The study looked at how different underwater plants collect copper, lead, cadmium, and zinc from water. They tested five types of plants in a river and found that the levels of these metals varied between plants and over time. Zinc levels showed the most variation. Each plant had different abilities to collect these metals, with Potamogeton maackianus being best at collecting lead. This shows that underwater plants can help monitor and clean up polluted water, but the right plant must be chosen based on the specific metal being targeted.