Dynamic flows create potentially habitable conditions in Antarctic subglacial lakes

TL;DR

This study shows that geothermal heat induces vigorous turbulence in Antarctic subglacial lakes, promoting nutrient mixing and potentially supporting microbial life in these isolated, extreme environments.

Contribution

It demonstrates that geothermal flux causes turbulent convection in subglacial lakes, enhancing mixing and nutrient distribution, which was not previously understood.

Findings

Most lakes exhibit vigorous turbulent vertical convection.

Dynamic conditions enable suspension of particles up to 36 micrometers.

Stable ice layers can isolate well-mixed water from the ice-water interface.

Abstract

Trapped beneath the Antarctic ice sheet lie over 400 subglacial lakes, which are considered to be extreme, isolated, yet viable habitats for microbial life. The physical conditions within subglacial lakes are critical to evaluating how and where life may best exist. Here, we propose that Earth's geothermal flux provides efficient stirring of Antarctic subglacial lake water. We demonstrate that most lakes are in a regime of vigorous turbulent vertical convection, enabling suspension of spherical particulates with diameters up to 36 micrometers. Thus, dynamic conditions support efficient mixing of nutrient- and oxygen-enriched meltwater derived from the overlying ice, which is essential for biome support within the water column. We caution that accreted ice analysis cannot always be used as a proxy for water sampling of lakes beneath a thin (<3.166 kilometers) ice cover, because a stable layer isolates the well-mixed bulk water from the ice-water interface where freezing may occur.