A 21,000 year record of organic matter quality in the WAIS
Divide ice core
Juliana D'Andrilli1,2, Christine M. Foreman1,2, Michael Sigl3, John C. Priscu4, and Joseph R. McConnell31Dept. Chemical and Biological Engineering, Montana State University, Bozeman, Montana, USA 2Center for Biofilm Engineering, Montana State University, Bozeman, 59717, USA 3Division of Hydrologic Science, Desert Research Institute, Reno, 89512, USA 4Dept. of Land Resources & Environmental Science, Montana State University, Bozeman, 59717, USA
Received: 15 Nov 2016 – Accepted for review: 29 Nov 2016 – Discussion started: 30 Nov 2016
Abstract. Englacial ice contains a significant reservoir of organic material (OM), preserving a chronological record of materials from Earth's past. Here, we investigate if OM quality surveys in ice core research can provide paleoecological information on the dynamic nature of our Earth through time. Temporal trends in OM quality from the early Holocene extending back to the Last Glacial Maximum (LGM) of the West Antarctic Ice Sheet Divide (WD) ice core were measured by fluorescence spectroscopy. Fluorescent intensity fluctuations and PARAFAC modelling of fluorescent OM from the LGM (27.0–18,0 kyrs BP; before present 1950), through the last deglaciation (LD; 18.0–11.5 kyrs BP), to the early to mid-Holocene (11.5–6.0 kyrs BP) provided evidence of different types of OM chemical species in the WD ice core over 21.0 kyrs. Two proteinaceous PARAFAC components (C1 and C2) were characteristic of fluorescent OM prevailing in all climate periods, suggesting a strong signature of labile microbial OM. A humic-like component (C3), characteristic of terrestrial and marine OM fluorescence, was only observed during the Holocene, suggesting that recalcitrant OM may be an ecological marker of warmer climates. Fluctuations in WD ice core OM fluorescence over 21.0 kyrs BP may be driven by environmental changes at the source, and potentially its interaction with the atmosphere. We suggest that fluorescent OM signatures observed during the LGM were the result of greater continental dust loading of microbially derived proteinaceous material in a drier climate, with lower marine influences when sea ice extent was higher, and continents had more expansive tundra cover. As the climate warmed, the OM quality record in the WD ice core changed, reflecting shifts in carbon productivity as a result of global ecosystem response.
D'Andrilli, J., Foreman, C. M., Sigl, M., Priscu, J. C., and McConnell, J. R.: A 21,000 year record of organic matter quality in the WAIS
Divide ice core, Clim. Past Discuss., doi:10.5194/cp-2016-119, in review, 2016.