Part one of term paper
L. Lehr Freedman defines a pollutant as "the occurrence of toxic substances or energy in a larger quality then the ecological communities or particular species can tolerate without suffering measurable detriment" (Freeman, 562). Although the effects of a pollutant on an organism vary depending on the dose and duration (how long administered) ...

Part two of term paper
... pollution by nutrients which is referred to as eutrophication. Each of these pollutants pose a different effect on the ecosystem at different doses. This varied effect is what is referred to as dose and duration. The amount of the pollutant administered over what period of time greatly affects the impact that the pollutant will have on an ecosystem and population. Pollutants can affect both a population and an ecosystem. A pollutant on a population level can be either non-target or target. Target ...