Oxygen isotope analyses of biogenic opal and quartz using a novel microfluorination technique.

RATIONALE Measuring δ(18)O values in silicates is difficult and hazardous in comparison with measurements of carbonate minerals due to the difficulty in breaking Si-O-Si bonds. A novel method for measurement of δ(18)O values from quartz and biogenic silica utilizing high-temperature pyrolysis with continuous-flow isotope ratio mass spectrometry (CF-IRMS) is presented. METHODS Samples were prepared by offline dehydroxylation/dehydration under vacuum at 1060°C. The dehydroxylated samples are mixed with polytetrafluoroethylene (PTFE) powder (2.3:1 PTFE/Si) and graphite in silver foil capsules and reacted in a vario PYRO cube TC/EA system in a glassy carbon reaction tube. Quartz and biogenic opal samples react with available carbon in a microfluorination environment upon decomposition of the PTFE, producing CO for analysis via CF-IRMS. RESULTS Silicate samples reacted quantitatively, producing data with yields ≥88% from ~400 µg samples. Multiple analyses with international standards demonstrated accuracy for replicate measurements (1σ range ±0.3-0.6‰), comparing favorably with previously published techniques. CONCLUSIONS New data produced with the microfluorination technique are comparable with data from studies using existing methodologies. The microfluorination technique has the potential to greatly increase the number of laboratories producing silicate oxygen isotope data for mineralogic, paleoclimatic and biogeochemical applications.

[1]  M. Strobl,et al.  Small angle neutron scattering on an absolute intensity scale and the internal surface of diatom frustules from three species of differing morphologies , 2013, European Biophysics Journal.

[2]  M. Leng,et al.  Inter-laboratory comparison of oxygen isotope compositions from biogenic silica , 2011 .

[3]  H. Schmidt,et al.  Essential methodological improvements in the oxygen isotope ratio analysis of N-containing organic compounds. , 2010, Rapid communications in mass spectrometry : RCM.

[4]  A. Marent,et al.  A high-performance, safer and semi-automated approach for the delta18O analysis of diatom silica and new methods for removing exchangeable oxygen. , 2010, Rapid communications in mass spectrometry : RCM.

[5]  Z. Sharp,et al.  A laser fluorination method for oxygen isotope analysis of biogenic silica and a new oxygen isotope calibration of modern diatoms in freshwater environments , 2010 .

[6]  Peter G. Smith,et al.  The effect of surface area on the modelling of quartz dissolution under conditions relevant to the Bayer process , 2009 .

[7]  W. Brand,et al.  Comprehensive inter-laboratory calibration of reference materials for delta18O versus VSMOW using various on-line high-temperature conversion techniques. , 2009, Rapid communications in mass spectrometry : RCM.

[8]  M. Leng,et al.  A review of diatom δ18O in palaeoceanography , 2009 .

[9]  M. Leng,et al.  Oxygen isotope ratios of sedimentary biogenic silica reflect the European transcontinental climate gradient , 2008 .

[10]  M. Leng,et al.  Combined oxygen and silicon isotope analysis of biogenic silica , 2008 .

[11]  V. Garreta,et al.  IR laser extraction technique applied to oxygen isotope analysis of small biogenic silica samples. , 2008, Analytical chemistry.

[12]  R. Moschen,et al.  Transfer and early diagenesis of biogenic silica oxygen isotope signals during settling and sedimentation of diatoms in a temperate freshwater lake (Lake Holzmaar, Germany) , 2006 .

[13]  J. Meunier,et al.  Oxygen isotope analyses of fine silica grains using laser-extraction technique: Comparison with oxygen isotope data obtained from ion microprobe analyses and application to quartzite and silcrete cement investigation , 2006 .

[14]  M. Leng,et al.  A review of the oxygen isotope composition of lacustrine diatom silica for palaeoclimate reconstruction , 2006 .

[15]  R. Telford,et al.  A comparison of the palaeoclimate signals from diatom oxygen isotope ratios and carbonate oxygen isotope ratios from a low latitude crater lake , 2005 .

[16]  A. Mackay,et al.  Late glacial and Holocene environmental change in the Lake Baikal region documented by oxygen isotopes from diatom silica , 2005 .

[17]  R. Moschen,et al.  High-temperature carbon reduction of silica: A novel approach for oxygen isotope analysis of biogenic opal , 2005 .

[18]  M. Leng,et al.  Palaeoclimate interpretation of stable isotope data from lake sediment archives , 2004 .

[19]  M. Gehre,et al.  High-temperature elemental analysis and pyrolysis techniques for stable isotope analysis. , 2003, Rapid communications in mass spectrometry : RCM.

[20]  J. Zachos,et al.  Climate Response to Orbital Forcing Across the Oligocene-Miocene Boundary , 2001, Science.

[21]  E. Stoermer,et al.  OXYGEN ISOTOPE FRACTIONATION BETWEEN DIATOMACEOUS SILICA AND WATER , 1998 .

[22]  Z. Sharp,et al.  OXYGEN ISOTOPE ANALYSES OF FINE-GRAINED MINERALS AND ROCKS USING THE LASER-EXTRACTION TECHNIQUE , 1997 .

[23]  M. Kohn,et al.  UWG-2, a garnet standard for oxygen isotope ratios: Strategies for high precision and accuracy with laser heating , 1995 .

[24]  J. D. Hays,et al.  Late Pleistocene oxygen isotope records of biogenic silica from the Atlantic sector of the Southern Ocean , 1995 .

[25]  J. D. Hays,et al.  Meltwater Input to the Southern Ocean During the Last Glacial Maximum , 1994, Science.

[26]  D. Mattey,et al.  High-precision oxygen isotope microanalysis of ferromagnesian minerals by laser-fluorination , 1993 .

[27]  M. Conrad,et al.  Laser-based, in situ measurements of fine-scale variations in the δ18O values of hydrothermal quartz , 1992 .

[28]  R. Fairbanks,et al.  Oxygen Isotopes in Biogenic Silica: Global Changes in Ocean Temperature and Isotopic Composition , 1992, Science.

[29]  Z. Sharp.  A laser-based microanalytical method for the in situ determination of oxygen isotope ratios of silicates and oxides , 1990 .

[30]  G. Hut.  Consultants' group meeting on stable isotope reference samples for geochemical and hydrological investigations , 1987 .

[31]  R. Harmon,et al.  A note regarding CIF3 as an alternative to BrF5 for oxygen isotope analysis , 1982 .

[32]  L. Labeyrie,et al.  Oxygen isotopic exchangeability of diatom valve silica; interpretation and consequences for paleoclimatic studies , 1982 .

[33]  H. Pankratz,et al.  Changes in the physical and chemical properties of biogenic silica from the central equatorial Pacific; Part III, Specific pore volume, mean pore size, and skeletal ultrastructure of acid-cleaned samples , 1981 .

[34]  D. C. Hurd.  Interactions of biogenic opal, sediment and seawater in the Central Equatorial Pacific , 1973 .

[35]  R. Clayton,et al.  The use of bromine pentafluoride in the extraction of oxygen from oxides and silicates for isotopic analysis , 1963 .