Pollution of water

At the end of this activity, students should be able to:
– explain the composition and properties of natural water: oxygen content, pH, hardness, content of ionic compounds
– explain the toxic properties of heavy metals, give examples of poisoning by heavy–metal ions contained in water
– discuss the positive and negative effects of using pesticides
– explain the eutrophication of water by excess phosphate
– describe the purification of tap water and the treatment of sewage.