CAUSES AND EFFECTS OF POLLUTION

INTRODUCTION
Human activities generate a tremendous amount of waste materials, these are discharged into various component which bring about pollution in the environment. The term ‘Pollution’ refers to the act of contaminating one’s environment by introducing certain hazardous contaminants that disturb the ecosystem and directly or indirectly affect the living organisms of that environment. Pollution can also be defined as the presence or introduction of a substance or contaminant into natural environment that cause adverse change.
Environmental pollution is the contamination of air, water and land in such a manner as to cause real or potential harm to human health or well being of animals, plants, soil and properties. The types of environmental pollution include air pollution, water pollution, soil pollution, and noise pollution e.t.c.
Pollution control is a term used in environmental management. It is the control of emissions and effluents into air, water or soil. Without control, the waste product from consumption, heating, agricultural, mining and manufacturing, transportation and other human activities whether they accumulate or disperse will degrade the environment. Pollution control practices includes recycling, reusing, reducing and preventing while pollution control devices include dust collection system, baghouses, cyclone, spray tower, sewage treatment e.t.c.
Causes of Pollution
The causes of pollution in the environment include technological, economic, social and natural causes e.t.c.
Technological Cause of Pollution
1. Industrial activities resulting from technological processes yield toxic gases and greenhouse gases, thereby polluting the environment.
2. A large amount of exhaust gas from automobiles leads to serious air pollution
3. Owing to the development of modern agricultural technology, farmers tend to use lots of chemical fertilizers and pesticides to increase yield, which severely poison the soil and underground water.
Natural Causes of Pollution
The natural causes of pollution include:
a) Dust
b) Natural radioactivity
c) Ozone and nitrogen
d) Micro-organisms such as bacteria, spores, moulds and fungi from plants and animals
e) Forest fire
f) Soil erosion
Economic Causes of Pollution
This is as result of activities that contribute to the growth and development of nature and human welfare. Economic causes include:
• Agricultural activities for food production
• Health care for human beings and animals
• Dwelling for settlement in cities or villages
• Transportation
• Energy for various direct human and industrial needs.
Social Causes of Pollution
This is as a result of human activities in physical environment which may originate from tradition, culture, religion or some old practices. Schools, television shows, radio, newspaper, friends and co-workers are all social causes of pollution.
Man-made Contribution to Environmental Pollution;
• Burning of fuel like coal, diesel, gasoline, kerosene, that contains nitrogen, sulphur dioxide and hydrocarbons by power plant
• Domestic burning of fuels e.g firewood, kerosene
• Unpleasant noise from machines, factories and sound system
• Automobile source in rural and urban areas from aircraft engine, cars and trains
• Industrial activities such as quarrying, grinding and milling, iron and steel, cement industries e.t.c
• Dumping of domestic and industrial sewage in seas, rivers and ocean e.t.c


Other sources of pollution include;
Commercial sources: burning of refuse at market dumps, garbage producing offensive odour, dumping of refuse directly into water bodies pollute stream and river water, chemical substances from commercial sources pollute soil.
Agricultural sources: clearing of land and burning of farm residues produce air pollution, application of fertilizer destroy the soil.
Municipal sources: municipals are cities or towns where people live. People generate waste in their day to day activities. Indiscriminate dumping of refuse on plots of land pollutes the soil, so also is the disposal of sewage from houses into water bodies.
Harmful Effect of Pollution on Physical, Social and Cultural Environment
The physical effects of pollution are those that we can see, but they include effects other than actual physical change. Air pollution damages a wide variety of materials. Burning of oil and coal produce sulphur dioxides, and when combined with other pollutants such as soot, smoke, lead and sulphur oxides particulates causes corrosion at a faster rate. These particulates damage structures and equipments.
The most serious result of pollution is its harmful biological effect on human health and on the food chain of animals, birds and marine lives. Pollution destroys vegetation that provides food and shelter. Pesticides, which include herbicides and insecticides, can damage crops, kill vegetation, poison birds, animals and fish.
The wide spread use of pollutants, such as oil, chemicals and fertilizers pollute water ways.
Effects of Pollution on Human Health
• Some pollutants cause irritation of the eyes, nose, throat and respiratory tract
• Lead particulate causes lead poisoning resulting in convulsion, coma and even death
• Industrial effluents results in the addition of poisonous chemicals such as arsenic, mercury, cadmium and lead which reach human body through contaminated food
• Spread of water borne diseases like typhoid, dysentery, cholera are health hazards arising from drinking of contaminated water
• Toxic chemicals in water can be harmful to human health
• Some pollutants are carcinogenic
• Noise pollution can cause psychological problem, dizziness and tiredness
• It increases heart beat and rate of respiration
Effects of Pollution on Soil and Vegetation
• Particulates that settles on plant leaves may interfere with gaseous exchange during photosynthesis and respiration
• It leads to stunted growth in plants
• Pollution cause chlorosis, bleaching and other colour change in plants
• Loss of economic value
• Bush burning kills soil microbes and destroy vegetation cover of the soil
• Oil spill and toxic wastes destroy soil ecosystems
• Air pollution like sulphur dioxides, hydrogen sulphides cause serious damage to plants
• Air pollution make plants vulnerable to diseases and pest
Effects of Pollution on Water and Animals
• Thermal pollution leads to death and migration of aquatic animals
• The pH of the aquatic environment can be changed by added acid from industrial effluents
• Industrial waste contain toxic chemicals and can be harmful to aquatic life
• Some organic chemicals can impart bad taste and odour to water
• Waste with high organic matter content increases the biochemical oxygen demand of water
• Spread of diseases to animals and aquatic lives
• Poisonous air pollutant when inhaled can lead to death of animals e.g London Smog of 1952 which led to death of many cattle
• When animals graze on polluted grasses and crops, they may develop fluorosis and other health problems that can damage vital organs in their body.