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Earth Problems: Chemicals & Pollutants

Chemical pollutants created by man's activities harm the Earth by endangering living organisms. They may be from a single-point source such as a factory, sewer line, oil spill or farm. A non-point source pollutant discharge originates from across a large area such as storm water runoff. Some examples of chemical pollutants include oil, fertilizer, pesticides, and heavy metals such as mercury.

Oil
- Oil pollutes the Earth in many ways.
  
  Oil pollution affects the environment in many ways, including air pollution, climate changes and oil spills. Marine oil spills create a number of problems for wildlife both immediate and long term. Initially, the oil smothers organisms too slow to get out of harm's way. It coats their bodies. They ingest it, and breath the fumes. The severity of the oil spill depends on a number of factors such as location, time of year, number of species living in the area and the type of oil.
Pesticides
- Pesticides can have unintended consequences such as killing fish.
  
  Pesticides are used in homes, yards, businesses and farms to control insect populations. They are concentrated in bodies of water through storm water runoff. They can also end up in the water system by wind drift that occurs during spraying. Pesticides not only kill the intended victims, but also cause collateral damage. In strong enough concentrations they can kill birds, fish and frogs.
Fertilizers
- Rapid algae growth uses all the oxygen from the water and suffocates fish.
  
  Fertilizers are used by home owners and farmers to make their yards greener, flowers and gardens grow better and to increase crop yields. Fertilizers contain phosphorous and nitrogen. These chemicals wash into bodies of water during heavy rains, and cause rapid algae growth. The algae grows so fast, it uses all the oxygen in the water, resulting in dead fish.
Amphibians Under Assault
- Amphibians such as frogs are on the decline all over the world.
  
  About a third of the amphibian species around the world exhibit decreasing numbers. In the past 20 years, 168 species have become extinct. A number of causes are involved, but pollution appears to be a contributing factor. Among the pollution concerns are pesticides, heavy metals, acidification and nitrogen. Acidification lowers the pH of water. At extremely low pH, amphibian embryos do not develop. Even if the embryos develop, they may not be able to hatch from the egg capsule. Heavy metals such as aluminum, zinc, cadmium and mercury cause an increase in deformities and metabolic rate. They also decrease the rate of larval survival. Other pollutants cause the males to develop female characteristics, resulting in decreased population growth.

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