Limited impact of atmospheric nitrogen deposition on marine productivity due to biogeochemical feedbacks in a global ocean model. Issue 9 (14th May 2016)

• Record Type: Journal Article
• Authors: Somes, Christopher J.; Landolfi, Angela; Koeve, Wolfgang; Oschlies, Andreas
• Is Part Of: Geophysical research letters. Volume 43:Issue 9(2016)
• Page Start: 4500
• Page End: 4509
• Publication Date: 2016-05-14
• Subjects: atmospheric nitrogen deposition -- N2 fixation -- denitrification -- marine productivity; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1002/2016GL068335
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: The impact of increasing anthropogenic atmospheric nitrogen deposition on marine biogeochemistry is uncertain. We performed simulations to quantify its effect on nitrogen cycling and marine productivity in a global 3‐D ocean biogeochemistry model. Nitrogen fixation provides an efficient feedback by decreasing immediately to deposition, whereas water column denitrification increases more gradually in the slowly expanding oxygen deficient zones. Counterintuitively, nitrogen deposition near oxygen deficient zones causes a net loss of marine nitrogen due to the stoichiometry of denitrification. In our idealized atmospheric deposition simulations that only account for nitrogen cycle perturbations, these combined stabilizing feedbacks largely compensate deposition and suppress the increase in global marine productivity to <2%, in contrast to a simulation that neglects nitrogen cycle feedbacks that predicts an increase of >15%. Our study emphasizes including the dynamic response of nitrogen fixation and denitrification to atmospheric nitrogen deposition to predict future changes of the marine nitrogen cycle and productivity. Key Points: N2 fixation decreases in response to atmospheric nitrogen deposition Denitrification increases in response to atmospheric nitrogen deposition Nitrogen cycle feedbacks stabilize marine nitrogen inventory and limit changes to productivity