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Sulfur isotopes ratio of atmospheric carbonyl sulfide constrains its sources
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  • Alon Angert,
  • Ward Said-Ahmad,
  • Chen Davidson,
  • Alon Amrani
Alon Angert
The Institute of Earth Sciences, The Hebrew University of Jerusalem, The Institute of Earth Sciences, The Hebrew University of Jerusalem, The Institute of Earth Sciences, The Hebrew University of Jerusalem

Corresponding Author:[email protected]

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Ward Said-Ahmad
The Institute of Earth Sciences, The Hebrew University of Jerusalem, The Institute of Earth Sciences, The Hebrew University of Jerusalem, The Institute of Earth Sciences, The Hebrew University of Jerusalem
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Chen Davidson
The Institute of Earth Sciences, The Hebrew University of Jerusalem, The Institute of Earth Sciences, The Hebrew University of Jerusalem, The Institute of Earth Sciences, The Hebrew University of Jerusalem
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Alon Amrani
The Institute of Earth Sciences, The Hebrew University of Jerusalem, The Institute of Earth Sciences, The Hebrew University of Jerusalem, The Institute of Earth Sciences, The Hebrew University of Jerusalem
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Abstract

Carbonyl sulfide (COS) is the major long-lived sulfur bearing gas in the atmosphere, and is used to estimate the rates of regional and global (both past and current) photosynthesis. Sulfur isotope measurements (34S/32S ratio, δ34S) of COS may offer a way for improved determinations of atmospheric COS sources. However, measuring the COS δ34S at the atmospheric concentrations of ~0.5 ppb is challenging. Here we present high-accuracy δ34S measurements of atmospheric COS done by gas chromatograph (GC) connected to a multicollector inductively coupled plasma mass spectrometer (MC-ICPMS), after pre-concentrating from 2-liters of air. We showed that the precision of COS δ34S measurement for gas standards is ≤0.2‰, and that N2 and CO2 in the gas standard mixture had no effect on the measured δ34S. Natural air samples were collected in Israel and in the Canary Islands. The COS δ34S values in both locations were found to be 13.2±0.6‰, and are believed to represent the background tropospheric value. This δ34S value is markedly different from the previously reported value of 4.9‰. We estimate the expected isotopic signature of COS sources and sinks, and use the δ34S value of atmospheric COS we measured to estimate that ~48% of it originates from the ocean.
24 Jan 2019Published in Scientific Reports volume 9 issue 1. 10.1038/s41598-018-37131-3