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Salque M.,Organic Geochemistry Unit | Tagliacozzo A.,Sezione di Paleontologia del Quaternario e Archeozoologia | Pino Uria B.,Sezione di Paleontologia del Quaternario e Archeozoologia | Wolfram S.,University of Leipzig | And 8 more authors.

Analyses of organic residues preserved in ceramic potsherds enable the identification of foodstuffs processed in archaeological vessels. Differences in the isotopic composition of fatty acids allow differentiation of non-ruminant and ruminant fats, as well as adipose and dairy fats. This paper investigates the trends in milk use in areas where sheep and goats are dominant in the faunal assemblage and in some sites from the Linearbandkeramik culture. Sites include: Colle Santo Stefano, Abruzzo, Italy, and the Oldest to Young Linearbandkeramik sites of Zwenkau, Eythra and Brodau, Saxony, and Wang and Niederhummel, Bavaria, Germany. More than 160 potsherds were investigated including cooking pots, bowls, jars, and ceramic sieves. The lipid residues presented provide direct evidence for the processing of ruminant and non-ruminant commodities at Zwenkau and Eythra, despite the absence of faunal remains at the sites. No dairy residues were detected in potsherds from LBK sites, except in a ceramic sieve at Brodau. Lipids from non-ruminant and ruminant fats, including from dairy fats, were detected at the site of Colle Santo Stefano showing a reliance on dairy products during the first half of the sixth millennium at this site; where sheep and goats were the major domestic animals. © Publications Scientifiques du Muséum national d'Histoire naturelle. Source

Aquilina A.,Organic Geochemistry Unit | Aquilina A.,UK National Oceanography Center | Knab N.J.,MPI for Marine Microbiology | Knittel K.,MPI for Marine Microbiology | And 10 more authors.
Organic Geochemistry

The anaerobic oxidation of methane (AOM) is a major methane sink in marine sediments and plays a crucial role in mitigating methane fluxes to the overlying water column. We investigated biomarker distributions and compound specific isotopic signatures in sediments from sites on the Northern European continental margin that are characterized by a diffusive flux of methane. At all sites, the organic matter (OM) is predominantly derived from terrestrial higher plants, with subordinate abundances of algal biomarkers, but biomarkers for archaea and bacteria are also present. The co-occurrence of the archaeal lipids archaeol, sn-2-hydroxyarchaeol and 2,6,10,15,19-pentamethylicosane (PMI) with non-isoprenoidal glycerol diethers inferred to derive from sulfate-reducing bacteria (SRB) is similar to microbial biomarker assemblages observed at cold seeps. The archaeal and inferred SRB biomarker concentrations typically reach maxima close to the sulfate-methane transition zone (SMTZ), where archaeal biomarkers are depleted in 13C. The 16S rRNA gene sequences from the SMTZ of the Aarhus Bay sediment core indicate the occurrence of ANME-1 archaea, consistent with inferences derived from biomarker distributions. The observations suggest that AOM in these diffusive settings is mediated by consortia of archaea and bacteria similar to those found at many seep and methane hydrate sites around the world. © 2009 Elsevier Ltd. All rights reserved. Source

Styring A.K.,Organic Geochemistry Unit | Sealy J.C.,University of Cape Town | Evershed R.P.,Organic Geochemistry Unit
Geochimica et Cosmochimica Acta

Stable nitrogen isotope analysis is a fundamental tool in assessing dietary preferences and trophic positions within contemporary and ancient ecosystems. In order to assess more fully the dietary contributions to human tissue isotope values, a greater understanding of the complex biochemical and physiological factors which underpin bulk collagen δ15N values is necessary. Determinations of δ15N values of the individual amino acids which constitute bone collagen are necessary to unravel these relationships, since different amino acids display different δ15N values according to their biosynthetic origins. A range of collagen isolates from archaeological faunal and human bone (n = 12 and 11, respectively), representing a spectrum of terrestrial and marine protein origins and diets, were selected from coastal and near-coastal sites at the south-western tip of Africa. The collagens were hydrolysed and δ15N values of their constituent amino acids determined as N-acetylmethyl esters (NACME) via gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS). The analytical approach employed accounts for 56% of bone collagen nitrogen. Reconstruction of bulk bone collagen δ15N values reveals a 2‰ offset from bulk collagen δ15N values which is attributable to the δ15N value of the amino acids which cannot currently be determined by GC-C-IRMS, notably arginine which comprises 53% of the nitrogen unaccounted for (23% of the total nitrogen). The δ15N values of individual amino acids provide insights into both the contributions of various amino acids to the bulk δ15N value of collagen and the factors influencing trophic position and the nitrogen source at the base of the food web. The similarity in the δ15N values of alanine, glutamate, proline and hydroxyproline reflects the common origin of their amino groups from glutamate. The depletion in the δ15N value of threonine with increasing trophic level indicates a fundamental difference between the biosynthetic pathway of threonine and the other amino acids. The δ15N value of phenylalanine does not change significantly with trophic level, reflecting its conservative nature as an essential amino acid, and thus represents the isotopic composition of the nitrogen at the base of the food web. Δ15NGlu-Phe values in particular are shown to reflect trophic level nitrogen sources within a food web. In relation to the reconstruction of ancient human diet the contribution of marine and terrestrial protein are strongly reflected in Δ15NGlu-Phe values. Differences in nitrogen metabolism are also shown to have an influence upon individual amino acid δ15N values with Δ15NGlu-Phe values emphasising differences between the different physiological adaptations. The latter is demonstrated in tortoises, which can excrete nitrogen in the form of uric acid and urea and display negative Δ15NGlu-Phe values whereas those for marine and terrestrial mammals are positive. The findings amplify the potential advantages of compound-specific nitrogen isotope analysis in the study of nitrogen flow within food webs and in the reconstruction of past human diets. © 2009 Elsevier Ltd. All rights reserved. Source

Bingham E.M.,Organic Geochemistry Unit | McClymont E.L.,Organic Geochemistry Unit | Valiranta M.,University of Helsinki | Mauquoy D.,University of Aberdeen | And 4 more authors.
Organic Geochemistry

The n-alkane distributions from total lipid extracts of ten modern Sphagnum moss species, collected from a suite of ombrotrophic bogs across Europe, were determined using gas chromatography/mass spectrometry (GC/MS). n-Alkane distributions are reported for the first time for Sphagnum balticum, S. majus, S. angustifolium and S. lindbergii, which are all dominated by C 23 with the exception of S. lindbergii, which exhibits a bimodal distribution with C 23 and C 31 as the major homologues. The distributions for individual species generally agree with published compositions, confirming the conservative nature of the n-alkane compositions, which provide a basis for differentiating the n-C 23 and n-C 25 dominated species. Investigations of the variation in n-C 23/n-C 25 and n-C 23/n-C 31 ratios of Sphagnum species, using the new and published n-alkane distributions, reveal that intra-species variation is generally minor. Critically, the distributions and ratios for most species do not vary among the sites studied, suggesting that they are conservative tracers for a given species, despite differences in growth conditions. In contrast, inter-species variation exists, allowing differentiation of individual Sphagnum species based on vegetation biomarkers, specifically the C 25 n-alkane in S. fuscum and the n-C 23/n-C 25 ratio. Biomarker stratigraphic analysis of a 150 cm peat core (Kontolanrahka Bog, Finland) reveal shifts in the n-C 23/n-C 25 ratio, which track changes in the abundance of S. fuscum in the macrofossil record. This supports the application of n-alkane biomarkers in peat archives for tracking past shifts in individual Sphagnum species abundance. This will be particularly important where fossil plant remains are highly degraded in, or absent from, peat records. © 2009 Elsevier Ltd. All rights reserved. Source

News Article
Site: http://www.nature.com/nature/current_issue/

Geoffrey Eglinton was curious about the history of molecules. He followed their passage from living organisms into soils and sediments, and tracked their geological fate in sedimentary rocks and fossil fuels. His exploration of the natural history of biochemicals and their geochemical remnants established the modern field of organic geochemistry. In 1969, he analysed Moon rocks collected by Neil Armstrong and Buzz Aldrin on Apollo 11. Eglinton, who died on 11 March, was born in Cardiff, UK, in 1927. He studied chemistry at the University of Manchester, from where he earned three degrees: a BSc in 1948, a PhD in 1951 and a DSc (a doctorate of science) in 1966. He worked for two years as a postdoctoral researcher at Ohio State University in Columbus and then returned to the United Kingdom as an Imperial Chemical Industries (ICI) fellow at the University of Liverpool. In 1954, he became a lecturer at the University of Glasgow. Eglinton's original training was in synthetic chemistry. His early accomplishments included devising a new way to form carbon–carbon bonds by joining two compounds, each of which contained a carbon triple bond — a process now known as the Eglinton reaction. His shift towards the chemistry of natural products, and ultimately to geochemistry, followed the arrival of a new analytical tool in the early 1950s: gas chromatography. The technique, which separates compounds carried by a gas along a liquid surface in a narrow column, proved invaluable to untangling complex mixtures of natural organic compounds. Eglinton was the first to use gas-chromatography separation in the analysis of chemicals called terpenoid lipids, which are found in plants as well as in ancient sediments. Soon, he became interested in the waxy lipids that cover the surfaces, or cuticles, of leaves, and began to determine their distributions. Waxes protect leaves from water loss and from insects and fungi. During the late 1950s, Eglinton became fascinated with plant-wax compounds, which persist in soils, sediments, rocks and petroleum. In 1960, he took his young family to the University of La Laguna in Tenerife, Spain, for a sun-filled sabbatical. He wanted to discover whether different plant taxa have characteristic patterns of long-chain cuticular lipids; if they did, he knew that the compounds would be of enormous value in reconstructing the ecosystems of the past. Eglinton's pioneering work elegantly wove together chemistry, biochemistry and botany, and culminated in a comprehensive paper published in 1967 in Science on leaf waxes, which is still a defining document in the field and Eglinton's most cited work ( and Science 156, 1322–1335; 1967). He studied the geochemistry of plant waxes for the rest of his career and well into his retirement. Indeed, his prescient admiration for plants' persistent waxes laid the foundation for their wide use today as palaeoclimate signatures. In 1963, Eglinton began seeking molecules from the earliest life on Earth, in collaboration with the biochemist and Nobel laureate Melvin Calvin. Eglinton used his analytical expertise to search for biologically derived organic molecules in sedimentary rocks that were more than a billion years old. His work with Calvin revealed that early life had a biochemistry that was fundamentally similar to that of modern cells. The discovery of the startling antiquity of chemical remains from ancient cells sparked people's imaginations, and helped to introduce the concept of 'molecular fossils' to a broad audience. During the mid-1960s, Eglinton's exquisite studies attracted the interest of researchers at NASA. They recognized that the ancient molecular fossils were definitive biosignatures and that organic geochemistry would be highly useful in studies of lunar samples. Eglinton's team included the leading organic geochemists of the day. The analytical detective work on the Moon rocks required extreme cleanliness to avoid contamination. So clean were the researchers' methods that they found minute traces of carbon from the solar wind blasted into lunar minerals. The work earned Eglinton the NASA Gold Medal for Exceptional Scientific Achievement and further elevated the growing field of organic geochemistry. In 1967, Eglinton moved from Glasgow to the University of Bristol, where, with his friend and colleague James Maxwell, he established the Organic Geochemistry Unit (OGU). The OGU quickly became a global centre of excellence in organic geochemistry. Generations of students and postdocs studied fossil molecules there, which they used to study life in and trace the temperature of ancient oceans, and to probe oil transformation in geological basins. Geoffrey, whom I knew professionally and through friendship with his family, always paid the highest compliment to young scientists: he listened intently to their ideas. After retiring from Bristol in 1993, he continued to work as an emeritus professor and through adjunct appointments with various institutions, including the Swiss Federal Institute of Technology in Zurich, where he often collaborated with his son, Timothy, a professor of biogeoscience and contemporary of mine. Geoffrey published more than 500 papers and received numerous honours, including being elected fellow of the Royal Society in London. His greatest reward was the work itself and his many collaborations with those who shared his passion. His joy in the rich world of molecular fossils radiates from the pages of a 2008 book that he co-authored with Susan Gaines and Jurgen Rullkotter, Echoes of Life (Oxford University Press), which chronicles the science and the scientists that helped him to build the field of organic geochemistry. Geoffrey was beloved by his wife of more than 60 years, Pam, his children, grandchildren and friends — and by his global scientific family working in the discipline that he founded.

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