Biological Carbon Pump — Ocean Marine Snow Simulator

Ocean Column Controls

Primary production 1.20 mol C/m²/day

Particle sinking speed 80 m/day

Water temperature 8 °C

Simulation speed 6 days/s

Live Carbon Flux

Export flux @ 100 m

–

Flux @ seafloor 1000 m

–

Sequestration efficiency (seafloor ÷ surface production)

0.0%

Remineralization rate k

–

e-folding depth

–

How it works

Phytoplankton fix CO₂ into organic carbon in the sunlit surface layer. A fraction of that production sinks out of the mixed layer as "marine snow" — dead cells, fecal pellets and aggregates — while bacteria respire the sinking carbon back to CO₂ as it falls. Modelled as first‑order decay at constant sinking speed v (m/day) and remineralization rate k (day⁻¹), the carbon flux F at depth z follows an exponential attenuation curve — the constant‑speed analogue of the empirical Martin curve F(z) = F₁₀₀·(z/100)⁻ᵇ observed in sediment‑trap data (b ≈ 0.86 in the open ocean):

F(z) = P₀ · exp(−k·z / v)
k(T)  = k₀ · Q₁₀^((T − T_ref)/10)      [Q₁₀ ≈ 2, T_ref = 0 °C]
z*    = v / k                          (e‑folding depth)

Primary production P₀ — carbon fixed per day at the surface; sets how many marine‑snow particles spawn.
Sinking speed v — faster aggregates outrun bacterial decay and reach depth with more carbon intact (a stronger pump).
Water temperature — warmer water speeds up bacterial remineralization (Q₁₀ kinetics), shrinking the e‑folding depth z* = v/k and weakening carbon export — a real climate feedback as the upper ocean warms.
Sequestration efficiency — the share of surface production that survives to the seafloor at 1000 m, i.e. carbon effectively locked out of the atmosphere for centuries.

Real-world relevance: this biological pump moves roughly 5–12 gigatonnes of carbon from the surface to the deep ocean every year and is why the ocean interior holds far more carbon than the atmosphere — its strength is a key uncertainty in how much ocean warming will slow future CO₂ drawdown.

Fresh marine snow Remineralized / decayed

0 m (surface)100 m1000 m (seafloor)

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