Mineral Dust Influence on the Glacial Nitrate Record from the RICE Ice Core, West Antarctica and Environmental Implications

Nitrate (NO 3 − ), an abundant aerosol in polar snow, is a complex environmental proxy to interpret owing to the variety of its sources and its susceptibility to post-depositional processes. During the last glacial period, when the dust level in the Antarctic atmosphere was higher than today by a fa...

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Bibliographic Details
Main Authors: Venugopal, Abhijith U., Bertler, Nancy A. N., Pyne, Rebecca L., Kjær, Helle A., Winton, V. Holly L., Mayewski, Paul A., Cortese, Giuseppe
Format: Text
Language:English
Published: 2020
Subjects:
Antarctic
Dome Fuji
Roosevelt Island
Southern Ocean
The Antarctic
West Antarctica
Antarc*
Antarctica
EPICA
ice core
Online Access:https://doi.org/10.5194/cp-2020-151
https://cp.copernicus.org/preprints/cp-2020-151/
Description
Summary:Nitrate (NO 3 − ), an abundant aerosol in polar snow, is a complex environmental proxy to interpret owing to the variety of its sources and its susceptibility to post-depositional processes. During the last glacial period, when the dust level in the Antarctic atmosphere was higher than today by a factor up to ~25, mineral dust appears to have a stabilizing effect on the NO 3 − concentration. However, the exact mechanism remains unclear. Here, we present new and highly resolved records of NO 3 − and non-sea salt calcium (nssCa 2+ , a proxy for mineral dust) from the Roosevelt Island Climate Evolution (RICE) ice core for the period 26–40 kilo years Before Present (ka BP). This interval includes seven millennial-scale Antarctic Isotope Maxima (AIM) events, against the background of a glacial climate state. We observe a significant correlation between NO 3 − and nssCa 2+ over this period and especially during AIM events. We put our observation into a spatial context by comparing the records to existing data from east Antarctic cores of EPICA Dome C (EDC), Vostok and central Dome Fuji. The data suggest that nssCa 2+ is contributing to the effective scavenging of NO 3 − from the atmosphere through the formation of Ca(NO 3 ) 2 . The geographic pattern implies that the process of Ca(NO 3 ) 2 formation occurs during the long-distance transport of mineral dust from the mid-latitude source regions by Southern Hemisphere Westerly Winds (SHWW) and most likely over the Southern Ocean. Since NO 3 − is dust-bound and the level of dust mobilized through AIM events is mainly regulated by the latitudinal position of SHWW, we suggest that NO 3 − may also have the potential to provide insights into paleo-westerly wind pattern during the events.

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