Accurate lifespan estimates cannot be obtained from 14C profiles in the crustose lichen Rhizocarpon geographicum (L.) DC.

2001 ◽  
Vol 33 (6) ◽  
pp. 539-542 ◽  
Author(s):  
G. Bench ◽  
B.M. Clark ◽  
N.F. Mangelson ◽  
L. L. St. Clair ◽  
L. B. Rees ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Carbon Cycling ◽  
Accelerator Mass Spectrometry ◽  
Isotope Ratio ◽  
Growth Patterns ◽  
Molecular Replacement ◽  
Crustose Lichen ◽  
Rhizocarpon Geographicum ◽  
The Relationship ◽  
Isotope Ratio Measurements

AbstractRadial 14C/C profiles across three individuals of the crustose lichen Rhizocarpon geographicum (L.) DC. have been determined using accelerator mass spectrometry. These data were used to assess whether lifespan estimates can be determined in this species using 14C/C isotope ratio measurements. 14C/C profiles are relatively flat with Δ14C values (deviations from the modern radiocarbon standard) for the radial samples displaying a small spread ranging from 130 to 200 per mil. The data are consistent with carbon cycling based on growth patterns involving replacement and fusion of areoles within the thallus as well as or instead of cellular or molecular replacement. Consequently, lifespan estimates cannot be obtained from 14C/C measurements of this species and the Δ14C profiles provide no insights into whether the relationship between size and age is linear or curvilinear in this species.

scholarly journals Isotope-Ratio and Background Corrections for Accelerator Mass Spectrometry Radiocarbon Measurements

Radiocarbon ◽  
1990 ◽  
Vol 32 (2) ◽  
pp. 135-142 ◽  
Author(s):  
D J Donahue ◽  
T W Linick ◽  
A J T Jull
Keyword(s):  
Mass Spectrometry ◽  
Mass Spectrometer ◽  
Accelerator Mass Spectrometry ◽  
Isotope Ratio ◽  
Isotope Ratios ◽  
Sample Contamination ◽  
Accelerator Mass Spectrometer

We present here the method we use to convert to radiocarbon ages (14C/13C) ratios measured in the Arizona Accelerator Mass Spectrometer facility. We describe the procedures we use to convert sample and standard isotope ratios to values appropriate for calculation of radiocarbon ages. We also discuss, in some detail, corrections to account for sample contamination.

scholarly journals Method for the determination of concentration and stable carbon isotope ratios of atmospheric phenols

2013 ◽  
Vol 6 (11) ◽  
pp. 2965-2974 ◽  
Author(s):  
M. Saccon ◽  
R. Busca ◽  
C. Facca ◽  
L. Huang ◽  
S. Irei ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Isotopic Composition ◽  
Isotope Ratio ◽  
Extraction Procedure ◽  
Carbon Isotopic Composition ◽  
Stable Carbon ◽  
Concentration Measurements ◽  
Isotope Ratio Measurements

Abstract. A method for the determination of the stable carbon isotopic composition of atmospheric nitrophenols in the gas and particulate phases is presented. It has been proposed to use the combination of concentration and isotope ratio measurements of precursor and product to test the applicability of results of laboratory studies to the atmosphere. Nitrophenols are suspected to be secondary products formed specifically from the photooxidation of volatile organic compounds. XAD-4TM resin was used as an adsorbent on quartz filters to sample ambient phenols using conventional high volume air samplers at York University in Toronto, Canada. Filters were extracted in acetonitrile, with a HPLC (high-performance liquid chromatography) clean-up step and a solid phase extraction step prior to derivatization with BSTFA (bis(trimethylsilyl) trifluoroacetamide). Concentration measurements were done with gas chromatography–mass spectrometry and gas chromatography–isotope ratio mass spectrometry was used for isotope ratio analysis. The technique presented allows for atmospheric compound-specific isotopic composition measurements for five semi-volatile phenols with an estimated accuracy of 0.3–0.5‰ at atmospheric concentrations exceeding 0.1 ng m−3 while the detection limits for concentration measurements are in the pg m−3 range. Isotopic fractionation throughout the entire extraction procedure and analysis was proven to be below the precision of the isotope ratio measurements. The method was tested by conducting ambient measurements from September to December 2011.

In situ 207Pb/206Pb isotope ratio measurements using two Daly detectors equipped on an ICP-mass spectrometer

2017 ◽  
Vol 32 (3) ◽  
pp. 686-691 ◽  
Author(s):  
Hideyuki Obayashi ◽  
Michitaka Tanaka ◽  
Kentaro Hattori ◽  
Shuhei Sakata ◽  
Takafumi Hirata
Keyword(s):  
Mass Spectrometry ◽  
Mass Spectrometer ◽  
Isotope Ratio ◽  
Simultaneous Detection ◽  
Pb Ions ◽  
Icp Mass Spectrometry ◽  
Isotope Ratio Measurements

The simultaneous detection of 206Pb and 207Pb ions has been made by multiple-ion counting ICP-mass spectrometry using two Daly detectors (MC-ICPMS).

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