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26541. 题目: The role of salinity on the changes of the biomass characteristics and on the performance of an OMBR treating tannery wastewater
文章编号: N18060204
期刊: Water Research
作者: M.J. Luján-Facundo, J. Fernández-Navarro, J.L. Alonso-Molina, I. Amorós-Mu?oz, Y. Moreno, J.A. Mendoza-Roca, L. Pastor-Alca?iz
更新时间: 2018-06-02
摘要: Tannery wastewaters are difficult to treat biologically due to the high salinity and organic matter concentration. Conventional treatments, like sequential batch reactors (SBR) and membrane bioreactors (MBR), have showed settling problems, in the case of SBR, and ultrafiltration (UF) membrane fouling in the case of MBR, slowing their industrial application. In this work, the treatment of tannery wastewater with an osmotic membrane bioreactor (OMBR) is assessed. Forward osmosis (FO) membranes are characterized by a much lower fouling degree than UF membranes. The permeate passes through the membrane pores (practically only water by the high membrane rejection) from the feed solution to the draw solution, which is also an industrial wastewater (ammonia absorption effluent) in this work. Experiments were carried out at laboratory scale with a FO CTA-NW membrane from Hydration Technology Innovations (HTI). Tannery wastewater was treated by means of an OMBR using as DS an actual industrial wastewater mainly consisting of ammonium sulphate. The monitoring of the biological process was carried out with biological indicators like microbial hydrolytic enzymatic activities, dissolved and total adenosine triphosphate (ATP) in the mixed liquor and microbial population. Results indicated a limiting conductivity in the reactor of 35 mS cm-1 (on the 43th operation day), from which process was deteriorated. This process performance diminution was associated by a high decrease of the dehydrogenase activity and a sudden increase of the protease and lipase activities. The increase of the bacterial stress index also described appropriately the process performance. Regarding the relative abundance of bacterial phylotypes, 37 phyla were identified in the biomass. Proteobacteria were the most abundant (varying the relative abundance between 50.29% and 34.78%) during the first 34 days of operation. From this day on, Bacteroidetes were detected in a greater extent varying the relative abundance of this phylum between 27.20% and 40.45%.
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26542. 题目: Transformation of dissolved organic matters produced from alkaline-ultrasonic sludge pretreatment in anaerobic digestion: From macro to micro
文章编号: N18060203
期刊: Water Research
作者: Dan Lu, Keke Xiao, Yun Chen, Yan Ni Annie Soh, Yan Zhou
更新时间: 2018-06-02
摘要: Soluble organic compounds released by alkaline (ALK), ultrasonic (ULS) and combined alkaline-ultrasonic (ALK-ULS) pretreatment as well as their transformation in the anaerobic digestion systems were investigated. The maximum methane production of 197.1 ± 3.0 mL CH4/g tCODfeed was observed with ALK-ULS pretreated sludge (pH 12 and specific energy input of 24 kJ/g TS). The combined treatment likely enhanced the sludge solubilization and produced more low molecular weight (LMW) substances, which were beneficial to improve the biogas generation rate. However, such pretreatment released not only easily biodegradable substances but also more recalcitrants, such as humic substances (HS) and complex high molecular weight (HMW) proteins. Thus, more residual dissolved organic matters (DOMs) were detected after digestion, which may pose adverse effects on the downstream water treatment. Refractory HS and hydrophobic dissolved organic carbon (HO DOC) were the main components of the residual DOMs, which accounted up to 35.0% and 22.3% respectively. At the molecular level, a large amount of residual polycyclic steroid-like matters, alkanes and aromatics were identified. Specific higher MW residual compounds, e.g. polar metabolites (like dipeptide, benzene and substituted derivatives), and non-polar lipids (like diacylglycerols, long chain fatty acids, alkenes, flavonoids, sphingolipids, glycerolipids, glycerophospholipids and their derivatives) were also identified. The results indicate that further polishing steps should be considered to remove the remaining soluble recalcitrant compounds. This study helps to understand the insight of sludge treatment from macro to micro level.
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26543. 题目: Impact of natural organic matter and increased water hardness on DGT prediction of copper bioaccumulation by yellow lampmussel (Lampsilis cariosa) and fathead minnow (Pimephales promelas)
文章编号: N18060202
期刊: Environmental Pollution
作者: Rebecca R. Philipps, Xiaoyu Xu, Gary L. Mills, Robert B. Bringolf
更新时间: 2018-06-02
摘要: We conducted an exposure experiment with Diffusive Gradients in Thin- Films (DGT), fathead minnow (Pimephales promelas), and yellow lampmussel (Lampsilis cariosa) to estimate bioavailability and bioaccumulation of Cu. We hypothesized that Cu concentrations measured by DGT can be used to predict Cu accumulation in aquatic animals and alterations of water chemistry can affect DGT's predict ability. Three water chemistries (control soft water, hard water, and addition of natural organic matter (NOM)) and three Cu concentrations (0, 30, and 60 μg/L) were selected, so nine Cu-water chemistry combinations were used. NOM addition treatments resulted in decreased concentrations of DGT-measured Cu and free Cu ion predicted by Biotic Ligand Model (BLM). Both hard water and NOM addition treatments had reduced concentrations of Cu ion and Cu-dissolved organic matter complexes compared to other treatments. DGT-measured Cu concentrations were linearly correlated to fish accumulated Cu, but not to mussel accumulated Cu. Concentrations of bioavailable Cu predicted by BLM, the species complexed with biotic ligands of aquatic organisms and, was highly correlated to DGT-measured Cu. In general, DGT-measured Cu fit Cu accumulations in fish, and this passive sampling technique is acceptable at predicting Cu concentrations in fish in waters with low NOM concentrations.
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26544. 题目: Combined effects of coagulation and adsorption on ultrafiltration membrane fouling control and subsequent disinfection in drinking water treatment
文章编号: N18060201
期刊: Environmental Science and Pollution Research
作者: Jiajian Xing, Heng Liang, Xiaoxiang Cheng, Haiyan Yang, Daliang Xu, Zhendong Gan, Xinsheng Luo, Xuewu Zhu, Guibai Li
更新时间: 2018-06-02
摘要: This study investigated the combined effects of coagulation and powdered activated carbon (PAC) adsorption on ultrafiltration (UF) membrane fouling control and subsequent disinfection efficiency through filtration performance, dissolved organic carbon (DOC) removal, fluorescence excitation-emission matrix (EEM) spectroscopy, and disinfectant curve. The fouling behavior of UF membrane was comprehensively analyzed especially in terms of pollutant removal and fouling reversibility to understand the mechanism of fouling accumulation and disinfectant dose reduction. Pre-coagulation with or without adsorption both achieved remarkable effect of fouling mitigation and disinfection dose reduction. The two pretreatments were effective in total fouling control and pre-coagulation combined with PAC adsorption even decreased hydraulically irreversible fouling notably. Besides, pre-coagulation decreased residual disinfectant decline due to the removal of hydrophobic components of natural organic matters (NOM). Pre-coagulation combined with adsorption had a synergistic effect on further disinfectant decline rate reduction and decreased total disinfectant consumption due to additional removal of hydrophilic NOM by PAC adsorption. The disinfectant demand was further reduced after membrane. These results show that membrane fouling and disinfectant dose can be reduced in UF coupled with pretreatment, which could lead to the avoidance of excessive operation cost disinfectant dose for drinking water supply.

26545. 题目: Microbial decomposition of marine dissolved organic matter in cool oceanic crust
文章编号: N18060136
期刊: Nature Geoscience
作者: Sunita R. Shah Walter, Ulrike Jaekel, Helena Osterholz, Andrew T. Fisher, Julie A. Huber, Ann Pearson, Thorsten Dittmar, Peter R. Girguis
更新时间: 2018-06-01
摘要: Marine dissolved organic carbon (DOC) is one of the largest active reservoirs of reduced carbon on Earth. In the deep ocean, DOC has been described as biologically recalcitrant and has a radiocarbon age of 4,000 to 6,000 years, which far exceeds the timescale of ocean overturning. However, abiotic removal mechanisms cannot account for the full magnitude of deep-ocean DOC loss. Deep-ocean water circulates at low temperatures through volcanic crust on ridge flanks, but little is known about the associated biogeochemical processes and carbon cycling. Here we present analyses of DOC in fluids from two borehole observatories installed in crustal rocks west of the Mid-Atlantic Ridge, and show that deep-ocean DOC is removed from these cool circulating fluids. The removal mechanism is isotopically selective and causes a shift in specific features of molecular composition, consistent with microbe-mediated oxidation. We suggest organic molecules with an average radiocarbon age of 3,200 years are bioavailable to crustal microbes, and that this removal mechanism may account for at least 5% of the global loss of DOC in the deep ocean. Cool crustal circulation probably contributes to maintaining the deep ocean as a reservoir of ‘aged’ and refractory DOC by discharging the surviving organic carbon constituents that are molecularly degraded and depleted in 14C and 13C into the deep ocean.

26546. 题目: Aliphatic hydrocarbon biomarkers as indicators of organic matter source and composition in surface sediments from shallow lakes along the lower Yangtze River, Eastern China
文章编号: N18060135
期刊: Organic Geochemistry
作者: Yongdong Zhang, Yaling Su, Zhengwen Liu, Lingyang Kong, Jinlei Yu, Miao Jin
更新时间: 2018-06-01
摘要: Aliphatic hydrocarbon biomarkers from the surface sediments of lakes along the lower reaches of the Yangtze River (Eastern China) were analyzed in order to determine the origin and composition of organic matter (OM) in the sediment. This is necessary to understand how anthropogenic environmental change in the region is impacting on OM dynamics and carbon cycles. The results indicate that OM in lake sediments is derived from biogenic sources, including phytoplankton, aquatic macrophytes, bacteria and terrestrial plants and abiotic sources of petroleum hydrocarbon contamination. The significance of each source varies greatly between lakes. Inputs of autochthonous OM to sediments were closely dependent on nutrient levels and the organisms present in the lake water column. Cyanobacterial OM input, signified by the distribution of short-chain n-alkanes, was most abundant in sediments from the most severely polluted lake, West Lake Chaohu. OM derived from diatoms, indicated by C25 highly branched isoprenoids (HBIs), was relatively abundant in sediments from lakes Gucheng and Shijiu, the two studied lakes with the lowest nutrient levels. Growth of macrophytes in lakes Gucheng, Shijiu, Gehu and Yangcheng resulted in a significant accumulation of OM from these organisms in the sediments. In contrast, the input of allochthonous OM was controlled mainly by natural and anthropogenic activities around the lakes. For example, terrestrial plant OM input, deduced from the abundance and proportion of long-chain n-alkanes, was exceptionally high in the sediment of Lake Nanyi, perhaps stemmed from frequent severe flooding in the catchment. Input of fossil fuel OM reflected direct petroleum contamination of the water or anthropogenic petroleum burning in the catchment. In addition, the allochthonous refractory OM tended to be enriched in sediments of lakes with strong hydrodynamic process. The results of this study provided a lot of detail in explaining the variation of terrestrial OM dynamics and carbon cycle in response to anthropogenic activities.

26547. 题目: Change in provenance of branched glycerol dialkyl glycerol tetraethers over the Holocene in the Baltic Sea and its impact on continental climate reconstruction
文章编号: N18060134
期刊: Organic Geochemistry
作者: Lisa Warden, Matthias Moros, Yuki Weber, Jaap S. Sinninghe Damsté
更新时间: 2018-06-01
摘要: The Baltic Sea is an enclosed basin that experienced a number of different salinity phases during the Holocene corresponding to the establishment of a connection with the North Sea. Branched glycerol dialkyl glycerol tetraethers (brGDGTs) in surface sediments and Holocene sedimentary successions from the Gotland and Arkona Basins were analyzed to examine their potential applicability as indicators for soil organic matter input, as well as their suitability for paleoclimate reconstructions. Our results show a marked change in brGDGT distributions and the branched and isoprenoid tetraether (BIT) index. The transition of the Ancylus Lake (fresh) to the Littorina Sea (brackish) phase is revealed by a large drop in the BIT index and an increase in the MBT′5Me, which reveals a large shift in provenance of the sedimentary brGDGTs. During the lake phase, brGDGTs are presumed to be primarily produced by in situ production in the water column. During the brackish phase, in situ brGDGT production in the alkaline pore waters of the surface sediments (as revealed by their high degree of cyclization) was predominant although there was evidence of occasional input of soil-derived brGDGTs. The predominant aquatic autochthonous production of brGDGTs does not allow the use of brGDGTs for continental air temperature reconstructions but they can be used for bottom water and lake temperature reconstructions during some intervals. The results from this study demonstrate that geological changes and concomittant salinity variations can be revealed by the provenance of brGDGTs.

26548. 题目: Correction for the siderite effect on Rock-Eval parameters: Application to the sediments of Lake Barombi (southwest Cameroon)
文章编号: N18060133
期刊: Organic Geochemistry
作者: David Sebag, Yannick Garcin, Thierry Adatte, Pierre Deschamps, Guillemette Ménot, Eric P. Verrecchia
更新时间: 2018-06-01
摘要: Originally developed for use in the petroleum industry, Rock-Eval pyrolysis is a technique commonly applied to lake sediments to infer paleoenvironmental reconstructions. The standard Rock-Eval parameters provide information on the amount of total organic and inorganic carbon (TOC and MinC, respectively), and are usually interpreted as proxies for the source (aquatic or terrestrial) of the primary production of organic matter (Hydrogen Index vs Oxygen Index). Although this method usually provides valuable evidence, the common presence of siderite in tropical lake sediments can alter the primary signal of the sedimentary organic matter (SOM). Indeed, the CO2 and CO released by the pyrolysis of siderite are integral to the calculation of the SOM-related standard Rock-Eval parameters. In this study, we analyze sediments from a core collected in the Lake Barombi (southwest Cameroon) and describe the impact of siderite on standard Rock-Eval parameters. We propose a workflow that allows standard Rock-Eval parameters to be corrected, based on the analysis of thermograms. The proposed corrections provide siderite-effect-free parameters, accurately reflecting the changes in sedimentary organic matter composition.

26549. 题目: Determination and geochemical implication of multiple series of long-chain oxygen-bearing compounds trapped in kerogen in the Lucaogou Formation, Santanghu Basin, NW China
文章编号: N18060132
期刊: Organic Geochemistry
作者: Bin Cheng, Jianbing Xu, Yungan Liang, Qian Deng, Yankuan Tian, Zewen Liao
更新时间: 2018-06-01
摘要: Studies of occluded oxygen-bearing compounds inside kerogen are scarce, although such studies are important in understanding early-stage transformation of organic matter. A relatively low-maturity kerogen from the late Permian mudstone of the Lucaogou Formation of the Santanghu Basin, northwestern China, was successively extracted with n-hexane, acetone and dichloromethane to release the adsorbed components, and the extracted kerogen was treated with a mild oxidation reagent H2O2 to release the occluded components. Gas chromatography–mass spectrometry analysis of the adsorbed and occluded components revealed a suite of oxygen-bearing compounds, including n-alkan-2-ones, n-aldehydes and fatty acid methyl esters. The n-alkan-2-ones were mainly detected in the adsorbed fraction and n-aldehydes in the occluded component. Comparison of the long-chain oxygen-bearing compound distributions and their individual stable carbon isotope characteristics both suggest that the oxygen-bearing compounds released by H2O2 treatment were occluded in the kerogen. The shorter-chain (C15 to C19) occluded n-aldehydes reflected similar isotopic distribution trends to the adsorbed n-alkan-2-ones, and the δ13C values of the mid-length (C21 to C25) occluded n-aldehydes were much closer to the adsorbed n-alkanes. Bacterially mediated methylation and decarbonylation of the n-aldehydes during kerogen formation may be important source(s) of n-alkan-2-ones and n-alkanes, respectively. The mid-chain ketones mainly originated from hydrothermal alteration of n-alkanes after kerogen formation. Uplift of the Lucaogou Formation in the Yuejingou section allowed surface-enhanced aerobic reactions.

26550. 题目: Effect of simulated diagenesis on the compositions, chemical stability and sorption properties of natural and engineered organic matter with different mineral contents
文章编号: N18060131
期刊: Organic Geochemistry
作者: Lanfang Han, Ziying Wang, Marco Keiluweit, Yan Yang, Ke Sun, Zheyun Zhang, Baoshan Xing
更新时间: 2018-06-01
摘要: Despite the abundance of diagenetically derived organic materials in the environment, the effects of diagenesis on the structure and some of the associated properties (e.g., stability and sorption behavior) of organic matter (OM) remain unclear. Here, subcritical water treatment, suggested previously to mimic the diagenesis process, was chosen to further investigate the impact of diagenesis on OM compositions, stability and sorption of selected hydrophobic organic compounds. Humic acids and biochars were selected as representatives of natural and engineered OM, respectively. To examine the impact of mineral constituents on the diagenesis of OM, de-ashed samples, as well as samples amended with minerals (kaolinite, calcite and calcium dihydrogen phosphate), were included in the diagenesis treatment system. Comparison of OM composition before and after treatment indicated that simulated diagenesis resulted in lower bulk polarity, higher surface polarity and aromaticity and greater microporosity. Thermal analysis and chemical oxidation suggested that as a result of the increase in aromaticity and decrease in O/C ratio of OM, the resistance of OM to thermal and chemical oxidation was enhanced after simulated diagenesis. Moreover, our diagenesis treatment of OM induced stronger sorption nonlinearity and higher sorption capacity, for phenanthrene. Additionally, minerals protected the structure of OM from being changed by simulated diagenesis. Consequently, with regard to the susceptibility of OM to oxidative decay, the presence of minerals mitigated the increase in chemical stability imparted by simulated diagenesis but, on the other hand, protected OM from degradation.

26551. 题目: Geochemical characterization of lacustrine and marine oils from off-shore Brazilian sedimentary basins using negative-ion electrospray Fourier transform ion cyclotron resonance mass spectrometry (ESI FTICR-MS)
文章编号: N18060130
期刊: Organic Geochemistry
作者: Ygor dos Santos Rocha, Rosana Cardoso Lopes Pereira, Jo?o Graciano Mendon?a Filho
更新时间: 2018-06-01
摘要: Lacustrine and marine crude oils from different off-shore Brazilian basins were analyzed using a 7.2 Tesla LTQ FTICR-MS instrument. The samples were analyzed via electrospray ionization in the negative ion mode focusing on the polar compounds, i.e., nitrogen-, sulfur-, and oxygen-containing (NSO) compounds. We also employed a combination of other geochemical methods, such as GC-FID and GC-MS analyses, to characterize and assess the depositional environments of the different oil families. The results indicate that lacustrine oils tend to be enriched in Nx compounds, while marine oils show preference for Ox compounds. The dominant heteroatomic classes in crude oils are N1, followed by O1, O2, and N1O1 with remarkable differences in their distributions between marine and lacustrine, strongly suggesting the control by the kerogen type of the heteroatomic compounds found in these crude oils. Considerable differences in the DBE distribution of the main classes analyzed between the crude oils allowed an efficient geochemical characterization regarding their origin. The use of negative ESI FTICR-MS as a geochemistry tool can provide additional information beyond that obtained with currently employed geochemical methods, resulting in the full comprehension of crude oil composition.

26552. 题目: Influence of vegetation type on n-alkane composition and hydrogen isotope values from a high latitude ombrotrophic bog
文章编号: N18060129
期刊: Organic Geochemistry
作者: Nicholas L. Balascio, William J. D'Andrea, R. Scott Anderson, Stephen Wickler
更新时间: 2018-06-01
摘要: The composition and hydrogen isotope values of leaf wax components can be powerful tools in reconstructing past climate and environments. However, interpretation of past environmental conditions from such components in sediments is complicated by species-specific influences and there is a need to better understand how vegetation type affects leaf wax composition and isotope ratios in modern environments. In this study we analyzed leaf wax (n-alkane) distributions and hydrogen isotope values of plants from a high latitude ombrotrophic bog in northern Norway. The isotopic analysis of surface water was also conducted on samples from 15 lakes along a ca. 150 km transect to contextualize the bog water isotopic composition and constrain fractionation factors among n-alkane homologues. We identified 14 different plant types growing on the bog surface, including mosses, graminoids and other herbs, sub-shrubs and a tree. n-Alkanes from the leaves of the modern plants had average chain lengths from 25 to 30.5, with a variety of distributions, and with the dominant compound of longer chain lengths (C27, C29, or C31). δD values of n-C25 to n-C33 for the vegetation samples ranged from -197‰ to -116‰, with an average of -162‰. The data also revealed that the δD values for the homologues for half of the vegetation types had ranges that were ≥20‰. Using the average isotopic value of bog water samples, -60‰, we calculated apparent fractionation factors that ranged from -66‰ to -134‰ (avg. -108 ± 22‰), similar to other sites across Europe and to a global data compilation. Our results demonstrate the range of species-specific influences on leaf wax composition and isotopic values at this site and presumably other ombrotrophic bog environments, and provide a dataset to help evaluate the influence of vegetation type on regional sedimentary leaf wax records.

26553. 题目: Modelling leaf wax n-alkane inputs to soils along a latitudinal transect across Australia
文章编号: N18060128
期刊: Organic Geochemistry
作者: S. Howard, F.A. McInerney, S. Caddy-Retalic, P.A. Hall, J.W. Andrae
更新时间: 2018-06-01
摘要: Leaf wax n-alkanes provide a valuable palaeoecological proxy, but their interpretation requires an understanding of the scale of temporal and spatial integration in soils. Leaf wax n-alkanes are continually deposited into soils directly from local plants as well as from more distant plants via wind or water transport. In addition, n-alkanes can persist in soils for thousands of years, and tend to decrease in age with shallower depth. To explore whether the uppermost soils reflect recent leaf fall inputs we compared surface soils and modern vegetation from 20 sites along a transect across Australia. At each site, the three most dominant plant species and a soil sample from the top 3 cm were analysed for n-alkane concentration, average chain length (ACL), proportional abundance of C33 and C29 (Norm33) and carbon preference index (CPI). Chain length distributions differ between trees and grasses, with a higher proportion of C29 in trees and C33 in grasses. Norm33 in soils correlates with proportional grass to tree cover across the transect. To model n-alkane inputs for each site, we calculated a predicted ACL, Norm33 and CPI using the dominant plants at that site, weighted by proportional species cover and n-alkane concentration. Predicted ACL, Norm33 and CPI inputs were generally higher than the soils, demonstrating that recent and local inputs do not dominate soil n-alkanes at our study sites. Thus, n-alkane distributions in surface soils do not correlate with local, current vegetation, but do correlate with proportional grass and tree cover, suggesting they provide a faithful record of large scale ecosystem structure.

26554. 题目: n-Alkan-2-one biomarkers as a proxy for palaeoclimate reconstruction in the Mfabeni fen, South Africa
文章编号: N18060127
期刊: Organic Geochemistry
作者: Andrea Baker, Joyanto Routh, Alakendra N. Roychoudhury
更新时间: 2018-06-01
摘要: The sub-tropical Mfabeni fen is the only continuous coastal peat deposit that documents glacial and interglacial palaeoenvironmental conditions since the late Pleistocene (ca. 47 cal kyr BP) in southern Africa. Published bulk geochemical, biomarker and leaf wax δ13C data, along with palynology and stratigraphic studies of the Mfabeni peat sequence, render it an ideal record for testing new palaeoreconstruction proxies. In this study, we aimed to establish the proxy potential of n-alkan-2-one (n-ket) compounds by tracing their source/origin and post-depositional diagenetic change, and if they preserve or not a robust palaeoenvironment signal that complements our understanding of palaeoclimatic variations. In the Mfabeni archive the most likely source for n-kets is via microbial decarboxylation of n + 1-alkanoic acids (n-FAs) and, to a lesser degree, oxidation of same chain length n-alkanes (n-alks). The n-ket average chain length (ACLket) and n-C23 and C25ket/precursor ratios displayed a statistical significant negative relationship with the n-alk aquatic plant proxy (Paq), suggesting the source of n-kets to be submerged aquatic plants during waterlogged conditions that suppressed microbial activity during the ensuing anoxic conditions. Both the mid-chain and long chain n-ket/precursor ratios displayed predominant water level fluctuation controls, with temperature as a secondary regulator. By comparing the n-ket data with published environmental and climate reconstructions from the same core, and with geomorphology and palynological studies of the Mfabeni basin, we conclude that the n-kets show promise as a palaeoclimate proxy and can be used in conjunction with other biomarker proxies to reconstruct ancient hydrological changes in sub-tropical peatlands.

26555. 题目: On the changes of polycyclic aromatic compounds in waterflooded oil and their implications for geochemical interpretation
文章编号: N18060126
期刊: Organic Geochemistry
作者: Xiangchun Chang, Yue Wang, Yaohui Xu, Jing Cui, Tao Wang
更新时间: 2018-06-01
摘要: Qudi oilfield had been producing for over twenty years and became waterflooded ten years ago. Samples from nine producing wells drilled recently in the Qudi oilfield were collected during the three recovery stages spanning an eight month interval of waterflooding and were analyzed for changes in their polycyclic aromatic compounds (PACs). The results indicate that most of waterflooded oils are characterized by increased tricyclic, tetracyclic, pentacyclic and triaromatic steroids concentrations. The irregular changes in parameters based on two or fewer alkyl-substituted naphthalenes (MNR, ENR, DBR, DNR-1) implies a different depletion order for the PACs because the abundances of the compounds are controlled by the predominance of water washing and biodegradation over a certain time. The increase in DBTs and DBFs with water washing reflects their strong resistance to biodegradation. Lower aqueous solubility and strong resistance to biodegradation are possibly responsible for the mainly unchanged values of the three or more alkylnaphthalene-related parameters (TNR-1, TDE-1, TDE-3, TBR and TeBR), tricyclic aromatics (MPI-1 and PP-1), tetracyclic aromatics (MCI, MCI2, 2-MC/1-MC, and BaA/(BaA + Chry)), triaromatic steroids parameters (C26-TAS/C28-TAS, C27-TAS/C28-TAS, C28-TAS 20S/(20R + 20S), and TA(I)/TA(I + II)), and heterocyclic aromatic parameters (4-MDBT/DBT, 4-MDBT/1-MDBT, and 4,6-DMDBT/(1,4 + 1,6)-DMDBT), confirming their validity for geochemical interpretation even after extensive water washing. However, pentacyclic aromatic parameters (BeP/Pe, (BeP + BaP)/Pe, BF/Pe, and BF/BeP), which are theoretically expected to be unaffected, change significantly with the advance of the waterflooding process, implying a complex alteration mechanism that needs further investigation.

26556. 题目: Organic matter in sediments of a tropical and upwelling influenced region of the Brazilian continental margin (Campos Basin, Rio de Janeiro)
文章编号: N18060125
期刊: Organic Geochemistry
作者: Lívia G.M.S. Cordeiro, Angela L.R. Wagener, Renato S. Carreira
更新时间: 2018-06-01
摘要: Lipid biomarkers [fatty acids (FAs), sterols and alcohols] and carbon stable isotopes (δ13C values) in surface sediments from 9 cross shelf transects (25–3000 m water depth) from the Campos Basin, SE Brazilian continental margin were analyzed. The aim was to investigate the link between the prevailing regional specific oceanographic conditions (upwelling events, intrusion of cold and nutrient-rich water, low river input) and the nature and distribution of organic matter (OM) in the basin. A general predominance of OM from autochthonous processes, but with a relevant spatial gradient in the quality and quantity of the sedimentary OM, was observed. On the shelf (<150 m), concentrations of lipids were usually low, except in areas influenced by upwelling, but the presence of labile compounds suggested the occurrence of fresh OM in the sediment. The export of continental OM was observed only in shelf sediments near the Paraíba do Sul River. The upper and middle slope (400–1300 m) exhibited the highest concentrations of total organic carbon (TOC) and lipids, but lipid biomarkers suggested the presence of OM with a high degree of bacterial degradation. This may result from the export of material from shallow areas, possibly due to the action of eddies and meandering of the Brazil Current and bottom currents in the region. On the lower slope (1900–3000 m), only the more recalcitrant compounds were above detection limit. The presence of labile lipids in high amount in the shelf and slope suggests the presence of OM with a high potential for supplying the food requirements of heterotrophic organisms in the sediment, which may in turn have a major influence on the ecology of benthic communities.

26557. 题目: Patterns of change in permanganate oxidizable soil organic matter from semiarid drylands reflected by absorbance spectroscopy and Fourier transform ion cyclotron resonance mass spectrometry
文章编号: N18060124
期刊: Organic Geochemistry
作者: Carlos M. Romero, Richard E. Engel, Juliana D'Andrilli, Chengci Chen, Catherine Zabinski, Perry R. Miller, Roseann Wallander
更新时间: 2018-06-01
摘要: Organic matter (OM) oxidized by slightly alkaline KMnO4, termed permanganate-oxidizable carbon (POXC), has recently emerged as a standardized indicator of active, labile carbon within soil quality frameworks. Yet, qualitative information on POXC, particularly in semiarid drylands, is very scarce. The aim of this study was to characterize POXC within three long-term field experiments in Montana, USA: (i) across a wide range of edaphic (e.g., % clay) and management conditions (e.g., cropping intensity) (n = 148); and (ii) to identify the molecular composition of soil OM before and after KMnO4 treatment using electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS). The content of POXC was significantly greater under perennial (382–685 mg/kg) or annual cropping (404–607 mg/kg) than fallow-wheat (359–543 mg/kg) systems. Soil OM changes, however, were equally or better expressed when considering soil organic carbon (SOC) concentration. The occurrence of POXC paralleled SOC (R = 0.87; P < 0.001) and total nitrogen (TN) (R = 0.82; P < 0.001) concentrations, regardless of soil textural differences. The ESI FT-ICR MS analyses of aqueous soil extracts indicated that the KMnO4 reaction oxidized dissolved OM of diverse molecular character. OM molecular composition after KMnO4 treatment was enriched by strongly reduced chemical constituents (O/C < 0.4) at greater condensed aromaticity (AI > 0.67) and hydrogen saturation (aliphatic composition; H/C > 1.5) across all heterogeneous groups (CcHhNnOoSs). Although POXC is a rapid assay widely used for characterizing soil OM dynamics, it may not provide a clear advantage over SOC concentration in semiarid drylands. The view of POXC as a merely labile, simple biodegradable OM fraction needs to be reconsidered.

26558. 题目: Production and turnover of microbial organic matter in surface intertidal sediments
文章编号: N18060123
期刊: Organic Geochemistry
作者: Weichao Wu, Travis Meador, Kai-Uwe Hinrichs
更新时间: 2018-06-01
摘要: Benthic microorganisms play a significant role in the remineralization of sedimentary organic matter (OM). In order to constrain the growth rate, turnover and carbon metabolism of microbial communities in anoxic sandy sediments, we quantified the rate of inorganic carbon (IC) assimilation and of lipid production via a recently developed dual isotope-labelling assay that can differentiate autotrophic vs. heterotrophic production in a 22 cm sediment core from the Janssand tidal flat (Wadden Sea, Germany). Despite an extremely low concentration of total organic carbon (TOC) in the majority of samples (<0.3%), the concentration of total fatty acids (TFAs) was in the range 4.5 to 28.4 μg/mg TOC, suggestive of a high contribution of fresh microbial and algal biomass to the TOC pool. This was corroborated by a production rate of microbial FAs, which ranged from 0.3 to 4.7 μg TFAs/gdw/yr (where dw = dry wt) and the mean turnover time of microbial FAs was 6 ± 5 yr. The enhanced production rate of iso- and anteiso-branched FAs was consistent with the presence of an active population of sulfate reducing Deltaproteobacteria. The assimilation rate of IC into bacterial lipids was relatively low (0.16 ± 0.07 μg C/gdw/yr) in OM-lean sandy sediments (i.e. upper 17 cm), such that the IC assimilation to lipid production ratio values was typically <0.3, indicating that heterotrophic bacteria were dominant and dark IC fixation played a minor role at the study site. The measured rates of FA production converted to an anaerobic heterotrophic C demand of 0.4–1.8 g C/gdw/d, assuming a bacterial growth efficiency of 10%. Such high biomass proportion, production rate and C demand suggested that dissolved OM must play a vital role in sustaining the active heterotrophic microbial populations in these sandy sediments.

26559. 题目: Wax lipids in fresh and charred anatomical parts of the Celtis australis tree: Insights on paleofire interpretation
文章编号: N18060122
期刊: Organic Geochemistry
作者: Margarita Jambrina-Enríquez, Antonio V. Herrera-Herrera, Carolina Mallol
更新时间: 2018-06-01
摘要: Leaf waxes have been assumed to be the dominant source of wax delivered to sediment. However, wooden branches and twigs have not been widely considered in this context and could be a potential source of wax lipids in fire places or combustion structures. Black sedimentary layers are the main material of open-air archaeological combustion structures and represent either carbonized fuel (wood) or the charred ground beneath the fire (mainly leaves) and it is difficult to discern between the two sources. To identify different plant parts as components of combustion residues, fresh and charred leaves, branches and twigs (bark and xylem) of the Celtis australis tree were analyzed for aliphatic and aromatic hydrocarbons and fatty acid concentrations, as well as the carbon isotopic composition of n-alkanes (δ13Calkane). Charred biomass was produced under limited oxygen conditions at 150, 250 (3 and 5 h), 350 and 450 °C for 1h. The n-alkyl profiles in different parts of C. australis are sufficiently distinct to allow their identification as components of combustion structures under low combustion temperature conditions. Average chain lengths and carbon preference index ratios decrease with increasing temperature and vary among plant parts. The δ13Calkane values remained slightly unaltered until 350 °C and changed by 3–4‰ at 450 °C. Our results provide new information on the molecular and isotopic changes that occur upon burning different plant parts, which in turn show potential for good preservation of organic matter in archaeological black layers and for positive identification of burned leaf and wood residues in them.
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26560. 题目: What is the meaning of Hydrogen-to-Carbon ratio determined in Archean organic matter?
文章编号: N18060121
期刊: Organic Geochemistry
作者: Frédéric Delarue, Sylvie Derenne, Kenichiro Sugitani, Fran?ois Baudin, Frances Westall, Barbara Kremer, Romain Tartèse, Adriana Gonzalez, Fran?ois Robert
更新时间: 2018-06-01
摘要: The search for hydrocarbon molecular biomarkers in Archean metasediments is of prime importance for deciphering the early evolution of life. Suitable criteria are required to identify promising targets for further molecular biomarkers. Possible criteria include the Hydrogen-to-Carbon (H/C) atomic ratio used as a proxy of the aliphatic content of the kerogen matrix. However, H/C ratio values exhibit large variation in Archean kerogens and their significance remains poorly understood. In this study, we thus investigate the significance of the H/C ratios of Archean kerogens by combining elemental analyses, Nanoscale Secondary Ion Mass Spectrometry (NanoSIMS), Rock-Eval pyrolysis and Raman spectroscopy. First, NanoSIMS investigations show the H/C ratio of kerogen can be compromised by residual minerals. In addition, Rock-Eval pyrolysis underlines the fact that thermal cracking of Archean kerogens does not just release hydrocarbon covalently linked to the macromolecular network but also a complex mixture of organic pools distinguished by their thermal maturity. Therefore, the H/C ratio alone cannot be used to probe the preservation of aliphatic compounds bound to kerogen since it can be biased by the presence of (i) residual bitumen, as well as (ii) refractory organic matter in secondary hydrothermal veins whose syngenecity is debatable. Rock-Eval pyrolysis then provides a useful and complementary method to check the significance of H/C atomic ratio as a proxy for hydrocarbon preservation in Archean kerogens.