Uncovering the mysteries of ocean biogeochemistry and ecology a computational odyssey

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Ocean Biogeochemical Model
Dissolved organic matter cycling
Carbon
Oxygen
Phosphorus
Particle sinking and respiration
Air-Sea fluxes
Nitrogen
Iron
SiO2 and CaCO3
Solubility pump
Mineral pump
Loss from system
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Ecological Model
N2-fix. Phyto.
Fish
Small Phyto.
Protists
Recycled nutrients
Filter Feeder
DOM
New Nutrients
Large Phyto.
Detritus
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Model Features
Three phytoplankton groups Variable FeN
ratios Variable CChl ratios Variable SiN
ratios Variable NP ratios for large phyto. Three
DOM components CaC a constant fraction of small
phyto. grazing Mineral protection during
sinking N2-fixation, water column denitrification
and sediment denitrification
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NUTRIENT UPTAKE Modified from Geider et al.
(1997) steady-state, light and nutrients
co-limitation 1) T-relation of Eppley
(1972) used. 2) ChlC ratio modulated by
anemia - the FeN ratio (Sunda and Huntsman
1997) QFeN FeN2 / (FeNlim
FeN2) f fmax /(1 fmax a Iz / (2
PCm)) QFeN2 /(QFeNirr2 QFeN2) mN
PCm / (1 z) (1 exp -aIzf/PCm) 3) PCmax,
fmax and a tuned for observed chl. and
productivity. 4) Phytoplankton take up Fe
as UptakeFe VFe LimFe ekEppleyT PN
(1 QFeN /(QFeNirr QFeN)) e(-FeN /
FeNSat) for Small 5) Nitrogen uptake with
ammonia inhibition (Frost and Franzen, 1992).
6) Diazotrophs take up N2, have a low growth
rates, and high NP. 7) Diatom SiN from
nutrients and light (Martin-Jezequel et al.,
2000 Mongin et al., submitted) SiNlim
(LimSi / min(LimN, LimIrr, LimFe))2 SiNDiatomUpt
ake (SiNmax SiNmin) SiNlim /(SiNmax
SiNlim) SiNmin 8) CaCO3 production a
fraction of small phytoplankton grazing (Moore et
al., 2002).
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Model fit to Sunda and Huntsman (1997) data for
Thalassiosira Pseudonana is shown for high light
(open) and low light (filled)
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PARTICLE RECYLING Grazing of Small
Phytoplankton ? PS2 instantaneous steady state
with implicit grazer Grazing of Large and
Diazotrophic Phytoplankton ? PL,Di4/3 moderate
imbalance Detritus production temperature
dependent fractions of grazing for Small and
Large A Michaelis-Menton threshold prevents
complete phytoplankton extinction. Dissolved Fe
adsorbs onto detritus and returns to the
dissolved phase only during remineralization
(I.e. no desorption or sediment
remineralization). Sinking detritus is be
partially protected from remineralization by
mineral material after Klaas and Archer (2002 7
wt for CaCO3 and 2.9 wt for SiO2) Dissolved
Organic Carbon production is a constant fraction
of grazing to - fixed 42 mM refractory
DOM - semi-labile DOM with different N and
P remin. timescales (10 yr 4 yr Abell et al.,
2000) - labile pool of fixed NP of 16 and
remin timescale of 3 mo