New insights into sea ice nitrogen biogeochemical dynamics from the nitrogen isotopes

New insights into the evolutionary history of biological nitrogen fixation

Nitrogenase, which catalyzes the ATP-dependent reduction of dinitrogen (N2) to ammonia (NH3), accounts for roughly half of the bioavailable nitrogen supporting extant life. The fundamental requirement for fixed forms of nitrogen for life on Earth, both at present and in the past, has led to broad and significant interest in the origin and evolution of biological N2 fixation. One key question is...

Nitrogen Isotopes in Paleoclimate Research

Ice sheets and nitrogen.

Snow and ice play their most important role in the nitrogen cycle as a barrier to land-atmosphere and ocean-atmosphere exchanges that would otherwise occur. The inventory of nitrogen compounds in the polar ice sheets is approximately 260 Tg N, dominated by nitrate in the much larger Antarctic ice sheet. Ice cores help to inform us about the natural variability of the nitrogen cycle at global an...

New Insights on Saturn’s Formation from Its Nitrogen Isotopic Composition

The recent derivation of a lower limit for the 14N/15N ratio in Saturn’s ammonia, which is found to be consistent with the Jovian value, prompted us to revise models of Saturn’s formation using as constraints the supersolar abundances of heavy elements measured in its atmosphere. Here we find that it is possible to account for both Saturn’s chemical and isotopic compositions if one assumes the ...

A new source of 'new' nitrogen in the sea.