Tag: economics

The amount of oxygen required by bacteria to break down the organic matter present in a certain volume of a sample of water is called Biochemical Oxygen Demand(BOD)
                             
The amount of BOD in the water is a measure of the amount of organic material in the water, in terms of how much oxygen will be required to break it down biologically.

Pollutant is a substance that pollutes something, especially water or the atmosphere.
Examples are particulate matter (Sooty particles that are most toxic when they are small),sulphur dioxide,carbon-monoxide etc.

Primary pollutants are those gases or particles that are pumped into the air to make it unclean. They include carbon monoxide from automobile (cars) exhausts and sulphur dioxide from the combustion of coal.

Lead is a major air pollutant.Smelters (metal refineries) and other metal industries; combustion of leaded gasoline in piston engine aircraft; waste incinerators (waste burners), and battery manufacturing.

All the options are causes of industrial pollution
Asbestos:
This pollutant has cancer-causing properties. When inhaled, it can cause illnesses such as asbestosis and some types of cancer.
Nitrates & Phosphates:
These are found in fertilizers, and are often washed from the soils to nearby water bodies. They can cause eutrophication, which can be very problematic to marine environments.
Oils:
Oils form a thick layer on the water surface because they do not dissolve in water. This can stop marine plants receiving enough light for photosynthesis.

Land pollution is the deterioration (destruction) of the earths land surfaces, often directly or indirectly as a result of mans activities and their misuse of land resources.
It occurs when waste is not disposed of properly, or can occur when humans throw chemicals onto the soil in the form of pesticides, insecticides and fertilizers during agricultural practices.

Rain can carry and deposit the nitrogen in some pollutants on rivers and soils. This will adversely affect the nutrients in the soil and water bodies. This can result in algae growth in lakes and water bodies, and make conditions for other living organism harmful.this is called eutrophication.

Chemical reactions involving air pollutants can create acidic compounds which can cause harm to vegetation and buildings. Sometimes, when an air pollutant, such as sulfuric acid combines with the water droplets that make up clouds, the water droplets become acidic, forming acid rain.

Secondary pollutants: When pollutants in the air mix up in a chemical reaction, they form an even more dangerous chemical. Photochemical smog is an example of this, and is a secondary pollutant.