Bioaccumulation models with time lags: Dynamics and stability criteria

Simple bioaccumulation models predict a monotonic increase in concentration with time until an equilibrium concentration is reached. However, unconsidered dynamics including deterministic oscillations occur if realistic time lags are incorporated. Stability criteria are provided for difference and differential forms of the simplest model. These criteria provide the means of identifying systems expected to exhibit monotonically damped, exponentially damped, or diverging oscillations in toxicant concentration. These unconsidered dynamics can render invalid the assumption of a single equilibrium concentration used in estimation of bioconcentration factors.