Isolation and analysis of polycyclic aromatic hydrocarbons from natural water using accelerated solvent extraction followed by gas chromatography-mass spectrometry

An innovative analytical procedure for the analysis of polycyclic aromatic hydrocarbons (PAHs) from large-volume water samples is presented. It involves sample preparation, sampling and the elution process in an automated continuous procedure involving the ASE technique. Prior to sampling, a XAD-2 resin column is prepared on the basis of a commercial accelerated solvent extraction (ASE) cartridge so that the resin bed is permanently fixed. Then, the XAD column inside the ASE cartridge is cleaned and conditioned. The sampling procedure involves conventional filtration with subsequent isolation of dissolved PAHs on an XAD-2 resin contained in the ASE cartridge. After sampling, the XAD-2 resin content inside the cartridge is eluted by ASE without any further sample preparation and subsequently reused. In order to validate the procedure, the PAHs were isolated from water samples from the Lake Maggiore (North of Italy) using both XAD-2 resin adsorption and hexane liquid-liquid extraction according to the International Standard Methodology ISO 17993. The mean percentages of deviation between concentrations obtained by both methodologies range from 6% for benzo(a)pyrene to 15% for fluoranthene and benzo(b,k)fluoranthene. Compared to the traditional techniques, this procedure offers numerous practical advantages: easy to perform, fast, savings in solvent volume and in time, all steps are fully automated thus avoiding any XAD-2 resin manipulation during and between steps and moreover, low detection limits were provided (0.001 ng l⁻¹ for chrysene, benzo(b,k)fluoranthene, benzo(a)pyrene, dibenz(a,h)anthracene, benzo(g,h,i)perylene and indeno(1,2,3-cd)pyrene, and 0.01 ng l⁻¹ for acenaphthylene and fluoranthene).This procedure was developed in the frame of a project aimed at evaluating the diffuse input of organic contaminants in the Lake Maggiore.     

柳大纲的广博与执著

柳大纲(1904-1991)是20世纪中国著名的化学家、卓越的科研组织者和领导者,是中国硅酸盐化学、盐湖化学和光谱学等方向的先驱,是中国近现代科技史上推动前科学向科学质变的代表人物。他的早期科研经历和成长过程显示,他不仅推动了传统手工业陶瓷、制盐等向现代工业的革新,还使用完善的科学范式与方法来研究陶瓷、玻璃和制盐过程。以上这些积累,使他于1958年以“赛马式”研发模式推动了盐湖钾肥和硼砂生产由手工业跃进到现代工业。他参与筹建并领导中科院化学所,规划和发展其研究领域,进而以中科院化学所为孵育基地,抽调该所力量,建设了中科院青海盐湖所等多个研究机构。他重视人才培养,重视发展中国化学会和期刊建设工作。     

贵阳市红枫湖底栖生物体中多溴联苯醚的初步研究

为了研究贵阳市红枫湖底栖生物体中多溴联苯醚(polybrominateddiphenyl ethers,PBDEs)的污染情况,通过索氏抽提、凝胶色谱柱和多层硅胶/氧化铝层析柱净化,对红枫湖底栖生物体中PBDEs的含量、分布模式、来源进行分析。结果表明,红枫湖样品中Σ18PBDEs为105.71～43902.73 pg/g(干重),各单体含量为1.05～20045.38 pg/g。红枫湖底栖生物体中PBDEs的污染尚处于较低水平。     

Determination of four phenolic endocrine disrupting chemicals in Dianchi Lake,China

An efficient derivatization method using phenyltrimethylammonium (PTA-OH) has been developed to determine simultaneously four phenolic endocrine disrupting chemicals, 4-n-nonylphenol (4-n-NP), 4-tert-octylphenol (4-t-OP), bisphenol A (BPA) and 4-cumylphenol (4-CP) in surface water of Dianchi Lake (China) by solid-phase extraction (SPE) and gas chromatography-mass spectrometry (GC-MS). Compared with silylation of target phenols using N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA)?+?1% trimethylchlorosilane (TMCS), methylation by PTA-OH displayed a higher response and stability based on the investigations of various derivatization conditions, including derivatization solvent, amount of derivatization reagent, reaction temperature and time. Experiments were carried out to examine the performance of the proposed method based on the correlation coefficient, the method quantification limit (MQL), mean recovery rate and relative standard deviation (RSD). Under optimum derivatization conditions, MQLs of the methylated target compounds were all below 1?ng?L^?1. Results revealed that the proposed method exhibited a satisfactory precision and reproducibility for the separation and determination of target phenols. The proposed method had been applied to determine four phenols in surface water of Dianchi Lake located in southwest of China. The concentrations of 4-n-NP, 4-t-OP, BPA and 4-CP were determined to be 13.6-141.6?ng?L^?1, N.D.-56.5?ng?L^?1, N.D.- 4713.6?ng?L^?1 and 23.3-48.5?ng?L^?1, respectively.     

Thermal characterization of lacustrine dolomites from the Sambhar Lake playa,Thar desert,India

The Sambhar Lake playa sediments in Thar desert, western India, host a variety of evaporite minerals. Carbonates form a major proportion of the evaporites in a 23 m deep core and several dolomite-rich horizons are recorded. Our XRD and DTA based investigations show that these dolomites are non-stoichiometric and disordered (proto-dolomites) except at one level (4.08 m) from where a well-ordered dolomite is reported. We also record frequent variation in the characteristics of dolomites with depth in terms of structural ordering, Ca/Mg ratio and Fe content. Dolomites reported form the Sambhar Lake playa are interpreted to be authigenic due to the absence of any carbonate rock in the catchment and seem to be derived from a precursor calcite under (sub-) evaporitic conditions. This revised version was published online in July 2006 with corrections to the Cover Date.     

东湖紫外光敏感磷与可酶解磷的分布及其相互关系

初步讨论了武汉东湖不同工作站中紫外光敏感磷(UVSP)与可酶解磷(PHP)的季节变化以及间隙水中二者和碱性磷酸酶活性(APA)的存在及其相互关系．间隙水中PHP与UVSP的存在，说明湖泊沉积物亦为间接有效的磷库．紫外光照射可显著提高间隙水中o-P的浓度，却明显抑制溶解态碱性磷酸酶(APase)的活性，这一结果未能支持UVSP释放o—P的过程仍遵从酶促机制的假说．     

Using Stable Isotope Analyses to Identify Allochthonous Inputs to Lake Naivasha Mediated via the Hippopotamus Gut

Abstract

The hippopotamus grazes nocturnally on land and resides in water during the day. Much of the ingested material must therefore be defecated directly into the aquatic system and can thus be considered an allochthonous resource available to aquatic consumers. The utility of stable isotope analyses of carbon and nitrogen to distinguish hippo faecal matter from other potential basal resources was tested at Lake Naivasha, Kenya. Hippopotami proved faithful to a short grass diet although supplementary grazing of aquatic macrophytes was observed. The typical isotopic ratios of C4 grasses ingested were not altered substantially by gut processes, and were clearly distinct from algal and aquatic macrophyte isotopic ratios. However, marginal plants such as Cyperus papyrus exhibit C4 ratios, and so the technique is suitable only for use in localities where ‘contamination’ from such sources is negligible.     

Conference and Research Reports

Groundwater discharge into an open pit lignite mining lake was investigated using radon-222 as a naturally occurring environmental tracer. The chosen study site was a meromictic lake, i.e., a water body that is divided horizontally into two separate layers – the upper mixolimnion (with seasonal mixing) and the lower monimolimnion (without seasonal mixing). For the estimation of groundwater discharge rates into the lake, a simple box model including all radon sinks and sources related to each layer was applied. Two field investigations were performed. During the October campaign, the total groundwater discharge into the lake was found to be 18.9 and 0.7 m³ d^?1 for the mixolimnion and monimolimnion, respectively. During the December campaign, the groundwater discharge into the mixolimnion was 15.0 m³ d^?1, whereas no discharge at all was observed into the monimolimnion. Based on the given water volumes, the residence time of lake water was 5.3 years for the monimolimnion and varies between 0.9 and 1.1 years for the mixolimnion. The investigation confirmed radon to be a useful environmental tracer for groundwater and surface water interactions in meromictic lake environments.     

基于多光谱数据的湿地景观格局变化对越冬候鸟生境影响

安徽升金湖是典型的长江中下游自然通江湖泊湿地,是越冬候鸟尤其是珍稀鹤类的理想越冬地,水利设施的修建改变了升金湖的自然连通状况,使湖泊水位变化受人为控制,继而引起景观格局变化,从而影响越冬候鸟生境。为探究水位波动对越冬候鸟生境影响规律,基于Landsat-8（OLI）多光谱遥感影像对升金湖土地利用类型进行分类,结合水位数据和候鸟种群特征数据,选取景观斑块谱特征指数并对其分级,分析不同水文期升金湖湿地水位变化规律,探索湿地景观斑块谱特征时空变化特征,探究不同水文时期自然湿地景观格局和越冬候鸟生境变化规律。结果表明：空间上该区域丰水期大斑块面积占优,枯水期中等斑块面积达到峰值,在退水期和枯水期景观格局分布良好,景观整体表现出大斑块面积占优、数量较少且形状复杂,小斑块分布分散、数量巨大且形状规则,中小型斑块面积均匀,形状各异。时间上景观格局随水位变化,斑块总数随水位升高先增后降,小斑块数量变化最大且稳定性差易受水位波动影响;水位对大斑块形状指数影响较大,水位升高大斑块形状趋于复杂化,涨水期和丰水期大斑块形状指数最大,趋于狭长式分布,景观边缘效应趋于明显,内部结构异质性降低;四个水文期香浓多样性指数分别为1.754 2（涨水期）、1.571 7（丰水期）、1.762 3（退水期）、1.790 1（枯水期）,香浓多样性指数减小,景观类型多样性趋于单一。越冬候鸟生境面积与水位高低呈负相关,草滩地、泥滩地和芦苇滩地三种类型面积此消彼长并长期处于平衡状态,草滩地面积在生境面积中占比最高起主导作用（68.01%）,总体生境面积在候鸟越冬末期（枯水期）达到峰值,利于越冬候鸟觅食等行为活动。基于此,建议在越冬候鸟前期（8月-翌年1月）通过控水闸人为调控升金湖水位,使各生境类型面积增加,为越冬候鸟提供优质生境。     

千岛湖有色可溶性有机物的生物可利用性特征及其环境指示意义

千岛湖水质优良,具有较低的初级生产力和较高的透明度(SDD),探究该湖有色可溶性有机物(CDOM)的微生物降解特征对探究清洁水体有机物迁移转化规律具有重要意义。通过对室内微生物培养实验前后CDOM吸收和荧光光谱的对比分析,探究该湖有色可溶性有机物生物降解特征及指示意义。结果表明,经28 d微生物降解培养后CDOM吸收系数a₂₅₄、光谱斜率S_275-295平均值均减小、荧光腐殖化指数HIX增大,说明微生物降解致使CDOM浓度降低,腐殖化程度相应升高。经生物培养28 d可降解的CDOM吸收系数a₂₅₄平均降幅可达14.3%±4.8%,各点位降幅范围为4.3%~23.6%。平行因子分析获得三种荧光组分,分别为陆源类腐殖酸C1、类色氨酸C2和C3,三种荧光组分在28 d微生物降解培养过程中均主要表现为降解,极少有累积;其中类色氨酸C2和C3生物可利用性水平分别可达54.1%±18.2%和53.2%±14.3%,陆源类腐殖酸C1生物可利用性为28.2%±9.1%;培养前后CDOM荧光主要贡献组分由类色氨酸C2变为陆源类腐殖酸C1,这说明千岛湖类色氨酸生物活性高于类腐殖酸,微生物降解培养过程中亦表现为削弱类蛋白峰保留类腐殖酸峰。培养前后CDOM吸收系数差值,亦即CDOM生物可利用性Δa₂₅₄的高值主要集中在下游东南湖区,这与类色氨酸C2分布特征具有一定的相似性,说明千岛湖东南湖区CDOM生物可利用性最高,可能与大量类色氨酸C2赋存具有一定关系。微生物降解培养致使类色氨酸C2和C3分布特征发生改变,经培养后其高值与C1、a₂₅₄培养后高值分布特征相似,说明生物培养过程中可能存在类蛋白物质的产生。微生物降解培养前后C1与a₂₅₄均具有很好的相关性,说明微生物降解培养对陆源类腐殖酸荧光峰应用于估算有机物浓度的影响较小,培养后湖心区及东南湖区类色氨酸C2-C3高值区消失,说明在水滞留时间较长的湖区微生物活动对类色氨酸荧光峰在点源污染识别的应用存在一定的影响。