UGC-NET (NTA) Environmental Sciences, December-2019

Arsenic is a ubiquitous element with several different forms. The toxicity of arsenic is determined by its form. The prevalent valences are the +3 and the +5 form. Arsenic is found in both an organic form and an inorganic form with valence numbers ranging from +3 to +5. As⁺³, or arsenite, is more toxic than arsenate, or As⁺⁵.

Packed towers are typically designated by the flow arrangement used for gas-liquid contact or by the material used as packing for the bed. The most common flow configuration for packed towers is countercurrent flow. A wet-film scrubber uses packing to provide a large contact area between the gas and liquid phases, turbulent mixing of the phases, and sufficient residence time for the exhaust gas to contact the liquid. These conditions are ideal for gas absorption. Large contact area and good mixing are also good for particle collection; however, once collected, the particles tend to accumulate and plug the packing bed.

Packed towers are typically designated by the flow arrangement used for gas-liquid contact or by the material used as packing for the bed. The most common flow configuration for packed towers is countercurrent flow. A wet-film scrubber uses packing to provide a large contact area between the gas and liquid phases, turbulent mixing of the phases, and sufficient residence time for the exhaust gas to contact the liquid. These conditions are ideal for gas absorption. Large contact area and good mixing are also good for particle collection; however, once collected, the particles tend to accumulate and plug the packing bed.

Atmospheric layers are characterized by variations in temperature resulting primarily from the absorption of solar radiation; visible light at the surface, near ultraviolet radiation in the middle atmosphere, and far ultraviolet radiation in the upper atmosphere. Earth's atmosphere is mainly composed of nitrogen and oxygen. Although our atmosphere extends upward for many hundreds of kilometers, 90% of the atmosphere's mass is confined within a 20 km of the earth's surface.

Artesian well, well from which water flows under natural pressure without pumping. It is dug or drilled wherever a gently dipping, permeable rock layer (such as sandstone) receives water along its outcrop at a level higher than the level of the surface of the ground at the well site. At the outcrop the water moves down into the aquifer (waterbearing layer) but is prevented from leaving it, by impermeable rock layers (such as shale) above and below it. Pressure from the water's weight (hydrostatic pressure) forces water to the surface of a well drilled down into the aquifer; the pressure for the steady upflow is maintained by the continuing penetration of water into the aquifer at the intake area.

A thermophile is an organism-a type of extremophile-that thrives at relatively high temperatures, between 41 and 122 °C (106 and 252 °F). Many thermophiles are archaea. Thermophilic eubacteria are suggested to have been among the earliest bacteria. The glacial ecosystems have very unique characteristics, which cannot be seen in other ecosystems. Thermophiles group of microorganisms dominate in glacial ecosystem.

Biotic weathering is often treated separately, although the processes can be related to either physical or chemical processes. Biotic activity can cause or aid chemical processes, and physical effects can be significant. The most important chemical processes are solution, carbonation, hydration, hydrolysis, oxidation and reduction, and organic complexing.

The Forest (Conservation) Act, 1980 an Act of the Parliament of India to provide for the conservation of forests and for matters connected therewith or ancillary or incidental thereto. It was further amended in 1988. The act came into force on 25 October 1980. It has five sections.
Section 3 of the Act deals with constitution of Advisory Committee. It gives Central Government the power to constitute a committee of such number of person as it may deem fit to advise the Government with regard to- (i) the grant of approval for the purpose which is prohibited in section of this act; or (ii) any other matter connected with the conservation of forests which may be referred to it by the Central Government.
Section 3A deals with Penalty for contravention of the provisions of the Act. It states that Whoever contravenes or abets the contravention of any of the provisions of
Section 2, shall be punishable with simple imprisonment for a period which may extend to fifteen days. Section 3B deals with cases in which the offence is made by Authorities or Government Departments. In such cases it says that the Head of the Department shall be considered Guilty, although if he proves that it was done without his knowledge or that he exercised all due diligence to prevent the commission of such offence.

(a) Environment Protection Act, 1986 is an Act of the Parliament of India. In the wake of the Bhopal gas Tragedy or Bhopal Disaster, the Government of India enacted the Environment Protection Act of 1986 under Article 253 of the Constitution. Passed in March, 1986, it came into force on 19 November, 1986.
(b) The Forest Act, 1980 an Act of the Parliament of India to provide for the conservation of forests and for matters connected therewith or ancillary or incidental thereto. It was further amended in 1988.
(c) Water Act 1974 aims to prevent and control water pollution. Under Water Act. 1974, pollution control boards were created, who are responsible for implementation of its provisions. One of the important provision of the Water Act.1974 is to maintain and restore the 'wholesomeness' of our aquatic resources.
(d)The Air (Prevention and Control of Pollution) Act, 1981 provide for the prevention, control and abatement of air pollution, for the establishment, with a view to carrying out the aforesaid purposes, of Boards, for conferring on and assigning to such Boards powers and functions relating thereto and for matters connected therewith.