Группа 1714. Урок 22

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Часть 2. Water Pollution

Chemical and other contaminants

Contaminants may include organic and inorganic substances. Organic water pollutants include:

- Disinfection by-products found in chemically disinfected drinking water, such as chloroform;

- Food processing waste, which can include oxygen-demanding substances;

- Insecticides and herbicides;

- Petroleum hydrocarbons, including fuels (gasoline, diesel fuel), motor oil, and fuel combustion byproducts;

- Tree and bush debris;

- Volatile organic compounds (VOCs), such as industrial solvents;

- Various chemical compounds found in personal hygiene and cosmetic products;

Inorganic water pollutants include:

- Acids from industrial discharges (especially sulfur dioxide from power plants);

- Ammonia from food processing waste;

- Chemical waste as industrial by-products;

- Fertilizers containing nutrients - nitrates and phosphates;

- Heavy metals from motor vehicles;

- Acid mine drainage; Trash (e.g. paper, plastic, or food waste);

Thermal pollution

Thermal pollution is the rise or fall in the temperature of a natural body of water caused by human influence. A common cause of thermal pollution is the use of water as a coolant by power plants and industrial manufacturers. Elevated water temperatures decreases oxygen levels (which can kill fish) and affects ecosystem composition, such as invasion by new thermophilic species.

Measurement of water pollution

Water pollution may be analyzed through several broad categories of methods: physical, chemical and biological. Most involve collection of samples, followed by specialized analytical tests. Some methods may be conducted in situ, without sampling, such as temperature measurement. Common physical tests of water include temperature, solids concentration like total suspended solids (TSS) and turbidity.

Water samples may be examined using the principles of analytical chemistry. Frequently used methods include pH, biochemical oxygen demand (BOD), chemical oxygen demand (COD), nutrients (nitrate and phosphorus compounds), metals (including copper, zinc, cadmium, lead and mercury), oil and grease, total petroleum hydrocarbons (TPH), and pesticides.

Biological testing involves the use of plant, animal, and/or microbial indicators to monitor the health of an aquatic ecosystem.