Modern analogs for ammonia flux from terrestrial hydrothermal features to the Archean atmosphere.

ABSTRACT: The isotopic composition of nitrogen in the rock record provides valuable evidence of reactive nitrogen sources and processing on early Earth, but the wide range of δ¹⁵N values (- 10.2 to + 50.4‰) leads to ambiguity in defining the early Precambrian nitrogen cycle. The high δ¹⁵N values have been explained by large fractionation associated with the onset of nitrification and/or fractionation produced by ammonia-ammonium equilibrium and water-air flux in alkaline paleolakes. Previous flux sensitivity studies in modern water bodies report alkaline pH is not a prerequisite and temperature can be the dominate parameter driving water-air flux. Here, I use the chemical and physical components of 1022 modern hydrothermal features to provide evidence that water-air NH₃ flux produced a significant source of fixed nitrogen to early Earth's atmosphere and biosphere. With regard to the modeled average NH₃ flux (2.1 kg N m^-2 year^-1) and outlier removed average flux (1.2 kg N m^-2 year^-1), the Archean Earth's surface would need to be 0.0092, and 0.017% terrestrial hydrothermal features, respectively, for the flux to match the annual amount of N produced by biogenic fixation on modern Earth. Water-air NH₃ flux from terrestrial hydrothermal features may have played a significant role in supplying bioavailable nitrogen to early life.

SUBMITTER: Felix JD 

PROVIDER: S-EPMC10794450 | biostudies-literature | 2024 Jan

REPOSITORIES: biostudies-literature