Our Environment Notes 6th Science Lesson 16 Notes in English

6th Science Lesson 16 Notes in English

16] Our Environment

Introduction

• The surroundings or space in which a person, animal, or plant lives, is known as on environment.
• Environment is everything that is surrounding us. It can have both living (biotic) and non-living things (abiotic).
• Abiotic factors are non-living parts such as sunlight, air, water and minerals in soil.
• Biotic factors are living things of our environment such as plants, animals, bacteria and more.
• Organisms live, constantly interact with one another and adapt themselves to conditions to their environment.

The Ecosystem

• Ecosystem is a community of living and non-living things that work together. Each part of an ecosystem has a role to play.
• Any changes in the environment such as increased temperature or heavy rains can have a big impact on an ecosystem.
• Ecosystems can be either natural or artificial.

Natural ecosystem

• Ecosystem originated without human intervention is called a natural ecosystem.
• This can be an aquatic ecosystem or a terrestrial ecosystem.
• The ecosystem in water is called aquatic ecosystem. Sea, river, lake, pond and puddle are some examples of natural aquatic ecosystem.
• Ecosystems outside the water body and on land are called terrestrial ecosystems.
• Forests, Mountain regions, deserts etc., are examples of natural terrestrial ecosystems.

Artificial ecosystem

• Artificial ecosystems are created and maintained by human. They have some of the characteristics of natural ecosystems. They are much simpler than the natural ecosystems.
• These can be the terrestrial ecosystems such as paddy fields, gardens etc. or the aquatic ecosystem such as fish tank.

Food Chain and Food Web

• Living organisms need food to perform their life processes.
• Some organisms can produce their own food, such as plants, while other organisms cannot do this and need to feed on other organisms to obtain their energy.
• We can therefore identify different feeding types in an ecosystem; based on how the organism obtains (gets) its food. They are producers and consumers.

Producers

• Producers are organisms that are able to produce their own organic food.
• They do not need to eat other organisms to do this. Producers are also called autotrophs.
• Plants are producers because they make their own food by photosynthesis.

Consumers

• Organisms which cannot produce their own food, need to eat other organisms as food. These organisms are called consumers.
• All animals are consumers as they cannot produce their own food. Consumers are also called heterotrophs.
• There are many types of consumers and we can classify them into specific groups depending on the food that they consume. These are:

Herbivores

• Animals which eat plants or plant products
• e.g. cattle, deer, goat and rat.

Carnivores

• Animals that eat other animals
• E.g. Lion, tiger, frog and owl.

Omnivores

• Animals that eat both plants and animals
• e.g. Humans, dog and crow

Decomposers

• Micro-organisms that obtain energy from the chemical breakdown of dead organisms (both plants and animals).
• They break complex organic substances into simple organic substances that goes into the soil and are used by plants. (e.g.) Bacterium, Fungi

Food chain

• In a forest, deer eats grass; and in turn we know tiger eats deers.
• In any ecosystem there is a chain like relationship between the organisms that live there. This sequence of who eats whom in an ecosystem is called as food chain.
• It describes how organisms get energy and nutrients by eating other organisms.
• A food chain shows the relationship between producers (e.g. grass) and consumers (e.g. deer, goats, cows and tiger).

E.g. Food chain in a terrestrial (grassland) ecosystem

E.g. Food chain in an aquatic (lake) ecosystem

Energy flow

• The food chain begins with the energy given by the Sun. Sunlight triggers photosynthesis in plants.
• The energy from the Sun is stored in the plant parts. When the grasshopper eats the grass, the energy flows from grass to grasshopper.
• Frog gets energy by eating grasshopper.
• This energy is transferred to a crow, when the frog is eaten by a crow.
• Thus we conclude the primary energy production in the world of living things is made by a plant; that is by photosynthesis.
• The micro organism reduces the excreata and the dead bodies of animals into primary simple components and puts them back into soil.
• It is this material that helps the plants to grow. Thus we can see that there is a cycle of materials from primary producers to highest level predators, then back to soil.

Trophic levels

• Animals that eat plants are primary consumers.
• Animals that eat primary consumers are called secondary consumers.
• Animals that eat the secondary consumers (mostly predators) are the tertiary consumers.
• There may even be large predators that eat tertiary consumers. They are called as quaternary consumers.
• Each of these levels in the food chain is called a trophic level.
• Organism uses up to 90% of its food energy for its life processes.
• Only about 10% of energy goes into new body cells and will be available to the next animal when it gets eaten.
• This loss of energy at each trophic level can be shown by an energy pyramid.
• A rat eats grains; and in turn we know snake eats rat.
• Now snake is a prey for peacock and in turn peacocks are easy prey for tigers and leopards.
• In all food chain there is a top level predator that has no natural predators.
• In an aquatic ecosystem there are no natural predator for alligator; in a forest there are no natural predators for tigers.

Importance of food chain

• Learning food chain help us to understand the feeding relationship and interaction between organisms in any ecosystem.
• Understanding the food chain also helps us to appreciate the energy flow and nutrient circulation in an ecosystem. This is important because pollution impacts the ecosystem. The food chain can be used to understand the movement of toxic substances and their impacts.

Food web

• Consumers have different sources of food in an ecosystem and do not rely on only one species for their food.
• If we put all the food chains within an ecosystem together, then we end up with many interconnected food chains. This is called a food web.
• A food web is very useful to show the many different feeding relationships between different species within an ecosystem.

Waste Management and Recycling

• To protect our environment, it is very important to reduce waste, manage it properly and maximize recycling.
• Waste is any substance or material that has been used but is not wanted anymore. This is either because it is worn out, broken or no longer has any purpose.
• Everyone produces waste and our waste has an impact on all ecosystems.
• However, most of us do not know where our garbage goes. There are many types of waste.
• There is liquid waste (in our drains), there are gases hiding in the air (like pollutants from factories), and there is solid waste (garbage) we put in our waste bins.

Biodegradable and Non-biodegradable Waste

Solid waste we generate can be classified into two major types:

1. Biodegradable waste

2. Non-biodegradable waste

Biodegradable waste

• The term ‘Biodegradable’ is used for those things that can be easily decomposed by natural agents like water, oxygen, ultraviolet rays of the sun, micro-organisms, etc.
• One can notice that when a dead leaf or a banana peel is thrown outside, it is acted upon by several micro-organisms like bacteria, fungi or small insects in a time period.
• Biodegradable waste includes vegetable and fruit peels, leftover food and garden wastes (grass, leaves, weeds and twigs).
• Natural elements like oxygen, water, moisture, and heat facilitate the decomposition thereby breaking complex organic forms to simpler units.
• Decomposed matter eventually mixes or returns back to the soil and thus the soil is once again nourished with various nutrients and minerals.

Non-biodegradable waste

• Those materials which cannot be broken down or decomposed into the soil by micro-organisms and natural agents are labeled as non-biodegradable.
• These substances consist of plastic materials, metal scraps, aluminum cans and bottles, etc.
• These things are practically immune to the natural processes and thus cannot be fed upon or broken down even after thousands of years.

Solid Waste Management

• It is our duty to reduce creating waste and protect environment. 3R’s are important in protecting environment.
• The first R is reduce and the second R is reuse and the last R is recycle.
• The waste hierarchy or pyramid shows the best ways to manage solid waste.

1. Avoid

Avoid the usage of unwanted materials which create more debris. Before you buy anything, think that “Do I really need it?” (e.g.) Avoid buying packaged foods. Refuse to buy use and throw plastic products.

2. Reduce

• We can reduce the waste by using durable goods that last longer instead of things that are used once and thrown away. (e.g.) Write on both sides of papers.
• Instead of unnecessary printing, use electronic facilities. Share newspapers, magazines and other things with others.

3. Reuse

• Reusing means using a thing again and again, rather than using and throwing after a single use.
• (e.g.) Instead of using plastic bags, use and throw pens and batteries, use cloth bags, fountain pens and rechargeable batteries. Reuse glass bottles for other purposes.
• Repair foot wears and use them.

4. Recycle

• The process by which waste materials are used to make new products is called recycling.
• (e.g.) Using old clothes to make paper and melting some plastics to make floor mats, plastic boards and hose pipes.

5. Compost

• The process of degradation of organic wastes into manure by the action of microorganism is called composting.
• The manure thus obtained becomes natural fertilizer for the plants as well as increases the soil fertility.

6. Incinerate

• The burning of solid waste in incinerator is called incineration.
• Human anatomical wastes (discarded medicines, toxic drugs, blood, and pus) are disposed by means of incineration.
• During incineration, the enormous heat kills all contagious disease-causing germs. We can also produce electricity with the help of this heat.

7. Landfill

• Land filling is a method in which wastes are dumped into naturally occurring or man-made pits and covered with soil.
• Garbage buried inside landfills remain here for a long time as they decompose very slowly and become manure.
• These places can be converted into parks, gardens, etc.,

Earlier in the chapter, you learn about Rani and how she did not want to cause pollution. Simple steps in your daily life can make big differences. There are two steps you should remember.

• The first step should always be to reduce waste.
• Think of the 3R’s and the waste pyramid and remember the order of the levels.
• The second step is to keep waste separate.
• This way the waste will remain clean and can be easily reused or recycled.
• Mixing different types of waste together (e.g. biodegradable and non-biodegradable) makes waste dirty.
• Dirty waste gets sent to a landfill or open dump.

Waste separation exercise

The Solid Waste Management (SWM) rules, 2016 say that,

• Every Household should segregate and store the waste generated by them in three separate streams – namely bio-degradable, non bio-degradable and domestic hazardous waste in suitable bins and handover segregated wastes to authorized waste pickers or waste collector as per the direction or notification by the local authorities from time to time.
• Nobody shall throw, burn, or bury the solid waste on streets, open public spaces outside his premises or in the drain or water bodies.
• Domestic hazardous waste means discarded paint drums, pesticide cans, CFL bulbs, tube lights, expired medicines, broken mercury thermometers, used batteries, used needles and syringes and contaminated gauge, etc., generated at the household level.

Pollution

• Pollution occurs when the environment gets contaminated by waste, chemicals and harmful substances.
• Pollution is the damage caused to the environment mainly because of human activities.
• Any substance that causes pollution is known as a pollutant. Pollution is an unwanted change in the physical, chemical and biological characteristics of our land, air and water.

Types of Pollution

There are four major kinds of pollution:

1. Air pollution

2. Water pollution

3. Land (soil) pollution

4. Noise pollution

Air pollution

• Most air pollution is caused by the burning of fossil fuels (e.g. oil, petrol, coal and natural gas).
• These fossil fuels are used in factories (industries), power plants and motor vehicles.
• Burning these fossil fuels release toxic gases and fine particles (such as ash and soot) into the air causing air pollution.
• Air pollution is also caused by burning solid waste (especially some plastics), gases or chemicals released from factories and fumes from aerosols (like deodorant spray cans) or paints.
• Certain toxic gases produced by industries mix with raindrops high in the atmosphere and make rain unusually acidic.
• This is called acid rain. It damages plants, washes the nutrients out of soils and kills fish. Air pollution is harmful to all living organisms including humans.
• Polluted air affects skin, eyes and respiratory system.

How can we reduce air pollution?

1. Cycle or walk short distances instead of using a motor vehicle.

2. Travel by public transport (bus or train)

3. Do not burn solid waste.

4. Avoid fireworks.

Water pollution

• Water pollution occurs when wastes from factories, houses and farms mixes with the water in rivers, lakes, ponds, the ocean or even groundwater.
• Contaminated or polluted water can spread diseases and chemicals which are not good for our health.

The most significant sources of water pollutants are

1. Sewage (water we use at home for bathing, cleaning, cooking).

2. Industrial effluents (liquid wastes from factories).

3. Agricultural pollutants (chemical pesticides and fertilizers that get washed from farms).

4. Solid waste (when waste gets dumped into water bodies).

How can we reduce water pollution?

1. Do not pour leftover oil, old medicines or waste down the drain or into the toilet.

2. Reduce the use of chemical pesticides and fertilizers to grow crops.

3. Use waste water for garden in home.

4. Do not litter or dump waste – always use a waste bin.

Land (soil) pollution

• In the same way as water and air get polluted, land or soil pollution happens when toxic chemicals change the natural balance in soil.
• Land pollution comes from farming (Excess use of chemical pesticides and fertilizers), mining (digging up metals and other materials), factories (industrial waste) and the solid waste from our own homes like plastics and broken electronics.
• Soil pollution affects animals, humans and even plants because soil or land acts like a sponge. When it rains, pollutant sinks into the soil.
• If we grow plants to eat in polluted soils, these dangerous chemicals can get into our food.

How can we reduce land pollution?

1. First try to reduce waste, and then recycle the rest.

2. Always use a waste bin and never litter.

3. Do not burn waste, the ash mixes easily with soil.

Noise pollution

• Noise pollution affects the environment.
• We all like a quiet and peaceful place since unpleasant or loud sounds disturb us. Loud music, the sounds of motor vehicles, fireworks and machines cause noise pollution.
• Continuous noise disturbs our sleep and does not let us to study.
• Noise pollution has been directly linked to stress and health impacts such as high blood pressure and hearing loss. Loud noise or even loud music can damage our ears.
• Noise pollution also disturbs animals. Birds have to communicate (talk) louder so that, they can hear each other in noisy areas.
• Even underwater noise pollution from ships, can make whales lose their way as they use sounds to navigate.

How do we reduce noise pollution?

1. Turn off your electronics when you do not use them.

2. Lower the volume when you watch TV or listen to music.

3. Remind drivers not to use the horn too much.

4. Avoid fireworks.

5. Speak, do not shout (try to set an example).

More to know:

Aquarium:

• Aquarium is a place in which fish and other water creatures and plants are maintained.
• An aquarium can be a small tank, or a large building with one or more large tanks.

Terrarium:

• Terrarium is a place in which live terrestrial animals and plants are kept. Plants and animals are kept in a terrarium with controlled conditions that copy their natural environment
• Aquariums and Terrariums are used to observe animals and plants more closely. They are also used for decorations.

Creative reuse

• Creative reuse or Up- cycling is the process of converting waste materials or useless products into new materials or products of better quality or for better environmental value.
• When you up cycle, you are giving an item a new purpose. (e.g.) Used tyres into chairs. Used PET bottle into pen stand.

How much waste does each person make around the world every day?

• The average person in India produces 0.45kg of waste every day.
• It may be small amount of waste. But, India has a large population and imagines you collected all the waste today and put it into tractors.
• You would fill so many tractors that you could create a traffic jam approximately 2,800 kilometers long.
• Imagine a road all the way from Kanyakumari to New Delhi completely blocked with tractors carrying garbage and no space to walk in between.
• This is how much waste we create in India each day! If we reduce the waste, we reduce the pollution.
• India produces 532 million kilos of solid waste every day.

Preparation of vermi compost

• Dig a pit for about one feet depth in the backyard or garden of your home or school.
• Fill the pit by bio wastes, paper and food wastes, place few earth worms in it, sprinkle water and close the place with jute or cardboard and ensure moisture all the time.
• After 45 days the vermi casting layer formed just above the pit. These castings will be applied to the plant.
• This contains water soluble nutrients. This type of compost helps in plant growth as well as sustain the land is fertility.