Samacheer Class 10 Science - Environmental Management

Cutting down of trees gives rise to ecological problems like floods, drought, soil erosion, loss of wildlife, extinction of species, imbalance of biogeochemical cycles, alteration of climatic conditions and desertification.

The animal will not be able to find food, shelter or live with its community. Such animals tend to migrate into residential areas, fields etc., affecting human life.

Agents of soil erosion are high velocity of wind, air currents, flowing water, landslide, human activities (deforestation, farming and mining) and overgrazing by cattle.

Fossil fuels refer to coal and petroleum.
(i) The formation of these fossil fuels is a very slow process and takes very long period of time for renewal.
(ii) They are available in limited amounts in nature. Therefore the coal and petroleum reserves can get exhausted if we use them at a rapid rate. Thus they must be conserved.

It is said to be renewable since it is available in unlimited amount in nature. It can be renewed over a short period of time and can be harvested continuously.

E - wastes are generally called as electronic wastes, which includes the spoiled, outdated, non-repairable electrical and electronic devices. They are generated at houses, Industries etc.

(i) Rainwater harvesting is a technique of collecting and storing rainwater for future use.
(ii) The main purpose of rainwater harvesting is to make rainwater percolate under the ground so as to recharge 'groundwater level'.
Advantages of rainwater harvesting : Rainwater harvesting helps to
(iii) Overcome the rapid depletion of groundwater levels.
(iv) To Meet the increase demand of water.
(v) Reduces flood and soil erosion
(vi) Water stored in ground is not contaminated by human and animal wastes and hence can be used for drinking purpose.

(i) It burns without smoke and therefore causes less pollution.
(ii) An excellent way to get rid of organic wastes like bio-waste and sewage material.
(iii) Left over slurry is good manure rich in nitrogen and phosphorus.
(iv) It is safe and convenient to use.
(v) It can reduce the amount of greenhouse gases emitted.

(i) Untreated sewage or wastewater generated from domestic and industrial process is the leading polluter of water sources in India.
(ii) Sewage water , results in agricultural contamination and environmental degradation.

Deforestation gives rise to ecological problems like floods, drought, soil erosion, loss of wild life, extinction of species, imbalance of biogeochemical cycles, alteration of climatic conditions and desertification.

The main purpose of rainwater harvesting is to make the rainwater percolate under the ground so as to recharge ‘groundwater level’.
Methods of rainwater harvesting :
(i) Roof top rain water harvesting : Roof tops are excellent rain catchers. The rain water that falls on the roof of the houses, apartments, commercial buildings etc., is collected and stored in the surface tank and can be used for domestic purpose.
(ii) Recharge pit : In this method, the rain water is first collected from the roof tops or open spaces and is directed into the percolation pits through pipes for filtration.
(iii) After filtration the rainwater enters the recharge pit or ground wells.

Management of soil erosion :
(i) Retain vegetation cover, so that soil is not exposed.
(ii) Cattle grazing should be controlled.
(iii) Crop rotation and soil management improve soil organic matter.
(iv) Runoff water should be stored in the catchment.
(v) Reforestation, terracing and contour ploughing.
(vi) Wind speed can be controlled by planting trees in form of a shelter belt.

Sources of solid waste :
(i) Solid wastes mainly include municipal wastes, hospital wastes, industrial wastes and e-wastes etc.
(ii) The solid wastes are dumped in the soil which results in landscape pollution.
(iii) Solid - waste management involves the collection, treatment and proper disposing of solid material that is discarded from the household and industrial activities.
Methods of solid wastes disposal:
(i) Segregation : It is the separation of different type of waste materials like biodegradable and non biodegradable wastes.
(ii) Sanitary land fill : Solid wastes are dumped into low lying areas. The layers are compacted by trucks to allow settlement. The waste materials get stabilised in 2-12 months. The organic matter undergoes decomposition.
(iii) Incineration: It is the burning of non- biodegradable solid wastes (medical wastes) in properly constructed furnace at high temperature.
(iv) Composting : Biodegradable matter of solid wastes is digested by microbial action or earthworms and converted into humus.
Recycling of wastes :
(i) Papers from old books, magazines and news papers are recycled to produce papers in papermills.
(ii) Agricultural wastes like coconut shells, jute, cotton stalk, bagasse of sugarcane can be used to make paper and hard board. Paddy husk can be used as livestock fodder.
(iii) Cowdung and other organic wastes can be used in gobar gas plant to provide biogas and manure for fields.
3R Approach : The 3R approach such as, Reduce, Reuse and Recycle may be followed for effective waste management.

(i) Forests are an important component of our environment and are dominated by microorganisms, flowering plants, shrubs, climbers, dense trees and provide a vast habitat for wild animals.
(ii) Forests also contribute to the economic development of our country.
(iii) Forests are vital for human life, it is a source for a wide range of renewable natural resource.
(iv) They provide wood, food, fodder, fibre and medicine.
(v) Forests are major factor of environmental concern. They act as carbon sink, regulate climatic conditions, increase rainfall, reduce global warming, prevent natural hazards like flood and landslides, protect wildlife and also act as catchments for water conservation.
(vi) They also play a vital role in maintaining the ecological balance.

Removal of upper layer of soil by wind and water is called soil erosion. The top layers of the soil contains humus and mineral salts which are vital for the growth of plants.
Soil erosion causes :
(i) Significant loss of humus and nutrients.
(ii) It decreases the fertility of the soil.
(iii) Vegetation, cover cannot be retained.
(iv) This will affect ground water levels.

(i) Expanding human population results in expanding needs. Forests provide a variety of resources to fulfill man's needs.
(ii) Forests are destroyed for reasons like agriculture, urbanization, construction of dams, roads, buildings, industries, hydroelectric projects etc.,
(iii) A lot of these projects are related to the economic growth of the country.
(iv) Natural resources are conserved for their biological, economic and recreational values. The use of natural resources in excess and unplanned way leads to imbalance in the environment.
(v) Wildlife is needed for maintaining biological diversity. It also helps is promoting economic activities and generates revenue through tourism. Conservation of forest and wildlife is interrelated. Over exploitation of forest cover areas has resulted in animals becoming extinct, threatened or on the verge of extinction.
(vi) A judicious balance should be maintained between exploitation of resources and its replenishment. Proper utilization and management of nature and its resources is termed as conservation.
(vii) We have to build a sustainable world, which should last forever. There should be a sharing of global resources among living organisms.
(viii) Thus management of forests and wildlife is indeed a challenging task.

(i) Coal and petroleum are formed by the degradation of biomass of plants and animals buried deep under the earth millions of years ago.
(ii) The coal and petroleum reserves can get exhausted if we keep using them at a rapid rate.
(iii) The formation of these fossil fuels (coal and petroleum) is a very slow process and takes very long period of them for renewal.
(iv) Hence it is necessary to conserve them for future use.
(v) This can be done by reducing their consumption.

(i) The commercial sources of energy include fossil fuels (coal, oil and natural gas), and nuclear power.
(ii) These sources of energy are expensive and are becoming limited.
The non conventional energy resources such as solar power, wind energy, hydropower etc., seem to be promising since they are available abundantly, are cheap and can meet the demand of our Nation.
Hence steps are taken to replace commercial sources with non conventional sources of energy.

(i) Polythene bags and plastics are non bio degradable materials.
(ii) If they are used, they accumulate in the soil, water bodies etc.,
(iii) In the soil they get buried and alter the nature of the soil. It prevents aeration of the soil and affects microbes. Excessive accumulation of plastic can render the soil barren.
(iv) In water bodies they cover the water surface and prevent oxygen from diffusing into the water thereby affecting aquatic flora and fauna.
(v) Plastic covers also find their way into the stomach of animals during feeding and may even prove to be fatal.
(vi) Burning of plastics produces dioxin which can cause developmental and reproductive problems, damage the immune system.
Alternate methods to avoid plastics are :
(i) Use bags made of ecofriendly materials.
(ii) Use dining plates / cups made of biodegradable materials instead of plastic plates I cups.
(iii) Use vessels / containers made of steel.
(iv) Carry our own cloth bags for shopping.
The ban on plastics by the Government will improve the environment because :
(i) Plastic waste will be reduced and slowly disappear.
(ii) It will help the water bodies and soil to promote microbial growth.
(iii) It will lead to decrease in challenges faced by Government in disposal of solid waste.
(iv) Human beings will not be exposed to health hazards caused by use of plastics especially dining plates and cups.
X. Value based questions

(i) Solar cells are expensive.
(ii) If energy needs are high, huge solar panels need to be installed which is not economically viable for all.
(iii) Sunlight must be available throughout the year.

a. Domestic wastes like vegetable peels
b. Industrial wastes like metallic cans
Can the disposal protect the environment? How?
(a) It can be disposed by composting in the garden. This will help to decompose the waste and return the nutrients to the soil thereby adding tQ the fertility of the soil. This will also help to manage the waste.
(b) Metallic cans must be given to recycling units.
The cans will be melted and can be reused to make other objects. This will help to manage the waste and reuse it.

(i) Reduce use of natural resources. E.g: coal.
(ii) Reuse the waste whenever possible. Example water from kitchens can be used for growing plants.
(iii) Recycle materials wherever possible. Example (a) Use of treated sewage water for gardening. (b) Bio wastes to be made into compost.
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