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Watersheds

Water pollution


On the surface, so to speak, dumping unwanted materials and substances into a body of water is easy and convenient. But while it may not be immediately or obviously visible, the damage inflicted by such a practice can be lasting and can pose serious hazards for people and the natural environment. No matter how small, that waste will reappear, sometimes in an altered form, downstream. Although bodies of water have the capacity to break down some substances, those capacities are easily overcome by the quantities of waste generated by our modern lifestyles. Industries and manufacturing plants are among the largest contributors of polluting substances, which can include asbestos, grit, phosphates and nitrates, mercury, lead, oils, caustic soda and other sodium compounds, sulphur and sulphuric acid and petrochemicals. Municipalities can also be significant polluters; Canadians use hundreds of chemicals in their daily routines – from soaps and household cleaners, to cars, lawns and bedding. In addition to creating foul-tasting water, polluting substances such as alkylated lead, DDT, PCBs and mercury can cause a myriad of health problems, including infertility, immune system damage, genetic deformities and tumours and other cancerous growths. And due to the steadily increasing numbers and varieties of chemical substances being used in Canada and around the world, the problem of polluted water grows every day.

There are three major delivery modes of water pollution:

  1. Point Source pollution is discharged into the streamflow from a specific site, often a disposal pipe. In some cases, concentrations of toxic substances, such as oil spills, can be effectively - although never completely - cleaned up from a body of water such as a river, lake or inlet. Excess waste substances left to pile up in bodies of water, such as has happened in Lake Winnipeg, can cause eutrophication.
  2. Diffuse Pollution usually happens when potentially-polluting substances leach into surface waters and groundwater as a result of rainfall, soil infiltration and surface runoff. Contaminants can also seep into the earth from waste disposal sites and agricultural lands. When groundwater becomes polluted by accidental dumps and spills of toxic substances, or by leaking gasoline storage tanks, leaking septic tanks or even municipal or industrial landfill sites, the effects can be spread far beyond the initial contamination site. In rural, particular agricultural areas of Canada, everyday substances such as used motor oil, road salt, fertilizer, pesticides and livestock wastes can contaminate aquifers in those regions, ultimately spreading to wetlands, streams and lakes. Groundwater contamination can also be difficult or downright impossible to clean up, rendering that water unusable for decades, even centuries.
  3. Long-range transboundary air pollution is the transportation of airborne pollutants, which will ultimately settle on land or water or even become imbedded amidst successive layers of glacial ice where it can be preserved for millennia. This transfer of pollutants occurs daily from one region to another around the globe, and while some chemicals are rendered harmless through exposure to sunlight, others can survive to circulate for months or years. Acid rain originating from coal-fired generators, non-ferrous metal smelters, petroleum refineries, iron and steel mills, pulp and paper mills, and from motor vehicle exhaust, releases sulphur dioxide and nitrogen oxides, which are converted to sulphuric and nitric acids in the atmosphere. These acids return to the earth through wetulphate and/or nitrate deposition, carried in rain, snow and fog. Acid has caused the most damage in environments that cannot tolerate acidification, and has in some areas severely depleted species populations, including fish, insects and aquatic plants.

 
 


Synopsis

This piece features narrated descriptions of the impact of water pollution throughout Canada and the surrounding oceans (on various scales). Each description is supported by full colour imagery.











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Quiz :

Where are municipal water uses most prevelant in Canada?

Within 300 km of the US-Canada border
In Ontario
On the Prairies