Polar ice core organic matter signatures reveal past atmospheric carbon composition and spatial trends across ancient and modern timescales

We present polar ice core organic matter (OM) fluorescence signatures to reconstruct ancient and modern atmospheric compositions and relate OM signals to past ecological changes. OM composition from three Arctic ice cores (Canada and Greenland) was characterized by fluorescence spectroscopy and comp...

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Bibliographic Details
Published in:Journal of glaciology 2021-12, Vol.67 (266), p.1028-1042
Main Authors: D'Andrilli, Juliana, McConnell, Joseph R.
Format: Article
Language:English
Subjects:
Acidic soils
Amino acids
Analytical methods
Archives & records
Arctic ice
Aromatic compounds
Biodegradation
Carbon
Chemical speciation
Collaboration
Composition
Cores
Degradation products
Environmental degradation
Fluorescence
Fluorescence spectroscopy
global cryosphere organic matter comparisons
Hemispheres
Holocene
Holocene ice
Ice
ice core carbon paleoclimatology
Ice cores
Ice sheets
Markers
Microbial degradation
Microorganisms
Organic matter
Paleoclimate
Polar environments
Polar regions
Signatures
Soil
Spectroscopy
Spectrum analysis
Temperature
Trends
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Summary:We present polar ice core organic matter (OM) fluorescence signatures to reconstruct ancient and modern atmospheric compositions and relate OM signals to past ecological changes. OM composition from three Arctic ice cores (Canada and Greenland) was characterized by fluorescence spectroscopy and compared to an Antarctic OM record. Diverse OM was measured in ancient and modern ice in both hemispheres and similarities existed across vast spatiotemporal scales. We determined three OM markers, indicating paleoclimate and modern carbon trends: (i) ‘humic-like’, detected in Holocene ice of more complex and aromatic character, supporting trends of higher plant influences in warmer climates, (ii) monolignol- and non-amino acid-like, describing simple, lignin-like OM precursors ubiquitous in the environment and the microbial degradation products of more complex materials from plants/soils, and (iii) amino acid- and tannin-like, indicating microbial degradation of simple OM chemical species, compared to the other markers. Concentration trends were inferred from fluorescence intensities of individual OM types and related to warmer temperatures. No indicators of freshly produced OM by microbes were detected; signals were interpreted as materials externally produced from the ice and transported to polar regions. This marks the first global comparison of atmospheric reconstructions from OM across vast spatiotemporal scales.
ISSN:0022-1430
1727-5652
DOI:10.1017/jog.2021.51