Stable carbon isotope ratios of carbon dioxide from EDC and Berkner Island ice cores for 40-50 ka BP


Autoria(s): Schaefer, Hinrich; Lourantou, Anna; Chappellaz, Jérôme A; Lüthi, Dieter; Bereiter, Bernhard; Barnola, Jean-Marc
Cobertura

MEDIAN LATITUDE: -77.325000 * MEDIAN LONGITUDE: 38.833335 * SOUTH-BOUND LATITUDE: -79.550000 * WEST-BOUND LONGITUDE: -45.683330 * NORTH-BOUND LATITUDE: -75.100000 * EAST-BOUND LONGITUDE: 123.350000 * DATE/TIME START: 1993-01-01T00:00:00 * DATE/TIME END: 2004-12-31T00:00:00 * MINIMUM DEPTH, ice/snow: 729.30 m * MAXIMUM DEPTH, ice/snow: 860.75 m

Data(s)

03/04/2011

Resumo

The stable carbon isotopic signature of carbon dioxide (d13CO2) measured in the air occlusions of polar ice provides important constraints on the carbon cycle in past climates. In order to exploit this information for previous glacial periods, one must use deep, clathrated ice, where the occluded air is preserved not in bubbles but in the form of air hydrates. Therefore, it must be established whether the original atmospheric d13CO2 signature can be reconstructed from clathrated ice. We present a comparative study using coeval bubbly ice from Berkner Island and ice from the bubble-clathrate transformation zone (BCTZ) of EPICA Dome C (EDC). In the EDC samples the gas is partitioned into clathrates and remaining bubbles as shown by erroneously low and scattered CO2 concentration values, presenting a worst-case test for d13CO2 reconstructions. Even so, the reconstructed atmospheric d13CO2 values show only slightly larger scatter. The difference to data from coeval bubbly ice is statistically significant. However, the 0.16 per mil magnitude of the offset is small for practical purposes, especially in light of uncertainty from non-uniform corrections for diffusion related fractionation that could contribute to the discrepancy. Our results are promising for palaeo-atmospheric studies of d13CO2 using a ball mill dry extraction technique below the BCTZ of ice cores, where gas is not subject to fractionation into microfractures and between clathrate and bubble reservoirs.

Formato

text/tab-separated-values, 162 data points

Identificador

https://doi.pangaea.de/10.1594/PANGAEA.809527

doi:10.1594/PANGAEA.809527

Idioma(s)

en

Publicador

PANGAEA

Direitos

CC-BY: Creative Commons Attribution 3.0 Unported

Access constraints: unrestricted

Fonte

Supplement to: Schaefer, Hinrich; Lourantou, Anna; Chappellaz, Jérôme A; Lüthi, Dieter; Bereiter, Bernhard; Barnola, Jean-Marc (2011): On the suitability of partially clathrated ice for analysis of concentration and d13C of palaeo-atmospheric CO2. Earth and Planetary Science Letters, 307(3-4), 334-340, doi:10.1016/j.epsl.2011.05.007

Palavras-Chave #Berkner Island; BIC; Carbon dioxide; Carbon dioxide, standard deviation; delta 13C, carbon dioxide, atmospheric; delta 13C, standard deviation; DEPTH, ice/snow; Dome C; Dome C, Antarctica; DRILL; Drilling/drill rig; EDC; EPICA; European Project for Ice Coring in Antarctica; Event label; Gas age; ICEDRILL; Ice drill; Mass spectrometer Finnigan MAT 252; Sample code/label; see reference(s)
Tipo

Dataset