A pollutant enters the water column (the glowing base layer) at a controllable release rate and simultaneously breaks down by first-order kinetics — a fixed fraction decays per unit time regardless of concentration, the same law that governs radioactive decay and most environmental degradation of organic contaminants. Its concentration in water sets an equilibrium level that trophic levels above it sample from: plankton absorb it from the water, small fish eat many plankton, and the apex predator eats many small fish. Each step up concentrates the pollutant further because biological elimination is slower than uptake — this is biomagnification, and it's why top predators (and the humans who eat them) carry the highest body burden even though they never touch the original source directly.
dC_water/dt = release − k·C_water, k = ln(2)/half-life
C_level(n+1) = C_level(n) · magnification factor
- Half-life — time for half of the pollutant mass in water to break down; short half-life = fast self-cleaning environment, long half-life (like many legacy pesticides) = persistent contamination.
- Release rate — ongoing input to the water column, e.g. agricultural runoff or industrial discharge; set to zero to watch a pure decay curve after a release stops.
- Biomagnification factor — how much concentration multiplies at each trophic step; values around 3–10x are realistic for fat-soluble persistent organic pollutants like DDT or PCBs.
- Simulated speed — how many simulated days pass per real second, so multi-month decay curves are watchable in real time.
Real-world relevance: this is exactly why banned persistent pollutants (DDT, PCBs, mercury) still show up at dangerous levels in tuna, seals and birds of prey decades after their release stopped — the water cleared long before the food chain did.