Tag: zoology

Thermal pollution refers to effluents and hot water from thermal plants or atomic reactors which bring about the rise in water temperature. Warm water contains less oxygen, resulting in increased organic loading, and replacement of green algae by blue-green algae.

• There are wastes that are generated on an everyday level, classified as non-biodegradable wastes because they cannot be degraded by microbial activity.
• These wastes cannot be burned because they release harmful gases and result in air pollution. 
• Dumping and burying of this wastes may cause leaching of the chemicals which causes soil pollution. 
• Recycling is the best way to manage these waste forms. 
• Recycling will help in the reduction of the wastes and the waste will be transformed into useful forms.
• Thus, the correct answer is option D. 

About 71% of the Earth's surface is covered by water. There is only 3% of water which is considered as pure or fresh water. This water is present in lakes and rivers. This pure water is used for various different activities. It is also known as potable water. About 5-10% of pure water is used for the industrial purposes.

Industrial effluents are the major water pollutants because of their ingredients. Heavy metal waste like mercury, cadmium, dirt and gravel, masonry and concrete, scrap metal, trash, oil, solvents and chemicals etc. are present in the industrial effluents. Their treatment is a long and expensive procedure as compared to domestic sewage treatment. The industrial waste is corrosive, reactive and igniting. It poses dangerous effects on the aquatic life primarily and human health thereafter. These have shown the biomagnification capability as well.

• Suspended solids in water refer to various impurities like sand, slit, small stones, etc. These are heavy ad get submerged at the bottom of water. They do not easily mix or dissolved easily with water. So, they can be separated from water by various means like sedimentation, water filter, etc. 
• Bacteria are very minute organisms that are not even visible to naked eyes and thus their removal becomes very difficult. Proper disinfection is required to remove them. 
• Colloids and other suspended impurities also need special filtration and purification techniques to be separated from the water.
• So, option D is the correct answer.

Agricultural discharge such as large quantity of agrochemicals, organic matter, sediments and saline drainage, fertilizer extract directly released in water bodies contaminate water and cause waterlogging. Sewage and untreated waste containing the high amount of organic compound and industrial effluent including organic, non-organic and reactive waste released in water have the potential to acidify water bodies, the solid waste accumulation can result in drying up of waters.

Oxygen is less soluble in warm water. Hence, as the water temperature increases the dissolved oxygen decreases.

Cadmium (Cd) is one of the most toxic elements to which humans could be exposed at work or in the environment. The outbreak of itai-itai disease, which is the most severe stage of chronic Cd poisoning, occurred in the Cd-polluted Jinzu River basin in Toyama.