Using plants to clean up polluted soil?

 I need a PowerPoint presentation up to 10 slides  

Topic: Using plants to clean up polluted soil. 

What causes the contamination? How can plants clean a contaminated soil? What ingredient’s that are find in plants help eliminate the contamination? What other ways can you remove the contamination without using plants? Are there specific plants that are use for the contamination removal? Does the removing of the contamination by the plants kill the plants? What types of contaminations can be removed by plants?

It need to be simple but descriptive with a lot of images.