1. University of Khartoum Institute of Environmental Sciences Dip/ M.Sc in Environmental Sciences Semester 2 ENVIRONMENTAL POLLUTION COURSE By: Dr. Zeinab Osman Saeed

2. DEFINITION OF POLLUTION Lecture- 2 Dr. Zeinab Osman Saeed

3. Pollution  Environmental pollution is any discharge of material or energy into water, land, or air that causes or may cause acute (short-term) or chronic (long-term) detriment to the Earth's ecological balance or that lowers the quality of life. Pollutants may cause primary damage, with direct identifiable impact on the environment, or secondary damage in the form of minor perturbations in the delicate balance of the biological food web that are detectable only over long time periods.

4.  Environmental pollution is “the contamination of the physical and biological components of the earth/atmosphere system to such an extent that normal environmental processes are adversely affected”. (1)

5.  Pollution is the introduction of contaminants into the environment that cause harm or discomfort to humans or other living organisms, or that damage the environment” which can come “in the form of chemical substances, or energy such as noise, heat or light”. “Pollutants can be naturally occurring substances or energies, but are considered contaminants when in excess of natural levels.” (2)

6.  Pollution is “the addition of any substance or form of energy (e.g., heat, sound, radioactivity) to the environment at a rate faster than the environment can accommodate it by dispersion, breakdown, recycling, or storage in some harmless form”. (3)

7.  Pollution is a special case of habitat destruction; it is chemical destruction rather than the more obvious physical destruction. Pollution occurs in all habitats—land, sea, and fresh water—and in the atmosphere.” (4)

8.  Much of what we have come to call pollution is in reality the nonrecoverable matter resources and waste heat.” (5)  “Any use of natural resources at a rate higher than nature's capacity to restore itself can result in pollution of air, water, and land.” (6)  “Pollution is habitat contamination”. (7)

9.  According to the American College Dictionary, Pollution is defined as : to make foul or unclean, dirty.

10.  Perhaps the overriding theme of these definitions is the ability of the environment to absorb and adapt to changes brought about by human activities.  In one word, environmental pollution takes place when the environment cannot process and neutralize harmful by-products of human activities (for example, poisonous gas emissions) in due course without any structural or functional damage to its system.

11.  In fact, “the due course” itself may last many years during which the nature will attempt to decompose the pollutants; in one of the worst cases – that of radioactive pollutants – it may take as long as thousands of years for the decomposition of such pollutants to be completed.

12.  Pollution occurs, on the one hand, because the natural environment does not know how to decompose the unnaturally generated elements (i.e., anthropogenic pollutants), and, on the other, there is a lack of knowledge on the part of humans on how to decompose these pollutants artificially.

13.  Pollution is an unwelcome concentration of substances that are beyond the environment's capacity to handle. These substances are detrimental to people and other living things.

14.  In an undisturbed ecosystem, all substances are processed through an intricate network of biogeochemical cycles, such as the nitrogen and carbon cycles. During these cycles, substances are taken up by plants, move through the food chain to larger and more complex organisms, and when the latter die, are decomposed (broken down) into simpler forms to be used again when they are taken up by plants..

15.  Biodegradable substances are those that can be broken down by the environment's biological systems. Pollution occurs when the environment becomes overloaded beyond the capacity of these normal processing systems

16. Examples  * An excess of normally helpful substances, such as the nutrients nitrogen and phosphorus.  * An excess of substances that are harmless, and perhaps even necessary in tiny amounts, but toxic in concentration. Copper, for example, is necessary in small amounts for healthy plant growth, but becomes a pollutant if it occurs in greater quantities.

17.  * Synthetic (human made) compounds that are poisonous in the environment, often even in trace amounts, such as DDT, dioxin, PCBs and organochlorines (see Enviro Facts "Toxic waste" and "Poison, farmers and wildlife").  * Substances that, in any amount, are not biodegradable, such as plastics and highly persistent chemicals like DDT and other organochlorins.