the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Mineral Dust Influence on the Glacial Nitrate Record from the RICE Ice Core, West Antarctica and Environmental Implications
Abhijith U. Venugopal
Nancy A. N. Bertler
Rebecca L. Pyne
Helle A. Kjær
V. Holly L. Winton
Paul A. Mayewski
Giuseppe Cortese
Abstract. Nitrate (NO3−), 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 NO3− concentration. However, the exact mechanism remains unclear. Here, we present new and highly resolved records of NO3− and non-sea salt calcium (nssCa2+, 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 NO3− and nssCa2+ 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 nssCa2+ is contributing to the effective scavenging of NO3− from the atmosphere through the formation of Ca(NO3)2. The geographic pattern implies that the process of Ca(NO3)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 NO3− is dust-bound and the level of dust mobilized through AIM events is mainly regulated by the latitudinal position of SHWW, we suggest that NO3− may also have the potential to provide insights into paleo-westerly wind pattern during the events.
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Abhijith U. Venugopal et al.


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RC1: 'Review of the manuscript entitled “Mineral Dust Influence on the Glacial Nitrate Record from the RICE Ice Core, West Antarctica and Environmental Implications”', Anonymous Referee #1, 30 Dec 2020
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RC2: 'Review of Venugopal et al.,', Anonymous Referee #2, 18 Feb 2021


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RC1: 'Review of the manuscript entitled “Mineral Dust Influence on the Glacial Nitrate Record from the RICE Ice Core, West Antarctica and Environmental Implications”', Anonymous Referee #1, 30 Dec 2020
-
RC2: 'Review of Venugopal et al.,', Anonymous Referee #2, 18 Feb 2021
Abhijith U. Venugopal et al.
Abhijith U. Venugopal et al.
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