre-treatment and extraction/pre-concentration, separation, and quantification of Hg chemical species, and associated analytical challenges have been reviewed and briefly discussed based on recent reports.     

Modeling speciation effects on biodegradation in mixed metal/chelate systems

A new model, CCBATCH, comprehensively couples microbially catalyzed reactions to aqueous geochemistry. The effect of aqueous speciation on biodegradation reactions and the effect of biological reactions on the concentration of chemical species (e.g. H₂CO₃, NH ₄ ⁺ , O₂) are explicitly included in CCBATCH, allowing systematic investigation of kinetically controlled biological reactions. Bulk-phase chemical speciation reactions including acid/base and complexation are modeled as thermodynamically controlled, while biological reactions are modeled as kinetically controlled. A dual-Monod kinetic formulation for biological degradation reactions is coupled with stoichiometry for the degradation reaction to predict the rate of change of all biological and chemical species affected by the biological reactions. The capability of CCBATCH to capture pH and speciation effects on biological reactions is demonstrated by a series of modeling examples for the citrate/Fe(III) system. pH controls the concentration of potentially biologically available forms of citrate. When the percentage of the degradable substrate is low due to complexation or acid/base speciation, degradation rates may be slow despite high concentrations of substrate Complexation reactions that sequester substratein non-degradable forms may prevent degradation or stopdegradation reactions prior to complete substrate utilization. The capability of CCBATCH to couple aqueous speciation changes to biodegradation reaction kinetics and stoichiometry allows prediction of these key behaviors in mixed metal/chelate systems.     

Environmental and biochemical trace-metal speciation studies by radiotracers and neutron activation analysis

Although knowledge of the total concentrations of trace metals in the environment and living organisms is still the essential starting point for any toxicological evaluation, it is, however, not sufficient to explain the mechanisms responsible for retention and toxic effect of trace metals. Differentiation between their chemical and biochemical forms is necessary. The need to resolve the total concentration of trace metals into single chemical species poses great experimental difficulties and imposes the use of very sensitive analytical techniques for trace metal determinations after specific preseparation procedures of the different chemical species. Thus, once the chemical or biochemical metal species have been selectively isolated, the speciation becomes merely an analytical problem, which requires high sensitivity and accuracy, as well as the evaluation of matrix effects, blanks, contamination, loss, and sampling. This paper describes the use of nuclear and radiochemical techniques related to chemical and biochemical speciation problems at the Joint Research Centre, Ispra, with carrier-free radiotracers and radiochemical neutron activation analysis.     

Utilizing an intrinsic 31P NMR probe in studies of cobalamin ligation.

Phosphorous 31 nuclear magnetic resonance spectroscopy has been employed to observe changes in axial ligation in hydroxycobalamin solutions. The naturally occurring phosphorous nucleus in the benzimidazole side “arm” of the corrin is shown to exhibit different chemical shifts depending upon whether the benzimidazole is coordinated to the cobalt (III) ion or whether it has been displaced. The phosphorous resonance's linewidth at half maximum peak height seems also to be an indicator of the cobalt oxidation state, exhibiting a twenty fold larger width in the coblt (II) complex. The implications of these findings for future studies on certain coenzyme B₁₂ dependent enzymes is discussed.     

Structure and synthesis of a lipid-containing bacteriophage. The molecular weight and other physical properties of bacterophage PM2.

Several physical and chemical parameters of bacteriophage PM2 have been measured. The sedimentation constant was determined to be s-20,w=293 S. The buoyant density in sucrose at 20 degrees C was 1.24 g cm+-3 and in CsCl at 25 degrees C was 1.29 g cm-3. The high-speed equilibrium centrifugation method of Yphantis (1964) was used to measure the molecular weight of PM2. The necessary auxiliary parameters were also determined. A value of 0.771 plus or minus 0.005 cm-3 g-1 for the apparent specific volume at constant chemical potential in 1 M sodiium chloride has been obtained by pycnometry; the viral concentration was determined using the absorption coefficient at 260 nm (4.60 plus or minus 0.10 cm-2 mg-1), which in turn was calculated from the phosphorous content of the virus (17.89 plus or minus 0.28 mu-g of P per mg dry weight dry weight of virus). The molecular weight of PM2 determined with these parameters is (44.1 plus or minus 1.2 x 10-6). From the phosphorous content of the virus, the percentage of phosphorous known to be in its DNA (Camerini-Otero and Franklin, 1972), and the molecular weight of the bacteriophage, we have calculated a molecular weight for PM2 DNA of 6.26 x 10-6, which confirms values determined using empirical relationships.