title: Nitrogen reduction under hydrothermal vent conditions: implications for the prebiotic synthesis of C-H-O-N compounds.
abstract: Dinitrogen is reduced in dilute hydrogen sulfide (H2S) solutions to ammonium at 120 degrees C. Experiments with dissolved dinitrogen (partial pressure 50 bar) in a 12 x 10(-3) mol/L H2S(aq) solution yield approximately 10(-5) mol/L NH4+ within 2-7 days. These yields are consistent with the equilibrium NH4+ concentration for the N-S-H system under these conditions. The formation of ammonium is catalyzed by the presence of freshly precipitated iron monosulfide. These results indicate that dinitrogen can be reduced at moderate temperatures in hydrothermal vent systems. Abiotic nitrogen reduction could have taken place within primordial hydrothermal vents, supplying some ammonia for the synthesis of C-H-O-N compounds via abiotic processes. The yield of ammonia via dinitrogen reduction by hydrogen sulfide, however, is so low that it is doubtful this process could have produced enough ammonia to sustain prebiotic hydrothermal synthesis of C-H-O-N compounds in or around vent systems.
authors.affiliation: Department of Geosciences, State University of New York-Stony Brook, Stony Brook, NY 11794-2100, USA. mschoonen@notes.cc.sunysb.edu
authors.forename: M A
authors.initials: MA
authors.lastname: Schoonen
authors.forename: Y
authors.initials: Y
authors.lastname: Xu
mesh_terms: D000641:Ammonia; D002244:Carbon / Q000737:chemistry*; D018534:Earth, Planet; D005618:Fresh Water / Q000737:chemistry*; D019015:Geologic Sediments / Q000032:analysis* / Q000737:chemistry; D006358:Hot Temperature; D006859:Hydrogen / Q000737:chemistry*; D008956:Models, Chemical; D009573:Nitrites / Q000737:chemistry; D009584:Nitrogen / Q000737:chemistry*; D009792:Oceans and Seas; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry*; D012623:Seawater / Q000737:chemistry*; D013696:Temperature; D013997:Time Factors
chemical_list: D009573:Nitrites; D002244:Carbon; D000641:Ammonia; D006859:Hydrogen; D009584:Nitrogen; D010100:Oxygen