1. J. Savarino, A. Romero, J. Cole-Dai, S. Bekki, and M.H. Thiemens
UV induced mass independent sulfur isotope fractionation in stratospheric volcanic sulfate
J. Savarino, A. Romero, J. Cole-Dai, S. Bekki, and M.H. Thiemens
Universität Heidelberg Institut für Umweltphysik

2. Content Some explanations/definitions Sulphur-Cycle
Summary of the paper
Questions
Discussion
Universität Heidelberg Institut für Umweltphysik

3. What means d and D d = ( Rsample/Rstandard – 1) x 1000 R = [33S]/[32S]
D33S = d33S – 1000 x [(1 + d34S/1000)0.515 – 1 ]  0
D36S = d36S – 1000 x [(1 + d34S/1000)1.90 –1 ]  0
Universität Heidelberg Institut für Umweltphysik

4. Mass-dependent and mass- independent fraction
Mass dependent: only the different mass is the cause of different fraction of the isotopes
Mass independent: fractionation caused by something else as mass (example Photolyse in the case of SO2)
Universität Heidelberg Institut für Umweltphysik

5. Depth of penetration of solar radiation through the atmosphere
Universität Heidelberg Institut für Umweltphysik

6. Sulphur-Cycle
Universität Heidelberg Institut für Umweltphysik

7. The sense behind it ?
1. determination of the degree of UV light affected S
oxidation in the atmosphere
2. Determination of the stratospheric and tropospheric
nature of volcanic eruptions -> reassess the climatic
impact of past volcanic eruptions (?)
„sulfur isotopic analysis of ice core volcanic sulfate can be independent method to identify climatically significant eruptions in the investigation of the climate volcanic connection“
Universität Heidelberg Institut für Umweltphysik

8. Observation
Analysis of antarctic snow blocks, ice cores and aerosol filter
For volcanic sulfate, the S - isotopes demonstrate a significant range of variations
values d34S, d33S, d36S of aerosol and background sulfate are all within small isotopic ranges
mass-independent sulfur isotopes anomalies in the stratosphere appear to depend on the exposure of SO2 to UV radiation (experiments in the laboratory)
Universität Heidelberg Institut für Umweltphysik

9. Plot of D33S and D36S sulfur isotope anomalies of different sulfate sources?
Universität Heidelberg Institut für Umweltphysik

10. Plot of D33S versus D34S and Plot of D36S and D33S
Universität Heidelberg Institut für Umweltphysik

11. My Questions to the authors
Did you inspect carefully into the graphics? C.f., why Cerro Hudson eruption is not included in the D36S plot?
Why they show only this two examples of volcanic eruption, at least Tambora should have been a better examble than Cerro Hudson?
.....?

12. Thanks for your attention and tell me - what do you think...!!!

14. Plot of D33S values versus sample age
Farquar, 2000
Universität Heidelberg Institut für Umweltphysik