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A Comparison of 36 Cl Nuclear Bomb Inputs Deposited in Snow From Vostok and Talos Dome, Antarctica, Using the 36 Cl/Cl − ratio
Author(s) -
Pivot S.,
Baroni M.,
Bard E.,
Giraud X.
Publication year - 2019
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1029/2018jd030200
Subject(s) - snow , atmosphere (unit) , snowpack , ice core , stratosphere , atmospheric sciences , dome (geology) , chemistry , environmental chemistry , environmental science , geology , meteorology , physics , climatology , geomorphology
36 Cl production in the atmosphere is modulated by the magnetic field intensity of both the Sun and the Earth. The record of 36 Cl concentration along with that of 10 Be in ice cores may therefore provide information as to their variability. To better understand the 36 Cl signal in glaciological archives, we measured its concentration in Talos Dome snow samples (mean accumulation rate of 8 g cm −2 year −1 water equivalent) spanning the 1910 to 1980 CE period with a resolution of one sample every 3 years from 1955 to 1980 C.E., and in Vostok snow samples (mean accumulation rate of 1.96 g cm −2 year −1 water equivalent) spanning the 1949 to 2007 CE period with a 6‐month resolution that had never before been obtained. Marine nuclear bomb tests in the late 1950s produced anthropogenic 36 Cl, which was injected into the stratosphere and spread around the globe. In the late 1950s this anthropogenic pulse led to an increase of 36 Cl concentration at Talos Dome that was more than 100 times higher than the prebomb and postbomb values. It is noteworthy that the atmosphere of Vostok remains polluted by anthropogenic 36 Cl today. This pollution results from gaseous H 36 Cl mobility at low accumulation sites and implies re‐emission of 36 Cl from the snowpack that is not observed at Talos Dome. The 36 Cl/Cl − ratio may be used to discriminate the stratospheric anthropogenic 36 Cl source from the tropospheric natural 36 Cl source, which allows us to discuss the immobile vs. mobile 36 Cl in the Vostok snowpack.