Publication Date:
2022-05-25
Description:
Author Posting. © American Geophysical Union, 2009. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Global Biogeochemical Cycles 23 (2009): GB3016, doi:10.1029/2008GB003440.
Description:
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[PO4 3−]) distributions may offer useful insights for understanding changing ocean circulation and biogeochemistry.
Description:
This work was supported by funding from
NSF grant OCE-0452972 to J. K. Moore and C. S. Zender. Computations
were supported by the Earth System Modeling Facility at UCI (NSFATMO321380)
and by the Climate Simulation Laboratory at National Center for
Atmospheric Research. The National Center for Atmospheric Research is
sponsored by the U.S. National Science Foundation. N.M. would like to
acknowledge the assistance of NSF– Carbon and Water (ATM-0628472),
and N.M., S.D., and C.L. would like to acknowledge the assistance of
NASA-IDS (NNX07AL80G).
Keywords:
Soluble iron
;
Atmospheric nutrient
Repository Name:
Woods Hole Open Access Server
Type:
Article
Format:
application/pdf
Permalink
