What is it about?

Hydrogen gas can be generated by glaciers grinding underlying bedrock. This process can also generate oxidized iron compounds or rust. Microbes in such habitats can combine this hydrogen with ferric iron to fuel to support their metabolisms, analogous to how humans eat food and breath oxygen to fuel their metabolism. Many of these microorganisms can use this energy to convert carbon dioxide into biomass and in doing so can support a more diverse array of organisms in what is often referred to as a food web.

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Why is it important?

The majority of the life we are familiar with is supported by light through the process of photosynthesis. However, light cannot penetrate many of the environments where life persists. In such environments, life is supported by chemical energy. Glaciers can grind bedrock and in doing so can generate hydrogen gas, a potent source of fuel to support microbial communities. These observations help to explain how life could persist in icy environments such as during snowball Earth episodes or on other icy planets.

Perspectives

The ability to use hydrogen gas to fuel metabolism is widespread in the microbial world, in particular in microbial ecosystems that thrive in the absence of sunlight. Determining how, when, and where hydrogen gas can be released from the geosphere to support the biosphere is critical to understanding the distribution of life in extreme environments on Earth and potentially on other planets.

Eric Boyd
Montana State University

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This page is a summary of: Lithogenic hydrogen supports microbial primary production in subglacial and proglacial environments, Proceedings of the National Academy of Sciences, December 2020, Proceedings of the National Academy of Sciences,
DOI: 10.1073/pnas.2007051117.
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