Modeling the impacts of atmospheric deposition of nitrogen and desert dust–derived phosphorus on nutrients and biological budgets of the Mediterranean Sea (bibtex)
by , , , , , , , , , , ,
Abstract:
Atmospheric deposition represents a significant source of nutrients at the Mediterranean basin scale. We apply aerosol deposition fields simulated from atmospheric models into the high resolution oceanic biogeochemical model NEMOMED12/PISCES with nutrient ratios used for plankton growth set to Redfield ratio. We perform 3 simulations to determine the impact of nutrients on productivity over the period 1997–2012: (i) without atmospheric deposition, (ii) with nitrogen deposition from anthropogenic and natural sources, and (iii) with deposition of both nitrogen (from anthropogenic and natural sources) and phosphate from desert dust. Time series of modeled deposition fluxes are compared to available measurements. This comparison with measurements shows that both variability and intensity ranges are realistic enough for our main purpose of estimating the atmospheric deposition impact on Mediterranean biogeochemical tracers such as surface nutrient concentrations, chlorophyll a and plankton concentrations. Our results show that atmospheric deposition is one of the major sources of nitrogen and phosphorus for some regions of the oligotrophic Mediterranean Sea. More than 18 109gN month-1 are deposited to the whole Mediterranean Sea. This deposition is responsible for an average increase of 30 to 50 % in primary production over vast regions. Natural dust–derived deposition of phosphorus is sparser in space and time (0.5 109g month-1 on average over the entire basin). However, dust deposition events can significantly affect biological production. We calculate fertilizing effects of phosphate from dust to be low on average (6 to 10 %) but up to 30% increase in primary productivity can be observed during the months when surface water stratification occurs. Finally, these fertilizing effects are shown to be transmitted along the biological chain (primary production, Chl a, phytoplankton, zooplankton, grazing). We also perform a preliminary study on the maximal biological response of the Mediterranean by simulating extreme deposition events throughout the basin over a full year period. We show that nitrogen deposition effects observed in our long–term simulations (1997–2012) are close to maximal effects (i.e. those produced by high intensity deposition events) whereas dust–derived phosphate effects are substantially weaker than the effect on productivity reached when an extreme deposition event occurs.
Reference:
Modeling the impacts of atmospheric deposition of nitrogen and desert dust–derived phosphorus on nutrients and biological budgets of the Mediterranean Sea (Camille Richon, Jean-Claude Dutay, François Dulac, Rong Wang, Yves Balkanski, Pierre Nabat, Olivier Aumont, Karine Desboeufs, Benoît Laurent, Cécile Guieu, Patrick Raimbault, Jonathan Beuvier), In Progress in Oceanography, 2017.
Bibtex Entry:
@Article{	  richon.ea_2017_1,
  title		= {Modeling the impacts of atmospheric deposition of nitrogen
		  and desert dust–derived phosphorus on nutrients and
		  biological budgets of the {Mediterranean} {Sea}},
  issn		= {0079-6611},
  url		= {http://www.sciencedirect.com/science/article/pii/S0079661116301811},
  doi		= {10.1016/j.pocean.2017.04.009},
  abstract	= {Atmospheric deposition represents a significant source of
		  nutrients at the Mediterranean basin scale. We apply
		  aerosol deposition fields simulated from atmospheric models
		  into the high resolution oceanic biogeochemical model
		  NEMOMED12/PISCES with nutrient ratios used for plankton
		  growth set to Redfield ratio. We perform 3 simulations to
		  determine the impact of nutrients on productivity over the
		  period 1997–2012: (i) without atmospheric deposition,
		  (ii) with nitrogen deposition from anthropogenic and
		  natural sources, and (iii) with deposition of both nitrogen
		  (from anthropogenic and natural sources) and phosphate from
		  desert dust. Time series of modeled deposition fluxes are
		  compared to available measurements. This comparison with
		  measurements shows that both variability and intensity
		  ranges are realistic enough for our main purpose of
		  estimating the atmospheric deposition impact on
		  Mediterranean biogeochemical tracers such as surface
		  nutrient concentrations, chlorophyll a and plankton
		  concentrations. Our results show that atmospheric
		  deposition is one of the major sources of nitrogen and
		  phosphorus for some regions of the oligotrophic
		  Mediterranean Sea. More than 18 109gN month-1 are deposited
		  to the whole Mediterranean Sea. This deposition is
		  responsible for an average increase of 30 to 50 \% in
		  primary production over vast regions. Natural
		  dust–derived deposition of phosphorus is sparser in space
		  and time (0.5 109g month-1 on average over the entire
		  basin). However, dust deposition events can significantly
		  affect biological production. We calculate fertilizing
		  effects of phosphate from dust to be low on average (6 to
		  10 \%) but up to 30\% increase in primary productivity can
		  be observed during the months when surface water
		  stratification occurs. Finally, these fertilizing effects
		  are shown to be transmitted along the biological chain
		  (primary production, Chl a, phytoplankton, zooplankton,
		  grazing). We also perform a preliminary study on the
		  maximal biological response of the Mediterranean by
		  simulating extreme deposition events throughout the basin
		  over a full year period. We show that nitrogen deposition
		  effects observed in our long–term simulations
		  (1997–2012) are close to maximal effects (i.e. those
		  produced by high intensity deposition events) whereas
		  dust–derived phosphate effects are substantially weaker
		  than the effect on productivity reached when an extreme
		  deposition event occurs.},
  journal	= {Progress in Oceanography},
  author	= {Richon, Camille and Dutay, Jean-Claude and Dulac,
		  François and Wang, Rong and Balkanski, Yves and Nabat,
		  Pierre and Aumont, Olivier and Desboeufs, Karine and
		  Laurent, Benoît and Guieu, Cécile and Raimbault, Patrick
		  and Beuvier, Jonathan},
  year		= {2017},
  keywords	= {aerosol, biogeochemistry, Deposition, Mediterranean,
		  Nutrient}
}
Powered by bibtexbrowser