Showing papers in "Organic Geochemistry in 2011"

TL;DR: In this article, different analytical techniques were used to find the most reliable and economic method for determining the labile fraction of C in biochar, and the degree of biochar carbonisation was influenced by the type of feedstock and heating conditions and followed the order WI-400

TL;DR: In this paper, three Paleogene syn-rift intervals from the Bohai Bay Basin, the most petroliferous basin in China, were analyzed with sedimentological and geochemical techniques to characterize the lateral source rock heterogeneities, revealing the environmental and ecological changes through geologic time and to construct depositional models for lacustrine source rocks under different tectonic and climatic conditions.

TL;DR: In this paper, the authors presented geological and geochemical criteria to recognize secondary microbial methane in conventional petroleum reservoirs and estimated that ∼65,500 tcf of secondary microbial gas could have been generated in existing worldwide accumulations of oil and bitumen through their geological history.

TL;DR: In this article, Chestnut wood charcoal samples produced at heat treatment temperatures (HTT) from 200-1000°C were analysed using two different solid state 13 C NMR techniques.

TL;DR: In this paper, the authors analyzed the distributions of glycol dialkyl glycerol tetraether (GDGT)-based proxies in surface sediments from the Lower Yangtze River and East China Sea (ECS) shelf and revealed multiple sources and complex shelf processes that govern the distributions.

TL;DR: In this paper, solid-phase extracted samples from the western arm of Lake Superior and its watershed, including swamp, creek, river, lake-river confluence and offshore lake sites were compared using electrospray ionization (ESI), Fourier transform ion cyclotron resonance MS (FT-ICR-MS) and van Krevelen diagrams.

TL;DR: A large data set of organic markers for terrigenous, petroleum and combustion inputs [alkanes, hopanes and steranes, parent and alkyl polycyclic aromatic hydrocarbons (PAHs)] is examined for patterns in space and time using principal components analysis (PCA) and partial least squares (PLS) as discussed by the authors.

TL;DR: In this paper, the role of water in the formation of pyrobitumen and molecular hydrogen in Mahogany oil shale (Eocene Green River Formation) with Type-I kerogen was investigated.

TL;DR: In this paper, the authors compare branched glycerol dialkyl tetraethers (GDGTs) distributions and concentrations in lake sediments and catchment soils within a 3600 m altitudinal transect in western Uganda.

TL;DR: The authors used 13C/15N labeled litter addition and Curie-point pyrolysis gas chromatography-mass spectrometry combustion-isotope ratio mass spectrometer (Py-GC-MS-C-IRMS) to explore the transformation of litter with different composition and decay rate (ponderosa pine needle vs. fine root) to soil organic matter (SOM) during 18 months in a temperate conifer forest mineral soil.

TL;DR: In this article, the authors analyzed three major hydrocarbon bearing intervals in the Lunnan lower bulge for their stable carbon isotopes and molecular biomarkers and concluded that the recently discovered deep (6500m) eastern Lungu giant Ordovician gas condensate pool with an estimated reserve of 723 million bbl oil equivalent is a secondary hydrocarbon accumulation derived from the mixing of an early formed oil and a late formed gas.

TL;DR: In this article, carbon (C) 1s near edge X-ray absorption fine edge structure (NEXAFS) spectroscopy was used to characterize the C chemistry of a broad range of black carbon (BC) materials.

TL;DR: In this article, the authors provide a brief introduction to the basic principles of CPMAS NMR and give some explanation about the potential source of non-quantitative results, which are necessary for the correct adjustment of NMR acquisition parameters.

TL;DR: In this article, the authors conducted a survey of archaeal GDGT distributions in marine sediments deposited in a range of depositional settings and compared the two pools presumed to have distinct geobiological significance, i.e. intact polar GDGT (IP GDGTs) and core GDGT, and found that the former pool has been suggested to be related to living communities of benthic archaea in marine sedimentiments, while the latter is commonly interpreted to consist of molecular fossils from past planktonic arachnophase communities that inhabited the surface ocean.

TL;DR: In this article, the spatial distribution and the seasonal dynamics of chromophoric dissolved organic matter (CDOM) were explored in Lake Taihu in eastern China from 2005 to 2009, and the spatial seasonal dynamics of CDOM absorption and three CDOM composition variables, including spectral slope (S), spectral slope ratio (SR), and the M value, defined as the ratio of absorption at 250nm/365nm, were analyzed and discussed.

TL;DR: In this article, n-alkane biomarkers and plant macrofossils from a peat plateau deposit in the northeast European Russian Arctic were carried out to assess the effects of past hydrology on the m...

TL;DR: In this article, the microbial recalcitrance of char accumulated after vegetation fires and its transport within a soil column were studied in microcosms using 13C and 15N-enriched pyrogenic organic material (PyOM).

TL;DR: In this article, the authors analyzed three soils, which mainly differed in carbon content and overlying vegetation, but have similar clay mineralogy, using biomarker analysis and nuclear magnetic resonance (NMR) to measure chemical patterns of OM sequestration in sand-, silt-, clay-size and light fractions.

TL;DR: In this paper, a systematic solid state NMR protocol for characterization of humic substances using a humic acid as an example was presented, which included identification of specific functional groups using spectral editing techniques, occasionally assisted by 1H13C 2D HETCOR and 1H spin diffusion.

TL;DR: In this paper, Proterozoic to Cambrian aged oils from eastern Siberia were analyzed for their hydrocarbon biomarker contents and compound specific carbon isotopes in order to further understand the prevailing environment and its microbial and metazoan communities.

TL;DR: In this paper, the authors illustrate the use of PCA in marine geochemistry through examples that arose while investigating the geochemistry of sinking particles during the MedFlux project and show that constructing a one dimensional (1D) degradation index using only the first principal component (PC) is in most cases oversimplified, and that constructing 2D or 3D trajectories with the first 2 or 3 PC is more informative.

TL;DR: The identification and distribution of IPL-branchedGDGTs throughout a depth profile of a Swedish peat bog and similar IPL branched GDGTs as those in peat were present, albeit with different distributions.

TL;DR: The organic geochemistry of samples from 11 oil seeps was studied in this article, showing both the partial loss of n-alkanes and the microbial degradation of isoprenoids and steranes.

TL;DR: In this article, the authors reported the historical trends and sources of aliphatic hydrocarbons and polycyclic aromatic hydrocarbon (PAHs) in two 210 Pb dated sediment cores extracted from the central mud areas of Bohai Sea (Bohai).

TL;DR: Decoupling the concentration of archaeol and the more labile sn -2-hydroxyarchaeol below ca.

TL;DR: In this paper, a set of 45 samples were extracted and non-aromatic hydrocarbons were analyzed by way of gas chromatography-flame ionization detection (GC-FID) and GC-MS.

TL;DR: In this paper, the MBT-CBT proxy was used to estimate past annual mean air temperature (MAT) based on the distribution of bacterially-derived branched glycerol dialkyl glyceroline tetraether (GDGT) membrane lipids in peat and coal.

TL;DR: The abundance and structural diversity of bacteriohopanepolyols (BHPs) were examined in three marine pelagic environments that are characterized by strong vertical redox gradients and water column suboxia or anoxia as discussed by the authors.

TL;DR: Liu et al. as discussed by the authors used the molecular hydrogen isotope composition (dD) of leaf waxes from terrestrial plants to infer hydrological characteristics of ancient high latitude climates.

TL;DR: In this paper, the effects of time and pressure on vitrinite reflectance (VR) were investigated at 400°C and at pressures of 2, 10 and 20kbar.