Seasonality and relationship to ozone of the perchlorate signal at Summit, Greenland
Abstract
A 300-year record of perchlorate in the environment from a Summit, Greenland ice core shows (1) a very low natural background with limited variation, and (2) significant deviation (increase) from the low background in response to anthropogenic chlorine emissions since 1980 and after certain large volcanic eruptions. These events likely perturbed or impacted chlorine chemistry in the atmosphere, where perchlorate is thought to form naturally. These findings suggest that studying perchlorate in ice cores may provide a novel and effective way to investigate atmospheric chlorine chemistry. A strong seasonal oscillation is seen in perchlorate concentration since about 1980, whereas no significant seasonality is detected in periods (1916-1925 and 1967-1980) not impacted by volcanic eruptions or significant anthropogenic emission of organic chlorine to the atmosphere. Because halogen chemistry is closely related to stratospheric ozone abundance, as evidenced by the Antarctic ozone hole, temporal fluctuations of perchlorate in polar snow and ice cores may be quantitatively linked to stratospheric ozone. Weekly ozone measurements at Summit from 2005-2007 appear to show a negative correlation with perchlorate concentrations in ice core samples. From 1980 to 2007, a strong negative correlation is found between zonal (35-60° N) annual mean total ozone and annual perchlorate flux at Summit. These findings seem to indicate shared underlying chemical processes between ozone and perchlorate formation in the atmosphere, suggesting a tantalizing prospect of reconstructing a record of stratospheric ozone through measurement of perchlorate in polar ice cores.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.C11C1306K
- Keywords:
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- 0724 Ice cores;
- CRYOSPHERE;
- 1615 Biogeochemical cycles;
- processes;
- and modeling;
- GLOBAL CHANGE;
- 1616 Climate variability;
- GLOBAL CHANGE;
- 4994 Instruments and techniques;
- PALEOCEANOGRAPHY