Author: Edward Choong, Year 7S
Date: February 2022
Water pollution can be said to mean the contamination of bodies of water largely due to human activities. Examples of water bodies include rivers, lakes, groundwater, aquifers and oceans. Water pollution occurs when contaminants are added to the water bodies. In other words, water is said to be polluted when it is adulterated due to man made contaminants. Water that is polluted due to contaminants is not fit for human use like drinking.
Water pollution is a worldwide problem that requires serious evaluation of various policies in water resources. Water pollution can be classified into marine pollution, surface water pollution and also nutrient pollution. Water pollution sources can either be non point sources or point sources. Point source as the name indicates has just one cause of pollution that is identifiable such as wastewater treatment facility, storm drain, or stream. Non point pollution sources are quite diffuse and an example is the runoff from agriculture. Pollution is a result of a cumulative effect with respect to time.
Surface water pollution has pollution of lakes, rivers and oceans as examples and is basically of water bodies that are open. Marine pollution is a sub category of surface water pollution. It is the introduction of contaminants or their entry into large water bodies. Rivers are means by which seas are polluted due to rivers emptying into seas. A typical example is the discharge of industrial waste and sewage into the ocean and this is very common in nations that are just developing.
Groundwater pollution is also known as groundwater contamination and there are slight relationships between surface water and groundwater. Groundwater is quite exposed to contamination from some sources that are not contaminants for surface water. It is important to note that the difference between point and non-point sources is quite irrelevant.
Surface water and groundwater, even though they are separate resources are interrelated. It is surface water that percolates into the soil and it becomes groundwater. Also, groundwater can become surface water by feeding water bodies. Sources of water pollution are classified into two categories based on the origin.
Point source water pollution is contaminants that enter a water body through an identifiable and single source like a ditch or a pipe. A point source includes industrial storm water, storm sewer systems of municipals, and discharge from a sewage treatment facility, a factory or even a storm drain in the city.
Non-point source pollution is contamination that is not originated from just one single source. This form of pollution occurs from the agglomeration of little quantity of contaminants collected from a huge area. A typical example is the process of leaching of compounds of nitrogen from agricultural fields that are fertilized.
The particular type of contaminants that lead to pollution of water includes quite a wide range of pathogens, chemical and physical changes including discoloration and temperature elevation. Even though a number of the substances and chemicals that go under regulation occur naturally (calcium, manganese, iron, sodium, etc.) it is the concentration that determines what level is contamination and what level is a natural water component. It should be noted that negative impacts can arise from a high concentration of substances that occur naturally.
Substances that deplete oxygen can be materials that occur naturally like plant matter ( grass and leaves) and also chemicals that are man-made. Other man made and natural substances may lead to turbidity which disrupts growth of plants by blocking light and blocks the gills of a few fish species. The alteration of the physical chemistry of water includes electrical conductivity, acidity (pH change), eutrophication and temperature. Eutrophication is basically the concentration increase of chemical nutrients of an ecosystem to a level that causes an increase in the primary productivity in the ecosystem.
Pathogens are microorganisms that cause diseases. Waterborne diseases can be produced by pathogens in either animal or human hosts. A popular indicator of water pollution is Coliform bacteria; it does not cause any disease but is a good bacterial indicator. Poor onsite systems of sanitation (pit latrines, septic tanks) or insufficiently treated sewage can result in high pathogens levels. Older cities have ageing infrastructures that may include sewage collection systems (valves, pumps, pipes) that are leaky and can lead to overflow of sanitary sewers. There are also combined sewers that sometimes discharge sewage that is untreated during storms. Poor management of livestock operations is also a major cause of pathogen discharges.
Inorganic and organic matter can also be contaminants. A lot of chemical substances are very toxic. Examples of water pollutants that are organic include: waste from food processing, detergents, herbicides and insecticides, by-products of disinfection, petroleum hydrocarbons, drug pollution, etc. examples of water pollutants that are inorganic on the other hand include: ammonia, fertilizers, acidity, chemical waste, heavy metals and silt.
Sewage is basically treated by sewage treatment plants that are centralized.
If a household or business is not covered by a municipal waste treatment facility, there may be need for separate septic tanks that gives first treatment to the wastewater and infiltrates the wastewater into the ground. If this is not carefully and properly done, it can cause groundwater pollution.
Most industrial facilities churn out a lot of wastewater that is quite like domestic wastewater and can also be treated by wastewater treatment plants. Some industries generate wastewater with very high concentration of nutrients like ammonia, toxic pollutants ( organic compounds that are volatile, heavy metals), organic matter ( grease and oil), need extra and well suited treatment systems.
Water is a very important resource to the survival of human race and covers more than 70% of the surface of the earth so it is crucial that we look into the study of water. Water pollution harms this important resource by making it unfit for human use and invariably causes harm to human health and the environment if proper measures are not taken to battle water pollution.
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