Edexcel IGCSE Biology: Double Science 复习笔记 4.4.1 The Effects of Pollution

Edexcel IGCSE Biology: Double Science 复习笔记 4.4.1 The Effects of Pollution

The Effects of Pollution


  • Human population growth globally has been increasing exponentially for the last 150 years





Human population growth is growing exponentially




  • There are many reasons for this exponential growth, including:
    • Improved technology leading to an abundance of food = rapid increase in birth rate
    • Improved medicine, hygiene and health care = decrease in death rate


  • Rapid growth in the human population and an increase in the standard of living mean our negative effect on the environment is also increasing
  • As increasingly more resources are used to sustain the growing human population, more waste is produced and more pollution is created
  • Unless waste and chemical materials are properly handled, pollution will continue to be created



Water pollution 


Sources of Water Pollution and their Effects Table







Biomagnification and bioaccumulation of a pesticide in an aquatic ecosystem






Sequence of events causing eutrophication in lakes and rivers




Land pollution 


Sources of Land Pollution and their Effects Table





Air pollution 


Sources of Air Pollution and their Effects Table







How air pollution leads to acid rain



Exam Tip

Water pollution from sewage and water pollution from fertiliser runoff have the same end result (increase in decomposing bacteria leading to a decrease in dissolved oxygen and death of aquatic organisms) but they do not arrive at this point in the same way.You need to learn both and be aware of the differences between them. A common misconception is that sewage pollution also causes growth of water plants and algal blooms – this is very rarely the case, only runoff of fertiliser does this.