Role of mineral dust in the nitrate preservation during the glacial period:Insights from the RICE ice core

• Published in: Global and Planetary Change
• Main Authors: Venugopal, Abhijith U., Bertler, Nancy A. N., Pyne, Rebecca L., Kjaer, Helle A., Winton, V. Holly L., Mayewski, Paul A., Cortese, Giuseppe
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2022
• Subjects: RICE ice core; Last glacial period; Mineral dust-nitrate coupling; Nitrate scavenging; Atmospheric process; A new coastal record; CONTINUOUS-FLOW ANALYSIS; DOME C; NITRIC-ACID; ISOTOPIC CONSTRAINTS; SCALE VARIABILITY; ROOSEVELT ISLAND; SOUTHERN-OCEAN; ROSS SEA; SNOW; ANTARCTICA; Antarctic; Dome Fuji; East Antarctica; Roosevelt Island; Ross Sea; Southern Ocean; The Antarctic; West Antarctic Ice Sheet; West Antarctica; Antarc*; Antarctica; EPICA; ice core; Ice Sheet
• Online Access: https://curis.ku.dk/portal/da/publications/role-of-mineral-dust-in-the-nitrate-preservation-during-the-glacial-period(78a67960-a2d8-4f75-b87e-cc892ead4cbf).html; https://doi.org/10.1016/j.gloplacha.2022.103745

Nitrate (NO3-), an abundant aerosol in polar snow, is a complex environmental proxy to interpret owing to its diverse sources and susceptibility to post-depositional processes. During the last glacial period, when dust concentrations in the Antarctic ice were upto similar to 50 times than today, mineral dust appears to have a stabilizing effect on the NO3- concentration in snow. However, the mechanism leading to the stabilization remains unclear. Here, we present the new and highly resolved records of NO3- and non-sea salt calcium (nssCa(2+), a proxy for mineral dust) from the Roosevelt Island Climate Evolution (RICE) ice core. We focus on the glacial period from 83 to 26 kilo years Before Present (ka BP). The data show a statistically significant correlation between NO3- and nssCa(2+) over this period. To put our findings into a spatial context, we compare RICE data with existing records from east Antarctica (EPICA Dome C [EDC], Vostok and central Dome Fuji) and West Antarctica (West Antarctic Ice Sheet Divide Ice Core [WDC]). Spatial analysis suggests that nssCa(2+) is contributing to the effective scavenging of NO3- from the atmosphere perhaps through the formation of calcium nitrate (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 mid-latitude source regions by Southern Hemisphere Westerly Winds (SHWW). The data also suggest that the correlation observed at various Antarctic locations may depend on the level of dust reaching the sites from the mid-latitude sources.