Human Impact on Natural Environment!
Human activities have had a great impact on natural environment. This impact can be seen on climate and other atmospheric phenomena, on vegetation, soils, animals, water as well as on geomorphologic processes.
A brief review of the human impact on natural environment is given here just as an introduction which provides a base for environmental management and planning.
1. Climate and Atmosphere:
The increasing human population and the advancement in technology have not only become significant factors in the variations in world climate but are also responsible for the various changes in atmospheric conditions including air pollution.
The human influence on global climate is due to the following mechanisms:
1. Gas emissions
2. CO2—industrial and agricultural
4. Chlorofluorocarbons (CFCs)
5. Nitrous oxide
6. Krypton 85
7. Water vapour
8. Miscellaneous trace gases
9. Aerosol generation
10. Thermal pollution
11. Albedo change
12. Dust addition to ice caps
15. Extension of irrigation
16. Alteration of ocean currents by constricting straits
17. Diversion of fresh waters into oceans
The problem of carbon dioxide (CO2) emission has become a major environmental concern. Since the beginning of the Industrial Revolution humans have been taking stored carbon out of the earth in the form of coal, petroleum and natural gas, and burning it to make carbon dioxide, heat, water vapour and small amounts of sulfur dioxide (SO2) and other gases, which are responsible for air pollution, green house effect, increase in surface temperature, or in other words, global warming.
By 2050, it is possible that the increase in global surface temperatures ranges between 1.4 and 2.2 degree Celsius. All other aspects of atmospheric pollution will be discussed under the heading, ‘Air Pollution’.
The impact of human activities on the atmosphere is more because the atmosphere acts as a major channel for the transfer of pollutants from one place to another. It is in this way that harmful substances are transferred long distances from their sources of emission. Another example of the possible widespread and ramifying ecological consequences of atmospheric pollution is provided by acid rain.
In recent years, the greatest attention has been paid to the role of CFCs, the production of which has been rising in last few decades.
These gases may diffuse upwards into the stratosphere where solar radiation causes them to become dissociated to yield chlorine atoms which react with and destroy the ozone present there. The Antarctic ozone hole has been identified through satellite monitoring. In fact, air pollution and its variability both in space and time is more due to human action.
The human impact on vegetation is greater than on any of the other components of the environment. The nature of whole landscape has been transformed by human-induced vegetation change as depicted in Figure 3.1.
The extent of human influence on vegetation is provided by Westh off (1983) in the following four-part scheme:
(i) Natural—a landscape or an ecosystem not influenced by human activity.
(ii) Sub-natural—a landscape or ecosystem partly influenced by humans, but still belonging to the same formation type as the natural system from which it derives.
(iii) Semi-natural—landscape or ecosystem in which flora and fauna are largely spontaneous, but vegetation structure is altered so that it belongs to other formation type such as pasture, moorland, etc.
(iv) Cultural—& landscape or ecosystem in which flora and fauna have been essentially affected by human agencies in such a way that dominant species may have replaced by other species as in case of arable land.
Man has used fire for the clearance of forest cover, mainly for the use of land for cultivation or for habitation. This practice was common during the early stages of the development of civilisation. But, it is still prevalent among many tribals. Although controlled burning is a part of forest management, uncontrolled and deliberate fire destructs not only vegetation but also animals and other forest creatures.
Similarly, uncontrolled and heavy grazing is not only a cause of the disappearance of vegetation cover but is also responsible for desertification and other environmental problems.
The deliberate removal of forests or deforestation is one of the most long-standing and significant ways in which humans have modified the environment. Sometimes forests are cut down to allow agriculture, at other times to provide fuel for domestic purposes or to provide charcoal or wood for construction, etc.
One of the great phases of forest clearance occurring at the present time is in humid tropics. The annual regression rate of tropical moist forest is about 11 million hectares.
The spread of desert-like conditions (desertification) in arid and semi-arid areas is always due to man’s action. Some of the air pollutants, which humans have released into the atmosphere, have had detrimental effect on plants, for example, sulfur dioxide, which is toxic to them. Local concentrations of industrial fumes also kill vegetation. Photochemical smog is also known to have adverse effect on plants both within cities and also on their outskirts.
The adverse effects of pollution on plants are not restricted to air pollution; for water and soil, pollution can also be serious. Excessive amounts of heavy metals may prove toxic to them. Salt marshes, mangrove swamps and other kinds of wetlands are particularly sensitive to oil spills. In fact, human activities have become a major cause not only for the gradual removal of forest cover in many parts of the world but also for the degradation of the environment.
The range of impact that humans have had on animals, though large, can be grouped conveniently into five main categories: domestication, dispersal, extinction, expansion and contraction. The extinction of animals by human predators has been extensive over the past 20,000 years, and in spite of recent interest in conservation, it continues at a high rate.
The extreme effect of human interference with animals is extinction. The problem of extinction of several animal species has become a world-wide ecological problem.
This decline is partly due to intentional killings for subsistence and commercial purposes, but much wildlife decline occurs due to pollution and also due to change in ecosystem and natural habitat. For example, the use of DDT is one of the causes for the extinction of several types of insects, birds and small animals.
The polluted water containing heavy metals and methyl mercury is also harmful. Oil pollution is an increasingly serious problem for marine and coastal fauna and flora. Sea birds are especially vulnerable since oil clogs their feathers. Other industrial pollutants have a clear impact on aquatic systems. Pollution is a serious problem for coral reefs too.
The list of other indirect causes of wildlife decline is a vast one. Modern society is particular about the conservation of wildlife and efforts have been made by international, national and NGOs to protect them, but due to selfish and commercial motives, the killing of these animals is still going on. Various types of habitats have also started disappearing due to adverse human impact.
On the global basis the loss of wetland habitats is a matter of considerable concern. Such areas are important for the breeding of several animals. The other threats include drainage, dredging, mining, filling, pollution and channelisation.
Briefly, the human impact on animal extinction can be discussed in three categories as under:
(i) The blitzkrieg effect, which involves rapid development of human populations with big-game hunting technology so that there is very rapid demise of animal population;
(ii) The innovation effect, whereby long-established human population groups adopt new hunting technologies and erase fauna that have already been stressed by climatic changes; and
(iii) The attrition effect, whereby extinction takes place relatively slowly after a long history of human activity because of loss of habitat and competition for resources.
Soil is the most vulnerable of human resources and is one on which humans have had a very major impact, because they live close to and depend on it. Impact on soil can occur with great rapidity in response to land use change by new technologies. The major changes brought about by humans are chemical, structural and hydrological, while soil erosion is perhaps the most important.
Salinity is a natural characteristic in some semi-arid and arid soils. But humans have increased the extent and degree of salinity in different ways.
The extension of irrigation and different techniques, used for water abstraction, can lead to a build-up of salt levels in the soil through the mechanism of raising groundwater level. The construction of large dams and barrages to control water flow and to give a head of water creates large reservoirs from which further evaporation can take place. The seepage of water is also responsible for upward movement of groundwater.
In coastal areas, salinity problems are created by sea water incursion brought about by over pumping. The clearance of native forest vegetation is also a cause of increase in salinity. Measures have been taken for reclamation of salt affected areas through eradication, conversion and control techniques, but soil salinity is still a grave problem in many parts of the world.
Laterisation is a chemical process in the soil of the tropics where extensive sheets of a material called laterite have been deposited either through natural process or by human actions. Laterite is paleological leprosy. Man’s activities aggravate the dangers of laterisation when started by negligent removal of the forest.
Human activities are also responsible for the structural changes in soil. There are many ways in which humans can alter this, especially by compacting it with agricultural machinery and by changing its chemical character through irrigation.
Grazing is another activity that can damage soil structure through trampling and compaction. Soil drainage is a slow and gradual process and is responsible for certain environmental changes and also a cause for long-term damage to soil quality.
The introduction of chemical fertilizers has also changed the chemistry of soils. Sometimes, these create environmental problems such as water pollution, while their substitution for more traditional fertilizers may accelerate soil structure deterioration and soil erosion.
Nowadays, the use of three main fertilizers, viz., nitrates, phosphates and potash, has greatly increased the agricultural productivity but it has also changed the basic structure of the soil.
Soil erosion is the result of natural processes but at the same time it is also a result of human activities. Myers (1988) has summarised the scale of accelerated soil erosion that has been done by human actions.”Since the development of agriculture some 12,000 years ago, soil erosion is said by some to have ruined 4.3 million km2 of agricultural lands, or an area equivalent to rather more than one-third of today’s croplands-the amount of agricultural land now being lost through soil erosion, in conjunction with other forms of degradation, can already be put at a minimum of 200,000 km2 per year.”
In fact, soil erosion is a major and serious aspect of the human role in environmental change. The processes of construction, urbanisation, mining, etc., are also accelerating this problem, although the prime causes of soil erosion are deforestation and agriculture. Because of the adverse effects of accelerated erosion, several techniques have also been used to conserve soil resources. Some of them are revegetation, stoppage of full enlargement, crop management, slope run-off control, suppression of wind erosion, terracing, contour ploughing, etc.
Water is the source of life and, human beings use it for various purposes. The ancient civilizations have developed in river valleys. This is also true of medieval townships and other developments, and all modern developments are related directly or indirectly to water. The main concern is that by using water, humans have influenced both its quantity and quality.
Earlier, the influence of human activity on water resources was limited but now this has become a major problem of environmental degradation throughout the world. However, there are many ways in which humans influence water, for example, by direct channel manipulation, modification of watershed characteristics, urbanisation and pollution.
The construction of dams and reservoirs is widespread throughout the world for irrigation, to generate power or to provide a reliable source of water. More than 700 dams have been built worldwide and their number is increasing year after year.
In countries like Brazil, Argentina, Canada, India, Japan, Turkey, Spain and China, run-off of water has been regulated by water reservoirs.
The impact of human activities is especially marked in Africa and North America where about 20 per cent of total run-off is now controlled.
The impact of dam, construction is apparent in the form of change in ecosystem and environmental conditions. Bigger the dam more will be its impact. Dams like Hoover (USA), Kiev (Russia), Aswan (Egypt), Akosombo (Ghana), and Bhakra Nangal, Gandhi Sagar, Damodar and Rihand (India) have had their impact on regional ecology. The recent environmental controversy over Tehri and Sardar Sarovar dams shows people’s awareness against construction of dams and their possible damaging environmental impact.
The environmental consequences of dams include subsidence, earthquake triggering, transmission and expansion in the range of organism, the build-up of soil salinity, changes in groundwater levels, water logging, deforestation, etc.
The process of urbanisation has a considerable impact, in terms of controlling rates of erosion, the delivery of pollutants to rivers and influencing the nature of run-off and other hydrological characteristics.
The impact of urbanisation can be summarised as follows:
(i) Removal of trees or vegetation,
(ii) Construction of houses and sewerage lines,
(iii) Construction of septic tanks,
(iv) Diversion of nearby streams for public supply,
(v) Accelerated land erosion,
(vi) Larger quantities of untreated waste into local streams,
(vii) Pollution of streams and wells,
(viii) Drilling of deeper, large capacity industrial wells, and
(ix) Increased use of water for domestic and commercial purposes, etc.
Deforestation is a human activity that gives rise to floods, annual run-off levels and also affects on-stream flow. In many parts of the world humans obtain water supplies by pumping from ground water.
This has two main effects, i.e., the reduction in the level of water table and the replacement of coastal areas of fresh water by salt water. Environmental consequences of these two phenomena include ground subsidence and soil salinisation.
Water pollution has now become a common problem and is a result of human use and misuse of water for various purposes.
The causes and forms of water pollution created by humans are many and can be classified into the following groups:
1. Sewage and other oxygen-demanding wastes
2. Infectious agents
3. Organic chemicals
4. Other chemical and mineral substances
6. Radioactive substances
7. Heat (thermal pollution)
Many human activities can contribute to changes in water quality including agriculture, fire, urbanisation, industry, mining, irrigation, etc.
Apart from above mentioned impact of human activities on the natural environment, the human role in creating landforms and modifying the operation of geomorphological processes such as weathering, erosion and deposition also needs consideration.
The range of the human impact on both forms and processes is considerable.
Haigh (1978) has classified anthropogenic land forming processes as follows:
(a) Direct Anthropogenic Processes:
Tipping—loose, compacted, molten; graded—moulded, ploughed, terraced.
Digging, cutting, mining, blasting, etc.
Flooding, damming, canal construction, dredging, channel modification, draining, and coastal protection.
(b) Indirect Anthropogenic Processes:
(i) Acceleration of erosion and sedimentation, agricultural activity, clearances of vegetation, engineering, road construction, urbanisation.
(ii) Subsidence collapse, settling, mining, hydraulic, thermokarst.
(iii) Slope failure landslide, flow, accelerated creep, loading, undercutting, etc.
(iv) Earthquake generation loading (reservoirs) lubrication (fault plane).
7. Human Activities & Environmental degradation:
In the present century, environmental degradation has emerged as a major global concern for human survival. In the opinion of the World Commission on Environment and Development (WCED), the future generations are to face an ever-increasing environmental decay, poverty, hardship and a more polluted world.
The strains of the ecological crisis are so apparent that the task to preserve and protect the environment has become the primary requisite of the economics of development.
Modernisation is steadily transforming the nature into products. The resource squeeze has led to an ever-intensification of ecological damage.
Land, water and air are being polluted every minute. Approximately, 10,000 million tonnes of oxygen is being burnt and about 24,000 million tonnes of carbon dioxide is being discharged every year. The green revolution has turned red.
Deforestation is preceding an alarming rate depleting the genetic store. Mega technology has created problems of waste disposal and industrial revolution has now become a great hazard to the environment as well as to humanity.
Man’s environment by now is sufficiently saturated by the complex chemical emissions, aerosols, toxic effluents, sewage, pesticides, solid wastes, polluted rains, dust and radiation. UN report on Global Environments reveals that the globe will become more crowded, more polluted, ecologically less stable and more vulnerable to disruption than the world we live in today.
Degradation of environment has now become one of the most challenging problems not only for developing countries but also for the developed world. A large number of international organisations with the collective wisdom of scientists, planners and geographers have come up to settle the environmental issue confronting the most nations.
The environmental crisis has convinced the world to use technology and resources to repair the damage already done to our environment and also to use substitutes for certain harmful chemicals in order to protect and preserve nature and natural resources.
The environment is an integrated system in which all its elements act and react in such a way that a balance is always maintained.
All the physical elements such as relief, structure, climate, natural vegetation, soil, water bodies, etc., are the determining factors of environment on the one hand, and man’s activities on the other.
Man is a user of the environment for his developmental activities and always disrupts this natural system and creates a background for environmental degradation. When this degradation is lesser, nature recovers it by its own system of recovery, but whenever its quantity is more, it creates an imbalance in nature.
According to Paul Harrison, “rape of the earth has been central to the past progress of western civilisation. The plunder and waste of irreparable resources, the poisoning and destruction of the fragile ecosystem, the belief that man can mould the nature with no need to take account of nature’s reaction to such violation is a gross oversight”.
Scientific and technological developments have given several benefits to mankind but at the same time, they are also responsible for various types of environmental degradation. The impact of human activities on natural environment has already been discussed, but its impact on resource utilisation and other economic and social elements has also been responsible for the degradation of environment.
The various forms of pollution are the result of human activities. Here our discussion is limited to deforestation, construction of big dams, mining, use of pesticides, urbanisation, industrialisation, etc., which are responsible for the degradation of environment.
The herculean feats of economic gains and development have been at the cost of deforestation. Deforestation is one of the outcomes of various developmental activities having the character of extensional development and it is true that deforestation is a havoc wreaked by thoughtless destructive activities of development.
Forest clearings were made not only for village settlements but also for cultivation and pastures. As the population increased, more forests were cleared for various uses. Apart from this, the commercial exploitation of forests is the main cause of deforestation. There was a time when 70 per cent of the land area was covered with forests and now the total forest cover has shrunk to 16 per cent only.
Nowadays, tropical deforestation has become a concern for all and its impact is not only limited to the region itself, but on the whole world. The annual decline in forest cover in tropical countries has been depicted in Figure 3.2. It is clear from the diagram that in countries like Brazil, India, Indonesia, Thailand, etc., the rate of annual cutting of forests is very high and has become a great problem to the environment and ecosystem.
In India, deforestation is going on at a very fast rate. The story of overexploitation of forests started from World War II, when the British started clearing forests to meet their needs. In the post-independence period, the process has been accelerated to meet developmental needs of railways, industries, mining, river valley projects, defence, etc.
The urbanisation and expansion of agricultural activity have also contributed to the exploitation of forests. During the 1980-2000 periods, 28.67 lakh hectares of forest land have been lost to different developmental works. The commercial exploitation of forests is still going on in spite of several legal provisions to restrict it.
Maximum deforestation has occurred in Madhya Pradesh, where loss of forest is about 2 million hectares, while in Maharashtra, Orissa, Andhra Pradesh, Jammu & Kashmir over a million hectares and Rajasthan and Himachal Pradesh over half a million hectares have been cleared. But, in terms of proportion, Rajasthan, Haryana and Punjab lost over half of the forest cover and states like Himachal Pradesh and Jammu & Kashmir lost over a third of their forest cover. In Tripura, Manipur, Meghalaya and Mizoram the loss of forest cover was minimum during the 1970-2000 periods.
The impact of deforestation on the environment can be seen in the form of micro-climatic change, increase in temperature and decrease in humidity/rainfall, soil erosion in the form of sheet, rill and gully erosion, increase in frequency of floods and landslides, loss of soil fertility, etc.
All these lead to unaccountable destruction and also pose serious ecological challenges. Serious efforts will have to be made to protect and conserve forests both at government as well as public levels. Due attention should also be given to forest management.
Some useful steps in this direction are:
(i) A proper ratio between forest cutting and plantation of trees should be maintained;
(ii) Actual growth of trees should be supervised;
(iii) Strict prohibition of the cutting of trees for fuel should be imposed;
(iv) Alternative media for wood such as moulded plastic, etc. should be developed for furniture and other domestic articles;
(v) Protection from forest fires;
(vi) Development of national parks and game sanctuaries;
(vii) Social forestry should be developed;
(viii) Plantation of trees according to local ecological conditions;
(ix) Forest surveys should be conducted and classification should be done accordingly; and
(x) Long-term master plan for forest conservation and development should be prepared.
In fact, forests can be protected through public movements like ‘Chipko’.
9. Big Dams:
Throughout the world, big dams have been constructed in order to fulfill the growing needs of power and water for irrigation and other purposes. There is no doubt that these dams have become an indicator of the level of development and have boosted the economy of the respective regions.
But, during the last twenty years, environmentalists of the world have expressed the feeling that these dams may not be suitable from the point of view of the environment, or in other words, the ecosystem has been disturbed by these dams due to:
(i) Submergence of large areas under water,
(ii) Destruction of vegetation, wildlife and other animals,
(iii) Instability may provide sustainability to earthquakes,
(iv) Silting, and
(v) Large-scale human migration, etc.
In spite of these problems, the construction of dams continues unabated. However, it is necessary to examine big dam projects from the point of view of degradation of environment and then only implementation of the project should be allowed. As far as possible, emphasis should be given on small dams. Similarly, selection of dam site should be done in a manner that there is minimum impact on the environment.
In India, during post-independence period, several dams—both small and big—have been constructed. Certainly, these have changed the entire scenario of power supply and agricultural development. However, despite their negative impact on environment, all these projects are considered beneficial for the people. The controversy over the Tehri and Sardar Sarovar projects is the example of negative impact of big dams.
The Tehri project has gained significance mainly because of the dimensions of the dam. The points raised by environmentalists are:
(i) The ecology will suffer; invaluable forests will be destroyed because of submergence of forest lands. The wildlife and birds, etc., living in these areas, would face extinction.
(ii) The possibility of earthquakes would be more in view of the large size of the dam.
(iii) The deposition of silt in the base of dam may restrict flow of huge quantum of water.
(iv) The stagnant waters of the reservoir would spread water-borne diseases in adjoining areas.
(v) The rehabilitation of tribal’s and other people may not be proper.
All these issues are raised for other such projects also and experts are of the opinion that for sustainable development it is necessary to build only small dams. These will not only save cost and energy but will also be harmless for the environment. However, whenever there is national necessity, the decision should be taken after considering the environmental issues also.
In the case of Tehri dam, apprehension about its safety has been expressed by many on account of the fact that the dam is going to be located in a region of high seismicity and is, therefore, potentially unsafe. This has, however, been denied by experts.
There is no doubt about the fact that the Tehri dam will change the entire ecosystem of the region, but looking at the benefits in the form of power generation and water supply, this project has not only been approved by the government but its work is near completion. In fact, issues raised regarding environmental degradation are present but what is not generally pointed out is that environmental degradation is already there.
Similarly, the Sardar Sarovar project has been designed to provide irrigation water to drought-hit areas of Gujarat, Madhya Pradesh, Rajasthan and Maharashtra. This project, which is estimated to cost over Rs 6,400 crores, will on completion, provide irrigation facilities to about 18 lakh hectares of land and create installed capacity of power of 1,450 MW.
It will benefit about 25 lakh people in 3,340 villages. It will also provide drinking water for 295 lakh people residing in 131 towns and 4,720 villages in Gujarat. But it will create serious environmental problems, for which proper steps should be taken in advance in order to maintain the regional eco-balance.
Mining is one of the most important economic activities the world over. With growing knowledge of the mineral resources as well as due to technological and scientific developments, mining is today performed on a very large scale. The extraction of minerals is done not only to fulfill regional or national needs but also for trade. With the result the large-scale mining operations have become a threat to the environment.
Mineral resources are the product of geological structure and their formation may take a very protracted period, extending over several thousand years. Therefore, any mineral extracted cannot be formed again for use. There are three types of mineral resources, viz., non-metallic minerals, metallic minerals and mineral fuels. All these are useful to man in some way or the other.
Therefore, mining operations are expanding day by day without taking into consideration its adverse impact on the environment.
Digging of land is carried out on a very large scale and impacts the environment in multiple ways:
(i) In mining areas destruction of land due to deep and surface mining is a common feature. In USA alone, about 1, 50,000 acres of land has become wasteland due to mining. In areas of coal, iron ore, building material and other ores, etc., one sees no signs of the original relief. In mining areas of Bihar, Orissa,
Madhya Pradesh and Rajasthan, one can already see the destruction of land.
(ii) Heaps of unused material is also a great problem. Generally mine owners do not care for this waste material; therefore, it becomes the main cause of environmental degradation.
(iii) Large-scale destruction of natural vegetation and wildlife creates ecological problems.
(iv) Pollution due to dust spreading all over the area is not only a threat to the environment but also the cause of many diseases among the workers as well as the residents of nearby areas.
The other impacts may include:
(a) Expansion of barren land,
(b) Creation of ‘ghost town’ after mining, and
(c) Ecological crisis due to air, water, land and noise pollution.
Unplanned and unorganized mining is a danger to the environment and this should be checked. Measures in this direction could be:
(i) Leveling of mining areas,
(ii) Re-use of waste material,
(iii) Plantation in mining areas,
(iv) Rehabilitation of people,
(v) Measures to check air and land pollution,
(vi) Improvement in mining areas,
(vii) Health and safety measures,
(viii) Policy of resource conservation should be adopted and alternative material should be developed, and
(ix) Proper management and planned regulated mining can solve many problems.
The problem of contamination through pesticides in our food grains, dairy products, vegetables, fruits or in our living environment as a whole has been visualised very well. Pesticides have been used in farming (i) to minimise the loss of food caused by pests and ensure a more bountiful harvest, and (ii) to decrease the extent of vector-borne diseases.
Contrary to these benefits, it has seriously degraded environmental quality and altered the ecological balance, as shown in Figure 3.3.:
The pesticides, which have been widely applied throughout the world, are carried forth by wind and water and distributed elsewhere. It was found that the some pesticides slowly decomposed into compounds that were toxic to fish and wildlife species in recent years.
Worldwide, 70,000 chemicals are in use per day and 500 to 1,000 new ones are added each year. Between 4, 00,000 to two million pesticide poisonings occur worldwide each year, of which an estimated 10,000 are fatal.
Research has proved that continuous use of pesticides has many negative effects on the environment, such as:
(i) Killing non-targeted organisms,
(ii) Accumulation in the food chain,
(iii) Building of immunities by the targeted pests,
(iv) Lower reproductive potential,
(v) Synergistic effects,
(vi) Toxic effects on water,
(vii) Pesticide residue in food and tissues,
(viii) Effects on vegetation and milk, and
(ix) Direct pesticide poisoning.
Pesticides have their impact on all three components of the earth, i.e., lithosphere, hydrosphere and atmosphere.
Pesticides are toxic, hence it is assumed that their presence in soil will change or alter fundamental soil processes, such as: (a) organic matter decomposition, (b) nitrogen transformation, (c) sulfur transformation, (d) phosphate availability, (e) trace element availability, and (f) soil enzyme activity, which influence soil fertility and productivity.
The presence of toxic chemicals in water also has significance as they are picked up by unicellular aquatic organisms like plankton and get accumulated in the body by a phenomenon called bio-concentration.
The amount of pesticides released into the atmosphere, if larger than really required, pollutes the air.
Presently, in India, 123 pesticides are permitted and are being used over a total area of about 142 million hectares. Among all pesticides, insecticides constitute about 80 per cent, followed by fungicides at 10 per cent, herbicides at 7 per cent, and others at 3 per cent. Pesticides like DDT, DDE, TDE, deidrin, endrin, heptachlor-epoxide and aldrin are harmful.
Many developed countries have prohibited the use of those pesticides which have harmful effects on living organisms. Pesticides can even enter the body through the skin, lungs (inhaled) or the digestive tract. Nausea and vomiting, abdominal cramps, diarrhea and involuntary defecation are the usual symptoms following gastro-intestinal poisoning.
Many countries have enacted laws for the safe use of pesticides. In India, there are two laws, i.e. Prevention of Food Adulteration Act, 1954 and the Insecticides Act, 1968. In fact, the use of pesticides should be restricted and pest control should be done by other methods and also quality of pesticides should always be supervised and maintained.
12. Environmental Degradation and Technological Development:
With the help of scientific and technological developments man has achieved new dimensions in his own development and has improved his quality of life by adding several amenities and facilities. The industrial development is proceeding at a very fast rate; similarly, revolution in the transportation sector has also occurred not only in developed countries but also in developing countries.
In the fields of agriculture, resource utilisation, power consumption, and engineering and in other scientific fields man has achieved success of high level. But, the current strong feeling is that all these developments have been responsible for the degradation of the environment and there is an urgent need to evolve an environ- mental-friendly technology.
It is said that “technology produces the crisis and technology can solve it”. Some of the problems produced by technological and scientific developments are as follows:
(i) Degradation of environment and expansion of pollution through industrialisation.
(ii) Unorganised mining.
(iii) Rapid deforestation.
(iv) Pollution due to transportation.
(v) Danger of leakage of radio-activity from atomic reactors.
(vi) Disturbances in eco-sensitive areas like ozone layer, tropical forests, Antarctica, etc.
(vii) Population growth, urbanisation, decline in death rate and other demographic changes are responsible for more and more exploitation of resources.
(viii) Extinction of several species of wildlife, birds and plants.
(ix) Too much stress and strain has created several health problems.
In brief, the quality of environment is deteriorating day by day. It should be maintained through environment planning, people’s participation, environmental status evaluation, and environmental legislation and administration.
The above mentioned impacts of human activity on environment are just an introduction to the thinking that with the development in technology, the numbers of ways in which humans are affecting the environment are proliferating. The complexity, frequency and magnitude of impacts are increasing, partly because of rising population and party because of a general increase in per capita consumption.
The US Council on Environmental Quality in 1982 had predicted the conditions of environmental degradation for year 2000, which are still relevant.
The report states:
If present trends continue, the world in 2000 will be more crowded, more polluted, less stable ecologically, and more vulnerable to disruption than the world we live in now.
Serious stresses involving population, resources and environment are clearly visible ahead. Barring revolutionary advances in technology, life for most people on earth will be more precarious in 2000 than it is now unless the nations of the world act decisively to alter current trends.
In fact, nations of the world are coming closer at least on environmental issues and they are thinking in terms of sustainable development.