Earth’s Nitrogen and Carbon Cycles

Abstract Understanding the Earth’s geological nitrogen (N) and carbon (C) cycles is fundamental for assessing distribution of these volatiles between solid Earth (core, mantle crust), oceans atmosphere. This Special Communication about N C contains material that relevant researchers who are interested in Topical Collection on planetary evolution “Reading Terrestrial Planet Evolution Isotopes Element Measurements”. Variations fluxes major reservoirs through time influenced determined unique composition Here we review several key aspects which our understanding has significantly advanced during last decade field-based, experimental theoretical studies. Subduction zones most important pathway both from surface into deep Earth. A question flux quantification how much volatile elements stored downgoing slab introduced returned back to atmosphere arc magmatism. For N, retention as $\text{NH}_{4}^{+}$ NH 4 + minerals a influence reservoirs. The temperature-dependent stability -bearing determines whether predominantly retained depths (in subduction with low geothermal gradient) or devolatilized high gradient). Several lines evidence suggest regassing respect due net influx subducted over time, but this issue highly debated contrary also exists. Nevertheless, there consensus majority budget mantle, continental crust constituting significant reservoir. C, release subducting occurs decarbonation reactions, dissolution formation carbonatitic liquids, reprecipitation forearc wedge may limit effectiveness direct return Carbon regional metamorphism collision zone orogens potentially profound effects emerged such sources rather than sinks atmospheric CO 2 . On shorter timescales, contact interaction mantle-derived magmas C-bearing country rocks, resulting large quantities CH 4 and/or , been linked global warming events.