Natural Resources Class 9 Notes – Life on Earth depends on a various types of resources, both living (biotic) and non-living (abiotic), such as land, air, water, wind, sunlight, minerals, and fossil fuels. The biosphere encompasses all of these elements and supports the existence of life. Natural resources are essential for human well-being and the sustainability of the planet. The use of these resources should be managed responsibly to ensure their availability for future generations.
- Lithosphere: Earth’s outermost solid layer comprising rocks and soil.
- Hydrosphere: All water present on the Earth’s surface, including oceans, rivers, lakes, and groundwater.
- Atmosphere: The layer of gases surrounding the Earth, including nitrogen, oxygen, and trace amounts of other gases.
- Biosphere: The zone on Earth where all living organisms and ecosystems exist, which is created by the interaction of the lithosphere, hydrosphere, and atmosphere, and supports life.
Natural Resources Class 9 Notes
Natural Resource – Air
The atmosphere is a layer of gases that surrounds a planet, and on Earth, it is composed mainly of nitrogen (78%) and oxygen (21%), with (1%) trace amounts of other gases such as carbon dioxide, water vapor, and others.
- Nitrogen – Plants use nitrogen to synthesize proteins, which are essential building blocks for growth and development.
- Oxygen – Oxygen is crucial for life as it is used for respiration, which is the process by which organisms generate energy to sustain life. It is also required for combustion, which is the process of burning fuels to produce energy.
- Carbon dioxide – Carbon dioxide is an essential gas for photosynthesis in plants, which is the process by which they convert sunlight, carbon dioxide, and water into glucose (sugar) and oxygen.
Role of atmosphere
The atmosphere plays a crucial role in regulating the Earth’s temperature by slowing down the escape of heat into outer space at night and preventing sudden increases in temperature during the day. This process is known as the greenhouse effect.
Air pollution occurs when harmful substances such as pollutants, organic molecules, and other unsafe materials are introduced into the Earth’s atmosphere, either by human activities or natural processes.
- Causes – Air pollution is caused by both man-made and natural sources. Man-made sources of air pollution include combustion of fuels, industrial emissions, and burning of crackers, while natural sources include forest fires and volcanic eruptions.
- Effects – Air pollution can have severe consequences such as respiratory diseases, global warming, and acid rain.
Ozone (O3) molecules are highly concentrated in the area of the stratosphere known as the ozone layer. It serves as a shield, trapping the majority of the Sun’s harmful ultraviolet (UV) radiation before it reaches the surface of the Earth. In order to prevent skin cancer, cataracts, and harm to plants and ecosystems caused by UV radiation.
Ozone layer depletion
Ozone layer depletion is the thinning of the ozone layer in the Earth’s atmosphere due to the release of man-made chemicals, such as chlorofluorocarbons (CFCs). This depletion allows more harmful ultraviolet (UV) radiation to reach the Earth’s surface, leading to increased skin cancer rates, harm to marine life, and damage to crops. International efforts, such as the Montreal Protocol, have been successful in reducing the use of ozone-depleting chemicals and slowing the depletion of the ozone layer.
CFCs are man-made substances made of fluorine, chlorine, and carbon. Despite their widespread use as propellants, solvents, and refrigerants, it is now known that they contribute to ozone depletion, which is bad for the atmosphere and people’s health.
The Earth’s atmosphere naturally traps solar radiation through the greenhouse effect, which is caused by certain chemicals known as greenhouse gases. These gases include nitrous oxide, water vapour, chlorofluorocarbons, ozone, methane, and carbon dioxide.
Natural Resource – Water
Water is important for life, two-thirds of the human body are make up with water which helps to regulate body temperature. It is also used for various purposes such as agriculture, industry, and domestic use. However, only 3% of the Earth’s water is freshwater, and the rest is found in the ocean.
Water pollution refers to the contamination of water bodies, including lakes, rivers, oceans, and groundwater. It can be caused by various sources such as industrial waste, sewage, agricultural practices, and oil spills. Water pollution can have harmful effects on aquatic life, as well as human health if the contaminated water is consumed.
The water cycle, or hydrologic cycle, describes the ongoing process of water evaporating from the earth’s surface, rising into the atmosphere, cooling and condensing into clouds, and falling back to the ground as precipitation.
Transpiration and Evaporation
Transpiration and evaporation are two processes that play a crucial role in the water cycle. Evaporation is the process by which water changes from a liquid state to a gas or vapor state, and it mainly occurs from the surface of oceans, lakes, and rivers.
Natural Resource – Soil
Soil and its formation
Soil is the top layer of the Earth’s crust that is formed through the gradual process of mountain weathering. Soil formation depends on various factors such as parent material, climate, time, and organisms.
Soil is composed of a blend of organic and inorganic matter, including minerals, water, and air. Different soil types include clay, loam, silt, sand, and more.
As plant and animal matter decompose, they form a layer of organic material called humus, which is located at the top of the soil. Humus plays a crucial role in improving soil fertility.
When dangerous elements including chemicals, pesticides, heavy metals, radioactive materials, and other pollutants contaminate the soil, this is referred to as soil pollution. These contaminants can get into the soil through a variety of human activities, including poor industrial waste disposal, the use of chemical pesticides and fertilisers in farming, and improper residential trash disposal.
A form of soil degradation known as soil erosion is brought on by the action of wind, rain, and running water. It limits the potential for crop production and causes topsoil loss.
Different Cycles – Biogeochemical cycle
A chemical element or molecule passes through the biotic (living) and abiotic (non-living) components of the Earth’s system in a biogeochemical cycle. Because they enable the constant recycling and reuse of nutrients and other vital chemicals, these cycles are crucial for preserving life on Earth.
There are different types of Cycle –
- Carbon Cycle
- Nitrogen Cycle
- Oxygen Cycle
- Phosphorus Cycle
- Sulphur Cycle
- Water Cycle
The carbon cycle involves carbon exchange among living organisms, the atmosphere, and the geosphere. Plants use carbon dioxide for photosynthesis, while animals get carbon by consuming plants. When organisms die, their carbon returns to the environment through decomposition and respiration. Fossil fuels made of carbon release carbon dioxide into the atmosphere when burned.
The nitrogen cycle converts atmospheric nitrogen into forms used by living organisms, such as ammonia and nitrate, through processes like nitrogen fixation, nitrification, and denitrification. Plants use nitrogen to make proteins and DNA, which are consumed by animals. Decomposers break down nitrogen-containing molecules when organisms die, releasing nitrogen back into the environment. Human activities like fertilizer use can upset the nitrogen cycle and harm the environment.
The exchange of oxygen between living things and the atmosphere is referred to as the oxygen cycle. Animals use the oxygen released by plants during photosynthesis for breathing. During breathing, animals release carbon dioxide, which plants utilise for photosynthesis. In addition, other biogeochemical cycles including the carbon and nitrogen cycles involve oxygen. The oxygen cycle contributes to the preservation of the equilibrium of atmospheric gases required for life on Earth.