Causes and effects of Environmental Pollution in Zambia

Pollution can be defined as the introduction by man into the environment of substances that can adversely affect the health survival or activities of human and other living organisms.Pollutantsare unwanted solid, liquid or gaseous chemicals produced as by-products or wastes when resource is extracted, processed, made into products or used. Pollution can also take the form of unwanted energy emissions such as excessive heat,noiseor radiation. Alternatively, pollution has been expressed by Dix as one type of matter in a wrong place.

SOURCES OF ENVIRONMENTAL POLLUTION

Pollution can enter the environment by both natural and human activities. For instance, volcanic activity and erosion by water are natural processes and therefore inevitable sources of environmental pollution. However, most natural pollution is dispersed over a large area and is often diluted or broken down to harmless levels by natural processes. In contrast most serious pollution from human occur in or near urban and industrial areas, where large amount of pollutants is concentrated in small volumes of air, water and soil.

Some of the pollutants that are added to the atmosphere includecarbonoxides(C0₂, CO) largely generated from complete and incomplete combustion of hydrocarbons in petrol engines, Volatile organic compounds or hydrocarbons (HC) arising from combustion of fossil fuels and the oxides of nitrogen and sulphur (NO_x, SO_x) are created by burning fossil fuels particularly those containing sulphur.

We also add suspended particulate matter or solid particles like dust, soot, pesticides which include polychlorinated biphenyls (PCBs) and many others. Heat produced when any kind of energy is transformed from one form to another, noise produced by factories, mines, motor vehicles, air planes, cassette players and many others pose a source of environmental pollution.

EFFECTS OF ENVIRONMENTAL POLLUTION

The general effect of pollution produce deteriorating of the quality of the environment. This means pollution is responsible for the dirty streams, rivers and atmospheric contamination. Contaminated environment can have a number of unwanted effects like damage to human health caused by some chemical substances present in the air, food and water. Damage to plants and aesthetic quality of the environment caused by smoke, chemical fumes, dust, dumping of waste and dereliction. All these deleterious factors are affecting our environment in which we reside, work and spend our leisure time.

Substances like carbon monoxide at high concentration, causes death in human by blocking oxygen system in blood. SO_xgroups of pollutants are highly destructive and very common in metal smelting and coal mining. These also cause adverse chemical reactions to steel structures, power lines, some roofing materials, many natural stones, cement and paints. Long exposure to high noise levels can cause permanent hearing damage and similar exposure to dust can damage lung tissue and in extreme cases cause premature death. Pollution has many other effects on the environment some of which are irreversible.

ENVIRONMENTAL POLLUTION IN ZAMBIA

Africa has one of the fastest growing populations and the lowest standard of living. The increasing human population will affect the environment because more land will be needed for agriculture, shelter and recreation. The vast population must be fed, clothed and provided with basic needs. To do this government in Africa have to adopt chemical technologies which have deleterious effects on the environment.

The percent annual population growth rate in Zambia is usually a threat to the environment when the natural resources are reduced by the same percentage. And this has been the case in Zambia for some years. The ability of our environment to sustain us determines the future of our nation in social, economic and political spheres. Environmental pollution has become serious in Zambia with the development of modem industry in urban areas. The development of harmful materials in the atmosphere and water sources are increasing and people who are engaged in some special work are more likely to be hurt by pollutants.

1.SOURCES OF ENVIRONMENTAL POLLUTION IN ZAMBIA

Zambia’s main sources of environmental pollution are the many industries in urban areas. Industrial activity in Zambia is mainly confined to areas of Kafue and Copperbelt towns. In heavily industrialised areas, soil, water and air have become polluted with deleterious effects on the biota.

It is well known fact that mining and smelting operations can be detrimental to the environment. The mining industry in Zambia is highly developed and has been identified as the chief polluter on the copperbelt where mining activities are concentrated. Most of the pollution by Zambia Consolidated Copper Mines (ZCCM) arises from the mining and processing of copper and cobalt at the smelters.

The smelters are located in Kitwe, Mufulira and Luanshya. The Luanshya smelter is closed. Mining in Zambia has created serious environmental problems in localised areas. It is the main culprit for the environmental pollution in Kabwe, as found by Tembo, and on the Copperbelt. It emits large quantities of sulphur dioxide and particulate matter during processing of sulphur-bearing copper ore.

ZCCM Nkana division in Kitwe has an acid plant where some of the sulphur dioxide is converted into sulphuric acid. The excess is released into the atmosphere through the stacks. At Mufulira division there is no acid plant and all the sulphur dioxide is discharged into the atmosphere. Sulphur dioxide is also produced during the combustion of fossil fuels (petroleum and coal) as these contain sulphur.

The water effluents from ZCCM concentrators contain suspended solids (mainly copper and cobalt) which result in silt being deposited on the river bank. The amount of copper and cobalt in suspended phase in the Kafue river were found to be 0.3 pg Co/L and 462pg Cu/L at the municipal pump station in Chililabombwe before the river enters the mining area. Downstream at the Kafue mission centre in Kitwe, the amounts were found to be 3340pg Co/L and 3840pg Cu/L. The probable source of the enrichment was the mining processes.

Occupational hazards are often encountered in mining and other working environment. The major hazards arise from dusts, fumes and others. In Chingola there is an open pit mine where workers are exposed to dust, Chilanga cement in Lusaka and Ndola manufactures cement and is one of the major emitter of particulate matter. Cement dust from cement kilns is released to the atmosphere.

Ndola Lime Company emits lime (calcium oxide) dust from kilns. Ndola Lime and Lafarge cement are wrongly positioned in the eastern area of Ndola instead of the west. Quarrying operations results in dust emissions. These dusts are solid particles generated by handling, crushing, grinding and disintegrating inorganic materials such as rocks, ore, metal and coal. Coal is mined in Southern

Zambia at Maamba Coal mine by ZCCM. There are effects upon the lung tissue and lung function resulting from inhalation and deposition of dust. The exposure to man leads to respiratory diseases like silicosis from free crystalline silica, talcosis from talc and others described as pneumoconiosis with such dust as amorphous silica, coal dust and natural graphite involved.

Asbestos is widely used as a pipe and building material in Zambia. Inhalation of asbestos fibres by workers has been known to produce asbestosis with death from lung cancer as a sequel for many years. The sources of asbestos in the air include processing and manufacturing of asbestos-containing products. The people working in asbestos industries are at risk. Besides asbestos fibres have been demonstrated in lungs of persons not occupationally exposed but in the vicinity of the asbestos factory and asbestos mines.

The family members exposed to asbestos fibres brought home on the work clothes of asbestos industry workers may accumulate lung fibre burdens similar to those seen with occupational exposures and may be at risk for mesothelioma. In Kitwe, one of the asbestos factory raised public concern over workers working without protective materials. In USA asbestos is banned for use as water pipe, roofing material etc.

Many other industries take part in environmental pollution in Zambia like Nitrogen Chemicals of Zambia (NCZ) in Kafue which produce sulphuric acid for use in manufacture of fertilisers. The process results in sulphur dioxide emissions. Nitrogen oxide (NO_x) is also emitted during the production of nitric acid and ammonia gas. These fertiliser nutrients are washed down the Kafue river where they enrich the river bed and feed the Kariba weed (a shrub) clogging up the river.

The untreated effluents from NCZ, Kafue tannery, Municipal refuse etc. are released upstream into the river. The domestic water is treated from biological point of view only, and not from the chemical point of view. The effluents are diluted on entering the river. The dilution is more during the rainy season and less in the dry season. Whatever the season, the distance between municipal pump station and effluent release point is very short, and the river does not have the capacity to clean the water to safe levels.

Other potential polluters in Zambia may be dumping even more toxic wastes running into ground and river water, like the pharmaceutical companies. Textile industries like the Kafue textile which releases chemicals used during dyeing processes. Bata tannery releases vast amounts of chromium during tanning processes. Monarch Zambia Limited in Kitwe dumps zinc ash laden with lead from galvanising process inside its premises. The petroleum sludge on the Copperbelt has not been treated before release. Oil effluents from Indeni Petroleum refinery in Ndola contaminates water in Kaloko and Munkulungwe streams.

HEAVY METAL POLLUTION

Heavy metals are natural components of the lithosphere and as such may be found throughout the ecosystem. It has been known for several decades that trace quantities of certain elements exert a positive or negative influence on plant, animal and human life, Some elements are essential to life and nontoxic, and hence non-polluting in certain formulations. Heavy metals, recognised as highly toxic and dangerous pollutants, are placed only second to pesticides in environmental importance. Metals are not biodegradable, as a result they accumulate in vital organs of man and exert progressively long term growing toxic actions.

1.Spoil Heaps

Heavy metal pollution resulting from spoil heaps is usually a consequence of insanitary habits. In urban areas, soil pollution is associated with dumping on land of domestic refuse and solid resulting from the treatment of sewage and industrial wastes. The soil is thus polluted with chemicals including heavy metals and products of petroleum industries. These can reach surface and ground water beneath and ultimately get incorporated into food chain in the affected urban ecosystem. Water pollution usually severely damages aquatic communities and, can cause immediate and long term harmful effects to human life.

2. Industrial Sources

Apart from smoke and fumes released from industries, the disposal of industrial solid wastes constitutes a major source of environmental pollution by toxic chemicals. These wastes have given rise to severe problems of soil pollution either by poisoning the soil or crops or by eventual entry into surface and ground water sources.

Mining of minerals involve removing of material from earth’s crust and dumping on land of unwanted large masses of rock and waste material somewhere else, usually near mining site, resulting in slimes dams. Toxic substances leach out of such materials enter the soil and run off into streams and ground water. The processing of ores to recover economic mineral results in process effluent which contain suspended solids. Mining, therefore, has severe local, and sometimes regional, environmental impact on land, air and water.

Mining of base metals or heavy metals result in gradual release to natural environment of toxic substances of which the most important are metal ions and chemical reagents. It is unusual for lethal concentrations to be released from a mine, however the long term of exposure to sub-lethal doses are uncertain. Spoil tips associated with non-ferrous mines contain anomalously high levels of heavy metals compared with other environments. The table below shows some industrial and agricultural sources of heavy metals in the environment.

Table 1.1: Industrial and Agricultural Sources for Metals in the Environment Use Metal

AIR POLLUTION

There are a range of atmospheric pollution problems currently threatening the Earth’s general environment.

1.Acid rain

This problem arises from the acidic gases produced by burning fossil fuels in a number of different situations.

The majority of power stations in industrialised countries burn coal or oil. Both these fuels are contaminated with sulphur, which produces sulphur dioxide when it burns:

sulphur + oxygen → sulphur dioxide

S(s) + 0₂(g) → S0₂(g)

Oxides of nitrogen (NO⁺) (for example nitrogen dioxide, N0₂) are also produced when air is heated in furnaces or in vehicle petrol engines. These gases dissolve in rain water to produce‘acid rain’.

There are numerous effects of acid rain, for example:

• limestone buildings, statues, etc., are worn away.
• lakes are acidified, and the presence of metal ions (for example Al³⁺ions) leached (washed) out of the soil damages the gills of fish. The fish can die.
• nutrients are leached out of the soil and from leaves. Trees are deprived of these nutrients. Aluminium ions are freed from clays as aluminium sulphate and damage tree roots.

The tree is unable to draw up enough water through the damaged roots, and it dies.

The wind can carry acid rain clouds away from the industrialised centres, causing the pollution to fall on other countries.

Remedies for the effects of acid rain are limited. Lime can be added to lakes and the surrounding land, to decrease the acidity.

Methods of prevention are expensive, but they are more useful and beneficial in the long term. Petrol (gasoline) for cars has now been made almost free of sulphur. Fuel for power stations could be desulphurised further. Flue-gas desulphurisers can be fitted to power station and factory chimneys to reduce the levels of sulphur dioxide given off.

2.Global warming and the ‘greenhouse effect’

The presence of water vapour, carbon dioxide (CO₂) and other gases in the air has served the planet well. The‘trapping’of heat by the atmosphere has kept the Earth warm. Without thisgreenhouse effect, the average temperature of the Earth’s surface would be -18°C, rather than 15°C. However, higher levels of certain gases produced by human activity are increasing this heating effect and producing global warming.

The‘greenhouse gases’that produce this warming include water vapour, carbon dioxide, methane, the oxides of nitrogen and CFCs (chlorofluorocarbons). These gases absorb heat from the Sun that is reflected from the Earth’s surface. They prevent this heat from being re-radiated back into space. So the Earth’s surface becomes warmer.

The levels of carbon dioxide released into the atmosphere are very high (about 5000 million tonnes per year). Large-scale deforestation, particularly of the tropical rainforests, to provide land for agriculture, also increases the level of carbon dioxide in the air because it removes trees j which absorb the gas for photosynthesis.

The effects of global warming are complex. The polar ice-caps would begin to melt as the temperature rose. The increase in sea level would threaten low-lying lands. Extensive climate change I is possible but is difficult to predict. In some regions the effects may be good; but others may suffer long droughts. There could be major shifts in desert and fertile regions. Tropical storms could | increase in their intensity.

There is evidence, from dying corals to an increase in warm-water fish in the North Sea, to show that global warming is taking place. Whether this is due to increased carbon dioxide levels remains to be proved. Certainly the concentration of CO₂in the Earth’s atmosphere has increased over the last century (in 1850 it was 0.027%, and in 1993 it was 0.036%).

Ozone layer depletion

A protective layer of ozone in the stratosphere prevents harmful ultra-violet radiation reaching the Earth’s surface. CFCs and other halogen compounds are thought to cause the damage. International agreement has been reached on restricting the use of these compounds (the Montreal Protocol). If the situation were allowed to grow worse, exposure to higher levels of ultraviolet radiation could cause more cases of skin cancer in humans, and cause damage to crops.

There are various types of pollution that occur over smaller, local areas. These usually occur in large cities, where there is heavy use of motor cars. These forms of pollution are:

• photochemical smog,
• high levels of carbon monoxide, and
• high levels of lead compounds.

Photochemical smogis formed in regions where there is a large amount of traffic. It was first identified in Los Angeles, and forms only under certain conditions. Severe photochemical smog often occurs in cities located in valleys, or surrounded by hills or mountains. On sunny, windless days, oxides of nitrogen are trapped by the hills in air that is close to the ground. A complicated series of reactions takes place and ground-level ozone is one of the products. In these circumstances ozone is harmful, particularly for asthma sufferers.

Carbon monoxideis the most common air pollutant in the industrialised world. It is produced when hydrocarbon fuels are incompletely burnt. Carbon monoxide is poisonous at levels of only 0.1%. Oxygen is very important to living things.

In our bodies it is carried round the body attached to haemoglobin in our red blood cells. Carbon monoxide is attracted to haemoglobin over 200 times more strongly than oxygen. In the blood, carbon monoxide prevents haemoglobin from carrying oxygen. This leads to dizziness and headaches. Prolonged exposure to carbon monoxide causes death.

Lead compoundsare the most toxic heavy-metal pollutants in the air. Lead compounds form part of the ‘urban dust’ that forms in a city atmosphere.

People living next to busy roads can have high levels of lead in their blood. This has been linked with nervous disorders and with learning disabilities in children. The increased moves to use unleaded petrol are reducing this health hazard.

WATER POLLUTION

Water is another major resource that is essential to our life. However, as with the atmosphere, we are continually guilty of polluting the rivers and oceans. Industrial waste has been pumped into rivers in spite of legal restrictions. Many pollutants are involved, but among the most dangerous are the heavy metals such as cadmium and mercury. These can have disturbing effects on living things even at very low levels. They can also pass from one living thing to another along the food chain and affect life at various levels in the chain.

Industries and power stations use water from rivers as a coolant. When this water is returned to the river at a higher temperature, it causesthermal pollution. Less oxygen can dissolve in this warmer water, so that plants and animals in the water have greater difficulty breathing.

Sewage, detergents and run-off from fertilised fields can all reach rivers and cause damage to plant and aquatic life. The beaches of Italian resorts in the Adriatic have in the past been troubled by a green slime. This slime was due to the flow of effluent (waste) from the delta of the river Po.

Pesticides also pose problems, as they can be concentrated through the food chain in fish. Apart from dangers to fish stocks, the concentration of possible cancer-causing chemicals at stages in the food chain is a source of great concern.

POLLUTION IMPACT ON THE ZAMBIAN ENVIRONMENT

The environmental consequences of chemical emissions are a subject of continuous debate. Some of the pollutants are a direct threat to the health of people living in this exposed area.

Mining brings about noise pollution in three categories, these are fixed plant, mobile plant (used internally) and external transport movement. Fixed plant include equipment like crushers or processing machinery, loading facilities and others. Mobile plant used on site is associated with drilling, blasting and service operations. The other source of noise in mining is external movements associated with all mining operations, the despatch of all valuable products and waste and the movement of personnel. As stated earlier long term exposure to high noise levels can cause permanent hearing damage to people.

Soil is not only vulnerable to pollution by the mines but also to several other industrial sources. Where commercial fertilisers have been used over and over contamination of soil has taken place.

The use of pesticides does not solve pest problems but increases them by killing beneficial species and building resistance in pests. Farming depends on the quality and therefore the state of preservation of the soil. Our physical development as human beings depends on the quality of what we eat and therefore on the quality of farming.