Along with climate change and resources, other environmental issues are currently a concern in Canada’s North.
The ozone layer is a layer of gases that is about 30 km above the Earth that filters the sun's ultraviolet (UV) rays. The layer has been thinning in some places in the world because of chemicals created by humans.
An international agreement that banned the use of those chemicals has caused the ozone layer to stop thinning and even become thick again in some places. In the winter, the ozone layer over Canada’s North is sometimes thinner than it should be. UV rays affect the growth of algae and plants and can lead to skin cancer and eye cataracts in animals and humans.
Contaminants are substances that are found in places where they should not be. Depending on the type of contaminant and the amount that is present, a contaminant can be harmful for the environment, animals and human health.
The types of contaminants that are found in Canada’s North include:
- Persistent Organic Pollutants (POPs), a group of mostly human-made chemicals that can stay in the environment for many years without changing. They can be transported over long distances in the atmosphere.
- Heavy metals such as mercury, cadmium, and lead.
- Radio nuclides such as cesium, strontium, and polonium.
The increase in concentration of a substance in living organisms as they take in contaminated air, water, or food.
As bigger animals eat smaller animals, the level of contamination in the food is added to the level of contamination already in their body.
Most of these contaminants arrive in the North by wind and ocean currents from agricultural and industrial sources from all over the world. Contaminants are found in the water, air and soil and negatively affect the health of humans and animals.
Contaminants end up in the North from all over the world because the cold temperatures cause contaminants that are in the atmosphere to mix with water vapour and fall to the ground as snow and rain. Contaminants move up the food chain as bigger animals eat smaller animals. Contamination is greater in bigger animals because of bioaccumulation (see box). Contamination is stored in the fat of animals. Northern animals have a lot of fat because they need it to keep them warm. People in the North are also affected by contaminants in their food and water.
Fishing is an important source of food and employment for northern communities. New techniques in fishing have increased the number of fish caught in recent decades. Over-fishing leads to low numbers of some species of fish. When fish populations are low, seals and seabirds that eat the fish have a hard time finding food. Low numbers of fish also negatively affect the food supply and income of northern communities.