Ostrom N.E.,Michigan State University |
Sutka R.,Isoprime Ltd |
Ostrom P.H.,Michigan State University |
Huizinga K.M.,Monsanto Corporation |
And 2 more authors.
Soil Biology and Biochemistry | Year: 2010
The source of N2O in terrestrial ecosystems has long been debated. Both nitrification and denitrification produce N2O but their relative importance remains uncertain. Here we apply site preference, SP (the difference in δ15N between the central and outer N atom in N2O), to estimate the relative importance of bacterial denitrification (including nitrifier denitrification) to total N2O production from soil. We measured SP over a diurnal cycle following the third year of tillage of a previously uncultivated grassland soil at the Kellogg Biological Station (KBS) in southwestern Michigan. Fluxes of N2O in our study ranged between 7.8 and 12.1 g N2O-N ha-1 d-1 and were approximately 3 and 10 times greater than fluxes observed in managed agricultural and successional fields, respectively, at KBS. Consequently, our study captured a period of high flux resulting from the cultivation of a historically never-tilled soil. Concentration weighted SP values decreased from 12.9‰ in the morning to a minimum value of -0.1‰ in the afternoon. Based on SP values reported for bacterial denitrification (-5 to 0‰; Toyoda et al., 2005; Sutka et al., 2006), hydroxylamine oxidation (nitrification) and fungal denitrification (33-37‰; Sutka et al., 2006) we found that production attributable to bacterial denitrification increased from between 52.9 and 60.9% in the morning to between 87.5 and 100% in the afternoon. Further, we observed diurnal variation in flux and SP that is consistent with increased production from bacterial denitrification associated with temperature-driven increases in respiration. © 2009 Elsevier Ltd. All rights reserved.
Petchey F.,University of Waikato |
Spriggs M.,Australian National University |
Leach F.,Archaeozoology Laboratory |
Seed M.,Isoprime Ltd. |
And 3 more authors.
Journal of Archaeological Science | Year: 2011
Archaeologists have long debated the origins and mode of dispersal of the immediate predecessors of all Polynesians and many populations in Island Melanesia. Such debates are inextricably linked to a chronological framework provided, in part, by radiocarbon dates. Human remains have the greatest potential for providing answers to many questions pertinent to these debates. Unfortunately, bone is one of the most complicated materials to date reliably because of bone degradation, sample pre-treatment and diet. This is of particular concern in the Pacific where humidity contributes to the rapid decay of bone protein, and a combination of marine, reef, C4, C3 and freshwater foods complicate the interpretation of 14C determinations. Independent advances in bone pre-treatment, isotope multivariate modelling and radiocarbon calibration techniques provide us, for the first time, with the tools to obtain reliable calibrated ages for Pacific burials. Here we present research that combines these techniques, enabling us to re-evaluate the age of burials from key archaeological sites in the Pacific. © 2010 Elsevier Ltd.
Fourel F.,University Claude Bernard Lyon 1 |
Martineau F.,University Claude Bernard Lyon 1 |
Lecuyer C.,University Claude Bernard Lyon 1 |
Lecuyer C.,Institut Universitaire de France |
And 4 more authors.
Rapid Communications in Mass Spectrometry | Year: 2011
We have used a high-precision, easy, low-cost and rapid method of oxygen isotope analysis applied to various O-bearing matrices, organic and inorganic (sulfates, nitrates and phosphates), whose 18O/16O ratios had already been measured. It was first successfully applied to 18O analyses of natural and synthetic phosphate samples. The technique uses high-temperature elemental analysis-pyrolysis (EA-pyrolysis) interfaced in continuous-flow mode to an isotope ratio mass spectrometry (IRMS) system. Using the same pyrolysis method we have been able to generate a single calibration curve for all those samples showing pyrolysis efficiencies independent of the type of matrix pyrolysed. We have also investigated this matrix-dependent pyrolysis issue using a newly developed pyrolysis technique involving 'purge-and-trap' chromatography. As previously stated, silver phosphate being a very stable material, weakly hygroscopic and easily synthesized with predictable 18O/16O values, could be considered as a good candidate to become a reference material for the determination of 18O/ 16O ratios by EA-pyrolysis-IRMS. Copyright © 2011 John Wiley & Sons, Ltd.
Cincinelli A.,University of Florence |
Cincinelli A.,Lancaster University |
Pieri F.,University of Florence |
Zhang Y.,Wuhan University |
And 2 more authors.
Environmental Pollution | Year: 2012
Chlorinated and brominated compounds belong to the class of organohalogen compounds that have received attention because of their widespread occurrence, use and applications. Understanding the sources and transformation processes of these contaminants in the environment enables assessment of their possible impact on humans and ecosystems. Recently new and innovative methods of Compound Specific Isotope Analysis have started to be applied to characterize the origin and fate of compounds, their breakdown products and degradation rates in different environmental compartments. Almost all studies have focussed on determination of isotopes of C and H, only recently new methodologies have been developed to measure isotopes of Cl and Br. This review firstly gives a brief description of chemistry properties and geochemical cycle of chlorine and bromine followed by a summary of their uses and applications. In the second section, an overview of CSIA techniques and new challenges and successful applications are also presented. © 2012 Elsevier Ltd. All rights reserved.
Menzies C.D.,UK National Oceanography Center |
Teagle D.A.H.,UK National Oceanography Center |
Craw D.,University of Otago |
Cox S.C.,Institute of Geological & Nuclear Sciences |
And 4 more authors.
Earth and Planetary Science Letters | Year: 2014
Rapid tectonic uplift on the Alpine Fault, New Zealand, elevates topography, regional geothermal gradients, and the depth to the brittle ductile transition, and drives fluid flow that influences deformation and mineralisation within the orogen. Oxygen and hydrogen stable isotopes, fluid inclusion and Fourier Transform Infrared (FT-IR) analyses of quartz from veins which formed at a wide range of depths, temperatures and deformation regimes identify fluid sources and the depth of penetration of meteoric waters. Most veins formed under brittle conditions and with isotope signatures (δ18OH2O = -9.0 to +8.7‰VSMOW and δD = - 73 to - 45‰VSMOW) indicative of progressively rock-equilibrated meteoric waters. Two generations of quartz veins that post-date mylonitic foliation but endured further ductile deformation, and hence formation below the brittle to ductile transition zone (>6-8 km depth), preserve included hydrothermal fluids with δD values between -84 and -52‰, indicating formation from meteoric waters. FT-IR analyses of these veins show no evidence of structural hydrogen release, precluding this as a source of low δD values. In contrast, the oxygen isotopic signal of these fluids has almost completely equilibrated with host rocks (δ18OH2O = +2.3 to +8.7‰). These data show that meteoric waters dominate the fluid phase in the rocks, and there is no stable isotopic requirement for the presence of metamorphic fluids during the precipitation of ductilely deformed quartz veins. This requires the penetration during orogenesis of meteoric waters into and possibly below the brittle to ductile transition zone. © 2014 The Authors.
Gagnevin D.,University College Dublin |
Boyce A.J.,Scottish Universities Environmental Research Center |
Barrie C.D.,Scottish Universities Environmental Research Center |
Barrie C.D.,Isoprime Ltd. |
And 2 more authors.
Geochimica et Cosmochimica Acta | Year: 2012
The genesis of hydrothermal ore deposits is of crucial economic importance. This study investigates the extent, causes and consequences of zinc and iron isotope fractionation in a large hydrothermal system at the world-class Navan Zn-Pb orebody, Ireland. Large variations in Zn, Fe and S isotope compositions have been measured in microdrilled sphalerite (ZnS) at the millimetre scale. δ 66Zn and δ 56Fe display a well-defined positive correlation and both also correlate with δ 34S. These relationships represent the combined effects of kinetic Zn and Fe isotope fractionation during sphalerite precipitation, and S isotope variation through mixing of hot, metal-rich hydrothermal fluids and cool, bacteriogenic sulfide-bearing brines. Combined with S isotope data, δ 56Fe and δ 66Zn data on mine concentrates confirm that hydrothermal sulfide is a minor component of the overall deposit signature. Our data suggest that incoming pulses of metal-rich hydrothermal fluid triggered sulfide mineralisation, and that rapid precipitation of sphalerite from hydrothermal fluids will lead to strong kinetic fractionation of Zn and Fe isotopes at very short time and length scales, thereby limiting the use of Fe and Zn isotopes as exploration tools within deposits, but revealing the possibility of detecting new deposits from isotopically heavy Zn-Fe geochemical halos. © 2012 Elsevier Ltd.
Torremans K.,Catholic University of Leuven |
Gauquie J.,Catholic University of Leuven |
Boyce A.J.,Scottish Enterprise |
Barrie C.D.,Scottish Enterprise |
And 4 more authors.
Journal of African Earth Sciences | Year: 2013
The Konkola deposit is a high grade stratiform Cu-Co ore deposit in the Central African Copperbelt in Zambia. Economic mineralisation is confined to the Ore Shale formation, part of the Neoproterozoic metasedimentary rocks of the Katanga Supergroup. Petrographic study reveals that the copper-cobalt ore minerals are disseminated within the host rock, sometimes concentrated along bedding planes, often associated with dolomitic bands or clustered in cemented lenses and in layer-parallel and irregular veins. The hypogene sulphide mineralogy consists predominantly of chalcopyrite, bornite and chalcocite. Based upon relationships with metamorphic biotite, vein sulphides and most of the sulphides in cemented lenses were precipitated during or after biotite zone greenschist facies metamorphism. New δ34S values of sulphides from the Konkola deposit are presented. The sulphur isotope values range from -8.7‰ to +1.4‰ V-CDT for chalcopyrite from all mineralising phases and from -4.4‰ to +2.0‰ V-CDT for secondary chalcocite. Similarities in δ34S for sulphides from different vein generations, earlier sulphides and secondary chalcocite can be explained by (re)mobilisation of S from earlier formed sulphide phases, an interpretation strongly supported by the petrographic evidence. Deep supergene enrichment and leaching occurs up to a km in depth, predominantly in the form of secondary chalcocite, goethite and malachite and is often associated with zones of high permeability. Detailed distribution maps of total copper and total cobalt contents of the Ore Shale formation show a close relationship between structural features and higher copper and lower cobalt contents, relative to other areas of the mine. Structural features include the Kirilabombwe anticline and fault zones along the axial plane and two fault zones in the southern limb of the anticline. Cobalt and copper behave differently in relation to these structural features. These structures are interpreted to have played a significant role in (re)mobilisation and concentration of the metals, in agreement with observations made elsewhere in the Zambian Copperbelt. © 2012 Elsevier Ltd.
Barrie C.D.,GeoMark Research |
Taylor K.W.R.,Isoprime Ltd. |
Zumberge J.,GeoMark Research
Rapid Communications in Mass Spectrometry | Year: 2016
Rationale Stable isotope analysis is a powerful tool in understanding the generation, history and correlation of hydrocarbons. Compound-specific δ13C measurements of oils allow detailed comparison of individual compound groupings; however, most studies of these sample materials separate and isolate individual fractions based on the chemistries of particular compound groups, potentially losing considerable valuable isotopic data. Even if all fractions are analyzed, this represents a large increase in the data-processing burden, effectively multiplying data evaluation time and effort by the number of fractions produced. Gas chromatography/isotope ratio mass spectrometry (GC/IRMS) of untreated, whole crude oils allows the immediate collection of a larger suite of valuable isotopic data for these studies. Methods Untreated ('neat', undiluted), whole crude oils were directly injected and measured on a GC/IRMS system, using split (40:1) injections and a 50 m HP-PONA column. The GC method, 97 min in duration, was designed to maximize baseline separation of target analyte peaks, while an additional oxygen flow was admitted into the combustion reactor to maximize the lifetime of the combustion chemicals. Results The method and setup utilized allow the measurement of a much greater range of the n-alkanes (n-C4 to n-C25+) than traditional methods, while also retaining important cycloalkane, aromatic and isoprenoid peaks within the same analysis. Carbon isotope (δ13C) evaluation of these additional compound classes reveals trends in maturity and origins which are not identifiable when exclusively assessing the traditional n-alkane package (>n-C12). Conclusions The described setup and method open up new possibilities for assessing the origins and histories of crude oil samples. The data generated for the whole oil n-alkanes by this method is equivalent to that reported for isolated n-alkane studies, while also providing valuable additional data on many other important compounds. The end result of this method is a more complete assessment of the carbon isotopic composition of crude oils. Copyright © 2016 John Wiley & Sons, Ltd.
PubMed | British Antarctic Survey, University of Plymouth, Hanyang University, Isoprime Ltd and Korea Polar Research Institute
Type: | Journal: Nature communications | Year: 2016
The presence of a di-unsaturated highly branched isoprenoid (HBI) lipid biomarker (diene II) in Southern Ocean sediments has previously been proposed as a proxy measure of palaeo Antarctic sea ice. Here we show that a source of diene II is the sympagic diatom Berkeleya adeliensis Medlin. Furthermore, the propensity for B. adeliensis to flourish in platelet ice is reflected by an offshore downward gradient in diene II concentration in >100 surface sediments from Antarctic coastal and near-coastal environments. Since platelet ice formation is strongly associated with super-cooled freshwater inflow, we further hypothesize that sedimentary diene II provides a potentially sensitive proxy indicator of landfast sea ice influenced by meltwater discharge from nearby glaciers and ice shelves, and re-examination of some previous diene II downcore records supports this hypothesis. The term IPSO25-Ice Proxy for the Southern Ocean with 25 carbon atoms-is proposed as a proxy name for diene II.
PubMed | Isoprime Ltd and GeoMark Research
Type: Journal Article | Journal: Rapid communications in mass spectrometry : RCM | Year: 2016
Stable isotope analysis is a powerful tool in understanding the generation, history and correlation of hydrocarbons. Compound-specific (13) C measurements of oils allow detailed comparison of individual compound groupings; however, most studies of these sample materials separate and isolate individual fractions based on the chemistries of particular compound groups, potentially losing considerable valuable isotopic data. Even if all fractions are analyzed, this represents a large increase in the data-processing burden, effectively multiplying data evaluation time and effort by the number of fractions produced. Gas chromatography/isotope ratio mass spectrometry (GC/IRMS) of untreated, whole crude oils allows the immediate collection of a larger suite of valuable isotopic data for these studies.Untreated (neat, undiluted), whole crude oils were directly injected and measured on a GC/IRMS system, using split (40:1) injections and a 50 m HP-PONA column. The GC method, 97 min in duration, was designed to maximize baseline separation of target analyte peaks, while an additional oxygen flow was admitted into the combustion reactor to maximize the lifetime of the combustion chemicals.The method and setup utilized allow the measurement of a much greater range of the n-alkanes (n-C4 to n-C25+ ) than traditional methods, while also retaining important cycloalkane, aromatic and isoprenoid peaks within the same analysis. Carbon isotope ((13) C) evaluation of these additional compound classes reveals trends in maturity and origins which are not identifiable when exclusively assessing the traditional n-alkane package (>n-C12 ).The described setup and method open up new possibilities for assessing the origins and histories of crude oil samples. The data generated for the whole oil n-alkanes by this method is equivalent to that reported for isolated n-alkane studies, while also providing valuable additional data on many other important compounds. The end result of this method is a more complete assessment of the carbon isotopic composition of crude oils. Copyright 2016 John Wiley & Sons, Ltd.