water Pollution, Sources and Effects

 

Water pollution

The contamination of water due to various contaminants which change the properties of water and make it unfit or toxic for drinking or other purposes is referred to as water pollution. Water gets contaminated easily because it is considered as universal solvent.

Water pollutants

According to Tripathi et al., (1990) about 1500 substances have been listed as pollutants in freshwater ecosystem they come from different sources. Frank R. Spellman in his book the Science of Environmental Pollution mentioned eight chief water pollutants:

Biological Oxygen Demand (BOD); Nutrients; Suspended Solids; pH, fats, oil and grease (FOG); Pathogenic microorganisms; Toxic pollutants; and nontoxic pollutants.

Sources of water

surface water

The water which is present on the surface of earth in springs, ponds, rivers, lakes, oceans is known as surface water. Contamination of such water bodies is known as surface water pollution. Surface water is further classified as fresh water and marine water.

Ground water

Water which is present beneath the earth’s surface in aquifers is called ground water the contamination of such water is referred to as ground water pollution

Types of water pollution

It is categorized as natural as well as anthropogenic

Natural

Nutrients and thermal pollution

Anthropogenic                      

Chemicals, Heavy metal, Agricultural runoff, Municipal, Domestic, Thermal, radioactive

Sources of water pollution

There are two sources of water pollution point source and non-point source

Point source

According to Clean Water Act (CWA) point sources are considered as localized sources or we can say that they have discrete and confined location which originate from a single point. examples a factory, a sewer pipe etc.

Non-point source

Non-point sources are considered as non localizes that is a number of sources over a large area contribute to the water pollution. They are difficult to localize. Example runoff carrying topsoil, agricultural chemicals, animal feces runoff from urban, forestry and construction sites. According to Frank R. Spellman (2010) non-point source of water pollution comprise the largest source contributing an estimated 70% of the contamination.

The various point and non-point sources of water pollution are discussed below:

Sewage and wastewater:

The waste that enters the sewerage system from kitchens, bathrooms, toilets or from industrial and business units which is composed of 99% water and remaining 1% of biodegradable pollutants is termed as sewage whereas wastewater is any water whose quality is effected by different anthropogenic activities. The waste generated from the sewers and household wastes contain a number of toxic elements and harmful microorganisms when these wastes are directed towards the water bodies they have enough tendency to pollute them.

Industrial wastes:

Industries produce toxic wastes in bulk they illegally divert this waste into water bodies without proper treatment. The various toxic contaminants produced by the industries include heavy metals, radioactive substances, organic toxins, sulfur, oil, heated water etc.

Agricultural wastes:

In this modern era a number of chemicals are used in agricultural sector these include nitrogen, phosphorous, potassium or NPK fertilizers, pesticide, herbicides and fungicides which are composed of a number of toxic chemicals. These remain persistent in the environment foe quite long rime when precipitation occur it take away these persistent chemicals along as runoff during this course of move they go on contaminating the water bodies. these toxins may also percolate deep into the soil and thus contaminate the ground water.

Mining activities

Mining is carried out for the extraction of various mineral elements meanwhile a number of toxic heavy metals such as mercury selenium lead etc become mobile and find their path into water bodies whereas mining activates may also contaminate the ground water to a great extent.

Leakage from sanitary landfill sites

These are the sites where municipal waste is buried under proper protocols leakage from such sites percolate into ground water or may find its way to surface water bodies and thus contaminate them.

Acid precipitation

The pollutants present in the atmosphere due to air pollution mix-up with the water vapors and fall down on land and water bodies as acid precipitation in the form of rain, snow hail etc.

Oil spillage:

Leakage of oil containers while shipping through sea routs contaminate the sea water to a great extent.

Animal wastes;

Throwing of animal wastes like cow dung and the remains of farm houses into or near the water bodies pollute the water resources.

Eroded sediments

Floods carry sediment load to water bodies and pollute them

 

Radioactive isotopes

A number of radioactive isotopes are used in industries in addition some naturally occurring radioactive isotopes may also enter into to the atmosphere and we know that these remain in the environment for thousands of years meanwhile they may contaminate the water bodies.

Heat

Heat may also become a source of water pollution this may result by different activities like runoff from the pavements which are heated by the sun results in the increase of average temperature of runoff water when this water enters a water body it leads to decrease in the dissolved oxygen of that water body

Volcanoes

It is one of the natural source of water pollution this natural phenomenon mobilizes various heavy metals and which finally find their way to different water bodies

Impacts of water pollution:

Water pollution is one leading environmental pollution throughout the globe. According to F.W. Owa (2014) about 14000 deaths occur per day due to the contamination of drinking water, moreover 1000 Indian children die of diarrhea every day.

Some prominent effects of water pollution are

Effects of water pollution on human health

The health of humans is effected to a great extent with contaminated water. Almost every water pollutant is detrimental for the human health but the effects of heavy metals such as mercury, cadmium, lead, arsenic fluoride is a matter of great concern.

o   Mercury show bioaccumulation in aquatic organisms such as fishes and on consumption of these aquatic animals it enters into the human body in the form of methyl mercury. And finally leads to a disease known as “Minamata disease” which is characterizes by the chromosomal aberration and neurological damage.

o   According to Friberg et al., (1974) cadmium reaches human body through food crops which are irrigated by industrial effluents. cadmium causes many renal diseases like “Itai-Itai” disease, nephrosis and nephritis.

o   Presence of lead in contaminated water cause lung and bladder cancer.

o   Arsenic cause cancer of respiratory tract and skin lesion

o   Fluoride in water is essential for dental health if it is present in limited quantities (below 0.5 mg/L) but the concentration increase beyond this limit it leads to a disease known as fluorosis.

According to Adetunde and Glover (2010) microorganisms such as Escheria coli, Salmonella, Shigella and vibrio cholera present in contaminated water are considered as potential causes of typhoid, dysentery, diarrhea, cholera and gastro intestinal tract problems. About 1.1 million children die every year due to diarrheal disease (Steiner and Gurrant 2006) similarly Shuval (2003) in his study mentioned that pathogenic microorganisms cause an economic loss of 12 billion dollars annually throughout the globe. WHO estimates that bathing in polluted seas causes 250 million cases of gastroenteritis and upper respiratory disorders every year,

Effect on aquatic flora and fauna

o   Water pollution cause death of aquatic flora and fauna

o   Acidification of water bodies decline the diversity of macrophytes, if someone survive they show retarted growth.

o   Diatoms and green algae disappear below pH 5.8 (Asha Gupta 2016)

o   Organic matter from outside and within the water bodies results in nutrient enrichment which favour the growth of Blue Green Algae (BGA) resulting in Algal bloom.

o   Nutrient enrichment of water bodies also enhances the growth of macrophytes to an un imaginable extent

o   The above two factors along with oil spills and suspended solids affect the penetration of sunlight and thus result in the decline of submerged flora and fauna.

o   The presence of phosphates in the water cause s retarted growth, elongation of root, damage cell membrane and chlorophyll pigments of aquatic flora.

o   Sediment load also reduce the penetration of light to lower reaches to a great extent.

Effect on the physical and chemical state of water bodies

Water pollution change the physical and chemical state of any water body beyond expectation because of the property of universal solvent pollutants masks its natural properties quite easily. Some prominent changes are:

Change in colour taste and odor. As we know that fresh water is devoid of any colour taste and odor but pollutants change these properties.

Eutrophication

The phenomenon of enrichment of water bodies with excessive nutrients is known as eutrophication, it results in the enormous growth of aquatic plants and decline in the dissolved oxygen which finally effect the life of aquatic fauna.

Increase in number of dead zones

The areas of anaerobic conditions at the sea bottoms are known as dead zones they are formed due to increased amounts of nutrient load. According to GPA, UNEP (2006) Their number has doubled since 1990 due to excessive nutrient load.

Decrease in the aesthetic value

Water pollution decrease the aesthetic value of any water body which ultimately pose threat to tourism economy.