Local and Global‐Scale Soil Nitrogen Stocks and Burial Rates in Mangroves

Abstract Coastal marine environments can mitigate the deleterious effects of terrestrial reactive nitrogen (N) loads through burial and long‐term storage in soils and sediments, although the quantification of these values is limited and poorly constrained. We utilized a spatially explicit global coastal typology for sedimentary settings and combined sedimentary‐geomorphic settings (SGS) to characterize global mangrove soil N stocks and burial rates. We found that carbonate setting mangroves store 24.64 (95% CI: 23.03–25.92) Mg N ha −1 in the top 1 m of soil, which is more than the 11.73 (95% CI: 11.41–12.26) Mg ha −1 stored by terrigenous settings. Burial rates were similar between terrigenous and carbonate settings, with 3.43 (95% CI: 2.80, 4.25) and 4.80 (95% CI: 3.95, 6.00) g N m −2 y −1 , respectively. Scaled to SGS land area, global N stocks and burial rates summed to 190.5 (95% CI: 95.9–264) Tg and 686.1 (95% CI: 583.2–803.6) Gg y −1 , the latter accounting for 3% of all marine burial, 5.6% of all coastal burial, and 1.4% of estimated annual N riverine fluxes. Our estimates constrain uncertainties in mangrove N stocks and burial across distinct coastal typologies and help place mangrove N storage and burial in a global biogeochemical context relevant to coastal water quality.