The biosphere can be understood as the layer on earth where life exists. This integration of animals, plants and non-living beings which are in interaction with various cycles keeping life on earth alive is called biosphere.
The two components of the biosphere are:
Biotic Elements: Living things of the biosphere.
Abiotic Elements: The air, the water and the soil form the non-living or abiotic component of the biosphere. The air is called the atmosphere, the water is hydrosphere and the soil is called lithosphere.
Air is a mixture of gases like nitrogen, oxygen, carbon dioxide and water vapour. All living beings need oxygen to break down glucose molecules and get energy for their activities. Combustion from human activities or a natural phenomenon like the forest fire, consume oxygen and release carbon monoxide.
Understanding how Carbon Dioxide is Fixed
(i) Green plants convert carbon dioxide into glucose in the presence of Sunlight through photosynthesis.
(ii) Marine animals use carbonates dissolved in sea-water to make their shells.
The Role of the Atmosphere in Climate Control:
Atmosphere covers Earth.
Air is a bad conductor of heat, thus the atmosphere keeps the average temperature of the Earth steady instead of drastic sudden temperature changes through the day and night.
The movement of air: winds
Water vapour is formed due to the heating of water bodies and the activities of living organisms. The rise in temperature creates a low-pressure zone which attracts cool air from high-pressure zone and pushes up the hot air. Thus the atmosphere can be heated from below by the radiation that is reflected back or re-radiated by the land or water bodies. On being heated, convection currents are set up in the air.
Air pollutants are the substance in the air that cause harm to humans and the environment. Pollutants can be in the form of solid particles, liquid droplets, or gases. Pollutants may be natural or man-made.
Pollutants can be classified as either primary or secondary. Usually, primary pollutants are substances directly emitted from a process, such as ash from a volcanic eruption, the carbon monoxide gas from a Factory, vehicle exhaust.
Secondary pollutants are not emitted directly. Rather, they form in the air when primary pollutants react or interact. An important example of a secondary pollutant is ground-level ozone.
When water bodies are heated during the day, a large amount of water evaporates and goes into the air. Some amount of water vapour also gets into the atmosphere because of various biological activities. The air also gets heated and rises up carrying the water vapour with it. As the air rises, it expands and cools. This cooling causes the water vapour in the air to condense in the form of tiny droplets. This condensation of water is facilitated if some particles could act as the ‘nucleus’ for these drops to form around. Once the water droplets are formed, they grow bigger by the ‘condensation’ of these water droplets. When the drops become big and heavy, they fall down in the form of rain.
Rainfall patterns are decided by the prevailing wind patterns. In large parts of India, rains are mostly brought by the southwest or north-east monsoons.
Water occupies a maximum area of the Earth’s surface and is also found underground. Some amount of water exists in the form of water vapour in the atmosphere. Most of the water on Earth’s surface is found in seas and ocean sand but this water is saline.
Freshwater is found frozen in the ice-caps at the two poles and on snow-covered mountains. Freshwater is also found in underground water and the water in rivers, lakes and ponds. However, the availability of fresh water varies from place to place.
All cellular processes need water medium. All the reactions that take place within our body and within the cells occur between substances that are dissolved in water. Substances are also transported from one part of the body to the other in a dissolved form. The salt in saline water makes it readily unusable for the terrestrial organisms, thus organisms need to maintain the level of water within their bodies in order to stay alive.
Water pollution is the contamination of water bodies such as lakes, rivers, ocean and groundwater caused by human activities, which can be hazardous and harmful to organisms and plants that live in these water bodies.
water-pollution to cover the following effects:
- The addition of undesirable substances to water-bodies. These substances could be the fertilizers and pesticides used in farming or they could be poisonous substances, like mercury salts which are used by paper-industries. It could also be disease-causing organisms, like the bacteria which cause diseases.
- The removal of desirable substances from water-bodies. Dissolved oxygen is used by the animals and plants that live in water. Any change that reduces the amount of this dissolved oxygen and other nutrients would adversely affect these aquatic organisms.
- A change in temperature. Aquatic organisms are used to living in a certain range of temperature in the water-body where they live, and a sudden marked change in this temperature would be dangerous for them or affect their breeding. The eggs and larvae of various animals are particularly susceptible to temperature changes.
Soil is an important resource that decides the diversity of life in an area. The outermost layer of our Earth is called the crust and the minerals found in this layer supply a variety of nutrients to life-forms.
The factors or processes that make soil:
- The Sun: The Sun heats up rocks during the day so that they expand. At night, these rocks cool down and contract. Since all parts of the rock do not expand and contract at the same rate, this results in the formation of cracks and ultimately the huge rocks break up into smaller pieces.
- Water: Water helps in the formation of soil in two ways. One, water could get into the cracks in the rocks formed due to uneven heating by the Sun. If this water later freezes, it would cause the cracks to widen. Two, flowing water wears away even hard rock over long periods of time. Fast flowing water often carries big and small particles of rock downstream. These rocks rub against other rocks and the resultant abrasion causes the rocks to wear down into smaller and smaller particles. The water then takes these particles along with it and deposits it further down its path. Soil is thus found in places far away from its parent rock.
- Wind: In a process similar to the way in which water rubs against rocks and wears them down, strong winds also erode rocks down. The wind also carries sand from one place to the other like water does.
The ozone layer is a layer in earth’s atmosphere which contains relatively high concentrations of ozone. This layer absorbs the maximum of the sun’s high-frequency ultraviolet light, which is potentially damaging to life on earth. The ozone layer is located in the stratosphere, approximately 10 km to 50 km above Earth's surface, though the thickness varies seasonally and geographically.
Because of heavy use of CFCs (Chlorofluorocarbons) in refrigerators and pressurized cans by human the ozone layer has broken at some places. This has caused an alarming rise in ultraviolet radiation leading to increased cases of skin cancers.
The depletion of ozone layer allows entering of UV rays from the sun into the earth’s atmosphere which is associated with a number of health related and environmental issues. Let us see its major impacts on human beings
- Exposure to UV rays from sun can lead to increased risk for developing of several types of skin cancers. Malignant melanoma, basal carcinomas are the most common cancers caused by exposure to UV rays.
- UV rays are harmful to our eyes too. Direct exposure to UV rays can lead to Cataract problems, and also snow blindness.
- Our immune system is also highly vulnerable to UV rays. Increased exposure to UV rays can lead to the weakening of the response of the immune system and even impairment of the immune system in extreme cases.
- Exposure to UV rays can lead to the acceleration of the ageing process of your skin. This will result in you looking older than what you actually are. It can also lead to photo allergy that results in the outbreak of rashes in fair skinned people.
Effect of ozone depletion on environment
Ozone layer depletion leads to decrease in ozone in the stratosphere and increase in ozone present in the lower atmosphere. Presence of ozone in the lower atmosphere is considered as a pollutant and a greenhouse gas. Ozone in the lower atmosphere contributes to global warming and climate change. The depletion of ozone layer has trickled down effects in the form of global warming, which in turn leads to melting of polar ice, which will lead to rising sea levels and climatic changes around the world.