聆听和学习科学/自然资源
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Our planet Earth is endowed with many natural resources. The things that occur in nature, and that are useful to us, are called natural resources. Many of these natural resources are essential, for our survival. Some of them are used, for satisfying our wants
A large number of these natural resources, are either living, or derived, from living organisms. Plants, Trees, Forests, and wild life, are examples of living natural resources. Planet earth was designed to support many forms of life. All living beings have symbiotic relationship with one another. Human beings need to responsibly make use of natural resources. We should not live at the cost of nature. Rather we should learn to live in harmony with nature.
Air, water, and soil, are the most important non living resources. If something is abundantly available, we sometimes think, that it has no economic value. Air is free. We breathe oxygen without paying for it. It costs nothing. This does not mean that it has no value. From the ecological viewpoint, Air is a valuable resource. So is water and soil. If we understand and recognise the ecological value of air, water and soil, We will learn to use them responsibly. We need to learn not to pollute these valuable resources.
Mineral ores like Copper, Iron, and Aluminium, are non living natural resources. We can mine them, and produce useful products from them. Fossil fuels like coal and petroleum, are considered as non living resources. We can extract it from the earth. Many of these resources are finite in nature. We cannot keep extracting them endlessly. Sometime or other, we will run out of supplies. Human population is increasing dramatically. The demand for natural resources is also increasing, at an accelerating pace. The ecologically sensible way of using these resources is Reduce, Reuse and Recycle. This way we stretch the use of natural resources for future generations.
Some of the natural resources can get renewed, with the help of nature. Such resources are called, renewable natural resources. Solar energy, is the best example, of nature’s renewable resource. The sun bestows us with solar energy, every day, endlessly. We are not going to run out of solar energy, in the conceivable future. It has been naturally harvested, by plants, for millions of years. Plants are the basis of food, for all living beings. Human beings have harvesting solar energy, in a small way, for their other energy needs. Solar energy, has the potential, to become the greatest source of renewable energy, in the future.
Air, water, and soil or other renewable resources. We need to nurture them, and take care not to pollute them.
Forests and wild life is a renewable resource. We need to learn to conserve them.
In nature when we say renewable, It does not mean it is unconditionally renewable. Solar energy is possibly, the only unconditionally renewable resource. Other natural resources require nurture and care.
Some of the natural resources have been formed on earth, long ago. Minerals like iron, and copper, were formed, when our planet came into being, billions of years ago. Fossil fuels are derived from dead organic matter, were formed millions of years ago. Such resources, which cannot be replenished once depleted, are called non renewable resources. That is, if we use up non renewable resources, it will take millions of years, for nature to produce it again. You can imagine that, it is not practical to wait, for millions of years, for nature to reproduce, non renewable resources.
Over the last two centuries, since the industrial revolution, we have being using an alarmingly large amount, of non renewable resources. Developed countries, use a disproportionate amount, of non renewable resources. You may be surprised to know that, if all the people in developing countries, use the same amount of non renewable resources, per person, our planet will run out, of non renewable resources. This should make us rethink, the objectives and means of development.
The ecologically sensible way of using these resources is Reduce, Reuse and Recycle. Reduce consumption where we can. The ecologically sensible way of using these resources is Reduce, Reuse and Recycle.
Reduce consumption where we can. For example, we can significantly reduce, use of fossil fuels, like petroleum, and develop alternate sources of energy. Solar energy and wind energy are examples.
Reuse anything that can be reused. Affluence leads to a throwaway culture. If we acquire a new product, we should think about whether the existing product, can be reused. Children grow up very fast, and dresses don’t fit. Other children can reuse these clothes. Textbooks, storybooks, and comics can be reused. We can think of many more things, that can be reused.
Recycle anything that can be recycled. If it cannot be reused, it can be recycled. We can recover the basic substances from cars, cycles, utensils appliances. Paper can be recycled. We cut down forests to make paper, which is the needless destruction of a precious resource. In fact, there are very few things, that cannot be recycled, if we have the will to do so.
Water is a unique natural resource. Though water has no nutrients, it is essential for the existence of life. All plant life also require water to survive. Plants and trees draw water, through roots to live. Agricultural crops, like rice and wheat, require water to grow Human beings and animals, drink water to live. Without water, a human being can survive, only for only 3 to 5 days.
Plants and trees draw water, through roots to live. Agricultural crops, like rice and wheat, require water to grow.
There is close relationship between Water and life. All the components in living cells, like D N A, and proteins, are dissolved in water. They derive their structure, and activity, from the interactions with water. Water allows organic components to react, in ways that ultimately, allow replication. Replication, is a fundamental characteristic, of living organisms. This is the reason, why scientists search for water, in mars and other planets. They believe, if there is water, there could be life.
Water is an excellent solvent. We use water, for bathing and cleaning, which is an essential part, of personal hygiene.
Water is also used in Industry. Chemical, leather, Textile,Cement, and many other industries, use water. In thermal power plants, water is converted to steam, which drives turbines, to produce electricity. In nuclear power plants, water is used as a coolant.
In nature, water exists in many forms and places. The total amount of water, in our planet, is almost constant. But it keeps changing its form, and location. Water from the sea evaporates, and is part of the clouds. This precipitates, as rain and snow. This flows into rivers, lakes, and underground aquifers. From the rivers, water flows back, into the sea. This is known as the as Water cycle or hydrologic cycle.
About 71% of the Earths surface is covered, by seas and Oceans. Sea water is saline, which is not fit for human consumption, or agriculture. About 97% of the water in earth, is in the seas, and oceans. A very small amount of water is in the atmosphere, as water vapour.
Water fit for human consumption, is called potable water, which is fresh water. Only 2.5% of the Earths water, is fresh water. Almost 99% of this fresh water is in polar ice caps, glaciers, and underground aquifers. Only 0.3% of all the fresh water, is in rivers and lakes. Though there is so much water on Earth, only about .75%, less than 1% of the water is directly usable. We source the fresh water mainly, from lakes and rivers. Some of the water is sourced, from underground aquifers.
If we imagine a bucket of water representing, all the water in the earth, only half a teaspoon of that water, is directly usable. Fresh water is actually a limited resource, and should be used like a precious commodity. More than a billion people, in the world, do not have access, to safe drinking water. There are some studies which indicate, that the demand for water will exceed the supply, in the future.
We human beings, directly use about 20 to 30 litres of water, per person, per day. We need much more water, to produce the food, we need. Agriculture, requires a large amount of water. It requires about 3000 litres of water, to produce food, for one person, for one day. In our country, we use 80% of the fresh water, for agriculture. Some crops, like rice require a very large, amount of water. Some crops, like Ragi require very little, water. Water availability varies from region to region. Agriculture in different regions, has to adapt to water availability, in that region. Where water availability is limited, We need to produce food, using minimal amount of water. Some countries use, drip irrigation for this purpose. Water needed for agriculture, has to be planned and managed, in a scientific way.
Increasing population, has resulted in increasing human waste. This is released into water bodies, polluting them. Industries release harmful effluents into water bodies, polluting them. Agriculture uses insecticides and pesticides. This finds its way to underground aquifers, polluting them. Ultimately, all this pollution comes back to us. We need to understand, and realise this fact. Water is a gift from nature. We need to learn, to use it responsibly.
Though we consume fresh water continuously, it gets replenished via rainfall. In some places, like the Himalayas it snows. Major rivers, in North India are snow fed. Rivers in South India are replenished, by rain during monsoons.
Monsoon rains, are essential, to our agriculture and our economy. When our monsoon fails, our food production reduces, and price of food increases. About 100 years back, we had a famine, where people died of starvation. Fortunately, such calamities, do not happen now. We now stock food grains, to take care of potential shortages.
The annual rainfall in our country is about, 400 million hectare metres. This is like saying 400 million hectares of land, receive 1 metre of rain, every year. In reality, rainfall in our country differs very widely, from region to region. Some regions, receive a very large amount of rain, and some regions very little amount of rain. In some regions, If the monsoon rains, are inadequate, it causes drought. In some regions, If there is excess rain or snow melts, it causes floods. We need to conserve fresh water, when it becomes available. Much of the rainfall, we receive, is not harvested. We can increase the harvest of rainfall, by creating watersheds. Watersheds helps to collect, and direct the flow of water. In towns and cities, we need to harvest rain water, and store it. Lakes and ponds are natures way, of storing fresh water. We need to protect the lakes, in our environment. , We also store water in dams, which are now available. Dams stock water when it rains. They release the water, as and when needed. Water as a resource, has to be managed. Hydrology is a branch of science, concerned with water management.
Soil formation occurred in nature, by weathering of rocks, over millions of years. Soil is a natural resource that provides, minerals and water to plants. Forests exist on natural soil, and thrive, without human intervention.
Agriculture, requires fertile soil, with nutrients. The first civilisations started near the banks of rivers, which had fertile soil. Examples are, Nile valley civilisation, and the Indus valley civilisation. The rivers, continuously enriched the soil, making agriculture easy. Soil is a place for living, or habitat, for a wide variety of organisms, Many detritivores, earthworms, termites, and insects live in the soil. Bacteria is an important decomposer. Bacteria can decompose just about any organic matter. One gram of soil contains about 40 million bacterial cells. Falling leaves and dead plants contain organic matter. Animal waste, and dead animals also contain organic matter. These organic matter contain nutrients. Decomposing organisms in the soil, feed on decaying organic matter. The decomposing organisms, return the nutrients to the soil. The soil and all the living organisms within it, can be considered as an ecosystem. A natural ecosystem, is self-sustaining. Forests which exist on natural soil, is also a self-sustaining ecosystem.
Agriculture is a human activity. It is essential, to produce food for us. In traditional agriculture, the nutrients for soil was supplied by organic matter. We can call this as organic agriculture.
Modern agriculture can also be called as Industrial agriculture. Industrial Agriculture uses inorganic fertilisers. These man made fertilisers, provide the nutrients, for the soil. Fertilisers increase the productivity of the soil. We can now produce more food, from the same amount of land. With increasing population, and demand for food, inorganic fertilisers, have become a necessity. Industrial agriculture, requires repeated use of inorganic fertilisers. In Industrial agriculture, Water stored in dams, is supplied by modern irrigation methods. Though monsoons are still important, but we are not as monsoon dependent, as we used to be.
When we irrigate soil with water, some salt is left behind, after the water evaporates. Fertilisers also contain some, salt. These salts can accumulate, over a period of time, in the soil. This is called, salt pollution, or salinisation of the soil. Salt pollution, diminishes the fertility, of the soil.
Industries release waste water, containing harmful chemicals, into the soil. This causes serious, soil pollution. Town and city drainage systems, also pollute, the soil. Pesticides are poisons, used to kill pests of in agricultural crops. These toxic substances, permeate into the soil, and pollute it. In fact, these toxic substances, ultimately find their way, into the food we eat.
Another threat to soil, is the process of soil erosion. Top soil, is the upper layer of soil. It has a high concentration of organic matter, and micro organisms. Organic matter, and micro organisms are important, for agriculture. Loss of top soil, is called as soil erosion. Deforestation, and Industrial agriculture contribute to soil erosion. Vind and water can also cause, soil erosion.
We need unpolluted, fertile soil, to produce food for us. We need to recognise soil, as an important, natural resource. Soil management is a multi disciplinary science. We need to adopt eco friendly, scientific, soil management practises.
Forests are a natural resource, Forests are an important constituent of the biosphere as they release water vapour into the atmosphere. Forests existed before human beings came into existence.However,humans have destroyed 80% of the forests that existed in order to provide land for human agricultural activities and animal habitat.
Forests are the natural habitat for plants, trees and wild life.Photosynthetic cells in plants and trees, harvest the sun’s energy, to produce bio mass.In this process they absorb carbon dioxide and release oxygen and water vapour. Human and most living organisms, breathe in oxygen, and breathe out carbon dioxide. Forests are the natural purifiers of air, in the biosphere. The respiration of trees, in the forest, also helps maintain, the water cycle. Forest provide habitat, for wild animals and maintain soil quality, by preventing soil erosion. They also provide timber, and many other forest products. Forests are a good indicator, of the natural wealth, of a nation. We need to conserve existing forests. Where possible we can create new forests, by afforestation. This would help in restoring, the environmental balance.
The term wild life is used to describe, the plants and animals, living in the wild. Many species of life inhabit our forests, seas and oceans. Human activities such as deforestation, have severely affected wild life. Many species, are facing a threat of extinction, in the near future. Efforts are being made, to conserve wild life, by protecting their natural habitats. Protected forest areas, National parks, wild life sanctuaries, are examples, of such conservation measures. Sometimes, sample populations are protected in zoos, and botanical gardens. Seed banks and gene banks, help preserve genetic resources.
Coal, petroleum products and natural gas, are natural resources, collectively called, as fossil fuels. These were formed by nature, from what was originally organic matter, millions of years ago. Fossil fuels are non renewable resources.
Coal is a natural resource, with high carbon content. It burns easily, and is a food fuel. Coal is the main fuel for thermal power plants.
Crude oil, present in nature, is the source for Petrol, diesel, and kerosene, Petrol and diesel is the primary fuel for transportation.
We can say that fossil fuel, was the fuel, for the industrial revolution. Now about 86 % of our current energy needs, comes from fossil fuels. This is not sustainable. Since the industrial revolution, we have been using up fossil fuels, at an ever-increasing rate. It is projected that fuels like petrol, derived from crude oil, will be exhausted in this century. Coal might last a little longer. We need to seriously work, to develop alternative sources of energy, for sustainable development.
Most of the minerals were formed, by geological processes, billions of years ago. These minerals are non renewable resources. We use more than 100 minerals, which can be metals and non metals. Examples of metals are copper, tin, iron, aluminium,Zinc, gold and silver. Salt, sand, silica, stone are examples, of non metals. Mining is a process by which, we extract and separate the mineral ores, from the earth. In the process of mining, we tend to destroy forests, and pollute, the environment. Minerals have become essential for modern life. For sustainable development, we need to recycle minerals. Fortunately it is possible, to recycle almost all of the metals we use. For example, we can recycle most of the materials, in old utensils, vehicles, appliances machinery, etc. We can think of many more things, which can be recycled. To make best use of mineral resources, we need to use them, in a responsible, and sustainable way.