Continuous high-resolution aerosol record from the East Greenland Ice Core Project covering the entire Holocene
Impurities preserved in the Greenland ice sheet are great sources of information about past atmospheric processes along with long-range transport, and atmospheric composition. The information from the impurities can be unraveled through the analysis of ice cores. The particulate and soluble impuriti...
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| Format: | Doctoral or Postdoctoral Thesis |
| Language: | English |
| Published: |
2021
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| Online Access: | https://boris.unibe.ch/158023/1/Thesis_lib.pdf https://boris.unibe.ch/158023/ |
| Summary: | Impurities preserved in the Greenland ice sheet are great sources of information about past atmospheric processes along with long-range transport, and atmospheric composition. The information from the impurities can be unraveled through the analysis of ice cores. The particulate and soluble impurities in ice cores, originating from a wide variety of sources and processes, are measured using the continuous flow analysis (CFA) system, specifically developed for simultaneously melting and measurements of ice cores with very high, often seasonal, resolution. Chemical analysis of several deep Greenland ice cores has been obtained, using the CFA system. However, due to the brittle ice zone causing poor sample quality over several hundred metres of the ice cores, a gap of several thousand years during the mid-Holocene remained unaccounted for in the records. This motivated the strive for a new continuous high-resolution record to improve our understanding of the mechanisms of climate variations during the Holocene period. As the framework for this study, chemical analysis of the upper 1393 m (from 14 m depth) of the East Greenland Ice-core Project (EGRIP) core, covering the last 15k years, was performed using the Bern CFA system. The analysis took place over three measurement campaigns and resulted in the first continuous high-resolution multi-proxy record from interior Greenland covering the entire Holocene. One of the major species preserved in the ice is ammonium. The ammonium record is composed of a background signal reflecting the seasonal cycle in nitrogen turnover in soils mainly in North America (NA), and occasional high summer peak caused by biomass burning events that again mainly derive from NA fire sources. This study focuses on the development of a simple yet refined approach to determine NA fire events frequency in the EGRIP ammonium record. The fire peaks were detected by defining the background concentrations and trends, subtracting those from the initial time series to determine the residuals. This was ... |
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