Pollution Of The Environment, Ecological Systems Continued Survival And Extinction

This paper concentrates on the study of the long-time behavior of a single-species population, located in a polluted environment.. An organism in the polluted environment takes with it a quantity of internal toxicant,and the toxicant in the organism affects the growth of the population. And an organism egests some toxicant into the environment. By the method of Bruno Buonomo et al.(l), we modify the most basic model in Ecotoxicology established by Hallam et al. (2, 3, 4), assuming that a born organism takes with it a quantity of internal toxicant, and the amount of toxicant stored in the living organisms which die is drifted into the environment. Sufficient criteria on uniform persistence, weak persistence in the mean and extinction of the population are obtained. The threshold between persistence and extinction can be established in some cases. We generalize the results into the asymptotically autonomous system, and obtain the same results as the case of autonomous.Considering the effect of resources on the population, we also modify the Gallopin's system in 5 and get some sufficient conditions on weak persistence and extinction. The threshold between weak persistence and extinction can be established in some cases. We also improve the results into asymptotically autonomous Gallopin's system.The tree of this paper is the following: Chapter one focuses on the background of the problem being investigated. Chapter two obtains some main results: In section 1, we gives some basic conception and knowledge. In section 2, one single population model is established, easily verifiable sufficient criteria for the uniform persistence, weak persistece in the mean and extinction of the population in the polluted environment are obtained. What's more, we generalize the results into the asymptotically autonomous system. In section 3, considering the effect of toxicant and resources on the population, we modify the Gallopin's system in a polluted environment, and analysepersistence and extinction of the population in this system. We also generalize the results into the case of asymptotically autonomous Gallopin's system. In secdton 4, we discuss the further work.