Water Quality Pollutant Sources and Impacts: Pure water, H2O, is hard to find outside of the laboratory. As water moves over and through the earth, it may pick up natural chemicals which become dissolved in the water or pollutants placed on the land. These pollutants can have harmful effects on both aquatic and terrestrial ecosystems, if present in high enough concentrations. The types of pollutants, their sources, pathways, impacts, and strategies to control their impact will be described. Supports water unit lessons 4 and 9.