Characterization of organic matter in total suspended particles by thermodesorption and pyrolysis-gas chromatography-mass spectrometry

The organic matter in tropospheric aerosol plays an important role in atmospheric physical and chemical processes. The bulk of organic matter, representing a significant proportion of the total suspended particulate （TSP） mass, is bound to polymeric material whose structure and properties are largely unknown. Here we used thermodesorption gas chromatography/mass spectrometry （Td-GC/MS） to study organic compounds of low molecular mass and pyrolysis gas chromatography/mass spectrometry （Py-GC/MS） to characterize the chemical structure of macromolecules in TSP samples collected in different seasons from different sites in Guangzhou. n-Alkanes, fatty acids and nitriles were the predominant compounds in the thermodesorption products, whereas aromatics, fatty acids, nitriles and n-alkanes/alkenes were the major compounds in the pyrolysates. The results indicated that aromatics were main units in macromolecules. The fatty acids and nltriles formed from carboxylic ammonium salts were detected in both thermodesorption products and pyrolysates at a certain concentration, indicating the importance of these compounds in TSP formation. The TSP source mainly determined the occurrence of compounds in samples from urban, suburban and forest sites, whereas the TSP source and formation process maybe controlled the seasonal variation in compounds detected. High levels of nitriles in summer samples from suburban and forest sites coincide with the release of ammonium from the land and of fatty acids from vegetation at these sites.

练江沉积物中多溴联苯醚的污染特征、来源和潜在生态风险研究

为考察贵屿电子垃圾拆解区污染沿水体向下游的迁移行为和影响,本文对练江贵屿段及其上下游表层沉积物进行了系统采样和多溴联苯醚(PBDEs)分析,并对其污染来源和潜在生态风险进行了探讨.结果表明:PBDEs在练江上下游沉积物中普遍存在(检出率100%),在贵屿上游浓度较低(10.2~2120 ng·g^-1),进入贵屿段急剧升高(7470~193000 ng·g^-1),至贵屿下游后有所起伏但整体下降(734~11300 ng·g^-1).练江的PBDEs污染主要来自于沿途排放,贵屿电子垃圾拆解业是其中最大的污染排放源.贵屿下游沉积物的PBDEs浓度比上游高约一个数量级,说明贵屿高浓度的PBDEs污染可沿水体迁移至下游.主因子分析结果表明练江沉积物中的PBDEs污染存在3种模式,上游和下游主要支流(贵屿支流除外)呈现Deca-BDE污染模式(BDE-209为绝对优势单体),这是我国沉积物中PBDEs的典型污染模式,可视为练江沉积物中PBDEs污染的背景模式;贵屿则呈现出两种特异模式:Penta-BDE模式(优势单体BDE-47&-99)和Deca-BDE脱溴降解模式(以BDE-197为主,其次是-209),这分别与贵屿地区的电路板拆解和塑料的高温处理方式(烘烤、焚烧、熔融等)有关;贵屿下游支流和主干道样品中的PBDEs呈现与贵屿相似但多种模式共存的特征,进一步证实贵屿的PBDEs污染已沿水体迁移至下游并影响其PBDEs组成特征.练江上游和下游主要支流(贵屿支流除外)PBDEs的风险商值(HQ)均<1,表明生态风险可接受;贵屿段PBDEs的HQ值均>1,最高达63.9,存在严重生态风险;受贵屿污染迁移影响,贵屿下游支流及部分练江主干道样品的HQ值也>1,为PBDEs污染高风险区;Penta-BDEs(三-五溴代BDEs)为HQ值主要贡献污染物,其次是Hexa-BDEs和Deca-BDE.鉴于PBDEs具有环境持久性且在贵屿段的沉积通量高达(477±648) t(贵屿下游为(152±169)t),其在贵屿及其下游20 km以内的污染急需开展进一步调查并采取相应的污染治理和修复措施.

Molecular organic geochemical peculiarities of lacustrine core sediments in Fildes Peninsula, King George Island, Antarctica

The peculiarities of lipids in lacustrine core sediments from Fildes Peninsula, King George Island, Antarctica, are reported. The origin of high-molecular-weight n-alkanes, alkenes, fatty acids, alcohols is supposed to be related to the abundant moss occurring in the sediments. Abundant iso- and ante/so-fatty acids that occur in the sediments indicate a relatively strong bacterial activity in non-ice-cover zone than in other regions in Antarctica. The C18:2 unsaturated fatty acids mainly originate from autochthonous algae in the sediment pool, and the C18:2/C18:0 ratios in the profile are controlled more by paleotemperatures than source assemblies. Long-chain alkenones were identified in freshwater lacustrine sediment in Antarctica for the first time, of which Prymnesiophyceae is assumed to be the source organism. High relative abundance of C37:4 homologue in long-chain alkenone well correlates to the severely cold climate in Antarctica.

Immature crude oils in the salt lake depositional environment are related to organic matter precipitated at stage of carbonate in salt lake sedimentation sequences

The present paper studies the mineralogy and geochemistry of a geological section in Jianghan basin. Widely distributed immature oils in this basin have been shown to relate to the carbonate depositional stage of salt lake sedimentation cycle. It is concluded that only when the content of organic carbon in the rocks is taken into account, is it meaningful to calculate the immature oil in the source rocks.

Sequential extraction and compositional analysis of oil-bearing fluid inclusions in reservoir rocks from Kuche Depression, Tarim Basin

The free oils, adsorbed oils and oil-bearing fluid inclusions have been extracted separately and analyzed by GC and GC-MS in reservoir rock samples collected from the Kuche Depression. The results demonstrate that the molecular compositions of oil-bearing fluid inclusions are significantly different from those of the free oils (the current oils). Compared with the current oil, the oil-bearing fluid inclusions are characterized by relatively high values of parameters Pr/nC17 and Ph/nC18, low values of Pr/Ph, hopanes/steranes, C30-diahopane/C30-hopane and Ts/Tm, low content of C29Ts terpane and high maturities as indicated by C29 steranes 20S/(20R+20S). In addition, the oil-bearing fluid inclusions correlate very well with the oils in northern and central Tarim Basin, which were derived from Cambrian-Ordovician marine source rocks. The adsorbed oils appear to be an intermediate type between free oils and oil-bearing fluid inclusions. The above analytical data indicate that there are at least two

Water quality criteria for 4-nonylphenol in protection of aquatic life

Here reproduction and death toxicity data were selected for 4-nonylphenol based on endocrine disrupting properties of the re- productive system. Assessment factor （AF） and species sensitivity distribution （SSD） curve were employed to derive criteria maximum concentration （CMC） and criteria continuous concentration （CCC） of three different 4-nonylphenols for protection of aquatic life. The results showed that the CMC and CCC based on SSD method and death toxicity data for three different 4-nonylphenols （CAS No： 104405, 25154523, 84852163） were 26.7, 13.6, 3.84μg L-1 and 8.86, 2.21, 0.97 μg L-1, respectively. Based on SSD and reproductive toxicity data, the CCC values of different 4-nonylphenols （CAS No： 104405, 25154523） were 1.59 and 1.34μg L-l, respectively. The CCC values obtained by the AF for three different 4-nonylphenol （CAS No： 104405, 25154523, 84852163） were 0.165, 1.03, 0.74 μg L -1 and 0.5, 0.5, 0.1μg L-1, respectively, based on death toxicity data and re- productive toxicity data. The CCC values obtained by AF were all lower than the corresponding criteria values obtained by SSD, and the CCC values based on reproductive toxicity data were less than those based on the death toxicity data. This study provides a useful method for deriving water quality criteria for endocrine disruptors.

Geochemical identification of coal-sourced oils and inter-bedded shale-sourced oils as revealed by compound specific carbon isotopic analysis

To date, questions remain as to how to differentiate between coal- and interbedded shale-sourced oils in coal measures. Based on the hypothesis that δ13C value of sedimentary organic matter is controlled by the depositional environment and productivities of biota grown in such depositional setting, this note examines compound specific carbon isotopic profiles from coal and interbedded shale extracts using the gas chromatography-isotope ratio mass spec-trometry technique (GC/IRMS). The results show that compound specific carbon isotope values from coal extracts are enriched in 13C relative to that of interbedded shale extracts, and provide useful information in characterizing coal- and interbedded shale-sourced oils in coal measures. An example for its successful application from the Turpan Basin, Northwestern China is presented.

Experimental study and evaluation on hydrocarbon generation of macerals

Some typical coal and maceral samples are selected for oil and gas-generatingsystematic thermal simulation experiments, Rock-Eval, GC and GC-MS analyses. Results cause productivity curves of extracts and gaseous, light, liquid as well as total hydrocarbon. Effects of macerals and maturation on hydrocarbon productivities and compositions are synthetically discussed. Evaluation indexes and plan on coal-generated oil and gas in bituminous coal rank are suggested according to the data from experiments and analyses.

Measurement of aerosol effective density by single particle mass spectrometry

Single particle mass spectrometry has been widely used to determine the size and chemical compositions of at- mospheric aerosols; however, it is still rarely used for the microphysical properties measurement. In this study, two methods were developed for determining aerosol effective density by a single particle aerosol mass spectrometer （SPAMS）. Method I retrieved effective density through comparison between measured light scattering intensities and Mie theoretical modelled par- tial scattering cross section. Method Ⅱ coupled a differential mobility analyzer （DMA） with SPAMS to simultaneously deter- mine the electric mobility and vacuum aerodynamic diameter, and thus the effective density. Polystyrene latex spheres, ammo- nium sulfate and sodium nitrate were tested by these methods to help validate their effectiveness for determining the aerosol effective density. This study effectively extends SPAMS measurements to include particle size, chemical composition, light scattering, and effective density, and thus helps us better understand the environment and climate effects of aerosols.

Sorption and desorption of 1,4-dichlorobenzene on peat

Sorption and desorption of 1,4-dichlorobenzene (DCB) on peat (】92% organic matter) display large-scale hysteresis and nonlinearity. The magnitude of desorption hysteresis decreases in the order: untreated Pahokee peat (P)】 acid treated peat (FP)】 humin (TP). The desorption percentages are lower than 28% of the sorbed 1, 4-DCB after desorbing for 6 days. The sorption and desorption isotherms are well fitted to Freundlich equation, whose parameter 1/n ranges from 0.055 to 0.527. Moreover, the parameter 1/n of the desorption isotherm is significantly lower than that of the sorption isotherm, but the parameter logK increases on contrary to 1/n. The desorption isotherms are very well fitted to Langmuir equation, whose Qm decreases in the order: TP】FP】 P. The apparent partition coefficients (Kp) increase with increasing sorption time or decreasing aqueous equilibrium concentration of DCB. And Kp of P is significantly higher than that of FP or TP.

Identification and formation of sulfur-containing steroids in sulfur-rich heavy oils in the Jinxian Sag,Bohai Bay Basin,North China

High abundant sulfur-containing steroids were identified and detected in saturate hydrocarbon fractions of heavy oil with a high sulfur content in the Jinxian Sag,Bohai Bay Basin,North China.These sulfur-containing steroids were structurally merged into the D-ring of steroid nucleus with thiophene ring and/or combined into the C-22 in the side-chain.Based on the previous reports of sulfur-containing steroids with methylthio-steroids and intra-molecular form,four formation mechanisms of sulfur-containing steroids and diagenetic pathway of steroids under S-rich conditions were proposed in this paper according to the double bond positions in the sterene compounds.Hydrogenation and sulfurization both occurred in the diagenetic processes of olefinic bond in the side-chain of steroids:abiogenic chemical hydrogenation of H2S and HS-leads to the formation of regular steranes;a successful sulfurization process leads to the formation of the side-chain sulfur-containing steroids whereas unsuccessful cyclization and/or sulfurization result in the generation of short-chain steranes.This kind of mechanism of hydrogenation/sulfurization of side-chain olefinic bond provides a potential genesis clue for the occurrence of high abundance of short-chain steranes(higher than the common regular steroids,phytane and n-alkanes)in S-rich heavy oils and source rocks in the Jinxian Sag,Bohai Bay Basin,North China.

Molecular characterization of sulfur compounds in some special sulfur-rich Chinese crude oils by FT-ICR MS

Routine GC/MS analysis may apply to the volatilized Low-Molecular-Weight compounds in saturate and aromatic hydrocarbon fractions;thus,relative studies using this technique inevitably bring about some limitations on distribution of miscellaneous sulfur atom.In this article,Fourier Transform Ion Cyclotron Resonance Mass Spectrometry(FT-ICR MS)with high resolution is employed to investigate the distribution of organic sulfur compounds(OSCs)in the crude oil typically derived from the Eogene carbonate-evaporite sediments with further chemical compositional characterization in molecular level by miscellaneous atomic type,carbon number,and double bond equivalent(DBE).A variety of miscellaneous atomic types with S1,S2,S3,OS,OS2,O2S,O2S2,NS,and NOS etc.(S1 means those OSCs with one sulfur atom in a molecule)were identified in OSCs in these oil samples.High levels of alkyl thioether series compounds with one ring structure were presented mainly in the crude oil in the Jianghan Basin whereas high amounts of benzothiophene,dibenzothiophene etc.compounds with higher values in DBE and carbon number range occurred in the sulfur-rich heavy oil in the Jinxian Sag.Although carbonate-evaporite sediments deposited in the saline lacustrine facies in the Eogene basin both occurred in the Jinxian Sag and Jianghan Basin,obviously,they possess different chemical diagenetic pathway of sulfur under various microbial reactions,leading to diverse distributional characteristics on biomarkers,OSCs,and even different hydrocarbon generation mechanism of immature crude oil.

Tricyclic aromatic diterpanes found in the Tertiary sediments and their geochemical significance

One monoaromatic tricyclic diterpane and two aromatic tricyclic diterpanes were found in three low-maturity source rocks and five crude oils of the Tertiary Shahejie Formation in Shengli Oil Field. The compounds found include C19H28 (m/z 145, M+ 256) ring-C monoaromatic tricyclic terpane, C17H20 (m/z 209, M+ 224) and C18H22 (m/z 223,M+ 238) rings-B,C diaromatic diterpanes. The results show that these compounds are biomarkers of immature organic matter with a stability sequence of C18H22 】 C17H20 】 C19H28. The cleavage of ring-D of pentacyclic triterpanoids, such as oleanene, hopene, fernene, ursene, in the early stage of diagenesis may be one of the origin pathways of rings-B, C diaromatic tricyclic diterpanes.

Factors influencing the purification efficiency of photosynthetic bacteria

One strain of photosynthetic bacteria (PSB) was isolated from substrate sludge of fresh-water fishpond. Influence of the use level of PSB culture solution, illumination condition, temperature, salinity, the use level of copper sulfate and dipterex on the purification efficiency was investigated. The results showed that the optimum use level of PSB culture solution was 10 mg/L, and the purification efficiency at illumination was higher than that at black, and if the temperature was lower than 15@, or the use level of sodium chloride, copper sulfate and dipterex were higher than 10 000 mg/L, 0.4 mg/L and 2.0 mg/L, respectively, the purification efficiency dropped distinctly.

High-resolution sedimentary record of hydrocarbon contaminants in a core from the major reaches of the Pearl River, China

The concentrations and compositions of hydrocarbon contaminants, and molecular marker indices in modern sediments from a core in the major reaches of the Pearl River were investigated. The sedimentary record of hydrocarbons in the core, in combination with 210Pb-dating, was used to reconstruct the pollution history of hydrocarbon pollutants in the Pearl River in the past 100 years.