6-1 Chapter 6 Photolysis of Pyruvic Acid in Ice. Possible Relevance to

• Main Authors: Co Ice, Core Record Anomalies
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: ice core
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.425.3948; http://thesis.library.caltech.edu/4688/7/Chapter_6_Photolysis_Ice.pdf

The abnormal spikes detected in ice core CO and CO2 records reveal chemical activity in deep sections by processes that forgo diffusional approach. The correlation of CO and CO 2 excesses with CO/CO2 yields in the photolysis of natural organic matter would support a photochemical process if such matter were coextensive with the spikes and a source of actinic radiation could be identified. We showed that the UV radiation generated by cosmic muons could account for the irregularities found in some CO records, should the photolysis of natural organic matter proceed with similar yields in water and ice. We find that the photodecarboxylation of pyruvic acid (PA, an ice contaminant) actually occurs by the same mechanism, and nearly as efficiently, in both media. CO 2 is promptly released by frozen PA/H2O films upon illumination, but continues to evolve after photolysis. The concerted photodecarboxylation of benzoylformic acid (the aryl analogue of PA) does not yield post-illumination CO2 under similar conditions. We infer that 3 PA * reacts with PA to produce acetylcarbonyloxyl, CH3C(O)C(O)O⋅, and ketyl, CH C(OH)C(O)OH, as primary intermediates. The