6S Elaine Leung 25

2. Human exploitation of natural resources has modified the environment. Give examples of renewable and non-renewable resources. What are the appropriate attitudes and practice in the wise use of our natural resources?

Natural resources refer to all materials in nature that are required by humans for their well-beings. In other words, humans are totally dependent on natural resources for survival. For instance, they grow crops, catch fish, and rear livestock and poultry for food; they exploit fossil fuels for energy supply; they cut down timber, extract minerals, and collect water for various uses in industry, construction, and many aspects in daily life. Natural resources are customarily classified into renewable resources and non-renewable resources.

Renewable resources are resources that can be regenerated fairly rapidly through natural processes. Examples include oxygen, minerals in soil, wildlife, timber, fish, and fresh water. Theoretically, these resources are renewed naturally and are always available. However, if the rates of use exceed the rates of renewal, the resources will become depleted. Three of the renewable resources: timber, fish and fresh water, will be discussed below.

Timber is a very useful raw material in our daily lives. We obtain timber by removing forests in various parts of the world. Forests cover about 25% of the land surfaces on the earth. They have a special role in the conservation of biodiversity and provide homes for more than half of the world’s plant and animal species.

Water covers about 70%of the surface of the earth. This huge biological system comprises very diverse habitats and very great biodiversity. The oceans are very important for human existence. It is a regulator of atmospheric composition and a site for nutrient cycling. The oceans, of course, are important in supplying humans with food; the most important ones are fish.

Oceans, lakes, rivers, glaciers, and other sources of water cover about 70% of the earth’s surface. Although water is abundant on the earth, most of it is unavailable for human use due to salinity or unreliability. Only less than 3% of water on earth is fresh water, and about three-quarters of which is tied up in glaciers, ice caps, and snowfields. Nevertheless, ground water is another important sources of fresh water. It is held underground in porous, water-bearing layers of sand, gravel and rocks.

Non-renewable resources are resources that are limited in availability. They are fixed in total quantity in the earth’s crust and are not replenished by natural processes in short time scales. Notable examples include fossil fuels. They are essential for humans for various purposes. If these materials continue to be extracted rapidly, their exhaustion will be speeded up. Thus wise utilization of non-renewable resources and the adoption of substitutions of these resources are essential.

Fossil fuels include petroleum, coal and natural gas. They are formed from the fossilized remains of prehistoric organisms. The processes of formation take millions of years and thus fossil fuels are regarded as non-renewable resources.

A mineral resource is am inorganic substance that has a definite chemical composition. Geologists have discovered over 3000 different types of minerals. Minerals, such as iron, copper, lead, tin, aluminium and gold, are non-renewable resources. They are extracted from ores and converted to different forms for use. The ores cannot be replenished after extraction.

Over-population of timber can pose serious threats to the environment and, in turn, to humans in different ways: destruction of habitats, loss of nutrient availability, soil erosion and its consequences and climatic changes.

A timber town will be able to log indefinitely if it cuts timber no faster than the forest can regenerate. A farm town can remain viable only if farmers add nutrients to replace those removed by wind, water, and harvest (and only if the nutrients don't irreversibly pollute area water supplies).

Exploitation of fish has impact on the environment and the ecosystem. The modern fishing methods involve large and powerful vessels, effective nets and traps, as well as advanced electronic devices. These usually lead to destruction of aquatic habitats in fishing areas. Dredges and bottom trawls are responsible for the damages. In trawling, heavy nets are dragged along the ocean floor. This damages sea grass, disrupts the availability of food for aquatic organisms, and kills a large number of bottom-dwelling organisms, especially coral reef and the fishes associated. Also, the intensive exploitation of target fish stocks can cause a great impact on the ecosystem. The food web will be affected by the removal of a large biomass of organisms at a critical trophic level. This may lead to an uncontrolled increase in particular types of organisms occupying the lower trophic levels due to the lack of predators; this may also push other types of organisms occupying the higher trophic levels to extinction due to the lack of food.

Fishing technologies developed rapidly during the 1950s and 1960s. The world’s fish catch sharply increased from 60 million tones to 86million tones between 1974 and 1989. In 1992, the food and Agricultural Organization recorded 16 major species of fish with a decline in global catch for about 50% over the previous three decades. In 1995, the FAO acknowledged that 70% of the world’s fish stocks were exploited. So, although the fish is a kind a renewable resources, it will become extinct when we catch the fish faster than they can reproduce! So, we need to cherish the food we get!

Population growth and socio-economic development are currently driving a rapid increase in the demand for water, especially from the industrial and household sectors. The world is facing an increasing pressure of water shortages. It is mainly due to the rising demand, uneven distribution of usable fresh water sources and increasing pollution of the existing water sources. Many developing countries understand rapid industrialization that causes serious problems of water pollution. Because of overgrazing and inappropriate agriculture practices, the exposed topsoil speeds up the running off of water. Nutrients and soil are easily washed away into the aquatic bodies by heavy rainfall. Improper treatment of domestic and agricultural sewage may contaminate the existing water sources, and threaten human life. It is estimated that about 80% of the diseases that people suffer in the poorest countries are caused by contaminated water supply. Ground water plays an important role in providing fresh water for agriculture and domestic uses, especially in rural areas. Over-use of the ground water causes the following problems: water depletion, subsidence and seawater infiltration. In the global scale, agriculture accounts for most of the water used by humans. Humans use a large quantity of water in agriculture, especially in developing countries. Industry accounts for about 1/4 of the water used by human. The cooling water used in power stations is by far the largest single industrial use of water. Primary metal smelting and fabrication, petroleum refining, pulp and paper manufacturing, and food processing altogether account for about 2/3 of the water used in industry. Only a small fraction of water is consumed domestically for cooking, bathing and cleaning household utilities.

In the foreseeable future, fossil fuels will still be the major source of energy in the world. However, they are limited and cannot be replenished once used. With the rapid growth of human population, there is increasing rate of consumption of fossil fuels. Although the reserve of coal is the most abundant, the burning of coal generates the greatest amount of pollutants that adversely affect the environment. Today, people are concerning about the total reserves of fossil fuels on the earth. They are also concerned about the impact of the extensive utilizations of fossil fuels on the environment in the following aspects: Generation of various air pollutants, Accidental contamination of the environment.

Throughout the past few decades, petroleum has been most important source of energy globally. It is expected to remain in this position, supporting about 40% of the total energy consumption, until the 2020s, the demand for petroleum is expected to drop because various countries are expected to switch from petroleum to natural gas and other fuels, particularly for electricity generation. Natural gas is the cleanest fossil fuel for combustion. It is mainly composed of methane. The methane molecule is made up of one carbon atom and four hydrogen atoms. When methane burns completely, the end products are carbon dioxide and water vapor. In comparison, the combustion of petroleum and coal produces ash particles and various sulphur and nitrogen compounds, which are the principal substances causing air pollution. In other words, the replacement of petroleum and coal by natural gas for combustion can help to control pollution problems.
Fossil fuels are the major source of energy used by human. A substantial quantity of fossil fuels is used produce electricity. Electrical energy, a convenient form of energy, is thus available for various purposes, such as operating machinery, heating, cooking, lighting and also transportation.

Increase in human population, advancement in technology, increasing living standards and the development of international trade have dramatically increased the global demand for minerals and their rates of depletion. A number of environment issues are associated with the exploitation of minerals. Although law controls the mining operations, the disturbance to the environment is often inevitable and permanent. They are habitat destruction, great energy consumption, air pollution and water pollution.

Most of the industrial products that we use today originate from mineral resources. Minerals provide the raw materials for construction such as building tower blocks and factories, making machines and transport equipment such as dynamos and aeroplanes, manufacturing tools and commodities such as surgical instruments, electrical appliances and ornaments. Copper, for example, is an important metallic mineral used in telecommunication and transportation technologies. Gold is frequently used in medicinal devices and electronic circuitry because it is malleable, highly conductive, and does not react with other common materials.

We know that the renewable and non-renewable resources are both important to us. Therefore, we need to retain the resources that mean we cannot make the demand outweigh the supply. Otherwise, the resources will be run out soon. We need to cherish the resources because it takes so many times to rebuild. In fact, non-renewable resources can be replaced by renewable one in some generation, for example, the solar energy, wind power, etc.