Plants in a copper-contaminated mine site in Brazil were studied to see if they could help clean up the soil. The researchers looked at how much copper the plants absorbed and how it affected the soil. They found that some plants took up more copper than they released, which is good for restoring the site. Other plants released more copper than they absorbed, which could be harmful. This shows that certain plants can help reduce copper levels in contaminated soil and aid in the restoration of mine sites.