Water is the major mineral on the Earth that can not be replaced by any other substance. It is a big part of any organisms: vegetable, animal, human. Water is a habitat for many organisms, determines the climate and weather change, contributes to the cleansing of the atmosphere from harmful substances, it dissolves, leaches rocks and minerals and transports them from one place to another, etc. For people water has important industrial significance: it is the transport path, the source of energy and raw materials for production and cooling engines, cleaner, etc.
The problem of preserving water quality is currently very topical. Science knows more than 2.5 thousand pollutants of natural waters (Franca, 2011). This adversely affects the health of populations and leads to death of fish, waterfowl and other animals, as well as the loss of vegetation water. Not only toxic chemical and oil pollution, the excess of organic and mineral substances entering flush fertilizers from the fields, are dangerous to aquatic ecosystems. A very important aspect of water pollution is thermal pollution also. Thus, there are a lot of causes of water pollution that lead to negative affects.
Wastewater. The most famous source of water pollution is domestic (or municipal) wastewater. Urban water consumption is usually estimated based on the average daily water consumption per person (in the U.S. it is approximately 750 liters), including drinking water, cooking and personal hygiene products, for household plumbing devices, as well as for watering lawns, fighting fires, cleaning streets and other urban needs. Almost all of the used water goes down the drain. Since the daily sewage gets a huge amount of feces, the main task of urban services while the processing domestic waste water in the reservoirs is to remove the pathogens. The repeated use of inadequately cleaned sewage effluent, the contained in them bacteria and viruses can cause intestinal diseases (typhoid, cholera and dysentery) as well as hepatitis and polio.
The wastewater contains the soaps in dissolved form, synthetic detergents, disinfectants, bleaches and other household substances. The houses supply water with paper trash, including toilet paper and baby diapers, waste vegetable and animal foods. The streets supply water with rainwater and melted snow water, often with sand or salt, used to accelerate the melting of snow and ice on the roadway of streets and sidewalks.
Industry. In industrialized countries, the main consumer of water and the largest source of waste is the industry. Industrial effluents into the rivers are three times more than municipal. Water performs various functions, it serves as a raw material, a heater and cooling in industrial processes, it also transports, sorts and washes a variety of materials. Water also removes waste at all stages of production – from raw material extraction, preparation of semi-finished products prior to release of the final product and its packaging. Since it is cheaper to throw away wastes of different production cycles than recycle and dispose them, so the discharged wastewater contains enormous variety of organic and inorganic substances. More than half of wastewater that comes to the water is given by four major industries: pulp and paper, petroleum refining, organic synthesis industry and ferrous metallurgy (the domain and steel production). Due to the increasing amount of industrial waste, the ecological balance of many lakes and rivers changes, although the most part of effluent is not toxic and lethal to humans (Harrison, 2001).
Thermal pollution. The most massive one-time use of water is the electricity production, in which it is used mainly for cooling and condensing steam turbines produced by thermal power plants. The water is heated by an average of 7 ° C and then dumped directly into rivers and lakes, as the main source of additional heat, which is called “thermal pollution” (Donald, 2002). The change in water temperature in rivers and lakes often cause extinction of fish.
Agriculture. The second major consumer of water is agriculture, which uses it for irrigation. Flowing from water is full of salts and soil particles and chemical residues that contribute to higher yields. They include insecticides; fungicides, which are sprayed over the orchards and crops; herbicides, famous tool for weed control, and other pesticides, organic and inorganic fertilizers containing nitrogen, phosphorus, potassium and other chemical elements.
In addition to chemical compounds, a great amount of feces and other organic residues from farms where people grow meat and dairy cattle, pigs or poultry, fall into rivers. Also, a lot of organic waste goes to the processing of agricultural products (for cutting meat carcasses, processing of leather, manufacture of food products and canned goods, etc.). This issue makes people worry about their health and lives. Although the natural environment is already so severely infected that it became impossible to eliminate pollution completely (Ostopowich, 2010).
Pesticides and fertilizers used in agriculture are washed into rivers, lakes, seas with rain water and become food for bacteria. In this case, the bacteria consume the oxygen dissolved in water, resulting the lack of it for fish and aquatic animals, which begin to suffocate. In some places, raw sewage is washed into rivers and seas and cause illness and sometimes death of animals and humans. Water pollution carries the same threat to humans, as pollution of soil.
Intensive development of industry, transport, overpopulation of some regions of the planet has led to considerable contamination of the hydrosphere. According to the World Health Organization (WHO), about 80% of all infections worldwide are related to poor drinking water quality and violations of sanitary standards of water supply (Franca, 2011). The pollution of water surface with slick of oil, grease, lubricants, prevents gas exchange between water and atmosphere, which reduces the oxygen saturation and souses negative impact on the phytoplankton and is the cause of mass mortality of fish and birds.
Pollution, entering water reservoirs, depending on their size and composition may have different effect on them:
- There appears the change of water physical properties (transparency and color, smells and tastes);
- There appear the floating substance on the surface of the reservoir and sediment (lees) is formed;
- There appears the change of the water chemical composition (the reaction, the content of organic and inorganic substances, while harmful substances appear, etc.);
- There is a decrease of dissolved oxygen in water due to its consumption by oxidation of upcoming organic compounds;
- There is a change in number and types of bacteria (pathogens appear), introduced into the reservoir together with sewage. Polluted waters become unsuitable for drinking and sometimes for technical use; fish died in it.
In the first decade of the 21st century the anthropogenic pollution of natural waters has become global and has significantly reduced available operating resources of fresh water on Earth (Ferguson, 2011). Thus, the 21st century is characterized by intensive development of industrial and agricultural production, and as a result – a strong pollution of the hydrosphere (rivers, lakes, seas and oceans, ect.). The main causes of water pollution are emissions from various waste streams such as domestic and industrial origin. These include: chemical, physical or biological agents, which hit the water causing a significant decrease of its quality. Water pollution has negative effects: the problem of fresh water, and organic pollution of water bodies, destruction of plants and animals, uncontrolled algal growth, destruction of aquatic ecosystems with stagnant water. The main task for humanity nowadays is to find the way out of this situation and save our planet.
Donald, Rhonda Lucas. Water Pollution. 2002. p. 32. Print.
Franca, Elvis., Camilli, Leandro., Fernandes, Elisabete A. De Nadai. Atmospheric Chemical Element Pollution in an Urban Water-associated Environment. International Journal of Environment and Health, April 2011, Volume 5, Numbers 1-2, pp. 148-162.
Ferguson, Briony., Mudd, Gavin. Water Quality, Water Management and the Ranger Uranium Project: Guidelines, Trends and Issues. Water, Air, and Soil Pollution, May 2011, Volume 217, Numbers 1-4, pp. 347-363.
Harrison, Roy M. Pollution: causes, effects and control. 2001. p. 326. Print.
Ostopowich, Melanie. Water Pollution. 2010. p. 15. Print.