Water pollutants can have an effect on both the ecology of ecosystems and on humans. As a result of water pollution, humans may not be able to use a waterway for recreation and fishing. Drinking water can also be affected if a toxin enters the groundwater.
Eutrophication is an over-enrichment of chemical nutrients in a body of water. Usually these nutrients are the nitrogen and phosphorous found in fertilizers. Run-off from lawns or farms can wash fertilizers into rivers or coastal waters.
Plants are not the only things that grow more quickly with added fertilizers. Algae like the excess nutrients in fertilizers too. When there are high levels of nutrients in the water, algae populations will grow large very quickly. This leads to overgrowths of algae called algal blooms.
Ocean acidification occurs when excess carbon dioxide in the atmosphere causes the oceans to become acidic. Burning fossil fuels has led to an increase in carbon dioxide in the atmosphere. This carbon dioxide is then absorbed by the oceans, which lowers the pH of the water.
Unsafe water supplies have drastic effects on human health. Waterborne diseases are diseases due to microscopic pathogens in fresh water. These diseases can be caused by protozoa, viruses, bacteria, and intestinal parasites.
High levels of nutrients, called eutrophication, can cause conditions that deprive fish of oxygen.
Ocean acidification occurs when excess carbon dioxide in the atmosphere causes the oceans to become acidic, which harms corals and shellfish.
Debris can be dangerous to aquatic wildlife.