Validation of sampling antarctic subglacial hypersaline waters with an electrothermal ice melting probe (IceMole) for environmental analytical geochemistry

ABSTRACT

Geochemical characterisation of hypersaline waters is difficult as high concentrations of salts hinder the analysis of constituents at low concentrations, such as trace metals, and the collection of samples for trace metal analysis in natural waters can be easily contaminated. This is particularly the case if samples are collected by non-conventional techniques such as those required for aquatic subglacial environments. In this paper we present the first analysis of a subglacial brine from Taylor Valley, (~ 78°S), Antarctica for the trace metals: Ba, Co, Mo, Rb, Sr, V, and U. Samples were collected englacially using an electrothermal melting probe called the IceMole. This probe uses differential heating of a copper head as well as the probe’s sidewalls and an ice screw at the melting head to move through glacier ice. Detailed blanks, meltwater, and subglacial brine samples were collected to evaluate the impact of the IceMole and the borehole pump, the melting and collection process, filtration, and storage on the geochemistry of the samples collected by this device. Comparisons between melt water profiles through the glacier ice and blank analysis, with published studies on ice geochemistry, suggest the potential for minor contributions of some species Rb, As, Co, Mn, Ni, NH₄⁺, and NO₂⁻+NO₃⁻ from the IceMole. The ability to conduct detailed chemical analyses of subglacial fluids collected with melting probes is critical for the future exploration of the hundreds of deep subglacial lakes in Antarctica.

KEYWORDS:

• IceMole
• englacial brine
• trace metals
• Antarctica
• environmental geochemistry

Acknowledgments

This work was supported through NSF grants ANT-1144176 (to WBL) and ANT-1727387 (to JAM). We are extremely grateful to the entire EnEx-Team which was funded by DLR grants 50NA1206 to 50NA1211, and the MIDGE Science Team (https://github.com/MikuckiLab/MIDGE-EnEx-Science-Team), and the Antarctic Support Contractor (ASC). Ryan Davis assisted with sample collection and processing. Trace metal analysis were done in the Trace Element Research Laboratory (TERL) in the School of Earth Sciences at OSU.

Disclosure statement

No potential conflict of interest was reported by the authors.

Data availability

All data is presented in the tables.

Additional information

Funding

This work was supported by the Deutsches Zentrum für Luft- und Raumfahrt [50NA1206–50NA1211, 50NA1502]; National Science Foundation [ANT-1144176, ANT-1727387].