Showing papers in "Organic Geochemistry in 2006"

TL;DR: In this article, the authors assess the relative importance of either biotic or abiotic oxidation of biomass-derived black carbon (BC) and characterize the surface properties and charge characteristics of oxidized BC.

TL;DR: In this paper, a diverse collection of globally distributed soil samples was analyzed for its glycerol dialkyl glycerolic tetraether (GDGT) membrane lipid content, and it was shown that branched GDGTs, derived from anaerobic soil bacteria, were the most dominant and were found in all soils.

TL;DR: In this paper, the use of a newly synthesized C46 GDGT as an internal standard was used to measure absolute GDGT abundances more accurately, and the accuracy in the determination of GDGT concentration improved significantly when using the internal standard (5% standard deviation) compared to that obtained with the monthly external standard curve (43% standard deviations).

TL;DR: In this paper, the authors investigated the origin of the hydrogen isotope signal of n -alkanes from higher terrestrial plant biomass in sedimentary organic matter of small lakes and found that terrestrial n-alkanes in lake sediments can deliver information on changes in these parameters over geological timescales.

TL;DR: The present-day state as well as the history of isotope organic geochemistry is reviewed in this article, where theoretical aspects of fractionation in a system of complex organic molecules, fractionation of carbon isotopes in the biosphere, isotopes as applied to study the transformation of organic matter, geochemistry of oil and gas, evolution of the carbonate-organic carbon system and aspects of astrobiology are considered.

TL;DR: The molecular composition of water-soluble products generated by the natural degradation of charcoal particles over a period of 100 years in a temperate forest soil has been investigated by ultra-high resolution mass spectrometry with electrospray ionization as discussed by the authors.

TL;DR: In this paper, the authors presented a scientific approach to the production of synthetic wood char that has properties of a natural wood char produced by forest fire, and the natural char examined for this purpose was that of a pitch pine obtained from the New Jersey Pine Barrens.

TL;DR: The results confirm the validity of the contents, distribution patterns and molecular stable carbon isotopic compositions of long-chain n-alkanes and alkan-1-ols as indirect proxies of continental climate conditions in environmental studies of the tropics.

TL;DR: In this article, the suitability of the use of fluorescence and UV-visible spectroscopies to evaluate the humification degree of different organic alkaline extracts obtained from diverse materials (humic substances, composted and non-composted materials).

TL;DR: In this paper, the authors synthesized large quantities of two chars for use as commercially available reference materials for the quantification of black carbon (BC) using a N2 atmosphere, which mimics the oxygen-free conditions on the inside of burning material at moderate burning temperature.

TL;DR: In this article, the authors demonstrate that ratios of the abundances of n-alkanes provide a new and efficient way of reconstructing past peatland surface moisture change, and find strong correlations among nalkane indices, humification indices and testate amoebae-inferred water table depths from a single core.

TL;DR: The mussels were highly selective, assimilating most of their carbon from phytoplankton out of the total particulate organic carbon pool, however, on a seasonal basis, tissue d 13 C varied differently than d 13 CDIC and d 13 CPOC, most likely due to lipid content of the tissue.

TL;DR: Peters et al. as mentioned in this paper showed that even within a single petroleum accumulation, a number of mechanisms control changes in the abundance and composition of hopanes and 25-norhopanes.

TL;DR: In this paper, the retene/cadalene ratio is used as a chemostratigraphic tool for tracing both palaeoflora and palaeoclimatic changes during the Callovian and Oxfordian in the Paris Basin.

TL;DR: In this paper, the authors analyzed the hydrolyzable lipid composition of grassland and forest soils, and their overlying vegetation (i.e., prairie grasses, aspen, and pine) by alkaline hydrolysis and gas chromatography-mass spectrometry (GC-MS).

TL;DR: In this article, the effect of demineralization using hydrofluoric acid (HF) treatment on the elemental, isotopic and chemical composition of organic matter with increasing degree of humification was examined using four horizons of a forest humus profile.

TL;DR: Using cluster analysis, the combination of n-alkanes and n-alcohols from leaves is found to give the most meaningful clustering from the point of view of an UFL reconstruction, with all but one paramo grassland species and all but two peat bog species clustering separately from forest species.

TL;DR: The role of organic C in this process, whether from in situ organic matter (OM), i.e. organic C from within the sediment, or from other sources, is widely recognised.

TL;DR: In this article, the authors evaluate differences in the sources and potential transformations of organic matter (OM) using lipid biomarker, elemental ratios, and stable isotope (δ13C and δ15N) analyses.

TL;DR: In this article, a dual-isotope approach with δ 15 N and δ 18 O in nitrate was carried out to identify and quantify diffuse nitrate inputs into a river sub basin in Mecklenburg-Vorpommern (Germany).

TL;DR: In this paper, the relative proportions of aliphatic CH2, CH3, Hali, and CH3 in a series of Carboniferous, Permian, Jurassic and Cenozoic humic coals were analysed using FTIR and ruthenium tetroxide catalysed oxidation (RTCO) followed by GC-MS analysis of the n-monocarboxylic acids (esterified) to assess their ability to generate oil.

TL;DR: In this paper, a set of Late Jurassic to Early Cretaceous (Aptian/Albian), 13 C-depleted seep-limestones from forearc strata in western California were subjected to detailed molecular-isotopic biomarker analyses.

TL;DR: In this article, the authors studied the Upper Jurassic Draupne Formation in the North Viking Graben, North Sea to identify lateral and vertical variations in source rock characteristics and their effect on the timing of petroleum generation.

TL;DR: In this paper, the authors investigated the biomarker composition of sediments ranging in age from 30 to 70 Ma from the Kilwa area of Tanzania and found that they are dominated by terrestrial (n-alkanols, n-alkanoic acids, nalkanes and triterpenoids) and marine (hopanoids and a dipentadecyl glycerol diether) origin with only a minor contribution of marine origin.

TL;DR: In this paper, high resolution molecular abundance data for alkenones, dinosterol, long chain diols and n -alkanols from ODP Site 658 (20°45′N, 18°35′W; 2263 ǫm water depth) were reported.

TL;DR: In this article, oil-bearing fluid inclusions are present in four reservoir sandstone samples from the slope and fault zone areas in the northwestern margin of the Junggar Basin (NW China).

TL;DR: In this article, the mechanisms of organic matter stabilization and possible organic-mineral interactions in alkaline soils rich in Ca (calcareous soils) were investigated using density separation in combination with ultrasonic dispersion.

TL;DR: In this article, the tetraether index of lipids with 86 carbon atoms (TEX86) was applied to the suspended particulate organic matter (POM) and sediment core tops from eight sites in the southern North Sea in different seasons.

TL;DR: In this paper, the authors performed lipid analysis for three particle size fractions (i.e., sand-, silt-and clay-sized) isolated from a sandy spodosol of the Cestas cultivation sequence (Landes de Gascogne, France).

TL;DR: In this article, the influence of pH and the metal:humic substances (HS) ratio on HS complexing capacity and the stability and solubility of metal-HS complexes in solution was investigated.