Impacts of increasing anthropogenic soluble iron and nitrogen deposition on ocean biogeochemistry
Article first published online: 28 AUG 2009
Copyright 2009 by the American Geophysical Union.
Global Biogeochemical Cycles
Volume 23, Issue 3, September 2009
How to Cite
2009), Impacts of increasing anthropogenic soluble iron and nitrogen deposition on ocean biogeochemistry, Global Biogeochem. Cycles, 23, GB3016, doi:10.1029/2008GB003440., , , , , , and (
- Issue published online: 28 AUG 2009
- Article first published online: 28 AUG 2009
- Manuscript Accepted: 13 MAY 2009
- Manuscript Revised: 29 APR 2009
- Manuscript Received: 8 DEC 2008
- soluble iron;
- atmospheric nutrient
 We present results from transient sensitivity studies with the Biogeochemical Elemental Cycling (BEC) ocean model to increasing anthropogenic atmospheric inorganic nitrogen (N) and soluble iron (Fe) deposition over the industrial era. Elevated N deposition results from fossil fuel combustion and agriculture, and elevated soluble Fe deposition results from increased atmospheric processing in the presence of anthropogenic pollutants and soluble Fe from combustion sources. Simulations with increasing Fe and increasing Fe and N inputs raised simulated marine nitrogen fixation, with the majority of the increase in the subtropical North and South Pacific, and raised primary production and export in the high-nutrient low-chlorophyll (HNLC) regions. Increasing N inputs alone elevated small phytoplankton and diatom production, resulting in increased phosphorus (P) and Fe limitation for diazotrophs, hence reducing nitrogen fixation (∼6%). Globally, the simulated primary production, sinking particulate organic carbon (POC) export. and atmospheric CO2 uptake were highest under combined increase in Fe and N inputs compared to preindustrial control. Our results suggest that increasing combustion iron sources and aerosol Fe solubility along with atmospheric anthropogenic nitrogen deposition are perturbing marine biogeochemical cycling and could partially explain the observed trend toward increased P limitation at station ALOHA in the subtropical North Pacific. Excess inorganic nitrogen ([NO3−] + [NH4+] − 16[PO43−]) distributions may offer useful insights for understanding changing ocean circulation and biogeochemistry.