The Dynamic Behavior (Effects) of Impulsive Toxicant Input on a   Single-Species Population in a Small Polluted Environment
  In this paper, we study a single-species population model with pulse toxicant input to a small polluted environment. The intrinsic rate of population is affected by environment and toxin in organisms. The toxin in organisms is influenced by toxin in environment and the food chain. A new mathematical model is derived. By the Pulse Compare Theorem, we find the surviving threshold of the population and obtain the sufficient conditions of persistence and extinction of the population. 
Li Dongmei, Yue Wu, Xu Yajing
q-bio.PE math.DS