%0 Journal Article %1 Brandes1998 %A Brandes, J. A. %A Boctor, N. Z. %A Cody, G. D. %A Cooper, B. A. %A Hazen, R. M. %A Yoder, H. S. %D 1998 %J Nature %K imported %N 6700 %P 365--367 %T Abiotic nitrogen reduction on the early Earth %V 395 %X The production of organic precursors to life depends critically on the form of the reactants, In particular, an environment dominated by N-2 is far less efficient in synthesizing nitrogen-bearing organics than a reducing environment rich in ammonia (refs 1, 2). Relatively reducing lithospheric conditions on the early Earth have been presumed to favour the generation of an ammonia-rich atmosphere. but this hypothesis has not been studied experimentally. Here we demonstrate mineral-catalysed reduction of N-2, NO2- and NO3- to ammonia at temperatures between 300 and 800 degrees C and pressures of 0.1-0.4 GPa-conditions typical of crustal and oceanic hydrothermal systems. We also show that only N-2 is stable above 800 degrees C, thus precluding significant atmospheric ammonia formation during hot accretion, We conclude that mineral-catalysed N-2 reduction might have provided a significant source of ammonia to the Hadean ocean. These results also suggest that, whereas nitrogen in the Earth's early atmosphere was present predominantly as N-2, exchange with oceanic, hydrothermally derived ammonia could have provided a significant amount of the atmospheric ammonia necessary to resolve the early-faint-Sun paradox(3).

@article{Brandes1998, abstract = {The production of organic precursors to life depends critically on the form of the reactants, In particular, an environment dominated by N-2 is far less efficient in synthesizing nitrogen-bearing organics than a reducing environment rich in ammonia (refs 1, 2). Relatively reducing lithospheric conditions on the early Earth have been presumed to favour the generation of an ammonia-rich atmosphere. but this hypothesis has not been studied experimentally. Here we demonstrate mineral-catalysed reduction of N-2, NO2- and NO3- to ammonia at temperatures between 300 and 800 degrees C and pressures of 0.1-0.4 GPa-conditions typical of crustal and oceanic hydrothermal systems. We also show that only N-2 is stable above 800 degrees C, thus precluding significant atmospheric ammonia formation during hot accretion, We conclude that mineral-catalysed N-2 reduction might have provided a significant source of ammonia to the Hadean ocean. These results also suggest that, whereas nitrogen in the Earth's early atmosphere was present predominantly as N-2, exchange with oceanic, hydrothermally derived ammonia could have provided a significant amount of the atmospheric ammonia necessary to resolve the early-faint-Sun paradox(3).}, added-at = {2009-11-03T20:21:25.000+0100}, author = {Brandes, J. A. and Boctor, N. Z. and Cody, G. D. and Cooper, B. A. and Hazen, R. M. and Yoder, H. S.}, biburl = {https://www.bibsonomy.org/bibtex/2a446b29f42bc22db159fa30cf619ff0b/svance}, interhash = {31a7eddde0882859be4d8dbc416deec4}, intrahash = {a446b29f42bc22db159fa30cf619ff0b}, journal = {Nature}, keywords = {imported}, number = 6700, owner = {svance}, pages = {365--367}, timestamp = {2009-11-03T20:21:40.000+0100}, title = {Abiotic nitrogen reduction on the early Earth}, volume = 395, year = 1998 }