A population is a group of organisms of same species, living in the same space, in the same time. Population level helps to study the interactions among members of same species living in the same habitat.
Habitat means the area of the environment in which organism lives.
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Human population growth is the fundamental cause of all environmental problems. Human population is rapidly increasing like a gigantic snowball which not only gets bigger as it rolls but also goes faster as well. Our ecosystem has limited supply of resources. Due to over population of human, these resources are not distributed equally in all populations that cause poverty, war, famine and diseases among people.
Currently, earth population stands at 6.6 billion people. All environmentalists agree that rate is too high. They are making efforts to reduce population growth in many countries. The main reason for population increase is due to the number of people who are born in any year is being greater than the number who die that is a difference between the birth rate and death rate. The Age structure of populations shows the proportion of population in pre reproductive, productive and post productive classes. Figs 1 show the graph between developed and developing countries. In developing countries, graph has a broad base which indicates the high birth rate. In developed countries, due to the technologies death rates have been reduced. This practice causes population explosion.
The United Nation population division reports that birth rates are falling in some countries. Italy has Europe lowest birth rate of 1.19. In China birth rate is 1.8. Developed countries have made many strategies to reduce these birth rates. Due to these efforts, throughout the world, more women are enjoying higher standard of living. In the developing countries, death rates are increasing due to the epidemic diseases i.e. AIDS. From the above observations, it is predicted that the world population would double for 12 billion by 2050. The increased in human population is more prominent in the poorest countries. The United Nation of population division reports that population in U.S is increasing rapidly due to legal and illegal immigration and it is estimated that it would reach to 438 million in recent years.
Homeless, hunger, famine, pollution, resources depletion, starvation and poverty all are the results of increased human population. Some major effects are explained in detail as below.
Pollution is a hazardous change to the ecosystem. Human activities are the major causes of pollution in the ecosystem. Pollution means to change in the physical and chemical properties of air, earth and water that cause bad effect on the animals and natural resources. The substances which cause pollution called pollutants. There are many types of pollution.
Water pollution is the contamination of water bodies i.e. lakes, river, oceans and ground bodies. Water pollution occurs when pollutants are discharged directly into the water bodies without adequate treatment to remove harmful compound. Industrial effluents and domestic effluents are the major causes of water pollution. These effluents may contain highly toxic organic and in organic salts, heavy metals, mineral acid, oil, greases. On other hand, water use as cleaning agent in industries is directly discharged out in ground bodies and makes water unfit for human and aquatic life.
Use of detergent is increasing for cleaning purpose in houses and industries. The phosphate salt present in detergents causes rapid growth of algae in water bodies. Due to which plants die and decay. Decaying plants being biodegradable consume oxygen gas present in water. Thus depletion of oxygen gas and sunlight result in death of phytoplankton and other aquatic life.
Drinking Polluted water can cause water born disease and devastating for both animals and bird.
Air pollution is one of the major issues of today. It is define as the change of the composition of air by the addition of harmful substances. All activities of air pollution related to human activities.
– Burning of coal and petroleum produces sulphur dioxide, carbon dioxide, nitrogen oxide and hydrocarbons in atmosphere. These pollutants react with water in the atmosphere that produce acid rain. Acid rain attacks calcium carbonate present in the marble and limestone of building and monuments. Acid rain also damages the trees and plants by limiting their growth.
– Excess Carbon dioxide produces by the burning of fuels form a layer around the earth. It does not allow the rays of sun to pass through it and these rays reflect back to the earth surface. Therefore, the average temperature of the surface gradually increases called green house effect.
– Chlorofluorocarbons in the air are major cause of ozone layer depletion. Ozone layer like a cover protects the earth from the harmful ultraviolet radiations of sunlight. These compounds diffuse in the stratosphere. Ultraviolet radiations break the C-Cl bond in CFCl3 and generate chlorine free radicals. These free radicals react with ozone to form O2 molecules and destroy upto one lacs of ozone molecules called ozone hole. Ozone hole can cause skin cancer, eye cataracts. Ozone hole can change the life cycle of plants by disrupting food chain. It can change the wind pattern resulting in climate change all over the world especially in the Asia and Pacific will be most affected regions.
Soil is an important natural resource. .the pesticides used in agriculture that stays in soil for a long time. Acid rain changes the PH of the soil making it unsuitable for the cultivation. Materials like polythene block the passage of water in the soil and so decrease the water holding capacity of the soil. May industries produce harmful chemical which are disposed of without being treated. Improper disposal of nuclear waste also cause radioactive substances to remain in soil for a long time. These substances cause mutation. The non biodegradable substances are more severe. They accumulate in the body of organisms and cause death.
Environmental Pollution caused by the human activities can damage our ecosystem and food chain.
Resources are the materials in the environment that are ready for human use and may be used in future. Fossil fuel (coal, natural gas, oil), minerals, trees, animals, water, land all are natural resources. The resources on earth are limited. Many of them example minerals and fossil fuels are non-renewable resources. The resources that do not regenerate are called renewable resources. The unwise use of non renewable resources of energy may result into non recoverable loss. Human population should realize that once energy is consumed, it cannot be reused. Like energy human population also destroying other resources.
Water is a renewable resource. About 70% of world water use for irrigation purpose and remaining use for house hold purpose. Nearly a big part of world population is facing water shortage. In the poorest countries, water table level is reducing at alarming level. Due to water shortage, many varieties of animals and plants species are towards extinction.
Biodiversity is the amount of biological or living diversity in a specific area. Biodiversity increase ecosystem productivity; all of the species in that ecosystem, no matter their size, have a big role. A diverse e4cosystem can prevent and recover from lots of disasters. Human depend on plants and animals. For example, one quarter of all prescriptions medicines in the U.S have ingredients from plants. Many varieties of organisms increase soil fertility. Many of undescribed species provide food , and many other things. Biodiversity is providing its free service. Due to large population rate and pollution, the biodiversity of the ecosystem is threatened.
Deforestation: cutting down of trees due to the natural reasons or human population are called deforestation and overgrazing has resulted in a degrade environment with reduce biodiversity.
Pollution and urbanization are the major cause of depletion of resources. Main threat to biological diversity is the habitat destruction by expanding human populations. Human are either directly or indirectly using about 40% of earth production which result converting natural area into agriculture uses. To improve the living conditions, we are imposing serious threat to the survival of biodiversity. Habitat loss, over hunting and climate change are the major causes of species extinction.
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