Impacts of decadal increasing nitrogen deposition on North Pacific marine ecosystems

Atmospheric nitrogen deposition is one of the key sources of marine nutrients, significantly affecting marine ecosystems. However, the ecological response of marine ecosystems to current and future changes in nitrogen deposition remains unclear. This study investigates the effects of rising nitrogen deposition during the past decades on North Pacific ecosystems by utilizing a coupled physical-biological model. We estimate that the drastic 170% increase in nitrogen deposition during 1950-2020, as indicated by the ACCMIP project, leads to a 1% rise in plankton biomass and a 0.4% decrease in phosphate. These changes boost marine primary productivity and increase the demand for phosphorus, particularly in mid to low-latitude regions. Continued nitrogen deposition under different emission scenarios (RCP2.6, 6.0, and 8.5) during the next decades would exacerbate nutrient imbalances, with the nitrogen-to-phosphorus ratio rising by >0.25%, adversely affecting ecosystem stability. These findings provide insights into future responses of marine ecosystems to rising nitrogen deposition.