Arctic Circle : Whats the recent concern!

Arctic Circles : Real threat to the Earth & Ecology

Facts & figures about Article Circle

The Arctic circle is one of the two polar circles and most northerly of the five major circle of latitude. It marks the northernmost point at which the centre of the noon is just visible on the December solstice and the southernmost point at which the centre of the midnight sun is just visible on the June solstice. The region north of this circle is known as the earth as the Arctic, and the zone just to the south is called the Northern Temperate Zone.

The position of the Arctic Circle is not fixed and currently runs 66°33'48.1'' north of the equator.

Geographical figures

• Length - 1600 km
• Area - 20 mill sq. km
• passes through the Arctic Ocean, the Scandivian, North Asia, Northern America, Greenland
• Arctic Countries comprises Norway, Sweden, Finland, Russia, US (Alaska), Canada, Denmark (Greenland)and Iceland.

Climate

Long, cold winters and short, cool summer characteristics of the Arctic Climate. Sea ice, glacial ice, or snow covers some parts if the Arctic year-round, and almost all of the Arctic experiences long periods of the year with some form of surface ice. Winter temp. can drop below - 58° (-50℃), and summer temp. can occasionally exceed 86°F (30℃). Now, the Arctic is marked as the climatic laboratory for the rest of the planet.

Habitat to Flaura & Fauna

The Arctic circle is there polar bears, Arctic foxes, wolves and reindeer can be found as well as various species of birds such as snowy owls, bald eagles and those over so charming puffins (no penguins!) the Arctic Ocean provides a home for various types of whales, seals, walruses, fish and plankton.

Approx. 20,000 species of plants, animals, and microorganisms make the arctic home. Vegetation includes grasses, sedges, polar poppies, willow shrubs, dwarf birch, lichens, liverworts and mosses.

Arctic Fox

Polar Bear

Willow Vegetation

Major issues & threats

The Arctic Circle and impact of the Global Warming

The people and animals that live in the Arctic depend on its unique ecosystem to survive. For them the climate change is the actual threat to live their livelihood and it's a daily reality. And with the region warming twice as fast the rest of the world, the arctic ice is melting even faster, as the ocean absorbs the heat.

Oil drilling in the Arctic Circle

Arctic Ocean drilling is a gamble with catastrophic consequences for the people, wildlife and the sensitive ecosystem of the region. And yet major companies like Shell and the Exxon are making aggressive move to ushers a new "Oil rush" in the arctic ocean that we need a longer term fix we need to keep Arctic Ocean off limits to call drilling forever.

Climate Change

Anthropogenic climate change (due to human activities) is caused by greenhouse gases (GHGs) in the atmosphere, largely the result of fossil fuel use since in the industrial revolution and deforestation caused by land use changes. These gases trap energy in the atmosphere that would otherwise escape to space.

Changes in Biological diversity

The people of the north are heavily reliant, both for food and for social and cultural reasons, on the variety and abundance of organisms (biodiversity). Biodiversity is dramatically in the north, the result of over harvesting, global habitat loss in wintering and staging grounds used by the migratory species and most significantly climate change.

Accumulation of toxic chemicals

Wind & ocean currents carry persistent chemicals, many of which are toxic to the arctic mining and oil development in northern Canada, the Barents Sea and Alaska could increase the chemical load in the Arctic. Increased shipping as a result of climate change will expose the Arctic to a greater risk of pollution. In addition, radioactive waste much of the result of cold war activities in the former Soviet Union - found in the Arctic.

Chemicals of concern include your POPs, such as polychlorinated biphenyls (PCBs), DDT, and some organophosphate pesticides, as well as heavy metals such as mercury.

Recent in News

• 'Extreme fires erupt in the Arctic Circle' - Mashable.com Report

For the second straight year, an unusually large number of intense fires have ignited in the Arctic Circle, the polar region a top Earth.

• 'Siberian town hits highest temperature in records history for the Arctic Circle' - the Accuwaether Report

Verkhyoyansk, a Siberian town located 3000 miles east of Moscow, Russia, reached 100.4 °F on Saturday, breaking the record high temp for the Arctic Circle and Siberia and also making the first time that either region has reached 100°F in recorded history.

• 'Siberian town records 100°F day - the hottest in Arctic history' - Live Science Report

• 'Extreme weather 'record' likely in Arctic Circle, says UN weather agency WHO - UN reports

• 'Satellite images show wildfires ravaging the Arabic Circle' - by Yahoo!News

• 'Russian mining firm accused of using global heating to avoid blame of oil spill'

What does it signify?

Recent transition shows the clear evidence that the heatwave in the arctic aren't usual. Weather patterns around the world can align in such a way that hot air is transported quite far northward and colder air from the poles southward. Over the last few months a large area of high pressure in the eastern Russia has been dominant. This has led to southerly winds bringing warmer air from near the tropics, leading to higher than avg temp.

However, the persistence of this weather pattern has led to a congevity and scale of heat that is worrying. This is consistent with what climatologists believe will happen in the Arctic with Climate Change. Most scientist agree that over the past 30 years, the arctic has warned at a two times rate of global average.

Why its so concern the warming of Arctic?

• The North & South poles play a vital role in regulating the earth's climate - acting as natural cooling system.
• Warming in the Arctic is leading to the thawing of once permanently frozen permafrost below grow. (Permafrost thaws, CO₂ & CH₄ previously locked up below ground is released).
• Reduced snow cover will mean that the Earth absorbs more heat from the Sun & ocean current shift. Arctic region is also home to millions of people, many from unique, indigenous populations. These people and their cultures are also at risk.
• The impact of wildfires are also a consideration few years back, they ravaged parts of the Arctic. Although they are common in summer, high temp & strongly winds made them unusual several.

Renewable Energy

Renewable Energy

Renewable energy is a energy that is generated from natural resources that are continuously replenished. This includes sunlight, geothermal heat, wind, tides and various forms of biomass. This energy cannot be exhausted and is is constantly renewed.

Why do we need renewable source of energy

• To reduce pollutants, greenhouse gases and toxins that are by-products of non-renewable sources of energy;
• The use of alternative energy sources can help preserve the delicate ecological balance of the earth, and help conserve the non-renewable energy sources like fossil fuels; and
• Renewable sources are inexhaustible.

What renewable energy comprises of

• Solar energy - energy generated from the Sun
• Hydel energy - energy derived from water biomass - energy from firewood, animal dung, biodegradable waste and crop residues when it is burnt.
• Geothermal energy - energy from hot dry rocks, magma, hot water springs, natural geysers etc.
• Ocean thermal - energy from waves and also from tidle waves.
• Co-generation - producing two forms of energy from one fuel.
• Fuel cells - fuel cells are also being used as cleaner energy source

Sun - The Ultimate Source of Energy

The sun has been providing us heat and light for billions of years and it is expected that it will continue to do so for billions of years to come. All plants get their energy from the sun and all animals get their energy mainly from the plants.

Solar Grid to harness Solar Energy

The ways to produce electricity from sunlight

• Photovoltaic Electricity - uses photovoltaic cells that absorb the direct sunlight to generate electricity.
• Solar Thermal Electricity - uses a solar collector that has mirrored surface which reflects the sunlight onto a receiver that heats up a liquid. This heated up liquid is used to make steam that produces electricity.

Photovoltaic Electricity

Solar panels attached aluminium mounting system. Photovoltaic (PV) cells are made up of at least two semiconductor layers - a positive charge and a negative charge. As a PV cell is exposed to sunlight, photons are reflected, pass right through, or absorbed by the solar cell. When enough photons are absorbed by the negative layer of the photovoltaic cell, electrons are freed from the negative semiconductor material. These freed electrons migrate to the positive layer creating a voltage differential. When the two layers are connected to an external load, the electrons flow through the circuit creating electricity. The power generated - Direct Current (DC) is converted to Alternate Current (AC) with the use of inverter.

Concentrated Solar Power (CSP) or Thermal Technology

It utilized focused sunlight and convert it into high temperature heat. The heat is then channeled through a conventional generator to produce electricity. Solar collector captures and concentrate sunlight to heat a fluid which in turn generates electricity. There are several variations in the shape of the collectors. The most commonly used are the parabolic through. Parabolic through power plants use a curved, mirrored trough which reflects the direct solar radiation onto a glass tube containing a fluid and fluid gets heated owing to the concentrated solar radiation and the hot steam generated is used to rotate the turbine to generate electricity. Commonly used fluid are synthetic oil, molten salt and pressurized steam. The power generated - Direct Current (DC) is converted to Alternate Current (AC) with the use of inverters.

Potential of Solar Energy in India and it's installed capacity

India has the potential to generate 35 MW/km2 using solar voltaic and solar thermal energy. Solar energy of about 5000 trillion kWh per year is incident over India's land area with most parts receiving 4-7 kWh per sq. m per day. Hence both technology routes (solar thermal and solar photovoltaic) for conversion of solar radiation into heat and electricity can effectively be harnessed providing huge scalability for solar power in India (Specially in high solar radiation area : Rajasthan, Gujarat, Laddakh, Andhra Pradesh, Maharashtra & Madhya Pradesh)

The current installed capacity of solar grid connected power reached 37.627 GW as of 31st March, 2020. A major initiative called 'The National Solar Mission' was formed by Govt of India and its state govt. One of the main features of the mission is to make India a global leader in solar energy and the mission envisages an installed solar generation capacity of 100 GW by 2022.

International Solar Alliance

International Solar Alliance (ISA) is launched at the CoP21 Climate Conference in Paris as a special platform for mutual cooperation among 121 solar resources rich countries lying fully or partially between Tropic of Cancer and Tropic of Capricorn. The alliance is dedicated to address special energy needs of ISA member countries. International Agency for Solar Policy and Application (IASPA) will be the formal name of International Solar Alliance. The ISA secretariat will be set up in National Institute of Solar Energy, Gurugram (India).

Objectives

• to force down prices by driving demand;
• to bring standardization in solar technologies
• to foster research and development

Wind Energy

Wind energy is the kinetic energy associated with the movement of atmospheric air. Wind turbines transform the energy in the wind into mechanical power, further converting to electric power to generate electricity. Five nations - Germany, USA, Denmark, Spain and India account for 80% of the world's installed wind energy capacity.

Wind Energy

Wind farm

• Onshore wind farms : operate one land, where the wind tends to be the strongest. The turbines of a onshore wind farms are less expensive and easier to set up, mantain and operate than offshore turbines.
• Offshore wind farms : Construction of wind farms in large bodies of water to generate electricity. Offshore wind farms are more expensive than onshore wind farms of the same nominal power.

Wind Farm

Working of wind turbines

Wind turbines convert the kinetic energy in the wind into mechanical energy. This mechanical power can be used for specific tasks ( such as grinding grain or pumping water) or a generator can convert this mechanical power into electricity. Most turbines have three aerodynamically designed blades. The energy in the wind turns two or three propeller-like blades around a rotor that is connected to the main shaft , which spins a generator to create electricity. Wind turbines are mounted on a tower to capture the most energy. At 100 ft or more above ground, they can take advantage of faster and less turbulent wind.

Main factors that determine the electricity production

• Wind speed - stronger wind produce more energy. Wind turbine generates energy at a speed of 4-25 metres/sec.
• Blade radius - the larger the radius of blades, the more the energy produced. Doubling the blade radius can result in four times more power.
• Air density - Heavier air exerts more lift on a rotor. Air sensory is a function of altitude, temperature and pressure and lighter air so they are less productive turbine locations. The dense heavy air near sea level drives rotors faster and thus relatively more effective.
• Wind turbines can be of horizontal axis design and vertical axis design.

Potential of wind energy in India and it's installed capacity

The National Institute of Wind Energy (NIWE) has recently launched Wind Energy Resource Map of India at 100 m above ground level (AGL) on online Geographic Information System platform.

The wind energy potential in the country at 100 m AGL is over 302 GW. Gujarat has the maximum potential followed by Karnataka, Maharashtra, Andhra Pradesh according to the resource map.

Wind power generation capacity in India has significantly increased in recent years. As of 29 February 2020 the total installed wind power capacity was 37.669 GW, the fourth largest installed wind power capacity in the world. Wind power capacity is mainly spread across the Southern, Western and Northern regions.

World Wind Energy Association

WWEA is an international non-profit association embracing the wind sector worldwide, with  more than 600 members in around 100 countries. WWEA works for the promotion and worldwide deployment of wind energy technology.

• WWEA provides a platform for the communication of all wind energy actors worldwide.
• WWEA advises and influences national governments and international organisations.
• WWEA enhances international technology transfer.

WWEA Working Principles

• Wind energy shall serve as one cornerstone and a driving force for the immediate application of a world energy system driven by renewable energies to completely substitute fossil and nuclear sources.
• Global dissemination of grid-connected and stand-alone wind energy solutions should rely on experience gained from the most successful implementation strategies, based on favorable legal, political and social framework conditions as initiated by national associations. Local and rural communities and people should be involved and should benefit directly.
• WWEA shall stimulate and support the foundation of national and regional wind energy associations and encourage national governments to set ambitious targets and political frameworks for priority strategies in favour of a fast and sustainable development of all renewable energies.
• WWEA organises together with continental, national and regional wind energy associations World Wind Energy Conferences and further international events for mobilising a wide range of the different wind energy applications.
• WWEA plays an active role in the World Council for Renewable Energies and cooperates with further international renewable energy organisations in order to work for a full substitution of all polluting and hazardous waste causing energies.

Ocean Thermal Energy

Large amount of solar energy is stored in the oceans and seas. On an average, the 60 mill square km of the tropical seas absorb solar radiation equivalent to the content of 245 bill barrels of oil.The process of harnessing this energy is called OTEC (Ocean Thermal Energy Conversion). It uses the temperature differences between the surface of the ocean and the depth of about 1000 m to operate a heat engine, which produce electric produces electric power.

OTEC working Flowchart

Wave Energy

Waves result from the interaction of the wind with the surface of the sea and represent a transfer of energy from the wind to the sea.

The first wave energy, project with a capacity of 150 MW has been set up at Vizhinjam near Trivandrum.

Wave Energy Plant 

Tidal Energy

Energy can be extracted from tides by creating a reservoir or basin behind a barrage and then passing tidal waters through turbines in the barrage to generate electricity.

A major tidal wave power project costing of Rs 5k crores, proposed to be set up in the Hanthal Creek in the Gulf of Kutch in Gujarat.

Tidal Energy

Biomass

Energy from biomass is the oldest fuel used by human’s .Our ancestors burned wood to keep the cave warm. Biomass is a renewable energy resource derived from plants and animal waste. The energy from biomass (biomass conversion) is released on burning or breaking the chemical bonds of organic molecules formed during photosynthesis. Thus biomass represents an indirect form of solar energy. Biomass fuels can be used directly or they can be transformed into more convenient form and then used.

Biomass Plant

Sources of BioMass

It is derived from numerous sources, including the by-products from the timber industry, agricultural crops and their by products, raw material from the forest, major parts of household waste and wood.

Biomass can be burnt directly as a source for cooking, heating, lighting, generating steam, for industrial use for producing electricity.

• can be used to generate gaseous fuels (gasification).
• can be converted into alcohol (liquid biofuels) by distillation.

Methane and biogas can be produced from urban wastes in landfills and sewage at waste water treatment plants. In some facilities, manure from livestock and other organic waste is converted by microorganisms in specially designed digestion chamber to form methane(CH4), which is burned to produce electricity, used in fuel cell, or used as fuel for vehicles. Molasses obtained from sugarcane is fermented to produce ethanol, that can be used in automobiles.

Bagasse as biofuel

Indian sugar mills are rapidly turning to bagasse, the leftover of cane after it is crushed and its juice extracted, to generate electricity. This is mainly being done to clean up the environment, cut down power costs and earn additional revenue. According to current estimates, about 3500 MW of power can be generated from bagasse in the existing 430 sugar mills in the country. Around 270 MW of power has already been commissioned and more is under construction.

Biogas plant

The biogas plant consists of two components: 

A digester (or fermentation tank) and a gas holder. The digester is a cube-shaped or cylindrical waterproof container with an inlet into which the fermentable mixture is introduced in the form of liquid slurry. The gas holder is normally an airproof steel container that, by floating like a ball on the fermentation mix, cuts off air to the digester (anaerobiosis) and collects the gas generated. In one of the most widely used designs, the gas holder is equipped with a gas outlet, while the digester is provided with an overflow pipe to lead the sludge out into a drainage pit.
Any biodegradable (that which can be decomposed by bacteria) substance can be fermented anaerobically (in absence of oxygen) by methane-producing (methanogenic) bacteria. Cow dung or faeces are collected and put in a biogas digester or fermenter (a large vessel in which fermentation can take place). A series of chemical reactions occur in the presence of methanogenic bacteria (CH4 generating bacteria) leading to the production of CH4 and CO2.

Methanogenesis is a microbial process, involving many complex, and differently interacting species, but most notably, the methane-producing bacteria. The biogas process is shown below in figure 30.3, and consists of three stages; hydrolysis, acidification and methane formation.

Petro-crops (Plants)

Petroleum and wood are chief energy resources from time immemorial, but they have been overused and not being replenished fast enough. This is cause for concern. There is a need for alternative energy providing sources that can be regenerated. Recent researches suggest that hydrocarbon producing plants can become alternative energy sources, which can be inexhaustible and ideal for liquid fuel. These plants called petroplants/petrocrops can be grown on land which are unfit for agriculture and not covered with forests. The most critical step in bioenergy production is the selection of plant species that produce substances from which useful products can be extracted in an economically viable way.

Many such promising species belong to the families Asclepiadaceae, Asteraceae, Anacardiaceae Euphorbiaceae, Convolvulaceae, Caprifoliaceae, Lamiaceae, and Moraceae. Jatropa Curcas is an important petro plant.

Jatropa Curcas : A fuel plant

Potential of Biomass Energy in India

India has a potential of about 18 GW of energy from Biomass. Currently, about 32% of total primary energy used in India is derived from Biomass. More than 70% of the country’s population depends upon biomass for its energy needs. India has ~5+ GW capacity biomass powered plants: 83% are grid connected while the remaining 17% are off-grid plants. The off- grid plants are divided between co-generation plants that do not utilize bagasse, biomass gasifiers for rural applications and biomass gasifiers for thermal applications in industry. Around 70 Co-generation projects are under implementation with surplus capacity aggregating to 800 MW.

Biomass potential of the world

The world production of biomass is estimated at 146 billion metric tons a year, mostly wild plant growth. Biomass accounts for 35% of primary energy consumption in developing countries, raising the world total to 14% of primary energy consumption. In the future, biomass has the potential to provide a cost-effective and sustainable supply of energy, while at the same time aiding countries in meeting their greenhouse gas reduction targets. By the year 2050, it is estimated that 90% of the world population will live in developing countries.

Co-generation

Co-generation is producing two forms of energy from one fuel. One of the forms of energy must always be heat and the other may be electricity or mechanical energy in a conventional power plant, fuel is burnt in a boiler to generate high pressure steam. This system is used to drive a turbine, which in turn drives an alternator steam turbine to produce electric power. The exhaust system is generally condensed to water which goes back to the boiler. As the low pressure steam has a large quantum of heat which is lost in the process of condensing, the efficiency of conventional power plant is only around 35%. In a co-generation plant, the low pressure exhaust steam coming out of the turbine is not condensed, but used for heating purposes in factories or houses and thus very high efficiency level, in the range of 75% to 95%, can be reached. Since co-generation can meet both power and heat needs, it has other advantage as well as in the form of significant cost savings for the plant and reduction in emission of pollutants due to reduce fuel consumption.

Potential in India and it's installed capacity

Biomass energy is one of the most important sources of energy forming 32% of total primary energy usage in the country with more than 70% of India's population dependent on it for energy needs.

The current availability of biomass is estimated at about 450-500 mill tonnes annually translating to a potential of around 18000 MW.

In addition, about MW power could be generated through bagasse based co-generation in the country's 550 sugar mills.

Approximately over 300 biomass power and co-generation projects aggerating 3700 MW have been installed in the country for feeding power to the grid. Also, 30 biomass power projects aggregating about 350 MW are under different stages of implementation.

The government plans to meet 20% of the countries diesel requirement by 2020 using bio-diesel. Potential sources of bio-diesel production have been identified in wild plants such as jatropha curcas, neem, mahua, karanj, simarouba (exotic tree) etc.

Geothermal Energy

Geothermal generation first to sing of geothermal energy of the vast reserver of heat stored in the earth's inner core. Below the earth's crust, there is a layer of hot and molten rock called 'magma'. Heat is continually produced there, mostly from the decay of naturally radioactive materials is Uranium and Potassium.

Thermal Energy emit from the Earth surface

How is it captured

Geothermal system can be found in regions with a normal or slightly above normal geothermal gradiant (gradual change in temperature is known as the geothermal gradiant, which expresses the increase in temperature with depth in the earth's crust. The average geothermal gradiant is about 2.5-3 ℃/100 m.) and especially in regions around plate margins where the geothermal gradiants may be significantly higher than the average value.

The most current way of capturing the energy from geothermal sources is to tap into naturally occurring "hydrothermal convection" systems where cooler water seeps into the earth's crust, is heated up and then rises to the surface. When heated water is forced to the surface, it is relatively easy to capture that steam and use it to drive electric generators.

Fuel Cells

Fuel cells are electrochemical devices that convert the chemical energy of a fuel directly and very efficiently into electricity (DC) and heat, thus doing away with combustion. The most suitable fuel for such cell is hydrogen. A fuel cell consists of an electrolyte sand witched between two electrodes. Oxygen passes over one electrode and hydrogen over the other, and they react electrochemically to generate electricity, water, and heat.

Hydrogen Fuel Engine

Fuel cells for automobile transport

Compared to vehicles powered by the internal combustion engine, fuel cell powered vehicles have very high energy conversion efficiency, and near-zero pollution, CO2 and water vapour being the only emissions. Fuel-cell- powered EV's (electronic vehicles) score over battery operated EV's  in terms of increased efficiency and easier and faster refuelling. In India, diesel run buses are a major means of transport and these emit significant quantities of SPM and SO2. Thus, fuel-cell powered buses and electric vehicles could be introduced with relative ease to dramatically reduce urban air pollution and to make a positive impact on urban air quality.

Fuel cells can supply combined heat and power to commercial buildings, hospitals, airports, and military installation at remote locations. Fuel cells have efficiency levels up to 55% as compared to 35% of conventional power plants. The emissions are significantly lower (CO2 and water vapour being the only emissions). Fuel cell systems are modular (i.e additional capacity can be added when ever required with relative ease) and can be set up where ever power is required.

REN21

REN21 is the global renewable energy policy multi-stake-holder network that connects a wide range of key actors form -

• Governments
• International organisation
• Industry associations
• Science and academia as well as civil society

To facilitate knowledge exchange, policy development and joint action towards a rapid global transition to renewable energy. REN21 promotes renewable energy to meet the needs of both industrialized and developing countries that are driven by climate change, energy security, development and poverty allevation.

REN21 is an international non-profit association and committed to the following objectives

• Providing policy-relevant information and research-based analysis on renewable energy to decision makers, multipliers and the public to catalyses policy change.
• Offering a platform for interconnection between multi-stakeholders actors working in the renewable energy field worldwide and identifying barriers as well as working to bridge existing gaps to increase the large-scale deployment of renewable energy worldwide.

International Renewable Energy Agency (IRENA)

IRENA has 150 member nations with Headquarters in Abu Dhabi.

The International Renewable Energy Agency (IRENA) is an intergovernmental organization that supports countries in their transition to a sustainable energy future, and serves as the principal platform for international cooperation, a centre of excellence, and a repository of policy, technology, resource and financial knowledge on renewable energy.

IRENA promotes the widespread adoption and sustainable use of all forms of renewable energy, including bioenergy, geothermal, hydro-power, ocean, solar and wind energy the pursuit of sustainable development, energy access, energy security and low-carbon economic growth and prosperity.

IRENA Official Logo

Conclusion

Efficient use of renewable energy would reduce our dependence on non-renewable sources of energy, make us energy self-sufficient and make our environment cleaner. As more green power sources are developed - displacing conventional generation - the overall environmental impacts associated with electricity generation will be significantly reduced.

Pollution : Effects & Measures

Pollution

Definition

An undesirable change in the physical, chemical and biological characteristics of the environment especially air, water, land and space that may adversely affect human population and the wild life, industrial processes, cultural assets (building and monuments), is called  pollution. 

The agents that pollute the environment or cause pollution are called pollutants.

Classifications

1. According to the form in which they persist after release into the environment

• Primary pollutants : These persist in the form in which they added to the environment e.g. DDT, plastic.
• Secondary pollutants : These are formed by interaction among the primary pollutants. e.g. peroxyacetyl nitrate (PAN) is formed by the interaction of nitrogen oxides and hydrocarbons. 

     2. According to their existence in nature.

• Quantitative pollutants : These occur in nature and become pollutant when there concentration reaches beyond threshold level e.g. carbon dioxide, nitrogen oxide. 
• Qualitative pollutants :  These do not occur in nature and are man-made. e.g. fungicide, herbicide, DDT etc.

     3. According to the nature of disposal.

• Biodegradable pollutants : Waste products which are degraded by microbial action e.g. Sewage. 
• Non Biodegradable pollutants : Pollutants which are not decomposed by microbial action e.g. plastic, glass, DDT, salts of heavy metal radioactive substances etc.

   

4. According to origin

 

1. Natural 
2. Anthropogenic

Causes of pollution

• Uncontrolled growth in human population
• Rapid industrialization
• Urbanization 
• Uncontrolled exploitation of nature
• Forest fires, radioactivity, volcanic eruptions, strong wind etc.

Types of pollution

Depending upon the area or the part of environment affected, pollution may be of the following types :

• Air pollution 
• Water pollution 
• Land pollution 
• Noise pollution
• Radioactive Pollution
• Thermal Pollution
• Space Pollution

Air Pollution

Air Pollution

Sources

i) Natural sources 

    

    (i) Ash from burning volcanoes, dust from storm, forest fires 

    (ii) Pollen  grains from flowers in air are natural sources of pollution 

ii)  Anthropogenic (human-made) sources                   

  (i) Power stations using coal or crude oil release CO2  in air 

 (ii) Also furnaces using coal, cattle dung cakes, firewood, kerosene, etc. 

 (iii) Steam engines used in railways, steamers, motor vehicles, etc. give out CO2. 

 (iv) So  do  motor and internal combustion engines which run on petrol, diesel, kerosene. etc.

(v) Vegetable oils, kerosene, and coal as household fuels 

(vi) Sewers and domestic drains emanating foul gases 

(vii) Pesticide residues in air

Major Air Pollutants

1. Carbon dioxide 

The increasing CO2  in the atmosphere is likely to have the following effects: 

(i) A rise in atmospheric temperature or  global warming due to greenhouse effect.  Also causes climate change. 

(ii) Reduced productivity of the marine ecosystem.

(iii) Due to Global warming,  the increased surface temperature would cause melting of continental and mountain glaciers  and thus would cause  flooding of coastal areas  of some countries. 

2. Sulphur dioxide

It is produced by the burning of coal in powerhouses and automobiles (car, trucks etc.).  It causes  chlorosis  and  necrosis  of plants, irritation in eyes and injury to the respiratory tract (asthma, bronchitis) in humans responsible for discoloration and deterioration of buildings. High concentration of sulphur dioxide in the atmosphere dissolves in rain drops to form sulphuric acid which causes  acid rain. 

3. Carbon monoxide 

Carbon monoxide is produced as a result of incomplete combustion of fossil fuels like coal, petroleum and wood charcoal.  Automobiles using diesel and petroleum are the major sources of carbon monoxide which gets added to the atmosphere.

4. Fluorides 

Upon heating„ rocks, soils and minerals that contain fluorides, give out hydrogen fluoride gas.  This is an extremely toxic gas, which causes serious injury to livestock and cattle. 

5. Oxides of nitrogen 

A few oxides of nitrogen, such as nitric oxide (NO), nitrous oxide (N2O) and nitrogen dioxide (NO2) are produced by natural processes as well as from thermal power stations, factories, automobiles and aircrafts (due to burning of coal and petroleum). They reduce the oxygen carrying capacity of blood, may cause eye irritation and skin cancer in human beings.

6. Smog 

Smog is a mixture of smoke, dust particles and small drops of fog.  Smog may cause necrosis and develop a white coating on the leaves (silvering) of plants. 

7. Aerosol spray propellants 

Suspended fine particles in the air  are known as aerosols.  Aerosols  contain chlorofluorocarbon carbons (CFCs) and fluorocarbons used in refrigerants and aerosol cans.  They cause depletion of the ozone layer.

Effects of Air Pollution

Prevention and control of air  pollution 

There are two types of air pollutants—gaseous and particulate. 

Methods of controlling gaseous air  pollutants 

(i) Combustion.  

This technique is used for controlling those air pollutants that are in the form of organic gases or vapours. In this technique, the organic air pollutants are subjected to flame combustion technique (also known as catalytic combustion). In this technique, organic pollutants are converted into less harmful products and water vapour. 

(ii) Absorption.  

Absorption is a process in which a substance penetrates into another substance like scrubbers. In this technique, gaseous pollutants are passed through absorbing material like scrubbers.  These scrubbers contain a liquid absorbent.  This liquid absorbent removes the pollutants present in gaseous effluents.  Thus the air coming into scrubber is free from pollutants and it is discharged into atmosphere. 

(iii) Adsorption. 

Adsorption is a process in which a substance sticks to the surface of another substance (called absorbent). In this technique, gaseous effluents are passed through porous solid absorbent kept in containers.  The gaseous pollutants stick to the surface of the porous material and clean air passes through.  The organic and inorganic constituents of gaseous effluents are trapped at the interface of solid adsorbent by physical adsorbent. 

Methods to control particulate air  pollutants 

The particulate air pollutants such as dust, soot, fly ash etc. can be controlled by using fabric filters, electrostatic precipitators, wet scrubbers and mechanical devices etc. 

(i) Fabric filters.  

In this technique, gaseous emission containing dust, soot and fly ash is passed through porous fabric filters made of fabric  (cloth) (woven or filled fabric).  The particles of pollutants get trapped in this fabric and are collected in the filter and the gases free from the pollutant particles are discharged. 

(ii) Mechanical devices.  

There are many mechanical devices that clean the air of pollutants either due to 

(a) gravity in which the particles settle down by gravitational force; or by 

(b) sudden change in the direction of gas flow in which particles separate out due to greater momentum. 

(c) Electrostatic precipitators.  

In this technique, a gas or air stream containing aerosols in the form of dust, mist or fumes, is passed between the two electrodes of the electrostatic precipitator. During this process, the aerosol particles get precipitated on the electrodes.

Water Pollution

Any physical, biological or chemical change in water quality that adversely affects living organisms or makes water unsuitable for desired use is called water pollution.

Water Pollution

Sources of water  pollution

  (i) point sources; and 

  (ii) non-point sources.

(i) Point sources  

Those sources which discharge water pollutants directly into the water are known as point sources of water pollution. Oil wells situated near water bodies, factories. power plants, underground coal mines, etc. are point sources of water pollution. 

(ii) Non-point sources

Those sources which do not have any specific location for discharging pollutants, in the water body are known as non-point sources of water pollution. Run-offs from agricultural fields, lawns, gardens, construction sites, roads and streets are some non-point sources of water pollution.

Water Pollutants 

River, lake and sea water may be polluted in many ways. 

• Domestic sewage  discharged into rivers from areas located on its banks 
• Industrial wastes  effluents from urban areas containing high concentration of oil, heavy metals and detergents 
• Minerals, organic wastes  and crop dusting  from agricultural fields with phosphate and nitrogen fertilizers that reach lakes, rivers and sea (water becomes deoxygenated and poisonous, thus, cannot support aquatic life) 
• Chemical fertilizers, pesticides, insecticides, herbicides and plant remains Industrial waste water containing several  chemical pollutants,  such as calcium, magnesium, chlorides, sulphide, carbonates, nitrates, nitrites, heavy metals and radioactive waste from nuclear reactor. 
• Excretory wastes of humans and animals in water  bodies 
• Disposal of urban and industrial waste matter into water bodies.

Effects of Water Pollution

Prevention and control of water pollution

Water pollution can be controlled by

• Treating industrial effluents before discharging into rivers, separate channels for river and sewage water
• Avoid contamination of rivers, lakes and ponds by washing clothes, bathing.etc.
• Not throwing waste, food materials, paper, biodegradable vegetables and plastic into open drains.
• Setting up sewage water treatment plants
• Use of septic tanks in houses to avoid direct outlet of faecal matter and other wastes
• Effluents from distilleries and solid waste containing organic matter diverted to biogas plants to generate energy
• Maintenance or  safety standards  for the effluents discharged into the water system.

Soil Pollution

Addition of substances that change the quality of soil by making it less fertile and unable to support life is called soil pollution. 

Soil Pollution

Sources of soil pollution

Soil pollution is caused due to :

• Domestic sources : plastic bags, kitchen waste, glass bottles, and paper
• Industrial sources : chemical residue, fly ash, metallic waste, and
• Agricultural residues : fertilizers and pesticides.

Harmful effects of soil pollution

• Decrease in irrigated land thereby reduction in agricultural production.
• Decrease in soil productivity.
• Carry over of pollutants into the food chain.
• Damage to landscape

Control of Soil Pollution

• Judicious use of chemical fertilizers and pesticides.
• Proper and appropriate irrigation practices
• Conversion of farm wastes into compost and much use of bio fertilizers and manure in farming.
• Ensure use of pollution free or treated waste water only for irrigation. 
• Recycling of waste material for example plastic, metal and glass are recyclable and incineration of non recyclable, wastes.

Soil Erosion 

The process of detaching and removal of loosened soil particles by water (running water, ground water, rain, sea waves) and wind is known as soil erosion.  Soil may be eroded by water and wind, each contributing towards a significant amount of soil loss every year in our country. 

Soil Erosion

Types of soil erosion 

1. Wind erosion 

Erosion of large quantity of fine soil particles and sand from deserts by wind is known as wind erosion. It is spread over the cultivated land and thus, destroys fertility of that land. 

2. Sheet erosion 

When water moves over the land surface as a sheet, it takes away the topmost thin layer of soil.  This phenomenon occurs uniformly on the slopes of hilly areas, riverbeds and areas affected by floods.  This type of erosion is known as  sheet erosion. 

3. Gully erosion 

When water moves down the slope as a channel, it scoops out the soil and forms gullies which gradually multiply and spread over a large area.  This type of soil erosion is known as  gully erosion. 

Gully Erosion

Effects of soil erosion 

Soil erosion may have several adverse effects such as,

• The top layer of productive land may be washed away. 
• Roads, fences, bridges, trees and houses may get damaged. 
• Fine soil may be transported far away. 
• Crops and pasture lands may be destroyed either by being washed out or by getting covered with mud. 
• Flooded fields may take a long time to recover and fertilizers may also be washed out leading to reduction in agricultural yield. 
• Organic matter of the soil, residues or any applied manure, is relatively lightweight and can be readily washed off the field. Crop emergence, growth and yield are directly affected by the loss of natural nutrients and fertilizers in the soil. Seeds and plants can get disturbed or completely removed from the eroded soil. 
• Soil erosion changes the composition of soil leaving infertile rock behind. Soil quality, structure. stability and texture may also be affected.
• The breakdown of aggregates and the removal of smaller particles or entire layers of soil or organic matter can weaken the structure and even change the texture.  Textural changes can in turn affect the water-holding capacity of the soil making it more susceptible to extreme conditions, such as drought. 
• Sediment which reaches streams or water-courses due to soil erosion clog drainage and stream channels, deposit silt in reservoirs and reduce quality downstream water. 

Causes of Soil Erosion 

(i) Natural Sources 

Water Erosion:  

During rainfall, drops of rain can break down soil aggregates and disperse them.  The loosened soil particles are transported with the runoff water. If vegetation is depleted by drought, raindrops are free to hit the soil, causing erosion during rainfall. 

Water Erosion

Wind Erosion: 

Wind can move large amounts of soil.  Wind erosion is a serious means of soil erosion. Blowing soil not only leaves a degraded area behind but can also bury and kill vegetation where it settles.  Winds blow away the fine particles of soil during drought. 

Wind Erosion

(ii)  Anthropogenic (Produced by humans) 

• Extensive cutting down of forests and trees exposes the ground surface to the direct impact of rain and wind. For example, in the absence of proper vegetation cover there is no interception of rainfall and the falling rain strikes the soil surface directly resulting in the throwing up of loose soil particles in the air which are washed away by rainwater. 
• Construction work, mining, digging canals and ditches change the structure of soil.  This accelerates soil erosion due to high-speed winds as well as rainwater. 
• While making roads. soil is cut and massive digging of earth takes place.  This leads to soil erosion by water or wind. 
• Excessive use of plough, machines, fertilizers and irrigation may damage the land. 
• In many areas, trees and grasses are depleted because of overgrazing by animals. This makes the soil susceptible to erosion. 

Prevention of soil erosion 

Some methods to control soil erosion are discussed below. 

• The roots of the trees hold soil material together.  Therefore, we should protect our forests and trees from being cut down.  Afforestation means planting trees in place of cut-down forest trees. Planting of trees along river-side, waste lands and mountainous slopes reduces excessive erosion of soil that takes place in these regions. It is also effective in controlling wind erosion.
• Grazing by domesticated animals in a planned way reduces soil erosion by protecting vegetation cover specially on the hill slopes which are more prone to soil erosion. 
• Protected channels for water movement must be provided to stop soil erosion. If the waterways are properly maintained the speed of water gets reduced and soil erosion decreases. Dam should be constructed on rivers to control flooding and consequently soil erosion.  This can also be done by diverting water to dry areas through canals, in a planned way. 
• Obstructions known as bunds should be constructed in lands affected by gully erosion. 
• Terracing is a method of farming to conserve the thin soil layer on the mountain slopes.  This helps in controlling soil erosion and using water resources of these areas more economically and effectively for growing crops on these terraces. 
• Ploughing and tilling of land along the contour levels in order to cause furrows to run across the land slopes is known as the contour ploughing.  This method is most suited to areas that have a rolling landscape. 
• Windbreaks which means planting trees to protect bare soil from the full force of wind also help in preventing soil erosion by wind.  Windbreaks reduce the velocity of wind thereby decreasing the amount of soil that it can carry away.

Noise pollution 

Noise can be simply defined as “unwanted sound’’. It is generally higher in urban and industrial areas than in rural areas.  Workers using heavy machinery are exposed to high noise levels for long period of work hours every day. Intensity of sound is measured in a unit called  decibel  or  dB.  The lowest intensity of sound that human ear can hear is 20 dB.

Noise Pollution : Heavy Machinery at Construction

Sources of noise pollution 

The major sources of noise pollution are : 

• Use of loud speakers, loud music system and television at public places 
• Means of transport i.e. automobiles, railways, aircrafts, etc. 
• Heavy machines in industries fireworks.

Effects of noise pollution

• Inability to sleep, slow recovery from sickness. 
• Irritability and interference in communication. 
• Temporary loss of hearing, earache, sometimes even leading to permanent deafness. 
• Inability to concentrate, headache.
• Ringing of ears (a feeling, sound coming from within the ear in a very quiet environment). 
• Increased blood pressure, irregular heart beat.

Prevention and control of noise pollution

Following steps can be taken to control or minimize noise pollution : 

• Control the noise emanating from your radio and television. 
• Use automobile horn only in case of emergency. 
• Do not burn fire crackers as they are noisy and also cause air pollution. 
• Get all machinery and engines properly tuned and serviced at regular intervals and by the use of silencers. 
• Use of sound proof cabins and sound-absorbing materials in the walls. A  green belt of vegetation is an efficient absorber of noise. 
• Not playing loudspeakers during odd hours. It is legally banned and should be reported to the police immediately.

Radioactive Pollution

Radioactive is a phenomenon of spontaneous emission of proton (Alpha particle), electrons (beta particles) and gamma rays (shortwave electromagnetic waves) due to disintegration of atomic nuclei of some elements. These causes radioactive pollution.

Radioactive Container

Radioactivity : Radioactivity is a property of set an elements radium, thorium uranium etc.) spontaneously emit protons, electrons, and gamma rays by disintegration of their atomic nuclei.

Types of radiations

• Non-ionizing radiation affect only those components which absorb them and have low penetrability.
• Ionizing radiations have high penetration power and cause breakage of macro molecules.

Types of radiation particle

• Alpha particles can be blocked by a piece of paper and human skin.
• Beta particles can penetrate through skin, while can be blocked by some piece of glass and metal.
• Gamma rays can penetrate easily to human skin and then cell on its way through, reaching far, and can only be blocked by very thick, strong, massive piece of concrete.

Sources

Natural

• They include cosmic rays from space and terrestrial radiations from radio-nuclides present in earth's crust such as radium-224, uranium-238, thorium-232, potassium-40, carbon-14, etc.

Man-made

• Nuclear power plants
• Nuclear weapon
• Transportation of nuclear material
• Disposal of nuclear waste
• Uranium mining
• Radiation therapy

Effects

• The effects of radioactive pollutant depend upon

1. half-life
2. energy releasing capacity
3. rate of diffusion
4. rate of diffusion of pollutants

 Control Measures

• Prevention is the best control measure as there is no cure available for radiation damage.

1. All safety measures should be strictly enforced. Leakage of radioactive elements should be totally checked.
2. Safe disposal of radioactive waste.
3. Regular monitoring through frequent sampling and quantative analysis.
4. Safety measures against nuclear accidents.
5. Nuclear explosions and use of nuclear weapons should be completely banned.
6. Appropriate steps should be taken to protect from occupational exposure.

E-Waste

• The discarded and end-of-life electronic products ranging from computers, equipment used in Information and Communication Technology (ICT), home appliances, audio and video products and all of their peripherals, are popularly known as Electronic waste (E-waste).
• E-waste is not hazardous if it is stocked in safe storage or recycled by scientific methods or transported from one place to the other in parts or in totality in the formal sector. The e-waste can, however, be considered hazardous if recycled by primitive methods.

Electronics Hardware Wastes

Solid Waste

Solid wastes are the discarded (abandoned or considered waste-like) materials. Solid waste means any garbage, refuse, sludge from a wastewater treatment plant, or air pollution control facility and other discarded materials including solid, liquid, semi-solid, or contained gaseous material, resulting from industrial, commercial, mining and agricultural operations, and from community activities. But it does not include solid or dissolved materials in irrigation return flows or industrial discharges.

Garbage heap

Plastic Waste

Plastic are considered to be one of the wonderful inventions of 20th century. They are widely used as packing and carry bags because of cost and convenience. But plastics are now considered as environmental hazard due to the "Throw away culture".

A Boy playing in plastic wastes

Sources of generation of waste plastics

• Household
• Health and medicare
• Hotel and catering
• Air/rail travel

Types

• Solid wastes are classified depending on their source:

1. Municipal Waste
2. Hazardous Waste and
3. Biomedical Waste or Hospital Waste

Thermal Pollution

Thermal pollution is the rise or fall in the temperature of a natural aquatic environment caused by human influence. This has become an increasing and the most current pollution, owing to the increasing call of globalization everywhere.

Thermal pollution is caused by either dumping hot water from factories and power plants or removing trees and vegetation that shade streams, permitting sunlight to raise the temperature of these waters, release of cold water which lowers the temperature. Like other forms of water pollution, thermal pollution is widespread, affecting many lakes and vast numbers of streams and rivers in various parts of the world.

Hot Smoke

Major sources

• power plants creating electrify from fossil fuel
• water as a cooling agent in industrial facilities
• deforestation of the shoreline
• soil erosion

Ecological Effects - Warm Water

The change in temperature impacts organisms by

1. decreasing oxygen supply, and
2. affecting ecosystem composition

Warm water contains less oxygen. Elevated temperature typically decreases the level of dissolved oxygen (DO) in water. So there is decrease in rate of decomposition of organic matter. Green algae are replaced by less desirable blue green algae. Many animals fail to multiply. It also increases the metabolic rate of aquatic animals results in consumption of more food in a shorter time than if environment were not changed. An increase metabolic rate may result in food source shortages, causing a sharp decrease in population.

Ecological Effects - Cold Water

Thermal pollution can be caused by the release of very cold water from the base of reservoirs into warmer rivers. This affect fish (particularly their eggs and larvae), macro invertebrates.

Space Pollution

• Space Debris, also known as orbital debris, space junk and space waste, is the collection of defunct objects in orbit around the Earth.
• This includes everything from spent rocket stages, old satellites, fragments from disintegration, erosion and collision.

Space Debris

Effects

• Debris poses a growing threat to satellites and could prevent the use of valuable orbits in the future.
• Many pieces of debris are too small to monitor but too large to shield satellites against.

Types of orbits

1. Low Earth Orbit (altitude between 160 km and 2000 km from the Earth's surface)
2. Medium Earth Orbit (2000 km to 36000 km)
3. Geostationary Earth Orbit (35786 km and above)
4. High Earth Orbit (above 36000 km)

Debris in LEO (Low Earth Orbit)

• Satellites in LEO are many different orbitals planes providing global coverage and the 15 orbits per day typical of LEO satellites result in frequent approaches between object pairs.
• After space debris is created, the orbital plane's direction will change over time, and thus collisions can occur from virtually any direction. This leads to cascading effect.

Debris at higher altitudes

• At higher altitudes, where atmospheric drag is less significant, orbital decay takes much longer.
• This issue is especially problematic in the valuable GEO orbits where satellites are often clustered to share the same orbital paths.

Earth Surrounded by debris

Sources of debris

• Dead spacecrafts
• Boosters
• Lost equipment

Clearance of space debris

i) Tug like satellites

• It drag the debris to a safe altitude in order to burn up in the atmosphere.
• It creates an electron emission to create a difference in potential between the debris as negative and itself as positive.
• The satellite then uses its own thrusters to propel itself along with the debris to a safer orbit.

ii) Electrodynamic tethers

• It provides a simple and reliable alternative to the conventional rocket thrusters.
• It works on the basic principle of Lorentz force and Fleming's Left hand rule.
• Magnetic force is exerted on a current carrying wire in a direction perpendicular to both the flow of current and the magnetic field.

iii) Laser Brooms

• The laser broom uses a powerful ground based laser to ablate the front surface off debris and thereby produce a rocket like thrust that slows the object.
• With continued application the debris will eventually decrease their altitude enough to become subject to atmospheric drag.
• Additionally, the momentum of photons in the laser beam could be used to impart thrust in the debris directly.

iv) Solar Sails

• The Solar sails uses the pressure from sunlight to navigate an object, just like a naval sail uses wind.
• This way debris can be navigated out of orbit and bum into the atmosphere.

v) Space nets

• Space nets or umbrellas are satellites which eject a huge net that fishes or collects the debris and is later disposed off into a graveyard orbit.

vi) Collector Satellite

• The most commonly used collector satellite is the sling sat.
• It has two extended arms which collect the debris as it is in motion.