Prasanna

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Three Domains of Life

Three domain classification was proposed by Carl Woese (1977) and his co-workers. They classified organisms based on the difference in 16S rRNA genes. The three domain system adds the taxon ‘domain’ higher than the kingdom.

This system emphasizes the separation of Prokaryotes into two domains, Bacteria and Archaea, and all the eukaryotes are placed into the domain Eukarya. Archaea appears to have more in common with the Eukarya than the Bacteria. Archaea differ from bacteria in cell wall composition and differs from bacteria and eukaryotes in membrane composition and rRNA types.

1. Domain Archaea

This domain includes single celled organisms, the prokaryotes which have the ability to grow in extreme conditions like volcano vents, hot springs and polar ice caps, hence are also called extremophiles. They are capable of synthesizing their food without sunlight and oxygen by utilizing hydrogen sulphide and other chemicals from the volcanic vents. Some of the them produced methane (methanogens), few live in salty environments (Halophiles) and are thermoacidophiles which thrive in acidic environments and at high temperatures.

2. Domain Bacteria

Bacteria are prokaryotic, their cells have no definite nucleus and DNA exists as a circular chromosomes and do not have histones associated with it. They do not possess membrane bound organelles except for ribosome (70S type). Their cell wall contains peptidoglycans.

Many are decomposers, some are photosynthesizers and few cause diseases. There are beneficial probiotic bacteria and harmful pathogenic bacteria which are diversely populated. Cyanobacteria are photosynthetic blue green algae which produce oxygen. These had played a key role in the changes of atmospheric oxygen levels from anaerobic to aerobic during the early geologic periods.

3. Domain Eukarya (Eukaryotes)

Eukaryotes are animals which have true nucleus and membrane bound organelles. DNA in the nucleus is arranged as a linear chromosome with histone proteins, ribsosomes of 80S type in the cytosol and 70S type in the chloroplast and mitochondria. Organisms in this domain are classified under kingdoms, namely, Protista, Fungi, Plantae and Animalia.

In 1987, Cavalier-Smith revised the six kingdom system to Seven Kingdom system. The concept of super kingdom was introduced and revised to seven kingdom classification. The classifiation is divided into two Super Kingdoms (Prokaryota and Eukaryota) and seven kingdoms, two Prokaryotic Kingdoms (Eubacteria and Archaebacteria) and five Eukaryotic Kingdoms (Protozoa, Chromista, Fungi, Plantae and Animalia). (Table 1.1).

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Diversity in the Living World

Earth has numerous habitats with a wide range of living organisms inhabiting them. Plants and animals are present in almost all the places, from polar icecaps to volcanic hot springs, from shallow lagoons to the deepest oceans, from tropical rain forests to dry and parched deserts. There are a variety of species that have been adapted successfully to live in diverse ecosystems.

Ecosystem is a community of biotic and a biotic factors and their interrelationships (A.G. Tansley, 1935). The presence of a large number of species in a particular ecosystem is called ‘biological diversity’ or in short ‘biodiversity’. The term biodiversity was first introduced by Walter Rosen (1985), and defined by E.D. Wilson.

Characterstic Features of Living Organisms

Living organisms show a variety of unique characters different from nonliving matter. The key characters of living organisms are, cellular organization, nutrition, respiration, metabolism, growth, response to stimuli, movement, reproduction, excretion, adaptation and homeostasis.

Numerous scientists and taxonomists have made tremendous contribution and documentation in the observation and study of even minute characters in living organisms. Their keen observations have led to the classification of living organisms and the study of their interrelationships.

Increase in mass and increase in number of individuals are essential criterion for the growth of the living organism. Growth of multicellular organisms occurs due to cell division. Reproduction is another characteristic of living organisms. Metabolism is another characteristic of living organisms.

Diverse form of living organisms are found in different types of habitats like ocean, fresh water bodies, forests, cold mountains, deserts, hot water springs etc.

Biodiversity is the variation of life forms, within a given ecosystem, biome or for the entire earth. It is a combination of two words; bio meaning life and diversity meaning variety. It refers to the varieties of plants,
animals and micro-organisms, the genes they contain and the ecosystems they form.

It means understanding that each individual is unique, and recognizing our individual differences. These can be along the dimensions of race, ethnicity, gender, sexual orientation, socio-economic status, age, physical abilities, religious beliefs, political beliefs, or other ideologies.

‘Living’ is something that is alive, something that can grow, move, reproduce, respire and carry out various cellular activities.

Diversity gives you access to a greater range of talent, not just the talent that belongs to a particular world-view or ethnicity or some other restricting definition. It helps provide insight into the needs and motivations of all of your client or customer base, rather than just a small part of it.

The term biodiversity (from “biological diversity”) refers to the variety of life on Earth at all its levels, from genes to ecosystems, and can encompass the evolutionary, ecological, and cultural processes that sustain life.

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Environmental Issues of Ecosan Toilets

About 150 liters of wastewater at an average is generated by an Indian individual daily, and a large amount of it is generated from toilets. Ecological sanitation (EcoSan) is a sustainable system for handling human excreta by using dry composting toilets.

EcoSan toilets not only reduce wastewater generation but also generate the natural fertilizer from recycled human excreta, which forms an excellent substitute for chemical fertilizers. This method is based on the principle of recovery and recycling of nutrients from excreta to create a valuable supply for agriculture.
‘EcoSan’ toilets are being used in several parts of India and Sri Lanka.

Eco-San is a specially formulated food contact surface sanitizer and destainer for use in low-temperature warewashing machines that rinses clear. Eco-San leaves dishes, flatware and glassware both sparkling and hygienically clean, as it combats a broad spectrum of organisms.

The EcoSan toilet is a closed system that does not need water, so is an alternative to leach pit toilets in places where water is scarce or where the water table is high and the risk of groundwater contamination is increased. When the pit of an EcoSan toilet fills up it is closed and sealed.

It is being used in Gulbarga, Karnataka. A self flushing e-toilet (using concept of pay & use toilet scheme) are toilets that are designed in such a way that it flushes itself on entry and exit with a drop of coin. They are
prevalent in Delhi, Kerala and Mumbai for footpath and slum dwellers.

Wherever the Need, an NGO in the UK build ecosan facilities (UDDTs) in various parts of the developing world. They predominantly work in Tamil Nadu (India), where the Tamil Nadu State Government
provides subsidies for their work.

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Solid Waste Management

Every day, tonnes of solid wastes are disposed off at landfill sites. This waste comes from homes, offices, industries and various other agricultural related activities. These landfill sites produce foul smell if waste is not stored and treated properly.

When hazardous wastes like pesticides, batteries containing lead, cadmium, mercury or zinc, cleaning solvents, radioactive materials, e-waste and plastics are mixed up with paper and other scraps and burnt, they produce gases such as dioxins. These gases are toxic and carcinogenic. These pollute the surrounding air, ground water and can seriously affect the health of humans, wildlife and our environment (Table 12.1).

Solid Waste management includes the activities and actions required to manage waste from its inception to its final disposal. This includes the collection, transport, treatment and disposal of waste, together with monitoring and regulation of the waste management process. It is all about how solid waste can be changed and used as a valuable resource.

Case Study:

The Corporation of Chennai looks after clearance and management of solid waste in Chennai. Every day around 5400 Metric Tonnes (MT) of garbage is collected from the city. Door to door collection of garbage is done in most zones apart from sweeping, collecting, and storing the waste in the specified bins.

At present garbage generated in Chennai is dumped at two sites. Proposals are there for remediation of the existing landfill or scientific closure and to have integrated waste processing facilities with waste to energy plants as one of the components at the existing Kodungaiyur and Perungudi sites.

Waste Management Practices

• Source segregation
• Composting
• Aerobic
• Anaerobic
• Vermicomposting
• Biogas generation
• Incineration

Radioactive Waste

Radioactive wastes are generated during various operations of the nuclear power plant. Radioactive waste can be in gas, liquid or solid form, and its level of radioactivity can vary. The waste can remain radioactive for a few hours or several months or even hundreds of thousands of years. Depending on the level and nature of radioactivity, radioactive wastes can be classified as exempt waste, Low and Intermediate level waste and High Level Waste.

Radioactive Waste Management

Radioactive waste management involves the treatment, storage, and disposal of liquid, airborne, and solid effluents from the nuclear industry.

Methods of Disposal of Radioactive Wastes are

1. Limit Generation:

Limiting the generation of waste is the first and most important consideration in managing radioactive wastes.

2. Dilute and Disperse:

For wastes having low radioactivity, dilution and dispersion are adopted.

3. Delay and Decay:

Delay and decay is frequently an important strategy because much of the radioactivity in nuclear reactors and accelerators is very short lived.

4. Concentrate and Confie Process:

Concentrating and containing is the objective of treatment activities for longerlived radioactivity. The waste is contained in corrosion resistant containers and transported to disposal sites. Leaching of heavy metals and radionuclides from these sites is a problem of growing concern.

Control and Management
Three ways are employed to manage nuclear wastes.

Spent Fuel Pools:

The spent fuel discharged from the reactors is temporarily stored in the reactor pool. The Spent fuel rods are used in stored cooling ponds. They protect the surroundings from radiation and absorb the heat generated during radioactive decay.

Vitrification Method:

This prevents reaction or degradation of nuclear waste for extended periods of time and encased in dry cement caskets.

Geological Repositories:

A deep geological repository is a nuclear waste repository excavated deep within a stable geologic environment. It is suited to provide a high level of long-term isolation and containment without future maintenance. In India at Tarapur and Kalpakkam, a wet storage facility of Spent Fuel is the main mode of storage.

Medical Waste

Any kind of waste that contains infectious material generated by hospitals, laboratories, medical research centers, Pharmaceutical companies and Veterinary clinics are called medical wastes.

Medical wastes contain body fluids like blood, urine, body parts and other contaminants, culture dishes, glasswares, bandages, gloves, discarded needles, scalpels, swabs and tissues.

Management:

The safe and sustainable management of biomedical waste is the social and legal responsibilities of people working in healthcare centers.

Waste Disposal:

Involved by incineration, chemical disinfection, autoclaving, encapsulation, microwave irradiation are methods of waste disposals. Final disposal includes landfill and burying as per norms inside premises.

E-Waste

Electronic waste or e-waste describes discarded electrical electronic devices as well as any refuse created by discarded electronic devices and components and substances involved in their manufacture or use. Their disposal is a growing problem because electronic equipment frequently contains hazardous substances.

In a personal computer, for example, there may be lead (Pb) in the cathode ray tube (CRT) and soldering compound, mercury (Hg) in switches and housing, and cobalt (Co) in steel components, among other equally
toxic substances. E-wastes are basically PCB (Polychlorinated biphenyl) based, which are non-degradable (Fig.12.8).

Used electronics which are destined for reuse, resale, salvage, recycling, or disposal are also considered e-waste. Unauthorised processing of e-waste in developing countries can lead to adverse human health effects and environmental pollution.

Recycling and disposal of e-waste may involve significant risk to the health of workers and communities in developed countries and great care must be taken to avoid unsafe exposure in recycling operations and leaking of materials such as heavy metals from landfills and incinerator ashes.

Plastic Waste – Solutions and Remedies

Plastics are low molecular weight organic polymers that are non-degradable in the natural environment. They are used in several items, including cars, bulletproof vests, toys, hospital equipment, carry bags and food containers.

Packaging materials used in supermarkets, retail outlets, manufacturing industries, households, hotels, hospitals, restaurants and transport companies are major contributors to plastic waste generation. Plastic waste constitutes a major part of municipal solid waste.

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Organic Farming and its Implementation

It is a method of farming system which primarily aims at cultivating the land and raising crops in such a way, so as to keep the soil alive and in good health by use of organic wastes (crop, animal and farm wastes, aquatic wastes) and other biological materials along with beneficial microbes (biofertilizers) to release nutrients to crops for increased sustainable production in an eco-friendly pollution free environment.

organic farming systems by the farmers in the following ways:

• The selection of locations not contaminated with chemicals
• Appropriate local types of rice plant
• Programming of appropriate crop rotation
• Processing soil with tools not contaminated with chemicals
• Intermitten irrigation
• Use of

Organic agriculture can be defined as “an integrated farming system that strives for sustainability, the enhancement of soil fertility and biological diversity while, with rare exceptions, prohibiting synthetic pesticides, antibiotics, synthetic fertilizers, genetically modified organisms, and growth hormones”.

Organic agriculture considers the medium- and long-term effect of agricultural interventions on the agro-ecosystem. It aims to produce food while establishing an ecological balance to prevent soil fertility or pest problems.

Advantages of Organic Farming

• Minimises the external cost of farming.
• Efficient use of resources.
• Soil and the environment is a public good.
• Healthier food.
• Healthier animals.
• Potential profits.
• Time involved.
• More labour intensive.

Organic farming eliminates the use of synthetic products to maximize the yields that can be produced. It works on creating a healthier soil instead, encouraging the link between healthy plants and protected soils. No chemical herbicides or pesticides are used. Only natural soil enhancement techniques are permitted.

There are basically two types of organic farming: pure organic farming and integrated organic farming. With pure organic farming, the method includes the use of manures and biopesticides with complete avoidance of inorganic chemicals and pesticides.

In the process of pure farming, fertilizer and pesticides obtain from natural sources. It is called a pure form of organic farming. (b) Integrated organic farming – Integrated organic farming consists of integrated nutrients management and integrated pest management.

In a few words, organic farming involves growing techniques and methods that seek to protect the environment, humans, and animals, through sustainable agriculture. As fertilization methods, they mainly use manure, compost, or special organic synthetic fertilizers.

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Eutrophication | Definition, Types, Causes, & Effects

When run-off from land containing nutrients reaches water bodies like lakes, it results in dense growth of plant life. This phenomenon is called Eutrophication. Natural aging of lakes also leads to nutrient enrichment of its water.

In a lake, the water is cold and clear (oligotrophic stage), supporting little life. With time, streams draining into the lake introduce nutrients such as nitrates and phosphates, which encourage the growth of aquatic organisms. Aquatic plants and animal life grow rapidly, and organic remains begin to be deposited on the lake bottom (mesotrophic stage) (Fig. 12.5).

Pollutants from anthropogenic activities like effluents from the industries and homes can radically accelerate the aging process. This phenomenon is known as Cultural or Accelerated Eutrophication.

Nutrients stimulate the growth of algae, water hyacinth and can cause clogging of canals, rivers and lakes as well as, displacing native plants. It causes unsightly foam and unpleasant odours, and deprives the water of dissolved oxygen.

Integrated Wastewater Management

Wastewater Treatment

Wastewater or sewage originates from domestic waste waters, industrial wastes and animal wastes. Realizing the importance of clean potable water, the Government passed the Water (Prevention and Control of Pollution) Act in 1974, which made it mandatory to treat wastewater in treatment plants. The main objective of a wastewater treatment process is to reduce organic and inorganic components in wastewater to a level that it no longer supports microbial growth and to eliminate other potentially toxic materials.

Microorganisms mainly bacteria and some protozoa play an essential part in the treatment of sewage to make it harmless. Sewage contains pathogenic bacteria. These bacteria must be destroyed in order to prevent the spread of diseases. Sewage treatment is usually performed in the following three stages (Fig. 12.6).

Primary treatment

Primary treatment involves the physical removal of solid and particulate organic and inorganic materials from the sewage through filtration and sedimentation. Floating debris is removed by sequential filtration. Then the grit (soil and small pebbles) are removed by sedimentation. All solids that settle form the primary sludge and the supernatant forms the effluent. The effluent from the primary settling tank is taken for secondary treatment.

Secondary treatment or biological treatment

The primary effluent is passed into large aeration tanks where it is constantly agitated mechanically and air is pumped into it. This allows vigorous growth of useful aerobic microbes into floc (masses of bacteria associated with fungal fiaments to form mesh like structures).

While growing, these microbes consume the major part of the organic matter in the effluent. This significantly reduces the BOD (Biochemical oxygen demand or Biological oxygen demand). BOD refers to the amount of the oxygen that would be consumed, if all the organic matter in one litre of water were oxidized by bacteria. The sewage water is treated till the BOD is reduced. The greater the BOD of the waste water more is its polluting potential.

Once the BOD of sewage water is reduced signifiantly, the effluent is then passed into a settling tank where the bacterial “flocs” are allowed to sediment. This sediment is called activated sludge. A small part of activated sludge is pumped back into the aeration tank to serve as the inoculum. The remaining major part of the sludge is pumped into large tanks called anaerobic sludge digesters. Here, the bacteria which grow anaerobically, digest the bacteria and the fungi in the sludge. During this digestion, bacteria produce a mixture of gases such as methane, hydrogen sulphide and CO₂. These gases form biogas and can be used as a source of energy.

Tertiary treatment

Tertiary treatment is the final process that improves the quality of the waste water before it is reused, recycled or released into natural water bodies. This treatment removes the remaining inorganic compounds and substances, such as nitrogen and phosphorus.

UV is an ideal disinfectant for wastewater since it does not alter the water quality – except for inactivating microorganisms. UV is a chemicalfree process that can completely replace the existing chlorination system and also inactivates chlorine-resistant microorganisms like Cryptosporidium and Giardia.

Case Study:

Auroville, located in South India near Puducherry has been experimenting with natural wastewater recycling systems (Decentralized Waste Water Treatment System (DEWATS)) (Fig.12.7a). Such treatment plants have now also been implemented in Aravind Eye Hospital, Puducherry (Root Zone Wastewater Treatment (RZWT)) (Fig.12.7 b) and the Chennai Mathematical Institute, Siruseri IT Park, Chennai.

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Biomagnification Definition and its Effects

Food chains are components of all ecosystems. Producers and consumers form trophic levels in a chain through which energy flow is carried out by the process of eating and being eaten. Usage, storage and transformation of food and biomolecules by metabolism are a normal process. Degradation or breakdown is an essential part of any food chain and hence all naturally occurring substances are degradable.

Biomagnifiation of DDT

When non-degradable substances enter the food chain, they do not get metabolized or broken down or expelled and instead get transferred up the tropic levels of the food chain. During this process, they show an increase in concentration which is referred to as biomagnification.

This results in increased toxicity and may even be lethal. This phenomenon is well established for mercury and DDT. Fig 12.4 schematically shows biomagnifiation of DDT in an aquatic food chain where the concentration of DDT is enhanced at successive trophic levels.

Biomagnification is the method of accruing toxic elements by different organisms within a food chain. A prominent example of it is the presence of mercury within predatory fish. This level is so high that consuming these can cause cancer.

What are the substances responsible for biomagnification. Biomagnification refers to the accumulation of toxic substances in the food chain. The pesticides and chemicals such as DDT, and mercury released into the lakes and rivers are ingested by the aquatic organisms.

Bioaccumulation refers to the accumulation of a toxic chemical in the tissue of a particular organism. Biomagnification refers to the increased concentration of a toxic chemical the higher an animal is on the food chain.

Biomagnification is the accumulation of a chemical by an organism from water and food exposure that results in a concentration that is greater than would have resulted from water exposure only and thus greater than expected from equilibrium.

Biomagnification is the increase of harmful substances or chemicals in the normal food chain process. It is bad because many living things die due increase in harmful chemicals.

Biomagnification can occur in both terrestrial and aquatic environments, but it is generally used in relation to aquatic situations. Most often, biomagnification occurs in the higher trophic levels of the food chain/web , where exposure to chemicals takes place mostly through food consumption rather than water uptake.

Bioaccumulation is when a harmful substance (pesticides or organic chemicals) gets absorbed by an organism at a higher rate than it can be excreted. Even if the environment doesn’t have a high amount of toxin in it, accumulation through the food chain can be devastating for organisms.

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An Overview of Agrochemicals

Chemicals which are used in agriculture for growth of plants and pest control are called agrochemicals or agrichemicals. Overuse of agrochemicals have been observed to generate residues that cause nutrient imbalance. In addition,

1. May kill beneficial bacteria and soil organisms.
2. Can cause eutrophication in water bodies.
3. Affect aquatic animals and their productivity.
4. Pesticide containing water, even in trace quantities is unfi for human consumption.
5. Particles (aerosols) and residues of these chemicals cause air pollution.
6. Inhalation of contaminated air can cause respiratory problems.
7. Consumption can lead to poisoning, side effects and after effects.
8. Chemicals can cause skin rashes and irritation of eyes.
9. Many of these chemicals are reported to be carcinogenic.
10. They can trigger hormonal disorders and neurotoxicity.
11. Beneficial insects and animals can be affected.

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Noise Pollution | Definition, Examples, Effects and its Causes

Sound that is unwanted and undesirable or can disrupts one’s quality of life is called as Noise. When there is lot of ‘noise’ in the environment, it is termed as Noise Pollution. The intensity of noise is meaured in decibels (dB).

Sources of Noise Pollution

Vehicle engines, air horns, audio video systems, trains, low flying aircrafts, factory machines, sirens, motors, drillers and crushers, compressor machines, crackers, explosives, modern supersonic transports are the common sources of noise pollution.

The threshold of pain is about 120 db. World Health Organization has proposed that noise must be recognized as a major threat to human well-being. This is applicable for all living organisms.

Effect of Noise Pollution

• According to the USEPA (United States Environmental Protection Agency) there are direct links between noise and health.
• Heart disease, high blood pressure, stress related illness, sleep disruption, hearing loss (deafness), and productivity loss are the problems related to noise pollution.
• Increased stress and tension, nervousness, irritability, anxiety, depression and panic attacks.
• Peptic ulcer, severe head ache, memory loss.
• Marine animals are affected by noise pollution from offshore activities and port activities.
• Fire crackers frighten animals. Birds are often affected by increased air traffic.

Control

• Planting trees in and around noise sources is an effective solution for noise pollution as plants are known to absorb noise and bring down sound levels.
• Regular servicing and tuning of automobile engines can effectively reduce noise pollution by vehicles and machinery.
• Workers should be provided with ear plugs and earmuffs at work sites that generate high noise levels.
• Lubrication of machinery and regular servicing minimizes noise levels.
• Regulations should be imposed to restrict the usage of loudspeakers in crowded areas and public places.

Legal Protection

Article 48-A and Article 51-A of the Constitution of India, Noise Pollution (Regulation and Control) Rules 2000, and Tamil Nadu State Environment Policy 2017 are some of the legal relief from noise pollution.

According to Noise Pollution (Regulation and Control) Rules, 2000, the permissible limit of noise in areas categorized as commercial is 65 decibels (dB) during day and 55 dB during night.

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Water Pollution | Definition, Causes, Effects and Solutions

Quality of Water

Water is essential for life and for the health of the environment. As a valuable natural resource, it comprises marine, estuarine, freshwater (river and lakes) and groundwater environments that stretch across coastal and inland areas.

Water has two dimensions that are closely linked: quantity and quality. Water quality is commonly defined by its physical, chemical, biological and aesthetic (appearance and smell) characteristics. A healthy environment is one in which the water quality supports a rich and varied community of organisms and protects public health.

Water Pollution

Water pollution occurs when there is a change in the chemical, physical or biological quality of water that has harmful effect(s) on living organisms that consume it or live in it. Water pollution adversely affects water bodies due to the large amounts of natural or man-made materials let into it. When it becomes unfit for its intended use, water is considered polluted.

Sources of Water Pollution

Even though water bodies or sources can be polluted by natural causes, water pollution is usually caused by human activities. There are three main types of sources: point sources, non-point sources, leaks and spills.

Point sources:

Discharge of pollutants at specific locations through pipelines or sewers into the water body. Factory effluents, sewage, underground mines, oil wells, oil tankers and agriculture are common point sources (Fig. 12.2 a).

Non-point sources:

Sources that cannot be traced to a single site of discharge like acid rain, dumping of the plastics in water bodies, agriculture chemical run off are common examples (Fig. 12.2 b).

Leaks and Spills:

This occurs mostly due to ship collision, off shore oil rigs, oil leakages and discharges into sea (Fig. 12.2 c).

Sources of water pollution can also be classified in three ways. They are municipal wastes, industrial wastes, and agricultural wastes.

1. Municipal waste water is from homes and commercial establishments.

2. Industrial discharge (effluents) may contain varieties of compounds such as heavy metals (cadmium, chromium, lead), and organic / inorganic chemicals containing waste water, sometimes in toxic concentrations. These discharges can affect temperatures of the water bodies as well as dissolved oxygen level.

3. Agricultural wastes include fertiliser and pesticide runof from agricultural fields, food processing waste, tree and saw dust from logging operations and bacteria from sewage or livestock operations. Water pollutants reach water bodies like rivers, streams and the marine system by precipitation, run-of and the groundwater by seepage or percolation.

Effect of Water pollution on Ecosystems

1. Destruction of ecosystems:

Ecosystems, especially aquatic systems, can be severely affected or destroyed by water pollution. Water pollutants affect existing niches and habitats and the survival of organisms. Soil fertility is affected and the system becomes uninhabitable.

2. Disruption of food-chains:

Water pollution disrupts the natural food chains as well as food webs. Pollutants such as lead and cadmium are taken up by primary consumers where they can be lethal or get stored. Later, when these animals are consumed by secondary consumers, the food chain can get disrupted at any trophic level or result in enhanced concentration of these pollutants (biomagnifiation). Hot water from industries when released into the water bodies affects aquatic density and diversity.

Effect of Water pollution on Organisms

1. Water pollution can be lethal to aquatic organisms and others that depend on these water bodies.

Accidental oil spills from tanker ships can cause substantial environmental damage. Oil spreads on the water surface, prevents the entry of light and oxygen into the water. This increases BOD and COD, resulting in mass death of organisms and degradation of water quality. It also clogs fish gills and the feathers of aquatic birds.

2. Humans and other organisms can get affected by diseases such as hepatitis and typhoid by consuming contaminated water and food. Excess of fluoride in drinking water causes fluorosis. In many poor nations, outbreak of water borne diseases and epidemics are a result of contaminated water and poor or absence of water treatment processes.

3. Water pollution can cause eutrophication due to nutrient enrichment. This causes algal blooms which affect the quality of water bodies (Fig. 12.3). Red tides, if occur, can be lethal to aquatic organisms.

Control Measures

1. Right to clean water is a fundamental right under the Indian Constitution (Article 21).

2. Water (Prevention and Control of Pollution) Act, 1974, sections 17 to 40 prohibit the pollution of a stream or well by disposal of polluting matter.

3. The Central/State Pollution Control Boards have the power to advise the central/state government on various matters concerned with the prevention and control of pollution of water.

4. The Ministry of Environment, Forest and Climate Change (MoEFCC) is the nodal agency of the Central Government for the planning, promotion, co-ordination and for overseeing the implementation of India’s environmental and forestry policies and programmes.

5. National river conservation plan (NRCP) was enacted in 1995 to improve the water quality of the rivers, which are the major fresh water resources in our country. This important assignment taken up under the NRCP includes, To capture the raw sewage flowing into the river through open drains and divert them for treatment.

Setting up sewage treatment plants for treating the diverted sewage. Construction of low cost sanitation toilets to prevent open defecation on river banks.

Prevention

• Regulate or control of pollutant(s) discharge at the point of generation.
• Wastewater can be pretreated by scientific methods before discharge to municipal treatment sources.
• Setting up of Sewage Treatment Plants (STP) and Effluent Treatment Plants (ETP).
• Regulate or restrict the use of synthetic fertilisers and pesticides.
• Public awareness and peoples’ involvement is essential.

Case study

Namami Gange (National Mission for Clean Ganga) Programme is an Integrated Conservation Mission approved as the ‘Flagship Programme’ of the Union Government in June 2014 with a budget outlay of 20,000 crores to accomplish the twin objectives of effective abatement of pollution, conservation and rejuvenation of River Ganga.