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Environmental Studies The Hong Kong Polytechnic University Recommended Reference Books 1. Introduction to Environmental Engineering and Science , 2nd edition Author: Gilbert M. Masters Publisher: Prentice Hall 2. Introduction to Environmental Engineering , 3rd edition
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1.Introduction to Environmental Engineering and Science, 2nd edition
Author: Gilbert M. Masters
Publisher: Prentice Hall
2.Introduction to Environmental Engineering, 3rd edition
Author: Davis, Cornwell
Publisher: McGraw-Hill International
3. Environment Hong Kong
Environmentis the physical and biotic habitat which surrounds us; that we can see, hear, touch, smell and taste.
Pollution can be defined as an undesirable change in the physical chemical, or biological characteristics of the air, water or land that can harmfully affect the health, survival or activities of humans or other living organisms.
2. Environmental systems
Environmental systems can be classified into 3 categories:
Water Resource Management System
Water supply subsystem
The nature of the water resource commonly determines the planning, design, and operation of the collection, purification, transmission, and distribution works.
The 2 major sources used to supply community and industrial needs are referred to as:
i.e. stream, lakes and rivers
i.e. water pumped from wells
3. Interaction of systems
A number of different environmental problems are associated with water, air or land systems. Many of these problems will apply only within one of these systems, justifying the breakdown into these categories.
Such a classification is also useful for easier comprehension of related problems within one system. Moreover, it is sensible because, for managerial and administrative reasons, such subfields as air pollution, water supply, wastewater disposal and solid waste disposal are often dealt with separately by governmental agencies.
Unfortunately, many important environmental problems are not confined to an air, water or land system but involve interactions between systems.
A current example is the acid rain problem stemming from the emission of sulfur dioxide and nitrogen oxide gases into the atmosphere from the emission of sulfur dioxide and nitrogen oxide gases into the atmosphere from the sacks of generating stations, smelters, and automobile exhausts. These gases are then transported by air current over wide regions. Rainfall “washes them out”, creating acid rain which is harmful to aquatic life, forest and agricultural crops.
While many environmental problems are local or regional, others must be viewed from an overall water-air-land interaction standpoint on a national, continental, or global basis. A simple illustration of this interaction is shown in following figure and hips to explain how an insecticide like DDT is now ubiquitous.
4. Environmental problems
Environmental problems are always interrelated . Sometimes a solution to one problem actually creates another problem.
For example, when people are sick and dying from disease, it is natural to want to improve human health. The health is improved and infant mortality is reduced, a pollution explosion may results. To feed this growing pollution, natural habitats are often converted into farmland. In turn, the destruction of natural habitats eliminates the native wild plants, predatory animals, and parasites. But when natural predators and parasites are killed, outbreaks of insect pests become more common. When farmers use pesticides to control the pests and protect the crops, they also pollute the environments.
The development of this entire cycle in itself consumes irreplaceable fossil fuel supplies and when fuel are burn, air pollutants are generated.
To make the task a bit more manageable, we can divide environmental descriptions into 5 main types.
The human population has risen very rapidly in recent years. This increase has led people to ask whether the earth has become overpopulated. Overpopulation may be defined as the presence in a given area of more people than can be supported adequately by the resources available in that area.
It is important first because overpopulation is major case of all other environmental problems. Fewer people would need less food, chop down fewer trees, burn less oil, and discharge less sewage into rivers. Second, remedies for overpopulation and the starvation that accompanies it are generally higher on our list of priorities than other environmental concerns.
Pollution is a reduction in the quality of the environment by the introduction of impurities. There are 2 distinctly different types of pollution.
A. Concentration of natural wastes
Before modern civilization, most organic wastes did not accumulate in the environment, because they were dispersed sufficiently so that decay organisms could consume and recycle them.
Thus, the quality of the environment was not impaired.
In modern times, the organic wastes are often produced in such a concentrated manner that natural decomposition cannot clean the environment rapidly enough. For example, a city may house several million people in a small area of land.
Organic wastes from such a city are not spread evenly about the countryside but instead are concentrated in a few locations sewage that is dumped into a river decays naturally but the process takes time. If the volume or the concentration of sewage is high, the water may not become purified by the time it reaches the next site downstream where pure drinking water is needed.
Natural wastes can be inorganic as well as organic. Inorganic wastes would include compounds of elements such as lead, cadmium and arsenic. These elements exist naturally in the soil and rock all around us and are also present in small concentration in our bodies. As a trace elements, some are harmless, and many are even essential to bodily functions. However, even moderate doses of most inorganic compounds are poisonous.
Such substances are often concentrated during mining and smelting operations.
B. Introduction of synthetic chemicals into the environment
People have recently learned to make new chemical compounds, called synthetic chemicals. In 1985, 70,000 different synthetic chemicals were produced in quantity for common use and about 2000 new compounds have been entering the environment every year since then.
They are present in paints, dyes, food additives, drugs, pesticides, fertilisers, fire retardants, building materials, clothes, cleaning supplies, cosmetics, plastics and so on.
Some of the synthetic chemicals are drugs that save millions of lives every year and other are poisons. But because most of them are new to the environment, the traditional patterns of decay and recycling do not necessarily apply.
A material that decomposes in the environment as a result of biological action is said to be biodegradable.
Most natural organic wastes are biodegradable many synthetic chemicals are not. For example, plastics remain in the environment for a long time because organisms that feed on them and bread them down are rare. Plastic shampoo bottles may produce unsightly litter, but they are not biologically active.
However, many other chemical compounds not only are persistent but also are poisonous. Therefore, represent a significant threat to the environment.
(3) Depletion of resources
Resources of fuels, minerals, water, soil, and timber can be depleted or used up as it becomes less available for its intended function. Materials can become depleted in three different ways.
1) A substance can be destroyed, that is converted into somethings else. Fuels are destroyed when they are used. Coal is converted to ashes and gas. Uranium is converted to radioactive waste products. The ashes or waste products are no longer fuels.
2) A substance can be lost by being diluted, by being displaced to some location from which it cannot easily be recovered. If you open a helium-filled balloon, the gas escapes to the atmosphere. Not only atom of helium is destroyed, but the gas is lost because it would be impossible, as practical matter, to recover it.
3) A substance can be rendered unfit for use by being polluted. In this way, pollution and depletion are related each other. If industrial or agricultural wastes are discharged into a stream or if they percolate down through soil and porous rock to reach a supply of groundwater, these water resources become less fit for drinking or in the case of the stream, for recreation or for the support of aquatic life.
(4) Changes in the global condition
Over the past 150 years or so a more instant in geological time-humans have significantly altered the chemistry of our environment. Today many scientists believe that these changes might affect the life support systems of the earth.
For example, when fossil fuels are burned, carbon dioxide is released. In turn, the excess atmosphere carbon dioxide could possibly cause a general warming of the entire earth.
Deforestation could affect global rates of photosynthesis and the composition of the atmosphere. Aerosol sprays and aircraft exhaust may be destroying the ozone layer in the atmosphere that filters out ultraviolet radiation.
b. Extinction of species
Throughout mush of the world, forests, shrublands and other natural systems are being converted to farmland. When habitats are destroyed, many organisms cannot survive. Therefore, hundreds of thousands of species of plants and animals are faced with extinction. People often do not know precisely what has been convinced that endangered species of plants or animals should be saved to preserve the genetic diversity of our planet.
Some of these species are especially important, because they may produce lifesaving drugs or may be essential in breeding valuable crops or domestic animals.
In many wars, war is a combination of all environmental problems rather than a separated category. In modern times, war ad the preparation for war have led to pollution and depletion of resources far more extreme than any single peacetime activity.
People are killed, cities and farms are ruined and forested regions are destroyed. But even in the absence of actual conflict, the cost of maintaining armaments and standing armies is enormous. Finally, the potential for a nuclear war places the global systems of the Earth, human civilization and even the human species itself at risk.
In many jurisdictions, regulatory are now focused on the generation of pollutants rather than on the capture and disposal of pollutants. The primary objective is to prevent or reduce pollution at its source. If pollutants cannot be prevented or reduced, they should be reused or recycled in an environmentally acceptable manner.
If pollutants cannot be prevented, reduced or recycled, then they should be controlled or treated to reduce their harmful effects on humans and the environment. Disposal of untreated pollutants should be used only as a last resort. The idea is to analyze the production, use and ultimate disposal of the product to avoid creating pollution.
Wastewater disposal subsystem
Safe disposal of all human wastes is necessary to protect the health of the individual, the family, and the community, and also to prevent the occurrence of certain nuisances. To accomplish satisfactory results, human wastes must be disposed of so that:
Wastewater Management Subsystem. (Source:R.K. Linsley and J.B. Fanzini, Water Resources Engineering, New York: McGraw-Hill, 1979. Reprinted by permission.)
Air Resource Management System
Our air resource differs from our water resource in 2 important aspects.
The balance of cost and benefit to obtain a desired quality of air is termed air resource management. Cost-benefit analyses can be problematic for at least 2 reasons.
Solid Waste Management
Generally, solid waste is considered a problem to be solved as cheaply as possible rather than a resource to be recovered. A simplified block diagram of a solid waste management system is shown in following figure.
A simplified block diagram of a solid waste management system. (Source: G. Tchobanoglous, H. Theisen, and R. Eliassen, Solid Wastes, New York: McGraw-Hill, 1977. Reprinted by permission.)
Environmental Protection depends on
Role of government in environmental protection
1. Environmental education in schools and colleges.
2.Public awareness promotion: informal teaching by publicity in media; drawing attention to health hazards and propagranda or programs to improve the environmental condition.
3.Release of information on affairs and policies of environmental concern, information on regulatory control, standards and enforcement procedures.
4.Education of the industrialists in providing guidelines, training, regulation information, self-esteemed motivation, and information on complaint procedures.
5.Provide incentive for pollution control practice for the polluters
6.Administrative control: good town and landuse planning, pollution control zone, frequent inspection on potential polluting industries, and enforcement of the pollution control legislation.
7.Legislation on pollution prevention, laws and ordinance on environmental protection.
Government should show their own compliance on the regulations for government development projects as an example to industries.
Role of environmental education in the enhancement of environmental protection
1. Government attitude on environmental education and its impact on secondary school students influences on the present and future attitude on environmental protection for the younger generation.
2. Tertiary and technical institute‘s environmental education programs and courses on the training of the technical and professional personnel for government and industrial sector on environment management and pollution control.
3. Environmental education on the public through government, mass media, broadcasters, press and their impact on the citizens and society.
4. Educaiton of the industrial sector through government persuasion, public awareness programs and mass media exposure and promotion of pollution control practice.
5. Education through social awareness programs and the promotion of environment friendly products.
1. District board: Industrial / Urban development
2. Environmental Protection COMmittee (EPCOM)
3. Environmental groups
Public Participationare important as different interests in the development are balanced through
Public participation will ensure that all interests are balanced and the parties concerned will include environmental consideration in the planning, design, constructional and operational stages and that steps are taken to minimize the adverse impacts on the environment to the satisfaction of society.
Social background on the individual‘s opinion and reaction to environmental pollution: