What is Water Pollution?

 Water pollution is defined as "the addition or presence of undesirable substances

to/in water, such as organic, inorganic, biological, radiological, or heat, which
degrades the quality of water to the point where it is unfit for use."
 Soil erosion, leaching of minerals from rocks (due to natural solubility and
solubility triggered by acid rain), and organic matter decay are all natural sources of
water pollution.
 Point source pollution occurs when pollutants are discharged from a specific
location, such as a drain pipe carrying industrial effluents discharged directly into a
water body.
 Non-point sources, on the other hand, include pollutant discharge from diffuse
sources or from a larger area, such as runoff from agricultural fields, grazing lands,
construction sites, abandoned mines and pits, and so on.
 Water pollution is not limited to surface water; it has also spread to groundwater, the
sea, and the ocean.
Causes of Water Pollution
1. Sewage Water
 Sewage water includes discharges from homes and businesses.
 Human and animal excreta, food residues, cleaning agents, detergents, and other
contaminants are found in sewage.
 Many pathogenic microorganisms can be found in household and hospital sewage.
2. Industrial Wastes
 Discharge of wastewater from industries such as petroleum, paper manufacturing,
metal extraction and processing, chemical manufacturing, and others that frequently
contain toxic substances.
 Particularly heavy metals (defined as elements with densities greater than 5 g/cm3
such as mercury, cadmium, copper, lead, and arsenic) and a variety of organic
compounds.
3. Agricultural Factors
 Dissolved salts such as nitrates, phosphates, ammonia, and other nutrients, as well
as toxic metal ions and organic compounds, are found in agricultural runoff.
 Fertilisers are rich in plant nutrients like nitrogen, phosphorus, and potassium.
 Excess fertilisers may leach into groundwater or be mixed with surface water.
 Pesticides include insecticides, fungicides, herbicides, and other chemicals.
 They contain a variety of chemicals, including chlorinated hydrocarbons (CHCs,
such as DDT and Endosulfan), organophosphates, metallic salts, carbonates, and
others.
 Many pesticides are non-biodegradable, and their residues last for a long time.
 Runoff carries waste from poultry farms, piggeries, and slaughterhouses into the
water.
4. Dissolved Oxygen (DO)
 The presence of organic and inorganic wastes in water reduces its dissolved oxygen
content.
 Water with a DO content less than 8.0 mg/L may be considered contaminated.
 Water with a DO content less than 4.0 mg/L is considered highly polluted.
 The DO content of water is critical for aquatic organism survival.
 Surface turbulence, photosynthetic activity, O2 consumption by organisms, and
organic matter decomposition are all factors that influence the amount of DO in water.
 The higher the amount of waste, the faster it decomposes and consumes O2, lowering
the DO content of water.
5. Biological Oxygen Demand (BOD)
 Organic waste water pollution is measured in terms of Biochemical Oxygen Demand
(BOD).
 BOD is the amount of dissolved oxygen required by bacteria to decompose organic
waste in water. It is measured in milligrammes per litre of water.
 A higher BOD value indicates that the water has a low DO content.
 BOD is not a reliable method of measuring water pollution because it is limited to
biodegradable materials.
6. Chemical oxygen demand (COD)
 COD (chemical oxygen demand) is a slightly better method for measuring pollution
load in water.
 COD measures the amount of oxygen required to oxidise organic (biodegradable and
non-biodegradable) and oxidizable inorganic compounds in a water sample in parts
per million.
7. Thermal and Radiation Pollution
 Thermal and nuclear power plants, as well as chemical and other industries, use a
lot of water for cooling, and the used hot water is discharged into rivers, streams, or
oceans.
 The discharge of hot water may raise the temperature of the receiving water by 10 to
15 degrees Celsius above the ambient temperature. This is called thermal pollution.
  The dissolved oxygen in water decreases as water temperature rises.
 Aquatic organisms, unlike terrestrial organisms, are adapted to a constant, uniform
temperature in their environment. Temperature spikes kill fish and other aquatic
animals.
 One of the most effective ways to reduce thermal pollution is to store hot water in
cooling ponds and allow it to cool before releasing it into any receiving water body.
 Nuclear accidents near bodies of water or during natural disasters such as tsunamis
and earthquakes pose the risk of radiation leakage (radiation exposure) into bodies of
water. Eg: Fukushima Daiichi nuclear disaster.
 Mutations in the DNA of marine organisms are caused by radiation exposure. If the
mutations are not repaired, the cell may develop into cancer.
 The thyroid gland absorbs radioactive iodine, which can lead to thyroid cancer.
8. Marine Pollution
 All natural and man-made pollutants eventually end up in the oceans.
 Coastal cities' sewerage and garbage are also dumped into the sea.
 Other sources of oceanic pollution include oil, grease, detergents, sewage, garbage,
and radioactive waste discharged during navigation, offshore oil mining, and oil
spills.
*For detailed notes of this topic, check this link Marine Pollution

Oil Spills
 Oil spills are among the most dangerous types of water pollution.
 Oil spills from tankers at sea or leaks from underground storage tanks on land are extremely difficult
to control because oil spreads quickly, affecting a large area in a short period of time.
 On land, crude is transported via pipelines or tankers, which can rupture and spew crude oil all over
the land, contaminating it.
 Because crude oil is lighter than water, it floats on the surface, posing the risk of rapid-spreading fire.
 Oil spills at sea reduce the oxygen level in the water and harm organisms.
 Oil spills also pollute the atmosphere and groundwater.
*For detailed notes of this topic, check this link Oil Spills

9. Invasive Species
 Water hyacinth plants are the world's most troublesome aquatic weed, also known as
the 'Terror of Bengal.'
 They proliferate in eutrophic water bodies, causing an imbalance in the ecosystem.
 They wreak havoc by causing stagnation of polluted water due to their rapid growth.
 10. Underground Water Pollution
 In many parts of India, groundwater is being contaminated by seepage from industrial
and municipal wastes and effluents, sewage channels, and agricultural runoff.
 Fluorides, uranium, heavy metals, and nutrients like nitrates and phosphates are
common pollutants in many parts of India.
 Nitrates: Nitrate in excess in drinking water reacts with haemoglobin to form non-
functional methemoglobin, impairing oxygen transport. Methemoglobinemia, also
known as blue baby syndrome, is the name given to this condition.
 High nitrate levels can cause carcinogenesis and hasten eutrophication in surface
waters.
 Metal traces: Lead, mercury, cadmium, copper, chromium, and nickel are all found.
These metals have the potential to be toxic and carcinogenic.
 Arsenic: Arsenic in groundwater can be caused by seepage of industrial and mine
discharges, as well as fly ash ponds from thermal power plants.
 Millions of people in India and Bangladesh (Ganges Delta) are exposed to
groundwater contaminated with high levels of arsenic, a highly toxic and dangerous
pollutant.
 Chronic arsenic exposure causes black foot disease. It can also cause diarrhoea, as
well as lung and skin cancer.
 Fluoride: Fluoride in excess in drinking water causes neuromuscular disorders,
gastrointestinal problems, tooth deformity, bone hardening, and stiff and painful joints
(skeletal fluorosis).
 Knock-Knee syndrome is characterized by pain in bones and joints as well as
outward bending of the legs from the knees.
 Fluorosis is a common problem in several states due to the consumption of high
fluoride content water.
*For detailed notes on this topic, check this link Groundwater Pollution
Effects of Water Pollution
On Human Health
 Domestic and hospital sewage contain many pathogenic microorganisms, and
dumping it into the water without proper treatment may result in an outbreak of
serious diseases caused by water pollution, such as typhoid, cholera, and others.
 Metals in industrial wastewater such as lead, zinc, arsenic, copper, mercury, and
cadmium are harmful to humans and other animals.
 Consumption of arsenic-polluted water causes arsenic accumulation in body parts
such as blood, nails, and hair, resulting in skin lesions, rough skin, dry and thickening
skin, and, eventually, skin cancer.
  Bacterial action converts mercury compounds in wastewater into extremely toxic
methylmercury, which can cause numbness of the limbs, lips, and tongue, deafness,
blurring of vision, and mental derangement.
 Mercury pollution of bodies of water causes Minamata (neurological syndrome)
disease in humans.
 Lead poisoning is caused when lead interferes with a variety of body processes and is
toxic to many organs and tissues.
 Lead compounds cause anaemia, headaches, muscle weakness, and a bluish line
around the gums.
 Water contaminated with cadmium can cause itai itai disease, also known as ouch-
ouch disease (a painful bone and joint disease), as well as lung and liver cancer.
*For detailed notes of this topic, check this link Effects of Water Pollution on human health
Economic Slowdown
 The United Nations estimates that by 2030, half of the world's population will be
living in areas of high water stress.
 It is difficult to have a thriving economy when fresh water is in short supply for
industrial, agricultural, and personal use.
 Lack of freshwater resources may limit the production of water-intensive goods such
as automobiles, food, and clothing.
On the Environment
 Microorganisms involved in the biodegradation of organic matter in sewage waste
consume a lot of oxygen and deplete the oxygen levels in the water, killing fish and
other aquatic creatures.
 The presence of high levels of nutrients in water causes algal bloom (excessive
growth of planktonic algae). Lakes age as a result of this.
 A few toxic substances, which are frequently found in industrial wastewater, can be
biologically magnified (Biomagnified) in the aquatic food chain. For example,
mercury and DDT.
 DDT at high concentrations disrupts calcium metabolism in birds, causing eggshell
thinning and premature breaking, eventually leading to a decline in bird populations.
On Aquatic Ecosystem
 Polluted water reduces the amount of dissolved oxygen (DO), which kills sensitive
organisms such as plankton, mollusks, and fish.
 A few tolerant species, such as Tubifex (annelid worm) and some insect larvae, may
survive in highly polluted water with low DO levels. These species have been
identified as indicator species for polluted water.
  Biocides, polychlorinated biphenyls (PCBs), and heavy metals kill sensitive aquatic
organisms directly.
Eutrophication
 The lakes' nutrient enrichment promotes the growth of algae, aquatic plants, and
various fauna. This is referred to as natural eutrophication.
 Human activities cause similar nutrient enrichment of lakes at an accelerated rate,
and the resulting ageing phenomenon is known as cultural eutrophication.
 Lakes are classified as Oligotrophic (very low nutrients), Mesotrophic (moderate
nutrients), or Eutrophic based on their nutrient content (highly nutrient-rich).
 Because of nutrients derived from their surroundings or organic wastes entering them,
the vast majority of lakes in India are either eutrophic or mesotrophic.
Algal Bloom
 Phytoplankton (algae and blue-green bacteria) thrive on the excess nutrients and
cover nearly the entire surface layer. This is referred to as an algal bloom.
 During the day, phytoplankton is photosynthetic, adding oxygen to the aquatic
ecosystem. However, they consume far more oxygen at night due to their aggressive
respiration.
 As the population of phytoplankton is very high, algal blooms accelerate the rate of
oxygen depletion.
 Primary consumers, such as small fish, are killed as a result of oxygen deprivation
caused by algal blooms.
 Algal blooms come in a variety of colours, but the most common are red or brown.
These blooms are also known as red or brown tides.
 Coral reef destruction: This occurs as a result of a decrease in water transparency
(increased turbidity).
Marine Pollution
 The discharge of chemicals into the ocean and its harmful effects are referred to
as marine pollution.
 The potentially toxic chemicals adhere to tiny particles, which are then consumed by
plankton and benthos animals, which are deposit or filter feeders that concentrate
upward within food chains.
 Toxins can be found in consumed food items obtained from livestock and animal
husbandry because animal feeds typically have a high fish meal or fish oil content.
 To reduce marine pollution and regulate individual states' use of the world's oceans,
nations have come together to form two major conventions:
 Convention on the Dumping of Wastes at Sea (to be replaced by the 1996
Protocol)
  United Nations Convention on Law of the Sea (UNCLOS)

Convention on Dumping of Wastes at Sea

 In November 1972, an intergovernmental conference on the Convention on the Dumping of Wastes at
Sea met in London to adopt this instrument, known as the London Convention.
 The Convention has a global scope and aims to bring international control and an end to marine
pollution.
 The Convention defines dumping as the intentional disposal at sea of wastes or other materials from
vessels, aircraft, platforms, and other man-made structures.
 'Dumping' in this context does not include wastes resulting from the exploration and exploitation of
sea-bed mineral resources.
 The Protocol, which went into effect in 2006, supersedes the 1972 Convention.
 The 1996 Protocol is far more stringent than the 1972 Convention, which permitted dumping if
certain conditions were met.
 When wastes thrown into the sea are likely to cause harm, the 1996 Protocol requires appropriate
preventive measures to be taken "even when there is no conclusive evidence to prove a cause
relationship between inputs and their effects."
 The amendments have established a legal foundation for regulating carbon capture and storage in
sub-sealed geological formations.
 It is one of the measures being considered to address climate change and ocean acidification, such as
developing low-carbon energy sources, particularly for large CO2 sources.
 The amendments allow for the storage of carbon dioxide (CO2) beneath the seafloor, but they restrict
the sequestration of CO2 streams resulting from CO2 capture processes in sub seabed geological
formations.
United Nations Convention on Law of the Sea
 The UN Convention on the Law of the Sea establishes general obligations for protecting the marine
environment and the freedom of scientific research on the high seas.
 It also establishes, through an International Seabed Authority, an innovative legal regime for
controlling mineral resource exploitation in deep seabed areas beyond national jurisdiction.
 The UN Convention on the Law of the Sea (UNCLOS) holds states liable for damages caused by
violations of their international obligations to combat sea pollution.

Water Crisis in India

 The difficulty in obtaining sources of freshwater for use due to depletion and
deterioration of available water resources is referred to as a water crisis.
 Climate change may cause water shortages through altered weather patterns such as
droughts or floods, increased pollution, and increased human demand and overuse of
water.
  Furthermore, water scarcity in India is expected to worsen as the country's population
grows to 1.6 billion by 2050.
 The NITI Aayog published the findings of a study warning that India is facing its
"worst" water crisis in history, with demand for potable water exceeding supply by
2030 if action is not taken.
 According to a 2018 report by the British charity WaterAid, nearly 163 million of
India's 1.3 billion people lack access to clean water close to home, the most of any
country.
 Every year, nearly 600 million Indians face high to extreme water stress, and
approximately 200,000 people die as a result of insufficient access to safe water.
 According to the study, twenty-one cities, including Delhi, Bengaluru, Chennai, and
Hyderabad, will run out of groundwater by 2020, affecting 100 million people.
 If current trends continue, the country's Gross Domestic Product (GDP) will fall by
6% by 2050.
Control Measures of Water Pollution
 Before releasing sewage water and industrial effluents into bodies of water, they
should be treated.
 Before hot water is released from power plants, it should be cooled.
 Domestic cleaning should be prohibited in tanks, streams, and rivers that supply
drinking water.
 Excess fertiliser and pesticide use should be avoided.
 Organic farming and the effective use of animal waste as fertiliser should be
encouraged.
 Water hyacinth (an aquatic weed) can purify water by removing some toxic materials
and heavy metals.
 Oil spills in water can be cleaned using bregoli, a byproduct of the paper industry that
resembles saw dust, an oil zapper, and microorganisms.
 Precipitation, the ion exchange process, reverse osmosis, and coagulation are some
chemical methods that aid in the control of water pollution.
 Individually, reusing, reducing, and recycling wherever possible will go a long way
toward mitigating the effects of water pollution.
 Implementation of the National Lake Conservation Plan (NLCP) and the National
Wetland Conservation Programme (NWCP) for the conservation and management
of identified lakes and wetlands in the country.
o They were merged in February 2013 into an integrated scheme of the National
Plan for Conservation of Aquatic Ecosystems (NPCA) to undertake various
conservation activities such as waste water interception, diversion, and
 treatment, pollution abatement, lake beautification, and biodiverse
management. Water Pollution Control Measures

o Before being released from power plants, hot water needs to be cooled.
o Domestic cleaning should be prohibited in tanks, streams, and rivers that
supply drinking water.
o Use of fertilizers and insecticides in excess should be avoided.
o Chemical fertilizers can be replaced by organic farming and efficient use
of animal waste as fertilizer.
o Water hyacinth (an aquatic weed and an invasive plant) can purify water by
removing harmful compounds and heavy metals.
o Bregoli, a by-product of the paper industry that resembles sawdust, oil
zappers, and microorganisms, can be used to clean oil spills in water.
o It has been suggested that eucalyptus trees be planted everywhere along
sewage ponds. These trees quickly absorb excess wastewater and emit pure
water vapour into the atmosphere.
o

 Implementation of the National Lake Conservation Plan (NLCP) and the National
Wetland Conservation Programme (NWCP) for the conservation and management
of identified lakes and wetlands in the country, which were merged in February 2013
into an integrated scheme of the National Plan for Conservation of Aquatic
Ecosystems (NPCA) to carry out various conservation activities such as waste water
interception, diversion, and treatment, pollution abatement, lake beautification, and
lake restoration.
 The Indian government recognised the necessity of maintaining the purity of water
bodies and passed the Water (Prevention and Control of Pollution) Act, 1974 to
protect our water resources.
 In 1985, the Ganga Action Plan, an ambitious plan to save the river, was started.
 The Central Pollution Control Board (CPCB), India's primary water quality
management authority, has created the idea of "approved best use."
 On the basis of pH, dissolved oxygen, BOD, total coliform, free ammonia, electrical
conductivity, and other factors, the water body is classified as A, B, C, D, or E.
 The CPCB has categorized all water bodies in the country, including coastal waters,
according to their "approved best uses," in consultation with the appropriate State
Pollution Control Boards.
 This classification aids water quality managers and planners in establishing water
quality goals and determining the needs and priorities for water quality restoration
programmes across the country.
 This effort resulted in the famous Ganga Action Plan and, later, the National River
Action Plan.
 Sewage water and industrial effluents are treated before being released into bodies of
water.
 BioToilets - Indian Railways collaborated with DRDO to develop bio-toilets.
 o The direct release of human waste from trains in the present toilet systems
causes track corrosion, which costs millions of dollars to replace.
o The bio-toilets are installed beneath the lavatories, and the human waste
released into them is converted into non-corrosive neutral water by a certain
type of bacteria.


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