suggest ways in which each person can help to preserve the quality of the water for future generations Copyright © 2010 The Ontario Educational Communications Authority. All rights reserved. ilc.org
Chemistry SCH4C-B Lesson 14 3 What Is Water Pollution? Canada has more freshwater per capita than any other nation in the world. Yet it’s not uncommon to hear of remote Canadian communities that, due to contamination, find themselves with limited or no access to fresh drinking water, and require water to be delivered by truck. Much of Canada’s population is concentrated in certain areas, particularly on the coast and in the south. As the population density in an area increases, the challenge of maintaining the quality of local freshwater also increases. Even with strictly enforced water management laws and practices, some of this water inevitably becomes polluted as a result of human activity. The contaminants found in water can be divided into three classes: physical, chemical, biological. Physical Contaminants Physical contaminants are usually solid materials that are insoluble in water. Some physical contaminants come from natural sources, including floating twigs and suspended sand particles stirred up by the action of waves. Physical contaminants from human activity include toilet paper, garbage, debris from construction, grit from mining activities, and spilled oil. When water enters a municipal treatment plant, most solid physical contaminants can be separated with some form of filtration. This process is effective at removing larger physical contaminants because they are too large to pass through the filtering system. Removing liquid contaminants such as oil is more difficult. If the water is calm, specially designed boats can sometimes skim oil off the surface, much like skimming the oil off the surface of a pot of homemade soup. When skimming the oil is not possible, chemicals are added to the oil slick to make it disperse, sink, or break up. The use of dispersing chemicals is not ideal because it doesn’t remove the oil from environment. It does prevent oil slicks from ruining one particular shoreline ecosystem and instead spreads the oil so that it has less impact. Chemical Contaminants Chemical contaminants are any liquid or solid chemicals dissolved in water. Some dissolved solid chemical contaminants are natural. For example, minerals such as iron and aluminum dissolved in groundwater make it naturally acidic. Unusually high concentrations of calcium and magnesium ions in the water make the water hard. As mentioned in Lesson 14, hard water can be a nuisance when you are bathing or doing laundry. Copyright © 2010 The Ontario Educational Communications Authority. All rights reserved. ilc.org
Lesson 14 Chemistry SCH4C-B 4 Figure 14.1 shows a survey of naturally occurring dissolved solids in selected Canadian rivers: Figure 14.1 : The dissolved ion concentrations in Canadian rivers vary considerably, with the hardest water in the Thames and Red Rivers.
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