noaa-icecore-12255
Pakitsoq Greenland Younger Dryas-Preboreal 14CH4 Data
Petrenko, V.V.; Smith, A.M.; Brook, E.J.; Lowe, D.; Riedel, K.; Brailsford, G.; Hua, Q.; Schaefer, H.; Reeh, N.; Weiss, R.F.; Etheridge, D.M.; Severinghaus, J.
Pakitsoq Greenland Younger Dryas-Preboreal 14CH4 Data
2011-10-16
NCDC-Paleoclimatology
ONLINE Files
Pending
https://www.ncdc.noaa.gov/paleo/study/12255
Investigator
V.V.
Petrenko
Investigator
A.M.
Smith
Investigator
E.J.
Brook
Investigator
D.
Lowe
Investigator
K.
Riedel
Investigator
G.
Brailsford
Investigator
Q.
Hua
Investigator
H.
Schaefer
Investigator
N.
Reeh
Investigator
R.F.
Weiss
Investigator
D.M.
Etheridge
Investigator
J.
Severinghaus
earth science
paleoclimate
ice cores
14C,methane,null,percent,null,ice cores,corrected,accelerator mass spectrometry,N,null
earth science
paleoclimate
ice cores
gas age,null,range lower bound,calendar year before present,null,ice cores,null,null,N,null
earth science
paleoclimate
ice cores
14C,methane,one standard deviation,percent,null,ice cores,corrected,accelerator mass spectrometry,N,null
earth science
paleoclimate
ice cores
14C,carbon monoxide,one standard deviation,percent,null,ice cores,null,accelerator mass spectrometry,N,null
earth science
paleoclimate
ice cores
14C,carbon monoxide,one standard deviation,percent,null,ice cores,corrected,accelerator mass spectrometry,N,null
earth science
paleoclimate
ice cores
14C,carbon monoxide,null,molecule per gram,null,ice cores,null,numerical simulation,N,null
earth science
paleoclimate
ice cores
14C,carbon dioxide,one standard deviation,percent,null,ice cores,corrected,accelerator mass spectrometry,N,null
earth science
paleoclimate
ice cores
14C,methane,null,percent,null,ice cores,null,accelerator mass spectrometry,N,percent modern
earth science
paleoclimate
ice cores
14C,carbon dioxide,null,percent,null,ice cores,null,accelerator mass spectrometry,N,null
earth science
paleoclimate
ice cores
sample identification,null,null,null,null,ice cores,null,null,C,null
earth science
paleoclimate
ice cores
14C,methane,one standard deviation,percent,null,ice cores,null,accelerator mass spectrometry,N,null
earth science
paleoclimate
climate forcing|ice cores
methane,bulk atmosphere,one standard deviation,parts per billion,null,climate forcing|ice cores,null,null,N,null
earth science
paleoclimate
ice cores
14C,carbon monoxide,null,percent,null,ice cores,null,accelerator mass spectrometry,N,null
earth science
paleoclimate
ice cores
14C,carbon monoxide,null,percent,null,ice cores,corrected,accelerator mass spectrometry,N,null
earth science
paleoclimate
climate forcing|ice cores
carbon dioxide,bulk atmosphere,null,parts per million,null,climate forcing|ice cores,null,null,N,null
earth science
paleoclimate
ice cores
gas age,null,range upper bound,calendar year before present,null,ice cores,null,null,N,null
earth science
paleoclimate
ice cores
14C,carbon dioxide,null,percent,null,ice cores,corrected,accelerator mass spectrometry,N,null
earth science
paleoclimate
climate forcing|ice cores
carbon monoxide,bulk atmosphere,null,parts per billion,null,climate forcing|ice cores,null,null,N,null
earth science
paleoclimate
ice cores
gas age,null,null,calendar year before present,null,ice cores,null,null,N,null
earth science
paleoclimate
climate forcing|ice cores
methane,bulk atmosphere,null,parts per billion,null,climate forcing|ice cores,null,null,N,null
earth science
paleoclimate
ice core
carbon isotopes
geoscientificInformation
Younger Dryas
11739 cal yr BP
11293 cal yr BP
Complete
69.48
69.48
-50.8
-50.8
Continent
North America
Greenland
Pakitsoq outcrop>LATITUDE 69.48>LONGITUDE -50.8
None
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English
DOC/NOAA/NESDIS/NCEI
National Centers for Environmental Information, NESDIS, NOAA, U.S. Department of Commerce
https://www.ncdc.noaa.gov/data-access/paleoclimatology-data
DATA Center Contact
Bruce
Bauer
bruce.a.bauer@noaa.gov
paleo@noaa.gov
303-497-6280
303-497-6513
325 Broadway, E/NE31
Boulder
CO
80305-3328
USA
online
ASCII
Petrenko, V.V., A.M. Smith, E.J. Brook, D. Lowe, K. Riedel,
G. Brailsford, Q. Hua, H. Schaefer, N. Reeh, R.F. Weiss,
D. Etheridge, and J.P. Severinghaus. 2009.
14CH4 Measurements in Greenland Ice: Investigating Last Glacial
Termination CH4 Sources.
Science, Vol. 324, pp. 506-508, 24 April 2009.
10.1126/science.1168909
The cause of a large increase of atmospheric methane concentration
during the Younger Dryas-Preboreal abrupt climatic transition
(~11,600 years ago) has been the subject of much debate.
The carbon-14 (14C) content of methane (14CH4) should distinguish
between wetland and clathrate contributions to this increase.
We present measurements of 14CH4 in glacial ice, targeting this
transition, performed by using ice samples obtained from an
ablation site in west Greenland. Measured 14CH4 values were
higher than predicted under any scenario. Sample 14CH4 appears
to be elevated by direct cosmogenic 14C production in ice.
14C of CO was measured to better understand this process
and correct the sample 14CH4. Corrected results suggest that
wetland sources were likely responsible for the majority
of the Younger Dryas–Preboreal CH4 rise.
STUDY NOTES: 14C measurements in large-volume ice samples from
Pakitsoq, West Greenland. This data set contains measurements
of 14C of methane made on ancient air extracted from large-volume
glacial ice samples spanning the Younger Dryas - Preboreal climatic
transition about 11,600 years ago. The data set also contains
supporting measurements of 14C of carbon monoxide and 14C
of carbon dioxide.
The measurements were made to test the hypothesis that catastrophic
destabilization of marine methane clathrates caused the methane
increase at the end of the Younger Dryas. The results suggested
little to no change in 14CH4 over the time of the methane increase,
arguing against major clathrate involvement.
The ice samples were collected between Jul 1 and Aug 15, 2005.
INSTRUMENT AND METHOD DESCRIPTION
The field and analytical system for determinations of 14CH4
in large-volume glacial ice samples have been described in
(Petrenko et al., 2008a; Petrenko et al., 2008b;
Petrenko et al., 2009). This system involves the melt-extraction
of occluded air from very large volumes of glacial ice or at the
sampling / ice coring site. Briefly, the present field system
consists of a large chemically polished aluminum vacuum melting tank
(~670 L internal volume) and a series vacuum and transfer pumps.
The ice is loaded into the tank, and the headspace is evacuated
and flushed 3x with either ultra-high purity (UHP) air, nitrogen
or argon. The ice is then melted, releasing the ancient air into
the headspace. The air is then extracted from the tank by clean
diaphragm transfer pumps and stored in electropolished stainless
steel canisters for further laboratory handling and analyses.
In the laboratory, the air is first processed through a system
that converts either CH4 or CO to CO2, and captures this CO2
for further handling. In the case of CH4 processing, H2O, CO2,
N2O and other condensibles are first removed by a series of traps
at liquid nitrogen temperature. CO is then quantitatively oxidized
to CO2 by the Sofonocat reagent and subsequently removed by further
cryotraps. CH4 is then combusted to CO2 by passing the air through
a 800°C furnace containing platinized quartz wool. The CH4-derived
CO2 is then captured. This CO2 is then converted to graphite over
ultra-high-purity iron powder and subsequently measured for 14C
by AMS. The combined procedural 14CH4 blank for all steps of
sampling handling was determined to be 0.75 ± 0.38 pMC,
on the basis of 72 processed blank and standard samples
(Petrenko et al., 2008b). For CO analyses, the sample handling
is very similar except that the air bypasses Sofnocat,
and the furnace temperature is reduced from 800 to 150°C.
This allows for complete combustion of CO while CH4 passes
through unaffected. CO2 derived from CO was diluted with 14-C
free CO2 to increase the carbon mass to allow for a 14C measurement.
For sample 14CO2 measurements, CO2 was extracted cryogenically
from ~0.5 L of air.
DATA COLLECTION AND PROCESSING
The 14CH4 data are corrected the procedural blank. Where indicated,
14CH4 data are also corrected for cosmogenic 14C production in ice.
For 14CO, corrections are applied for ambient air inclusion
and processing blank. For 14CO2, processing blank corrections
are applied where indicated.
GET DATA
https://www1.ncdc.noaa.gov/pub/data/paleo/icecore/greenland/pakitsoq2009-14ch4.txt
GET DATA
https://www1.ncdc.noaa.gov/pub/data/paleo/icecore/greenland/pakitsoq2009-14ch4.xls
USA/NOAA
DIF
Version 9.8.4
2018-12-11
2018-12-11