The elements that causes of water pollution are referred as the water pollutants. Water pollutants may be classified under the following categories: organic, inorganic, radioactive and so on.
The following organic pollutants causes of water pollution.
- Oxygen demanding waste: These types of wastes are different natural materials (as like plant leaves, grass), some artificial biodegradable substances (Food processing waste), and some others chemicals that may cause This environment helps to increase some Microorganisms.
Microorganisms mainly degrade these substances in presence of dissolve oxygen (DO) and the net results being the de-oxygenation process and quick depletion of dissolve oxygen.
- Synthetic organic compounds such as fuel, plastics, fibers, elastomers, paint, elastic, plasticizer, solvents, drug, personal hygiene and cosmetic
- Disease causing agents such as bacteria, viruses, protozoa and parasitic worms.
- Petroleum hydrocarbons, as like gasoline, diesel fuel, jet fuels, lubricants and fuel ignition byproducts.
- Different insecticides, herbicides, and organohalides (such as Trichloroethylene)
- Plant nutrients
- Oil, fats, grease etc.
The following inorganic pollutants causes of water pollution.
- Inorganic salts such as sulfate, nitrate, nitrite, chloride, phosphate etc.
- Mineral acids such as HCl, H2SO4, HNO3
- Toxic metals such as chromium, mercury, lead, arsenic etc.
- Heavy metals
- Chemical waste
Four human activities are responsible for radioactive pollution. They are:
- Mining and processing of ores for radioactive substances as U, Ra, Po etc.
- Use of radioactive materials in nuclear power plants.
- Use of radioactive materials in nuclear weapon plants.
- Use of radioactive materials in medicinal, industrial and research applications.
Thermal water pollution means the increase or decrease of the temperature of a natural water body. It is also cause of water pollution. It is the change of physical properties of water. Most cases it is occur by human activities, but some of the cases are occurs by naturally. Power plant, nuclear power plant and nuclear weapon plants, greenhouse, Global warming are the main thermal pollutants of water.
Some substances do not dissolve in water; they may float on the water or settle at the bottom of the water that is also causes of water pollution. The natural process of soil erosion gives rise to sediments in water, which are most extensive pollutants of surface water.