Environmental pollution - concepts and insights

The term "environment" means the surroundings of an organism. The total environment of an organism is the sum total of the biotic and abiotic environments. The natural environment is diverse, complex and dynamic. Environmental systems have complex and dynamic interplay between many physical, chemical and biological processes. Environment has a natural ability to absorb wastes, neutralize harmful by-products and adapt to changes caused by human activities. Above the self – purification capacity, the environment is vulnerable to human interference. The conditions of the environment affect the existence, growth and welfare of all organisms. The quality of Human life is directly related to the quality of Environment. Water, air and soil pollution causes 40 per cent of human deaths of the world. Introduction of pollutants into an environment causes instability, disorder. Harm or discomfort to the ecosystem.

Pollution 

Pollution means introduction of harmful substances into air, water and land. Pollution is ‘something in the wrong place at the wrong time in the wrong quantity.’ The word pollution is derived from Latin word ‘pollutionem’ meaning ‘to make dirty’.  
Pollutant is an element of pollution.
Environmental pollution consists of 5 basic types –air, water soil, noise and light.

Why does pollution happen?

Pollution occurs because no process is 100% efficient. Any process – either manufacturing or fuel burning – is not 100% efficient – each produces pollutants and waste. ‘Pollution is a symbol of design failure’.

Nature of pollutants

·   Some pollutants are trans-boundary in nature e.g. air pollutants.
·   Some pollutants stay in the ecosphere for many years.
·   Pollutants disrupt ecological balance and destroy biota and habitat.

Extent of environmental damage

Pollutants may cause primary or secondary environmental damages.Primary damage is in the form of direct identifiable impact in the environment.Secondary damage is in the form of minor perturbations in the delicate balance of the biological food chain that detectable only over long time

Categories of pollutants

Toxic or non-toxic pollutants
Toxic pollutants –may be toxic either lethally or sub-lethally. Most toxic pollutants are man-made and not needed for the ecosystem functions e.g. heavy metals, pesticides, organic compounds.
Non-toxic pollutants – are not poisonous. They present naturally and excess may cause ecological imbalance e.g. plant nutrients, organic debris.
Biodegradable and non-biodegradable pollutants
Biodegradable pollutants are degraded by living organisms and assimilated by the environment. E.g. organic wastes, phosphates, nitrates, plant debris, animal remains.
Non-biodegradable pollutants cannot be decomposed / metabolized by living organisms and persist in the environment for long periods of time. e.g. plastics, pesticides, radioactive isotopes.
Threshold and non-threshold pollutants
Threshold pollutants have a harmful effect only above or below some concentration e.g. phosphates, nitrates, silica, minerals.
Non-threshold pollutants are potentially harmful in almost any amount e.g. mercury, lead, cadmium.
Flux type or sink type pollutants:In flux type the pollutants are moving. Such movements may be fast flux e.g. river and air pollutants or slow flux e.g. soil pollutants.

Characteristics of pollutants:

1.    They are present in excessive quantities-‘concentration effects’.
2.    They are in the ‘wrong place at the wrong time’.
3.    They may transform into harmful ‘secondary pollutants’.
4.    Pollutants may interact with each other.
5.    Some pollutants are biologically concentrated.
6.    Some pollutants have cumulative effect which persists for longer period.
Biological characteristics of pollutants
Toxicity – injure organs and organ systems
Mutagenicity –alter genetic characteristics
Teratogenicity – cause birth defects
Carcinogenicity –cause cancers.

Factors influencing severity of pollutants

·   Chemical nature- active and harmful nature to living organisms.
·   Concentration – the amount per volume unit of air, water, soil or body wt.
·   Persistence – longevity of pollutants in air, water, soil or body.

Origin of pollutants

Point or Non-point sources; Visible or Invisible sources; Natural or Man-made sources.
Point sources are single identifiable sources e.g. smoke stack of power plants, drain pipe of factories, exhaust pipe of automobiles.
Non-point sources are dispersed often difficult to identify e.g. rain water runoff from city or agricultural fields.

Forms of pollutants: 

Pollutants come in the form of liquids, solids and gases. Each one can either do harm, cause damage or induce injury to the target it affects.
·    Liquid pollutants – effluents, drains.
·    Solid pollutants – raw materials, products, wastes.
·    Gaseous pollutants- process fumes, waste gases, radioactive gases, volatile chemicals.

Sources of Pollutants· 

Disposal of wastes – sewage, effluents, litter·
Purposeful applications – pest  control, vector control· 
Unintended release – mining operations, chemical / oil spills, fires, shipwrecks, accidents.
Unwanted effects of pollutants -Pollutants cause disruption of life-support systems. They damage plant and animal life, human health and property. The nuisance effects include noise, unpleasant smells tastes and sights.

Effects of pollutants

· Pollutant effect may be local or global.
· Some pollutants kill cells or attack DNA or jam signals.
· Pollutants cause many diseases/kill many people.
· Pollutants can reach catastrophic levels and destroy many species.
· Some pollutants may affect not only the exposed individuals but also the next generation.

Health effects of pollutants

It may be acute or chronic damage.
1.    Physiological damage- reversible/irreversible damage to the health of the organism.
2.    Carcinogenesis – induction of cancer.
3.    Mutagenesis – induction of genetic damage.
4.    Teratogenesis - induction of birth defects.

Pollution is a global problem 

It has affected the lives of millions of people and caused several deaths and health problems. According to “the World health report 2002” , indoor air pollution is responsible for more than 1.5 million deaths and 2.7 % of the global burden of diseases. WHO (2006) has estimated that around a quarter of the global disease burden is associated with environmental risk factors.

Prevention of pollution

Social scientists suggest 3 basic approaches:1. Persuasion – asking people to change polluting behaviors.2. Regulation – passing laws to restrict pollution.3. Incentive - rewarding behavior that reduces pollution.