Pollution

Chemical use can have adverse effects on the environment. For example, pesticides used on crops can kill not only the insects they're intended for, but also bees and other insects needed to pollinate plants.

Another example of pollution is acid precipitation: rain, snow or fog that has been polluted by acids in the atmosphere. This is caused by emissions of sulphur dioxide and nitrogen oxides. Many of these emissions are the result of human activity. Acid precipitation falls on and damages animals, plants, lakes, forests, even buildings and monuments.

Acid rain is the air pollutant that's caused the greatest changes in biodiversity in Canada. Authorities in Nova Scotia were concerned about the effects of acid rain. Kejimkujik National Park is one of Canada's main acid rain monitoring sites and this work led to the project monitoring forest biodiversity.

Many chemicals also have long lives. They can accumulate in food chains. For example, birds eat insects. Larger animals eat birds. The chemicals already contained in their tissues continue to accumulate in each animal in the food chain.

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