Macroplastic on the seabed slowly fragments into microplastic that can never be
recovered. Removing the big pieces takes them out of the system, but every gram of microplastic
already made stays. Drag the sliders to compare cleanup timings.
Cumulative microplastic in sediment over 50 years
No cleanup (baseline)With cleanup from year τCleanup starts
Solid micro curve = irreversible sediment load P(t). The gap between the two
curves is the microplastic you prevented. Model: dM/dt = Q − (k+R)·M, dP/dt = k·M.
Microplastic prevented by year 50
99.3%
23 kg vs 3164 kg without action
drag Q → this % won't move
On seabed (macro)In sediment (micro)
MP
live state at year 50
Table 2 · Does the conclusion survive an uncertain k?
The exact fragmentation rate is uncertain, so the model is re-run across the plausible range
for the cleanup year you picked (τ = 1).
If early action still gives the largest reduction in every row, the result is robust.
Fragmentation rate k
Half-life
P(50) no cleanup
Prevented at τ
Note: prevention rises as
fragmentation gets slower (96.3% at k=0.10 → 98.2% at k=0.02). When plastic lingers as big
recoverable pieces, a bin that removes big pieces works even better, so the "slow fragmentation =
no urgency" worry is the opposite of what the model shows. Early cleanup is the strongest case in
both the fast and the slow world.
What half-life means · watch it halve
Half-life = ln(2)/k = 14 years. The bar shows
macroplastic decaying as M = M₀·e−kt. Each grey marker is one half-life apart,
so the bar drops to ½, then ¼, then ⅛, the gap between markers always the same length of time.
That constant halving is the whole reason for the name.
Set the time to one half-life and the bar reads ~50%; two half-lives → ~25%.
The starting amount never changes how long a halving takes, which is what
"−kt in the exponent" produces.
Year by year · cleanup at year 1
Before year τ no bin is deployed and plastic piles up. At year τ the bin switches on and clears the
backlog. The macroplastic drops sharply, while the microplastic that has already formed stays in
sediment and keeps creeping up only slowly.
0 kg
macroplastic on seabed
0 kg
microplastic in sediment
bin: not deployed
Bars use a square-root scale so the settled macroplastic level is still visible
against the year-τ peak. The microplastic bar is the cumulative total, which only ever rises; once
the bin holds the pile low, it climbs only by the small permanent trickle.