MY SIMULATOR
CH4 emission - mg/m²/d oxidised - T - °C FPS 0
Cut-away Surface Close-up
Drag to orbit, wheel / pinch to zoom. Cut face: colour = methane in the pore water (red near the bubble threshold), blue = water-logged peat, white dots = bubbles; lime puffs above ground = methane leaving (schematic, the real gas is invisible); pale lines = roots.
WebGL is not available here — the numbers, charts and numerical checks on the right still work.
Wetland Methane Lab: Peat Column, Water Table, Q10 Warming, Bubbles and Plant Vents
A cut-away block of peat under a reed bed. Bacteria make methane (CH4 ) in the waterlogged peat; it escapes by slow diffusion, by bubbles and through plant stems, while methane-eating bacteria oxidise part of it in the aerated layer above the water table. Change temperature, water level, plants and carbon supply and see the emission, where it leaves, and its climate impact.
Educational 1-D model with typical, illustrative parameters. One vertical peat column, uniform in the other directions; no seasonal frost, no sulfate or iron competition, no pH, no gas-phase water table dynamics. Magnitudes are realistic for a temperate fen (tens to hundreds of mg CH4 m-2 d-1 ) but not calibrated to a site.
Pause Jump 60 days Reset Quality: High
Scenario
Weather, water and plants
Live readout
Methane in the pore water Where methane is made and lost, by depth Emission through time Experiment 1: how deep is the water table?
Steady state at each water-table depth with the current temperature and plant settings: emission, and how much of the methane made is oxidised before it can leave.
Run sweep
Experiment 2: warming and the apparent Q10
Production rises by the factor Q10 per 10 °C, but emissions rise more slowly because oxidation also speeds up and bubbles cap the pore-water methane. The sweep reports both.
Run sweep
One-year budget
Runs one year from the current state with a seasonal temperature cycle (amplitude from the slider, or 8 °C if it is 0).
Compute annual budget
Independent numerical checks running...
Also run in Node: node src/check.js.
Controls Drag / one finger: orbit; wheel / pinch: zoom. Camera buttons: Cut-away, Surface, Close-up. Sliders act at once and the column relaxes over days to months; "Jump 60 days" fast-forwards. Scenarios start from a settled state. Colours on the cut face show methane concentration (red = near the bubble threshold). White bubbles rise through the peat; lime puffs above ground are the emission (the real gas is invisible). Reeds: more plants means more roots (and root exudates) but also more vents. The science
Transport and reaction. Methane in pore water obeys ∂C/∂t = ∂/∂z(D ∂C/∂z) + P(z,T) − Ox − Plant − Bub, C in mmol m-3 (= µM), z positive downward, C = 0 at the surface (the atmosphere takes everything arriving), no flux at the base. D is small in water (6×10-5 m2 /d, tortuous peat) and 300 times larger in the aerated layer.
Production. Only below the water table: P = P0 · (carbon supply) · e-z/λ · Q10 (T-10)/10 with fresh organic matter concentrated near the surface (λ = 0.25 m). Root exudates add up to +80% in the root zone. Q10 of methanogenesis is typically 2-4, sometimes higher (a typical-value range, not a measurement).
Oxidation. Methanotrophs follow Michaelis-Menten kinetics Ox = Vmax C/(Km + C) (Vmax = 150 µM/d, Km = 25 µM at 10 °C, Q10 = 1.9) in the aerated layer above the water table, and 25% of that around living roots (oxygen leaking from roots).
Plant vents. Reeds and sedges have hollow tissue (aerenchyma): methane enters roots at rate kpl · (plant density) · C and travels to the air, bypassing the oxic layer (15% oxidised in the root zone).
Bubbles. When the pore-water concentration passes a threshold (600 µM, a typical value for peat with other dissolved gases), the excess forms bubbles that rise at once: rate kb (C − Cthr ). Up to 15% is oxidised when the bubbles cross a thick oxic layer.
Numerics. Backward Euler with the sink coefficients lagged one step, tridiagonal solve, 60 cells over 1.2 m, dt = 0.1 d (checked against 120 cells and dt = 0.05 d). Each step the production, oxidation, emission and storage terms are computed from the same new state, so the methane budget closes to round-off.
Climate impact. Mass flux = mmol × 16.04 mg. CO2 -equivalent with the 100-year global warming potential of 27 (typical IPCC AR6 value for biogenic methane). This ignores the carbon dioxide the wetland takes up, so it is not a net climate balance.
Honest simplifications. Single column, constant parameters, no peat accumulation, no oxygen model (the oxic layer is simply the part above the water table), no ice, no methane in the air-filled pores above the water table. Real fluxes vary by orders of magnitude between sites and days.
3D peat block and reeds modelled in Blender, baked PBR textures; rendered with Three.js