Variations in snow and firn chemistry along US ITASE traverses and the effect of surface glazing

D A Dixon,P A Mayewski,T A Scambos,D S Introne,S B Sneed,E Korotkikh,M J Handley

doi:10.5194/tc-7-515-2013

D A Dixon, P A Mayewski + Show 5 more

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https://doi.org/10.5194/tc-7-515-2013

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Journal: The Cryosphere	Publication Date: Mar 26, 2013
Citations: 61	License type: CC BY 3.0

Affiliation: University of Maine

Abstract

Abstract. This study provides a baseline from which changes in the chemistry of the atmosphere over Antarctica can be monitored under expected warming scenarios and continued intensification of industrial activities in the Southern Hemisphere. It is the first study to measure more than 25 chemical constituents in the surface snow and firn across extensive regions of Antarctica. We present major ion, trace element, heavy metal, rare earth element and oxygen isotope data from a series of surface snow samples and shallow firn sections collected along four US ITASE traverses across East and West Antarctica. In each sample we measure dissolved concentrations of Na+, K+, Mg2+, Ca2+, Cl−, NO3+, SO42−, and MS− using ion chromatography and total concentrations of Sr, Cd, Cs, Ba, La, Ce, Pr, Pb, Bi, U, As, Al, S, Ca, Ti, V, Cr, Mn, Fe, Co, Na, Mg, Li, and K using inductively coupled plasma sector field mass spectrometry (ICP-SFMS). We also measure δ18O by isotope ratio mass spectrometry. Satellite remote sensing measurements of microwave backscatter and grain size are used to assist in the identification of glaze/dune areas across Antarctica and determine if these areas can possibly contain useful chemical climate records. The majority of the non-glaze/dune samples in this study exhibit similar, or lower, concentrations to those from previous studies. Consequently, the results presented here comprise a conservative baseline for Antarctic surface snow chemical concentrations. The elements Cd, Pb, As and Bi are enriched across Antarctica relative to both ocean and upper crust elemental ratios. Local and global volcanic outgassing may account for the majority of the Bi measured in East and West Antarctica and for a significant fraction of the Cd and As. However, significant concentrations of Cd, Pb, and As remain across much of Antarctica.

Highlights

Deep ice cores from the high latitudes of both hemispheres provide us with valuable archives of past climate (Mayewski et al, 1993; Jouzel et al, 1989), but the chemical proxies that they contain must be interpreted in the context of their geographic location
This study presents chemistry data from shallow firn cores/snow pits, and surface snow samples collected along the US ITASE2002/2003 Byrd to South Pole traverse (ITASE-02), the US International Trans Antarctic Scientific Expedition (ITASE)-2003/2004 South Pole to Taylor Dome traverse (ITASE-03), and the US ITASE-2006/2007 and 2007/2008 Taylor Dome to South Pole traverses (ITASE-06/07)
The ITASE-06/07 backscatter and grain size are highest between 06-4 and 07-3, which is the part of the traverse that skirts/overlaps a large glaze/dune area (Fig. 3)

Summary

Introduction

Deep ice cores from the high latitudes of both hemispheres provide us with valuable archives of past climate (Mayewski et al, 1993; Jouzel et al, 1989), but the chemical proxies that they contain must be interpreted in the context of their geographic location. Over-snow traverses, such as those conducted by the International Trans-Antarctic Scientific Expedition (Mayewski et al, 2005), provide us with the opportunity to collect a large number of shallow cores from broad geographic areas These arrays provide the data needed, at a high enough spatial and temporal resolution, to form a more accurate assessment of the regional chemical and climate differences between deep core sites (Dixon et al, 2011; Kaspari et al, 2004; Bertler et al, 2005). This study presents chemistry data from shallow firn cores/snow pits (hereafter referred to as firn sections), and surface snow samples collected along the US ITASE2002/2003 Byrd to South Pole traverse (ITASE-02), the US ITASE-2003/2004 South Pole to Taylor Dome traverse (ITASE-03), and the US ITASE-2006/2007 and 2007/2008 Taylor Dome to South Pole traverses (ITASE-06/07) We use these data to determine the spatial variability of chemical deposition over extensive and highly inaccessible areas of the Antarctic continent (Fig. 1)

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Conclusion