Environmental Issues

Class 12 | Biology — Botany | Chapter 8

Class 12 Unit 8 Biology

Chapter 8: Environmental Issues

Learning Objectives

The learner will be able to:

• Understand the importance of growing more plants to mitigate the environmental problems.
• Distinguish between the importance and conservation of endemic and endangered species.
• Appreciate the use of technologies for agriculture and forestry.
• Participate in community activities to improve environmental conditions.
• Develop methods in conservation of water and plants for sustainable development.
• Get acquainted with satellite technology and utilising it in our daily life needs.

Chapter Outline

• 8.1 Green house effect, ozone depletion
• 8.2 Forestry
• 8.3 Deforestation
• 8.4 Afforestation
• 8.5 Alien invasive species
• 8.6 Conservation
• 8.7 Carbon Capture and Storage (CCS)
• 8.8 Rain water harvesting
• 8.9 Environmental Impact Assessment (EIA)
• 8.10 Geographic Information System

After understanding the structure and functions of major ecosystems of the world, now student community should observe and understand environmental problems of their surroundings at local, national and international level. Now we are going to understand some of the environmental issues.

Environmental issues are the problems and harmful effects created by human's unmindful activity and over utilisation of valuable resources obtained from the nature (environment). Student should understand not only the environmental issues we are facing now, but also find solutions to rectify or reduce these problems. Countries of the world agree that something needs to be done about these important environmental issues. Many global summits, conferences and conventions are regularly conducted by the United Nations and many steps are taken to minimise human-induced issues by signing agreements with around 150 countries.

Activity

Students may form 'ECOGROUPS' and discuss eco-issues of their premises and find solutions to the existing problems like, litter disposal, water stagnation, health and hygiene, greening the campus and its maintenance.

Drastic increase in population resulted in demand for more productivity of food materials, fibres, fuels which led to many environmental issues in agriculture, land use modifications resulting in loss of biodiversity, land degradation, reduction in fresh water availability and also resulting in man-made global warming by green house gases even altering climatic conditions.

8.1 Green House Effect and Global Warming

Green House Effect is a process by which radiant heat from the sun is captured by gases in the atmosphere that increase the temperature of the earth ultimately. The gases that capture heat are called Green House Gases which include carbon dioxide (CO₂), methane (CH₄), Nitrous Oxide (N₂O) and a variety of manufactured chemicals like chlorofluorocarbon (CFC). Increase in greenhouse gases lead to irreversible changes in major ecosystems and climate patterns. For example, coral ecosystem is affected by increase in temperature, especially coral bleaching observed in Gulf of Mannar, Tamil Nadu.

Human activities lead to produce the green house effect by:

• Burning fossil fuels, which releases CO₂ and CH₄
• Way of Agriculture and animal husbandry practices
• Electrical gadgets like refrigerator and air conditioners release chloro fluoro carbons
• The fertilizers used in Agriculture which release N₂O
• The emissions from automobiles.

The increase in mean global temperature (highest in 4000 years) due to increased concentration of green house gases is called global warming. One of the reasons for this is over population which creates growing need for food, fibre and fuel and considered to be the major cause of global warming.

Do You Know?

Clouds and Dust particles can also produce Green House effect. That is why clouds, dusts and humid nights are warmer than clear dust free dry nights.

8.1.1 Effects of Global Warming

• Rise in global temperature which causes sea levels to rise as polar ice caps and glaciers begin to melt causing submergence of many coastal cities in many parts of the world.
• There will be a drastic change in weather patterns bringing more floods or droughts in some areas.
• Biological diversity may get modified, some species ranges get redefined.
• Tropics and sub-tropics may face the problem of decreased food production.

8.1.2 Sources of Green House Gases Emission (Natural and Anthropogenic)

CO₂ (Carbon dioxide)

• Coal based power plants, by the burning of fossil fuels for electricity generation.
• Combustion of fuels in the engines of automobiles, commercial vehicles and air planes contribute the most of global warming.
• Agricultural practices like stubble burning result in emission of CO₂.
• Natural from organic matter, volcanoes, warm oceans and sediments.

Methane

Methane is 20 times as effective as CO₂ at trapping heat in the atmosphere. Its sources are attributed paddy cultivation, cattle rearing, bacteria in water bodies, fossil fuel production, ocean, non-wetland soils and forest or wild fires.

N₂O (Nitrous oxide)

It is naturally produced in Oceans from biological sources of soil and water due to microbial actions and rainforests. Man-made sources include nylon and nitric acid production, use of fertilizers in agriculture, manures, cars with catalytic converter and burning of organic matter.

Global Warming Effects on Plants

• Low agricultural productivity in tropics
• Frequent heat waves (Weeds, pests, fungi need warmer temperature)
• Increase of vectors and epidemics
• Strong storms and intense flood damage
• Water crisis and decreased irrigation
• Change in flowering seasons and pollinators
• Change in Species distributional ranges
• Species extinction

8.1.3 Strategies to deal with Global Warming

• Increasing the vegetation cover, grow more trees
• Reducing the use of fossil fuels and green house gases
• Developing alternate renewable sources of energy
• Minimising uses of nitrogeneous fertilizers, and aerosols.

8.1.4 Ozone Depletion

Ozone layer is a region of Earth's stratosphere that absorbs most of the Sun's ultra violet radiation. The ozone layer is also called as the ozone shield and it acts as a protective shield, cutting the ultraviolet radiation emitted by the sun. Just above the atmosphere there are two layers namely troposphere (the lower layer) and stratosphere (the upper layer). The ozone layer of the troposphere is called bad ozone and the ozone layer of stratosphere is known as good ozone because this layer acts as a shield for absorbing the UV radiations coming from the sun which is harmful for living organisms causing DNA damage.

The thickness of the ozone column of air from the ground to the top of the atmosphere is measured in terms of Dobson Units. The ozone shield is being damaged by chemicals released on the Earth's surface notably the chlorofluorocarbons widely used in refrigeration, aerosols, chemicals used as cleaners in many industries. The decline in the thickness of the ozone layer over restricted area is called Ozone hole.

Ozone is a colourless gas, reacts readily with air pollutants and cause rubber to crack, hurt plant life, damages lung tissues. But ozone absorbs harmful ultra violet Beta (UV-β) and UV-α radiation from sunlight.

What is Dobson Unit?

DU is the unit of measurement for total ozone. One DU (0.001 atm. cm) is the number of molecules of ozone that would be required to create a layer of pure ozone 0.01 millimetre thick at a temperature of 0°C and a pressure of 1 atmosphere (atm = the air pressure at the surface of earth). Total ozone layer over the earth surface is 0.3 centimetres (3 mm) thick and is written as 300 DU.

The false colour view of total ozone — The purple and blue colours are where there is the least ozone, and the yellows and reds are where there is more ozone.

September 16 is WORLD OZONE DAY

Ozone depletion in the stratosphere results in more UV radiations especially UV B radiations (shortwaves). UV B radiation destroys biomolecules (skin ageing) and damages living tissues. UV-C is the most damaging type of UV radiation, but it is completely filtered by the atmosphere (ozone layer). UV-a contributes 95% of UV radiation which causes tanning, burning of skin and enhancing skin cancer. Hence the uniform ozone layer is critical for the wellbeing of life on earth.

During 1970's research findings indicated that man-made chlorofluorocarbons (CFC) reduce and convert ozone molecules in the atmosphere. The threats associated with reduced ozone pushed the issue to the forefront of global climate issues and gained promotion through organisations such as World Meteorological Organisation and the United Nations.

The Vienna Convention was agreed upon at the Vienna conference of 1985 but entered into force in 1988 provided the frameworks necessary to create regulative measures in the form of the Montreal protocol. The International treaty called the Montreal Protocol (1987) was held in Canada on substances that deplete ozone layer and the main goal of it is gradually eliminating the production and consumption of ozone depleting substances and to limit their damage on the Earth's ozone layer.

Clean Development Mechanism (CDM) is defined in the Kyoto protocol (2007) which provides project based mechanisms with two objectives to prevent dangerous climate change and to reduce green house gas emissions. CDM projects helps the countries to reduce or limit emission and stimulate sustainable development. An example for CDM project activity, is replacement of conventional electrification projects with solar panels or other energy efficient boilers. Such projects can earn Certified Emission Reduction (CER) with credits/scores, each equivalent to one tonne of CO₂, which can be counted towards meeting Kyoto targets.

Plant Indicators

The presence or absence of certain plants indicate the state of environment by their response. The plant species or plant community acts as a measure of environmental conditions, it is referred as biological indicators or phytoindicators or plant indicators.

Plants	Indicator for
Lichens, Ficus, Pinus, Rose	SO₂ pollution
Petunia, Chrysanthemum	Nitrate
Gladiolus	Flouride pollution
Robinia pseudoacacia (Black locust tree)	Indicator of heavy metal contamination

8.1.5 Effects of Ozone Depletion

The main ozone depletion effects are:

• Increases the incidence of cataract, throat and lung irritation and aggravation of asthma or emphysema, skin cancer and diminishing the functioning of immune system in human beings.
• Juvenile mortality of animals.
• Increased incidence of mutations.
• In plants, photosynthetic chemicals will be affected and therefore photosynthesis will be inhibited.
• Decreased photosynthesis will result in increased atmospheric CO₂ resulting in global warming and also shortage of food leading to food crisis.
• Increase in temperature changes the climate and rainfall pattern which may result in flood/drought, sea water rise, imbalance in ecosystems affecting flora and fauna.

8.2 Forestry

8.2.1 Agro Forestry

Agroforestry is an integration of trees, crops and livestock on the same plot of land. The main objective is on the interaction among them. Example: intercropping of two or more crops between different species of trees and shrubs, which results in higher yielding and reducing the operation costs. This intentional combination of agriculture and forestry has varied benefits including increased bio-diversity and reduced erosion.

Some of the major species cultivated in commercial Agroforestry include Casuarina, Eucalyptus, Malai Vembu, Teak and Kadambu trees which were among the 20 species identified as commercial timber. They are of great importance to wood-based industries.

Benefits of Agroforestry

• It is an answer to the problem of soil and water conservation and also to stabilise the soil (salinity and water table), reduce landslide and water run-off problem.
• Nutrient cycling between species improves and organic matter is maintained.
• Trees provide micro climate for crops and maintain O₂–CO₂ balanced, atmospheric temperature and relative humidity.
• Suitable for dry land where rainfall is minimum and hence it is a good system for alternate land use pattern.
• Multipurpose tree varieties like Acacia are used for wood pulp, tanning, paper and firewood industries.

Agro-forestry is recommended for the following purposes: It can be used as Farm Forestry for the extension of forests, mixed forestry, shelter belts and linear strip plantation.

Rehabilitation of Degraded Forests and Recreation Forestry

The production of woody plants combined with pasture is referred to silvopasture system. The trees and shrubs may be used primarily to produce fodder for livestock or they may be grown for timber, fuel wood and fruit or to improve the soil. This system is classified into following categories:

1. Protein Bank: In this various multipurpose trees are planted in and around farm lands and range lands mainly for fodder production. Example: Acacia nilotica, Albizzia lebbek, Azadirachta indica, Gliricidia sepium, Sesbania grandiflora.
2. Livefence of fodder trees and hedges: Various fodder trees and hedges are planted as live fence to protect the property from stray animals or other biotic influences. Example: Gliricidia sepium, Sesbania grandiflora, Erythrina spp., Acacia spp.

8.2.2 Social Forestry

It refers to the sustainable management of forests by local communities with a goal of climate carbon sequestration, change mitigation, depollution, deforestation, forest restoration and providing indirect employment opportunity for the youth. Social forestry refers to the management of forests and afforestation on barren lands with the purpose of helping the environmental, social and rural development and benefits. Forestry programme is done for the benefit of people and participation of the people.

Trees grown outside forests by government and public organisation reduce the pressure on forests. In order to encourage tree cultivation outside forests, Tree cultivation in Private Lands was implemented in the state from 2007-08 to 2011-12. It was implemented by carrying out block planting and inter-crop planting with profitable tree species like Teak, Casuarina, Ailanthus, Silver Oak, etc. in the farming lands and by a free supply of profitable tree species for planting in the bunds. The Tank foreshore plantations have been a major source of firewood in Tamil Nadu.

The 32 Forestry extension centres provide technical support for tree growing in rural areas in Tamil Nadu. These centres provide quality tree seedlings like thorn/thornless bamboo, casuarinas, teak, neem, Melia dubia, grafted tamarind and nelli, etc. in private lands and creating awareness among students by training/camps.

8.2.3 Major Activities of Forestry Extension Centres

• Training on tree growing methods
• Publicity and propaganda regarding tree growing
• Formation of demonstration plots
• Raising and supply of seedlings on subsidy
• Awareness creation among school children and youth about the importance of forests through training and camps.

8.3 Deforestation

Deforestation is one of the major contributors to enhance green house effect and global warming. The conversion of forested area into a non-forested area is known as deforestation.

Forests provide us many benefits including goods such as timber, paper, medicine and industrial products.

Causes of Deforestation

• The conversion of forests into agricultural plantation and livestock ranching is a major cause of deforestation.
• Logging for timber
• Developmental activities like road construction, electric tower lines and dams.
• Over population, Industrialisation, urbanisation and increased global needs.

Effects of Deforestation

• Burning of forest wood release stored carbon, a negative impact just opposite of carbon sequestration.
• Trees and plants bind the soil particles. The removal of forest cover increases soil erosion and decreases soil fertility.
• Deforestation in dry areas leads to the formation of deserts.
• The amount of runoff water increases soil erosion and also creates flash flooding, thus reducing moisture and humidity.
• The alteration of local precipitation patterns leading to drought conditions in many regions.
• It triggers adverse climatic conditions and alters water cycle in ecosystem.
• It decreases the bio-diversity significantly as their habitats are disturbed and disruption of natural cycles.
• Loss of livelihood for forest dwellers and rural people.
• Increased global warming and account for one-third of total CO₂ emission.
• Loss of life support resources, fuel, medicinal herbs and wild edible fruits.

8.4 Afforestation

Afforestation is planting of trees where there was no previous tree coverage and the conversion of non-forested lands into forests by planting suitable trees to retrieve the vegetation. Example: Slopes of dams afforested to reduce water runoff, erosion and siltation. It can also provide a range of environmental services including carbon sequestration, water retention.

The Man who Single Handedly Created a Dense Forest

Jadav "Molai" Payeng (born 1963) is an environmental activist has single-handedly planted a forest in the middle of a barren wasteland. This Forest Man of India has transformed the world's largest river island, Majuli, located on one of India's major rivers, the Brahmaputra, into a dense forest, home to rhinos, deers, elephants, tigers and birds. And today his forest is larger than Central Park. Former vice-chancellor of Jawahar Lal Nehru University, Sudhir Kumar Sopory named Jadav Payeng as Forest Man of India, in the month of October 2013. He was honoured at the Indian Institute of Forest Management during their annual event 'Coalescence'. In 2015, he was honoured with Padma Shri, the fourth highest civilian award in India. He received honorary doctorate degree from Assam Agricultural University and Kaziranga University for his contributions.

Afforestation Objectives

• To increase forest cover, planting more trees, increases O₂ production and air quality.
• Rehabilitation of degraded forests to increase carbon fixation and reducing CO₂ from atmosphere.
• Raising bamboo plantations.
• Mixed plantations of minor forest produce and medicinal plants.
• Regeneration of indigenous herbs/shrubs.
• Awareness creation, monitoring and evaluation.
• To increase the level and availability of water table or ground water and also to reduce nitrogen leaching in soil and nitrogen contamination of drinking water, thus making it pure not polluted with nitrogen.
• Nature aided artificial regeneration.

Achievements of Afforestation

• Degraded forests were restored
• Community assets like overhead tanks, bore-wells, hand pumps, community halls, libraries, etc. were established
• Environmental and ecological stability was maintained.
• Conserved bio-diversity, wildlife and genetic resources.
• Involvement of community especially women in forest management.

8.5 Alien Invasive Species

Invasion of alien or introduced species disrupts ecosystem processes, threaten biodiversity, reduce native herbs, thus reducing the ecosystem services (benefits). During eradication of these species, the chemicals used increases greenhouse gases. Slowly they alter ecosystem, micro climate and nature of soil and make it unsuitable for native species and create human health problems like allergy, thus resulting in local environmental degradation and loss of important local species. According to World Conservation Union, invasive alien species are the second most significant threat to bio diversity after habitat loss.

What is Invasive Species?

A non-native species to the ecosystem or country under consideration that spreads naturally, interferes with the biology and existence of native species, poses a serious threat to the ecosystem and causes economic loss. It is established that a number of invasive species are accidental introduction through ports via air or sea. Some research organisations import germplasm of wild varieties through which also it gets introduced. Alien species with edible fruits are usually spread by birds. Invasive species are fast growing and are more adapted. They alter the soil system by changing litter quality thereby affecting the soil community, soil fauna and the ecosystem processes. It has a negative impact on decomposition in the soils by causing stress to the neighbouring native species.

Eichhornia crassipes

It is an invasive weed native to South America. It was introduced as aquatic ornamental plant, which grows faster throughout the year. Its widespread growth is a major cause of biodiversity loss worldwide. It affects the growth of phytoplanktons and finally changing the aquatic ecosystem. It also decreases the oxygen content of the waterbodies which leads to eutrophication. It poses a threat to human health because it creates a breeding habitat for disease causing mosquitoes (particularly Anopheles) and snails with its free floating dense roots and semi submerged leaves. It also blocks sunlight entering deep and the waterways hampering agriculture, fisheries, recreation and hydropower.

Prosopis juliflora

Prosopis juliflora is an invasive species native to Mexico and South America. It was first introduced in Gujarat to counter desertification and later on in Andhra Pradesh, Tamil Nadu as a source of firewood. It is an aggressive coloniser and as a consequence the habitats are rapidly covered by this species. Its invasion reduced the cover of native medicinal herbaceous species. It is used to arrest wind erosion and stabilize sand dunes on coastal and desert areas. It can absorb hazardous chemicals from soil and it is the main source of charcoal.

8.6 Conservation

India due to its topography, geology and climate patterns has diverse life forms. Now this huge diversity is under threat due to many environmental issues for this conservation becomes an important tool by which we can reduce many species getting lost from our native land. By employing conservation management strategies like germplasm conservation, in situ, ex-situ, in-vitro methods, the endemic as well as threatened species can be protected.

Conservation Movement

A community level participation can help in preservation and conservation of our environment. Our environment is a common treasure for all the living organisms on earth. Every individual should be aware of this and participate actively in the programs meant for the conservation of the local environment. Indian history has witnessed many people movements for the protection of environment.

Chipko Movement

The tribal women of Himalayas protested against the exploitation of forests in 1972. Later on it transformed into Chipko Movement by Sundarlal Bahuguna in Mandal village of Chamoli district in 1974. People protested by hugging trees together which were felled by a sports goods company. Main features of Chipko movement were:

• This movement remained non political
• It was a voluntary movement based on Gandhian thought.
• It was concerned with the ecological balance of nature
• Main aim of Chipko movement was to give a slogan of five F's – Food, Fodder, Fuel, Fibre and Fertilizer, to make the communities self sufficient in all their basic needs.

Appiko Movement

The famous Chipko Andolen of Uttarakhand in the Himalayas inspired the villagers of Uttar Karnataka to launch a similar movement to save their forests. This movement started in Gubbi Gadde a small village near Sirsi in Karnataka by Panduranga Hegde. This movement started to protest against felling of trees, monoculture, forest policy and deforestation.

In-situ Conservation

It means conservation and management of genetic resources in their natural habitats. Here the plant or animal species are protected within the existing habitat. Forest trees, medicinal and aromatic plants under threat are conserved by this method. This is carried out by the community or by the State conservation which include wildlife, National park and Biosphere reserve. The ecologically unique and biodiversity rich regions are legally protected as wildlife sanctuaries, National parks and Biosphere reserves. Megamalai, Sathyamangalam wildlife, Guindy and Periyar National park, and Western ghats, Nilgiris, Agasthyamalai and Gulf of Mannar are the biosphere reserves of Tamil Nadu.

Sacred Groves

These are the patches or grove of cultivated trees which are community protected and are based on strong religious belief systems which usually have a significant religious connotation for protecting community. Each grove is an abode of a deity mostly village God or Goddesses like Aiyanar or Amman. 448 groves were documented throughout Tamil Nadu, of which 6 groves (Banagudi shola, Thirukurungudi and Udaiyankudikadu, Sittannavasal, Puthupet and Devadanam) were taken up for detailed floristic and faunistic studies. These groves provide a number of ecosystem services to the neighbourhood like protecting watershed, fodder, medicinal plants and micro climate control.

Ex-situ Conservation

It is a method of conservation where species are protected outside their natural environment. This includes establishment of botanical gardens, zoological parks, conservation strategies such as gene, pollen, seed, in-vitro conservation, cryo preservation, seedling, tissue culture and DNA banks. These facilities not only provide housing and care for endangered species, but also have educational and recreational values for the society.

8.6.1 Endemic Centres and Endemic Plants

Endemic species are plants and animals that exist only in one geographic region. Species can be endemic to large or small areas of the earth. Some are endemic to a particular continent, some to a part of a continent and others to a single island. Any species found restricted to a specified geographical area is referred to as ENDEMIC. It may be due to various reasons such as isolation, interspecific interactions, seeds dispersal problems, site specificity and many other environmental and ecological problems.

There are 3 Megacentres of endemism and 27 microendemic centres in India. Approximately one third of Indian flora have been identified as endemic and found restricted and distributed in three major phytogeographical regions of India, that is Indian Himalayas, Peninsular India and Andaman Nicobar islands. Peninsular India, especially Western Ghats has high concentration of endemic plants. Hardwickia binata and Bentinckia condapanna are good examples for endemic plants. A large percentage of Endemic species are herbs and belong to families such as Poaceae, Apiaceae, Asteraceae and Orchidaceae.

Endemic Plants	Habit	Name of Endemic Centre
Baccaurea courtallensis	Tree	Southern Western Ghats
Agasthiyamalaia pauciflora	Tree	Peninsular India
Hardwickia binata	Tree	Peninsular and northern India
Bentinckia condappana	Tree	Western ghats of Tamil Nadu and Kerala
Nepenthes khasiyana	Liana	Khasi hills, Meghalaya

Majority of endemic species are threatened due to their narrow specific habitat, reduced seed production, low dispersal rate, less viable nature and human interferences. Serious efforts need to be undertaken for their conservation, otherwise these species may become globally extinct.

8.7 Carbon Capture and Storage (CCS)

Carbon capture and storage is a technology of capturing carbon dioxide and injects it deep into the underground rocks to a depth of 1 km or more and it is an approach to mitigate global warming by capturing CO₂ from large point sources such as industries and power plants and subsequently storing it instead of releasing it into the atmosphere. Various safe sites have been selected for permanent storage in various deep geological formations, liquid storage in the Ocean and solid storage by reduction of CO₂ with metal oxide to produce stable carbonates. It is also known as Geological sequestration which involves injecting CO₂ directly into the underground geological formations (such as declining oil fields, gas fields, saline aquifers and unmineable coal have been suggested as storage sites).

Carbon Sequestration

Carbon sequestration is the process of capturing and storing CO₂ which reduces the amount of CO₂ in the atmosphere with a goal of reducing global climate change. Carbon sequestration occurs naturally by plants and in ocean. Terrestrial sequestration is typically accomplished through forest and soil conservation practices that enhance the storage of carbon. As an example microalgae such as species of Chlorella, Scenedesmus, Chroococcus and Chlamydomonas are used globally for CO₂ sequestration. Trees like Eugenia caryophyllata, Tecoma stans, Cinnamomum verum have high capacity and noted to sequester carbon. Macroalgae and marine grasses and mangroves are also have ability to mitigate carbon-dioxide.

Carbon Foot Print (CFP)

Every human activity leaves a mark just like our footprint. This Carbon foot print is the total amount of green house gases produced by human activities such as agriculture, industries, deforestation, waste disposal, burning fossil fuels directly or indirectly. It can be measured for an individual, family, organisation like industries, state level or national level. It is usually estimated and expressed in equivalent tons of CO₂ per year. The burning of fossil fuels releases CO₂ and other green house gases. In turn these emissions trap solar energy and thus increase the global temperature resulting in ice melting, submerging of low lying areas and imbalance in nature like cyclones, tsunamis and extreme weather conditions.

To reduce the carbon foot print we can follow some practices like:

1. Eating indigenous fruits and products
2. Reducing use of electronic devices
3. Reduce travelling
4. Avoid buying fast and preserved, processed, packed foods.
5. Plant a garden
6. Reducing consumption of meat and sea food. Poultry requires little space, nutrients and less pollution compared to cattle farming.
7. Reducing use of Laptops (when used for 8 hours, it releases nearly 2 kg. of CO₂ annually)
8. Line drying clothes.

Example: If you buy imported fruit like kiwi, indirectly it increases CFP. How? The fruit has travelled a long distance in shipping or airliner thus emitting tons of CO₂.

Biochar

Biochar is another long term method to store carbon. To increase plants ability to store more carbon, plants are partly burnt such as crop waste, waste woods to become carbon rich slow decomposing substances of material called Biochar. It is a kind of charcoal used as a soil amendment. Biochar is a stable solid, rich in carbon and can endure in soil for thousands of years. Like most charcoal, biochar is made from biomass via pyrolysis (Heating biomass in low oxygen environment) which arrests wood from complete burning. Biochar thus has the potential to help mitigate climate change via carbon sequestration. Independently, biochar when added to soil can increase soil fertility of acidic soils, increase agricultural productivity, and provide protection against some foliar and soil borne diseases. It is a good method of preventing waste woods and logs from getting decayed and instead we can convert them into biochar thus converting them to carbon storage material.

Carbon Sink

Any system having the capacity to accumulate more atmospheric carbon during a given time interval than releasing CO₂. Example: forest, soil, ocean are natural sinks. Landfills are artificial sinks.

8.8 Rain Water Harvesting – RWH (Solution to water crisis – An ecological problem)

Rainwater harvesting is the accumulation and storage of rain water for reuse in-site rather than allowing it to run off. Rainwater can be collected from rivers, roof tops and the water collected is directed to a deep pit. The water percolates and gets stored in the pit. RWH is a sustainable water management practice implemented not only in urban area but also in agricultural fields, which is an important economical cost effective method for the future.

8.8.1 Environmental Benefits of Rain Water Harvesting

• Promotes adequacy of underground water and water conservation.
• Mitigates the effect of drought.
• Reduces soil erosion as surface run-off is reduced.
• Reduces flood hazards.
• Improves groundwater quality and water table / decreases salinity.
• Avoid land wastage for storage purpose and no population displacement is involved.
• Stores water underground as an eco-friendly measure and is a part of sustainable water storage strategy for local communities.

8.8.2 Importance of Lakes

Water bodies like lakes, ponds not only provide us a number of environmental benefits but they strengthen our economy as well as our quality of life like health. Lakes as a storage of rain water provide drinking water, improves ground water level and preserve the fresh water bio-diversity and habitat of the area where it occurs. In terms of services, lakes offer sustainable solutions to key issues of water management and climatic influences and benefits like nutrient retention, influencing local rainfall, removal of pollutants, phosphorous and nitrogen and carbon sequestration.

8.9 Environmental Impact Assessment (EIA)

Environmental Impact Assessment is an environmental management tool. It helps to regulate and recommend optimal use of natural resources with minimum impact on ecosystem and biotic communities. It is used to predict the environmental consequences of future proposed developmental projects (example: river projects, dams, highway projects) taking into account inter-related socio-economic, cultural and human-health impacts. It reduces environmental stress thus helping to shape the projects that may suit local environment by ensuring optimal utilization of natural resources and disposal of wastes to avoid environmental degradation.

The Benefits of EIA to Society

• A healthier environment
• Maintenance of biodiversity
• Decreased resource usage
• Reduction in gas emission and environment damage

Biomonitoring

The act of observing and assessing the current state and ongoing changes in ecosystem, biodiversity components, landscape including natural habitats, populations and species. An agricultural drone is an unmanned aerial vehicle applied to farming in order to help increased crop production and monitor crop growth. Agricultural drones let farmers see their fields from the sky. This bird's eye-view can reveal many issues such as irrigation problems, soil variation and pest and fungal infestations. It is also used for cost effective safe method of spraying pesticides and fertilizers, which proves very easy and non-harmful.

8.9.1 Biodiversity Impact Assessment (BIA)

Biodiversity Impact Assessment can be defined as a decision supporting tool to help biodiversity inclusive of development, planning and implementation. It aims at ensuring development proposals which integrate biodiversity considerations. They are legally compliant and include mechanisms for the conservation of bio-diversity resources and provide fair and equitable sharing of the benefits arising from the use of bio-diversity.

Bio-diversity impacts can be assessed by:

• Change in land use and cover
• Fragmentation and isolation
• Extraction
• External inputs such as emissions, effluents and chemicals
• Introduction of invasive, alien or genetically modified species
• Impact on endemic and threatened flora and fauna.

8.10 Geographic Information System

GIS is a computer system for capturing, storing, checking and displaying data related to positions on Earth's surface. Also to manipulate, analyse, manage and present spatial or geographic data. GPS is a satellite navigation system used to determine the ground position of an object. It is a constellation of approximately 30 well spaced satellites that orbit the earth and make it possible for the people with ground receivers to pinpoint their geographic location. Some applications in which GPS is currently being used for around the world include Mining, Aviation, Surveying, Agricultural and Marine ecosystem.

Importance of GIS

• Environmental impact assessment
• Disaster management
• Zoning of landslide hazard
• Determination of land cover and land use
• Estimation of flood damage
• Management of natural resources
• Soil mapping
• Wetland mapping
• Irrigation management and identification of volcanic hazard
• Vegetation studies and mapping of threatened and endemic species.

Remote Sensing is the process of detecting and monitoring the physical characteristics of an area by measuring its reflected and emitted radiation at a distance from the targeted area. It is a tool used in conservation practices by giving exact picture and data on identification of even a single tree to large area of vegetation and wild life for classification of land use patterns and studies, identification of biodiversity rich or less areas for futuristic works on conservation and maintenance of various species including commercial crop, medicinal plants and threatened plants.

Specific Uses of Remote Sensing

• Helps predicting favourable climate, for the study of spreading of disease and controlling it.
• Mapping of forest fire and species distribution.
• Tracking the patterns of urban area development and the changes in Farmland or forests over several years
• Mapping ocean bottom and its resources

Applications of Satellites

Name of the Satellite	Year of Launch	Application
SCATSAT – 1	Sep. 2016	Weather forecasting, cyclone prediction and tracking services in India
INSAT 3DR	Sep. 2016	Disaster management
CARTOSAT – 2	Jan. 2018	Earth observation
GSAT – 6A	March 2018	Communication
CARTOSAT – 2 (hundredth Satellite)	Jan. 2018	To watch border surveillance

Summary

• Green house effect leads to climate change which results in global warming.
• Deforestation causes soil erosion, whereas Afforestation helps to restore vegetation and increases ground water table.
• Regeneration of trees by Agroforestry is possible with the involvement of community and government.
• Help to conserve the flora and fauna in their natural habitat and man-made environments like zoological parks and national parks.
• Mitigation of carbon in the atmosphere done in the form of sequestration.
• Rain water harvesting is done for improving the ground water table.
• Importance and location of lakes in Tamil Nadu which aids water supply to the city is a measure of conservation of drinking water.
• Assessment of Environment and Biodiversity helps to study risk analysis and disaster management.
• Forest cover is monitored through Remote sensing and GIS.

Evaluation

Exercise MCQ – Choose the Correct Answer

1. Which of the following would most likely help to slow down the greenhouse effect?

a. Converting tropical forests into grazing land for cattle. b. Ensuring that all excess paper packaging is buried to ashes. c. Redesigning landfill dumps to allow methane to be collected. d. Promoting the use of private rather than public transport.

2. With respect to Eichhornia: Statement A: It drains off oxygen from water and is seen growing in standing water. Statement B: It is an indigenous species of our country.

a. Statement A is correct and Statement B is wrong. b. Both Statements A and B are correct. c. Statement A is correct and Statement B is wrong. d. Both statements A and B are wrong.

3. Find the wrongly matched pair.

a. Endemism – Species confined to a region and not found anywhere else. b. Hotspots – Western Ghats c. Ex-situ Conservation – Zoological parks d. Sacred groves – Saintri hills of Rajasthan e. Alien sp. of India – Water hyacinth

4. Depletion of which gas in the atmosphere can lead to an increased incidence of skin cancer?

a. Ammonia b. Methane c. Nitrous oxide d. Ozone

5. One green house gas contributes 14% of total global warming and another contributes 6%. These are respectively identified as:

a. N₂O and CO₂ b. CFCs and N₂O c. CH₄ and CO₂ d. CH₄ and CFCs

6. One of the chief reasons among the following for the depletion in the number of species making endangered is:

a. over hunting and poaching b. green house effect c. competition and predation d. habitat destruction

7. Deforestation means:

a. growing plants and trees in an area where there is no forest b. growing plants and trees in an area where the forest is removed c. growing plants and trees in a pond d. removal of plants and trees

8. Deforestation does not lead to:

a. Quick nutrient cycling b. soil erosion c. alteration of local weather conditions d. Destruction of natural habitat

9. The unit for measuring ozone thickness:

a. Joule b. Kilos c. Dobson d. Watt

10. People's movement for the protection of environment in Sirsi of Karnataka is:

a. Chipko movement b. Amirtha Devi Bishwas movement c. Appiko movement d. None of the above

11. The plants which are grown in silvopasture system are:

a. Sesbania and Acacia b. Solenum and Crotalaria c. Clitoria and Begonia d. Teak and sandal Exercise Short Answer Questions

12. What is ozone hole?

13. Give four examples of plants cultivated in commercial agroforestry.

14. Expand CCS.

15. How do forests help in maintaining the climate?

16. How do sacred groves help in the conservation of biodiversity?

Exercise Long Answer Questions

17. Which one gas is most abundant out of the four commonest greenhouse gases? Discuss the effect of this gas on the growth of plants.

18. Suggest a solution to water crisis and explain its advantages.

19. Explain afforestation with case studies.

20. What are the effects of deforestation and benefits of agroforestry?

Glossary

Algae Blooms Sudden sprout of algae growth, which can affect the water quality adversely and indicate potentially hazardous changes in local water chemistry. Atmosphere A major regional community of plants and animals with similar life forms and environmental conditions. Biodegradable waste Organic waste, typically coming from a plant or animal sources, which other living organisms can break down. Biosphere The portion of earth and its atmosphere that can support life. Oil spill The harmful release of oil into the environment, usually through water, which is very difficult to clean up and often kills birds, fish and other wildlife. Radiation A form of energy that is transmitted in waves, rays or particles from a natural source such as the sun and the ground or an artificial source such as an X-ray machine. Radioactive A material is said to be radioactive if it emits radiation. Recycle To break waste items down into their raw materials, which are then used to remake the original item or to make new items. Sustainable development Development using hand of energy sources in a way that meets the needs of people today without reducing the ability of future generation to meet their own needs.

ICT Corner – Environmental Issues

Let us know about the Environmental issues using the EARTH NOW app through this activity.

Steps:

• Type the URL or scan the QR code to open the activity page.
• Click on the satellite — it displays the shape and activities of the satellite.
• Click on the Vital Signs to see the global Climate data including surface air temperature, Carbon dioxide, Ozone, etc.

URL: https://play.google.com/store/apps/details?id=gov.nasa.jpl.earthnow.activity

Book-back Exercises — Questions & Answers

Answers generated strictly from the Samacheer Kalvi textbook content. Attempt each question first, then click "Show Answer" to check.

I. Choose the Correct Answer

1. Which of the following would most likely help to slow down the greenhouse effect?

a) Converting tropical forests into grazing land for cattle. b) Ensuring that all excess paper packaging is buried to ashes. c) Redesigning landfill dumps to allow methane to be collected. d) Promoting the use of private rather than public transport.

Answer: c) Redesigning landfill dumps to allow methane to be collected.

Explanation: Methane is one of the greenhouse gases that traps heat in the atmosphere. Collecting methane from landfills prevents it from being released into the atmosphere, thus helping to slow down the greenhouse effect.

2. With respect to Eichhornia — Statement A: It drains off oxygen from water and is seen growing in standing water. Statement B: It is an indigenous species of our country.

a) Statement A is correct and Statement B is wrong. b) Both Statements A and B are correct. c) Statement A is correct and Statement B is wrong. d) Both statements A and B are wrong.

Answer: a) Statement A is correct and Statement B is wrong.

Explanation: Eichhornia crassipes is an invasive weed native to South America (not indigenous to India). It decreases the oxygen content of water bodies and grows in standing water.

3. Find the wrongly matched pair.

a) Endemism - Species confined to a region and not found anywhere else. b) Hotspots - Western ghats c) Ex-situ Conservation - Zoological parks d) Sacred groves - Saintri hills of Rajasthan e) Alien sp. of India - Water hyacinth

Answer: d) Sacred groves - Saintri hills of Rajasthan

Explanation: The chapter mentions 448 sacred groves documented throughout Tamil Nadu and lists specific groves like Banagudi shola, Thirukurungudi, etc. Saintri hills of Rajasthan is not mentioned as a sacred grove location in the chapter text.

4. Depletion of which gas in the atmosphere can lead to an increased incidence of skin cancer?

a) Ammonia b) Methane c) Nitrous oxide d) Ozone

Answer: d) Ozone

Explanation: Ozone depletion in the stratosphere results in more UV radiations. UV-a contributes 95% of UV radiation which causes tanning, burning of skin and enhancing skin cancer.

5. One green house gas contributes 14% of total global warming and another contributes 6%. These are respectively identified as

a) N2O and CO2 b) CFCs and N2O c) CH4 and CO2 d) CH4 and CFCs

Answer: d) CH4 and CFCs

Explanation: According to the relative contribution of greenhouse gases discussed in the chapter, CH4 (methane) contributes 14% and CFCs contribute 6% of total global warming.

6. One of the chief reasons among the following for the depletion in the number of species making endangered is

a) over hunting and poaching b) green house effect c) competition and predation d) habitat destruction

Answer: d) habitat destruction

Explanation: According to the World Conservation Union, invasive alien species are the second most significant threat to biodiversity after habitat loss. Deforestation disturbs habitats and significantly decreases biodiversity.

7. Deforestation means

a) growing plants and trees in an area where there is no forest b) growing plants and trees in an area where the forest is removed c) growing plants and trees in a pond d) removal of plants and trees

Answer: d) removal of plants and trees

Explanation: The conversion of forested area into a non-forested area is known as deforestation, which essentially means removal of plants and trees from forest land.

8. Deforestation does not lead to

a) Quick nutrient cycling b) soil erosion c) alteration of local weather conditions d) Destruction of natural habitat weather conditions

Answer: a) Quick nutrient cycling

Explanation: Deforestation leads to soil erosion, alteration of local precipitation patterns and destruction of natural habitats. The chapter does not mention quick nutrient cycling as an effect of deforestation; in fact, deforestation disrupts natural cycles.

9. The unit for measuring ozone thickness

a) Joule b) Kilos c) Dobson d) Watt

Answer: c) Dobson

Explanation: The thickness of the ozone column of air from the ground to the top of the atmosphere is measured in terms of Dobson Units (DU). Total ozone layer over the earth surface is 0.3 centimetres (3 mm) thick and is written as 300 DU.

10. People's movement for the protection of environment in Sirsi of Karnataka is

a) Chipko movement b) Amirtha Devi Bishwas movement c) Appiko movement d) None of the above

Answer: c) Appiko movement

Explanation: The Appiko Movement started in Gubbi Gadde, a small village near Sirsi in Karnataka by Panduranga Hegde. It was launched to protest against felling of trees, monoculture, forest policy and deforestation.

11. The plants which are grown in silvipasture system are

a) Sesbania and Acacia b) Solenum and Crotalaria c) Clitoria and Begonia d) Teak and sandal

Answer: a) Sesbania and Acacia

Explanation: Under the Protein Bank category of silvopasture system, multipurpose trees like Acacia nilotica and Sesbania grandiflora are planted in and around farm lands mainly for fodder production.

II. Answer Briefly

12. What is ozone hole?

Answer: The decline in the thickness of the ozone layer over a restricted area is called an Ozone hole. The ozone shield is damaged by chemicals released on the Earth's surface, notably chlorofluorocarbons (CFCs) widely used in refrigeration, aerosols, and chemicals used as cleaners in many industries.

13. Give four examples of plants cultivated in commercial agroforestry.

Answer: The major species cultivated in commercial agroforestry include: (1) Casuarina, (2) Eucalyptus, (3) Malai Vembu, (4) Teak. These were among the 20 species identified as commercial timber and are of great importance to wood-based industries.

14. Expand CCS.

Answer: CCS stands for Carbon Capture and Storage. It is a technology of capturing carbon dioxide and injecting it deep into underground rocks to a depth of 1 km or more, as an approach to mitigate global warming.

15. How do forests help in maintaining the climate?

Answer: Forests help maintain climate by providing trees that maintain O2–CO2 balance, atmospheric temperature and relative humidity. They act as carbon sinks through carbon sequestration, reducing CO2 from the atmosphere. Deforestation, in contrast, leads to drastic climatic changes by altering local precipitation patterns and increasing global warming.

16. How do sacred groves help in the conservation of biodiversity?

Answer: Sacred groves are community-protected patches of cultivated trees based on strong religious beliefs. They provide ecosystem services like protecting watersheds, supplying fodder, medicinal plants and micro climate control. In Tamil Nadu, 448 groves have been documented, and six groves have been taken up for detailed floristic and faunistic studies, helping preserve local biodiversity.

17. Which one gas is most abundant out of the four commonest greenhouse gases? Discuss the effect of this gas on the growth of plants.

Answer: Carbon dioxide (CO2) is the most abundant among the greenhouse gases. Increased atmospheric CO2 results from decreased photosynthesis (caused by ozone depletion), leading to global warming. Global warming effects on plants include low agricultural productivity in tropics, frequent heat waves favouring weeds, pests and fungi, change in flowering seasons and pollinators, change in species distributional ranges, and even species extinction.

III. Answer in Detail

18. Suggest a solution to water crisis and explain its advantages.

Answer: Rainwater Harvesting (RWH) is an effective solution to water crisis. It is the accumulation and storage of rainwater for reuse on-site rather than allowing it to run off. Rainwater is collected from rivers and rooftops and directed to a deep pit where it percolates and gets stored.

Advantages of RWH:

• Promotes adequacy of underground water and water conservation.
• Mitigates the effect of drought.
• Reduces soil erosion as surface run-off is reduced.
• Reduces flood hazards.
• Improves groundwater quality and water table and decreases salinity.
• Avoids land wastage for storage purpose and no population displacement is involved.
• Stores water underground as an eco-friendly measure and is part of a sustainable water storage strategy for local communities.

19. Explain afforestation with case studies.

Answer: Afforestation is the planting of trees where there was no previous tree coverage and the conversion of non-forested lands into forests by planting suitable trees to retrieve the vegetation. For example, slopes of dams are afforested to reduce water runoff, erosion and siltation. It also provides carbon sequestration and water retention.

Objectives of Afforestation: Increasing forest cover, rehabilitation of degraded forests to increase carbon fixation and reduce CO2, raising bamboo plantations, mixed plantations of minor forest produce and medicinal plants, regeneration of indigenous herbs/shrubs, and increasing the level of ground water table.

Case Study – Jadav "Molai" Payeng (Forest Man of India): Born in 1963, Jadav Payeng single-handedly planted a forest on the world's largest river island, Majuli, on the Brahmaputra river, transforming a barren wasteland into a dense forest home to rhinos, deer, elephants, tigers and birds. His forest is larger than Central Park. He was named Forest Man of India by former JNU Vice-Chancellor Sudhir Kumar Sopory in October 2013 and was honoured with Padma Shri in 2015.

Achievements of Afforestation: Degraded forests were restored, community assets were established, ecological stability was maintained, biodiversity was conserved, and women were involved in forest management.

20. What are the effects of deforestation and benefits of agroforestry?

Answer:

Effects of Deforestation:

• Burning of forest wood releases stored carbon, negatively impacting carbon sequestration.
• Removal of forest cover increases soil erosion and decreases soil fertility.
• Deforestation in dry areas leads to the formation of deserts.
• Increases runoff water, creating flash flooding and reducing moisture and humidity.
• Alters local precipitation patterns leading to drought conditions.
• Triggers adverse climatic conditions and alters the water cycle in ecosystems.
• Decreases biodiversity significantly as habitats are disturbed.
• Loss of livelihood for forest dwellers and rural people.
• Increased global warming and accounts for one-third of total CO2 emission.
• Loss of life support resources like fuel, medicinal herbs and wild edible fruits.

Benefits of Agroforestry:

• Provides solution for soil and water conservation and stabilises soil (salinity and water table), reducing landslide and water run-off problems.
• Improves nutrient cycling between species and maintains organic matter.
• Trees provide micro climate for crops and maintain O2–CO2 balance, atmospheric temperature and relative humidity.
• Suitable for dry land where rainfall is minimum, serving as a good system for alternate land use.
• Multipurpose trees like Acacia are used for wood pulp, tanning, paper and firewood industries.
• Increases biodiversity and reduces erosion through the intentional combination of agriculture and forestry.
• Used for farm forestry, mixed forestry, shelter belts, linear strip plantation and rehabilitation of degraded forests.

📝 Summary

1. Environmental issues are problems and harmful effects created by human's unmindful activity and over utilisation of valuable resources obtained from nature, and countries worldwide regularly conduct global summits and conventions under the United Nations to minimise human-induced issues through agreements signed with around 150 countries.
2. The Green House Effect is a process by which radiant heat from the sun is captured by greenhouse gases — including CO₂, CH₄, N₂O, and CFCs — in the atmosphere, ultimately increasing the temperature of the earth and leading to irreversible changes in major ecosystems and climate patterns.
3. Human activities such as burning fossil fuels, agricultural and animal husbandry practices, use of electrical gadgets like refrigerators and air conditioners, application of fertilizers, and automobile emissions are major contributors to the greenhouse effect and global warming.
4. Global warming refers to the increase in mean global temperature — the highest in 4000 years — due to increased concentration of greenhouse gases, with overpopulation and its growing demand for food, fibre, and fuel considered a major cause.
5. The lesson covers a wide range of environmental topics including deforestation, afforestation, alien invasive species, conservation, carbon capture and storage, rainwater harvesting, Environmental Impact Assessment, and Geographic Information Systems, emphasising sustainable development and conservation of water and plants.