01_EnvComponents

8/10/2019 01_EnvComponents

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Environment & Its Components

Classification of EnvThe term ENV can be broadly defined as ones surroundings . To be more precise, we can saythat it is the physical & biological habitat that surrounds us, which can be felt by our physicalfaculties.

2 major classification of env are1. Physical Env - External physical factors like Air, Water, Land etc. Also called Abiotic

Env .2. Living Env - All living organisms around us like plants, animals etc. Also called Biotic

Env .

Earths env can be further subdivided into

Lithosphere - consisting of soil & rock. Hydrosphere - comprises all water resources both surface & groundwater. Biosphere - capsule encircling the earths surface wherein all the living things exist. Life

forms do not exist outside this zone. Biosphere covers parts of other segments of the env. Atmosphere - Gaseous envelope surrounding the earth and extends up to 500 KM above

earths surface. Atmosphere protects from cosmic radiations (UV), helps to maintain the

heat balance & medium of carriage of water from oceans to land.

The atmosphere can further divided into 4 major zones. Troposphere - is the layer of air nearest to the ground. Temperature decreases with

height. Most of the weather occurs in troposphere. Tropopause is the top of thetroposphere, which is a transition layer between troposphere and stratosphere.


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Stratosphere - is the layer above the troposphere where temp increases with height.Ozone is found in higher concentrations between 20 & 30 KM and hence this layer issometimes called Ozone layer. Stratopause is the top of stratosphere, which is a transitionlayer between stratosphere and mesosphere.

Mesosphere - Mesosphere is the layer of air above the stratosphere where temperaturedecreases with height. This is the coldest layer of the atmosphere. Mesopause is the topof the mesosphere, which is a transition layer between Mesosphere and Thermosphere.

Thermosphere - Thermosphere is the layer of air above the mesosphere. The temperaturesin the thermosphere increase with increasing height, but there are not many molecules inthis layer. The air becomes less and less dense as we reach space.

Every sphere has a flow of matter and energy to every other sphere. Such 2 way interactions arealso taking place within individual spheres. Env problems are hence not confined only to thecomponent/system where they arise, but spread to other components as well.

A Classical example is the buildup of gases like Carbon dioxide in the atmosphere. Theemissions may be localized but the impact is massive and global in nature leading to globalwarming which has far reaching consequences in terms of both area and time.

Ecology & EcosystemsEcology is the study of the interactions that take place among organisms and their env.

1. Autoecology or Species Ecology - This is the study of an individual species.2. Synecology or Ecology of Communities - This is the study of communities and their

interaction with the env.

An Ecosystem is defined as a group of plants, animals or living organisms living together andinteracting with the physical environment in which they live. An Eco system has a more or less aclosed boundary and the flow of mass in and out of the system is very less as compared to theinternal movement of mass. Ecosystems can be large or small. Examples of large ecosystems arerain forests, deserts, salt marshes, coral reefs, lakes and ponds, open ocean, grasslands etc.

Ecosystem can be classified as1. Natural ecosystem2. Artificial or Man made ecosystem


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Natural ecosystem operates by themselves under natural conditions without any majorinterference by man. On the basis of habitat, natural ecosystems can further classified as forestgrassland, desert & aquatic.

Artificial ecosystem is maintained by man, by addition of energy and planned manipulation. Forexample crop lands like wheat, rice etc, where man tries to control the biotic community as wellas the physical.

Any ecosystem consists of both living (biotic) and nonliving (abiotic) components, which arecalled env or ecological factors.

Abiotic Components

The physical factors of the env, which are non living, have a major influence on the life oforganisms.

Climatic factors consists of temp, rainfall, snow, wind, light, humidity etc. These areitself result of several other factors such as latitude, elevation, nearness to sea, monsoonactivities, ocean currents etc.

Edaphic or Soil factors are pH, mineral & organic matter in soil and texture of soil.

Biotic FactorsThe live component of an ecosystem comprises plants, animals & microorganisms. They carry

out different functions and based on their role they are classified into 3 main groups. Producers - mainly plants those produce carbohydrates through photosynthesis process.

In effect, plants convert solar energy into chemical energy using water and carbondioxide. These are called Autotrophs (self feeder) since they produce their own food. Partof the food produced by autotrophs are utilized for their own consumption for survival &growth while the remaining is stored in the plant parts for future consumption. This

becomes food for other biotic components in the env.


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Consumers - are living things who are unable to produce their own food. They rely on producers for their food requirements. Also known as heterotrophs.

Primary consumers or Herbivores - also known as first order consumers, they eatthe producers or plants. Cow, goat, deer, rabbit etc.

Secondary consumers or Carnivores - also known as second order consumers,they eat primary consumers. Cats, snakes etc.

Tertiary consumers - also known as third order consumers, they feed on secondorder consumers. Wolf.

Decomposers - called as saprotrophs are mainly microorganisms like Bacteria & fungi.The dead organic materials of producers & consumers are their food. They breakdownthe organic matter into simple compounds during their metabolic process. These simplecompounds are nutrients which are absorbed by the producers this completing a cycleexchange matter between biotic and abiotic components of the ecosystem.

Natural Resources - Forest, Fisheries, Wildlife & Energy Natural resources are the various life supporting components of the biosphere, which can bedrawn and utilized by the organisms from their env. These resources include energy, air, water,land, minerals, plants, animals, forests, forest products etc.

More commonly, natural resources can be classified as Inexhaustible - wind, tidal energy etc. Exhaustible - ground water, minerals, fuels etc.

Exhaustible resources can be further classified as renewable & non renewable.


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The resources that can be regenerated artificially or naturally (such as from the biomass of livingorganisms) are called renewable resources. E.g. crops, forests and other vegetations, wild anddomestic animals, microorganisms, water, land (soil), etc.

Non renewable resources are those natural resources which cannot be regenerated or replacedafter use or which lack the ability for recycling. Resources with a very long recycling time arealso considered non renewable e.g. fossil fuels (like coal, oil, natural gas) metals, minerals andores, rocks, etc.

ForestsForests are the vast renewable natural resources. Forests are of immense biological andecological significance. For example

They are the source of forest products like fuel, timber, lumber, food, medicinal plants,fodder, etc.

They provide ideal habitat for wildlife. They provide vegetation cover to the soil and thus check surface evaporation, increase

water-retaining capacity of soil and prevent floods and soil erosion by soil binding. They help in recycling of moisture in the nature and regulate rainfall. Indiscriminate deforestation reduces rainfall, groundwater level and makes the land

barren. This alters the climate of the region. In addition, it disturbs and destroys the wildlife.

Hence, conservation of forest is essential. There should be proper balance between harvest of

forest and its resources on the one hand and the afforestation on the other.

WildlifeIn a broader sense, the term wildlife covers any or all organisms which are non-cultivated (e.g.wild plants) and non-domesticated (e.g. wild animals). It also includes microorganisms and allother lesser-known human beings.


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One important and essential characteristic feature of the wildlife is that they are very welladapted to their natural environmental conditions. Hence, they grow and survive in their naturalhabitat without the care of human beings.

Existence of wildlife at all levels of the food chains in any ecosystem is essential for maintainingthe ecological balance of that ecosystem. In addition, it must be saved and preserved to maintainthe diversity of life. However, wildlife is often threatened with elimination from the region orextinction from the earth.

Thus, to save the wildlife and preserve the diversity of life on earth, it is essential to take definitesteps towards conservation of wildlife.

EnergyEnergy is the capacity to do work. It is needed by all organisms for maintenance of life.

Similarly, energy is needed constantly and on very large scale for domestic, industrial andtechnological purposes. In fact, the progress of human civilization and the economic growth ofevery country largely depend on the resource and supply of energy.

The more commonly used conventional source of energy is the various kinds of fossil fuels.These include petroleum, natural gas (e.g. methane), coal, and synfuels (i.e. naturally occurringorganic products which can be converted into synthetic petroleum) such as oil shale, tar sands,etc.

However, all the fossil fuels are the exhaustible non-renewable natural resources and shall befinished eventually. The realization of this fact is creating the fear of inevitable energy crisis allover the world. Hence, much before the crisis is reached, it is imperative to

Adopt urgent measures to conserve and regulate the existing stock of non-renewableenergy resources and

To find some suitable inexhaustible and/or renewable alternative energy resources.

In this regard, the following non-conventional renewable sources of energy hold considerable potential and promise, if investigated and exploited properly. These are

Solar energy Wind energy Tidal (ocean) energy Geothermal energy, etc.

In addition, there are number of biomass-based renewable energy systems. These include energysources such as


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Fire wood Petro plants (i.e. potential plant species, which can be the source of liquid hydrocarbons

to be used as a substitute for liquid fuels. Biogas Electric energy, etc.

Energy Flow & Food ChainThe sun is the source of all our energy. It is a continuously exploding hydrogen bomb wherehydrogen is converted to helium with the release of energy. Plants convert this energy intocarbohydrates and sugars using carbon dioxide and water. This process is known as

photosynthesis .

The carbohydrates undergo further modifications such as production of proteins, Suns energy

thus enters the living being and is passed from one organism to another in the form of food. Theflow of energy is unidirectional and is governed by the thermodynamic law that states thatenergy is neither created nor destroyed and can transform into different forms.

When energy travels from producers to different levels of consumers in an ecosystem there isloss at each level due to the energy dissipated as heat during the metabolic processes of theorganisms. Hence as we move step by step away from the primary producers the amount ofavailable energy decreases rapidly. Hence only 3 to 5 feeding levels are possible.

Food chain is an ideal model of flow of energy in the ecosystem. According to this model, the plants or producers are eaten by only the primary consumers, primary consumers are eaten byonly the secondary consumers & so on. The energy efficiency of each level is very low. Henceshorter the food chain greater will be the availability of food.

A typical food chain in a field of ecosystem might beGrass Grasshopper Mouse Snake Hawk


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Material FlowAs energy flows through the ecosystem, there is also a constant flow of matter. Living beingstake up several nutrients from their abiotic env and then they die, they are returned to the env.This cyclical movement of nutrient material between the biotic and abiotic env is calledBiogeochemical Cycle.

The most important & common biogeochemical cycles are Water cycle Carbon cycle Oxygen cycle Nitrogen cycle Sulphur cycle Phosphorous cycle

Water Cycle


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Water is a vitally important renewable natural resource. All organisms need water for survival.Rivers, lakes, ponds, and groundwater are the reservoirs of fresh water while oceans are the hugereservoirs of marine water. Rainwater is the natural source for the renewal/replenishment of thewater in these reservoirs.

Drought and floods are the two main natural factors responsible for the loss of natural waterresources directly or indirectly. In addition, non-judicious use and undue wastage by man alsocontribute towards the loss of available water. In addition, pollution of water renders itunsuitable for consumption as well as for existence of aquatic flora and fauna.

Reduction in soil water or non-availability of water directly affects vegetation growth anddisturbs the environment as a whole.

Water can be conserved by holding the rainwater in catchments areas by constructing dams andthen regulating the water supply through canals. Similarly, growing vegetation cover helps toretain soil water.

There is a constant and continuous exchange of water between air, land, sea & living beings.Considerable part of solar energy on earth is used for the massive evaporation of water fromvarious water bodies like rivers, oceans, lakes, streams etc. This leads to cloud formation and

precipitation in the form of rainfall & snow. This is the major source of fresh water for the living

beings. Surface water run off result in part of freshwater returning to the sea through rivers &streams. Ground water is replenished by surface accumulated water from precipitation. The

plants also absorb ground water. Thus hydrological cycle hence is the continuous and balanced process of evaporation, precipitation, transpiration & infiltration./

Carbon Cycle


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Carbon is an essential component of all plant, animal & organic matter. The atmosphere is animportant source of carbon, which is present in the form of carbon dioxide, which the plants or

producers absorb by photosynthesis and generate several organic compounds. These are passedto consumers in the form of food. Part of this is returned to the atmosphere by respiration. Thedead organic matter from plants and animals are decomposed by microorganisms releasingcarbon dioxide to the atmosphere. Burning of fossil fuels releases large quantities of carbondioxide.

The seas & oceans also serve as a sink for carbon dioxide by absorbing the same and convertingit into bicarbonates and mineral deposits.

Oxygen CycleOxygen is essential for the existence of all flora & fauna. The source of oxygen is atmosphere.Plants and animals absorb oxygen during respiration either from air or water. Part of the oxygen

returns to the atmosphere in the form of CO2 and water vapour in the respiration process itself.Gaseous oxygen is released during photosynthesis process completing the oxygen cycle.


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Agriculture & Eco Friendly FarmingAgriculture is the science & art of cultivation on the soil raising crops and livestocks. This is alsoknown firming.

A farming system can be represented as

Different types of agriculture or farming are

Primitive subsistence Small patches of land.

Primitive tools Family or community labour. Depending on monsoon, natural fertility, pest control etc.

Intensive subsistence Labor intensive.

Commercial Modern techniques Chemical fertilizers, insecticides and pesticides for higher

productivity. Diary, Paultry, Rice, Wheat etc.

Plantation Single crop on larger area. Capital intensive inputs.

Closely associated with related industries. Processing & marketing is very important. Tea, Coffee, Rubber, Sugar etc.

Sustainable AgricultureKey challenges to sustainable agriculture are

Quick rise in population - more people to feed. Greater need for production - existing farms to produce more. Increase in urbanism - less space available for farming. Widespread ecological impact

Many farmers choose to grow cash crops rather than subsistence crops.

Mass production of agricultural products resulted in numerous side effects.

Env Damages Human Impacts

Reduced biodiversity Farm land destruction

Habitat destruction Damage to soil fertility


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Deforestation Reduced nutritional value

Water, air, soil pollution Decreased social, cultural & economic values

Salinization of water

Decline in water resources

Sustainable agriculture refers to an integrated system of plant and animal production practicesthat will

Satisfy human food and fiber needs. Enhance env quality. Most efficient use of renewable resources Sustain economic viability of farming. Enhance quality of life of farmers and society as a whole.

Key env friendly farming practices are1. Crop rotation2. Nature friendly pest control strategies.3. Soil & water conservation practices.4. Usage of animal & green manures.5. Usage of natural or synthetic inputs.6. Natural fertilizers.7. Irrigation canals.8. Raised fields.9. Use of renewable energy.10. Better utilization of waste - biogas plants.


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India 2 /3 indian population engaged in agriculture. Key products - food grains, spices Export tea, coffee, rubber, spices etc. Different crops are grown in different seasons.

Agriculture Reforms Green revolution White revolution

Institutional Reforms Crop insurance against drought, flood, cyclone etc. Establishment of grameen banks / cooperative societies. Bank loans at lower rates.

Other Initiatives Kisan credit card. Personal insurance accident schemes. Weather bulletin / programs on radio, TV Minimum support prices. Subsidies


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Climate ChangeOur weather is always changing and now scientists are discovering that our climate does not staythe same either. Climate, the average weather over a period of many years, differs in regions of

the world that receive different amounts of sunlight and have different geographic factors, suchas proximity to oceans and altitude.

Climates will change if the factors that influence them fluctuate. To change climate on a globalscale, either the amount of heat that is let into the system changes, or the amount of heat that islet out of the system changes. For instance, warming climates are either due to increased heat letinto the Earth or a decrease in the amount of heat that is let out of the atmosphere.

Key climate system components are

1. Atmosphere - fastest changing & most responsive component.2. Ocean - fluid component covering 70% of surface.3. Cryosphere - includes land snow, sea ice, ice sheets, mountain glaciers etc.4. Land & Biomass - includes lakes, streams, soil moisture & vegetation5. Human Interaction - agriculture, urbanization, industry, pollution etc.

Internal Forcing External Forcing

Natural process within the climate system. Type & distribution of species. Changes in ocean currents.

Orbital variations

Changes in atmosphere Daily heating & cooling, gradual buildup of heat wave.

Changes in ice Historical changes near Iceland.


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Changes in vegetation Slow growth of trees to mature.

Changes on ocean Afternoon heating, higher beach temperature, rising sea level,stronger storms & increased storm damages

Changes in land surface Daily heating of upper ground surface, changing landscape, heat

related illness, increased risk of drought, fire & floods, economiclosses

Carbon CreditOur earth is undoubtedly warming. This warming is largely the result of emissions of carbondioxide and other Greenhouse Gases (GHGs) from human activities including industrial

processes, fossil fuel combustion, and changes in land use, such as deforestation etc. Addressingclimate change is not a simple task. To protect ourselves, our economy, and our land from theadverse effects of climate change, we must reduce emissions of carbon dioxide and othergreenhouse gases. To achieve this goal the concept of Carbon Credit has come into vogue.

Carbon credits are certificates issued to countries that reduce their emission of GHG (greenhousegases) which causes global warming.

Carbon credits are measured in units of certified emission reductions (CERs). Each CER isequivalent to one tonne of carbon dioxide reduction.

Under IET (International Emissions Trading) mechanism, countries can trade in the internationalcarbon credit market. Countries with surplus credits can sell the same to countries withquantified emission limitation and reduction commitments under the Kyoto Protocol.


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Developed countries that have exceeded the levels can either cut down emissions, or borrow or buy carbon credits from developing countries.

CARBON CREDITS are generated by enterprises in the developing world that shift to cleanertechnologies and thereby save on energy consumption, consequently reducing their greenhousegas emissions. For each tonne of carbon dioxide (the major Greenhouse gases) emission avoided,the entity can get a carbon emission certificate which they can sell either immediately or througha futures market, just like any other commodity.

The certificates are sold to entities in rich countries, like power utilities, who have emissionreduction targets to achieve and find it cheaper to buy 'offsetting' certificates rather than do aclean-up in their own backyard.

This trade is carried out under a UN-mandated international convention on climate change tohelp rich countries reduce their emissions.

The credit carbon mechanism was formalized in the Kyoto protocol, an international agreement between more than 170 countries, and the market mechanisms were agreed through thesubsequent Marrakesh Accords.

The main aim of this agreement is to reduce the carbon emission in the global atmosphere to balance the natural environment.

Under the Kyoto protocol, CDM or Clean Development Mechanism is established to reduce theemission and contribute to sustainable development of developing countries.

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