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

Gujarat Fluorochemicals Ltd (GFL) is a part of the $2 billion group of companies. It is a family-owned professionally managed business group, with interest in diverse businesses, including industrial gases, refrigerants, chemicals, carbon credits, cryogenic engineering, renewable energy, and entertainment.
Gujarat Fluorochemicals Ltd has been at the forefront in bringing the concept of carbon credits to India. GFL's Clean Development Mechanism (CDM) projects were the first in the world to seek registration by the CDM Executive Board, a body of the United Nations Framework Convention on Climate Change (UNFCCC). GFL is the largest CDM player in India.

Based on the availability of light, lentic ecosystem have well defined and characteristic stratification:
(a) Littoral zone: It is the shallow water zone near the shore of a lake or pond in which light penetrates up to the bottom. It is typically occupied by rooted and floating aquatic plants. Aquatic life is richest and most abundant in this littoral zone. In ponds and lakes, littoral zone is relatively large.
(b) Limnetic zone: It is the near-surface zone in the open water that extends up to the depth of effective light penetration and is usually surrounded by littoral zone. Planktons (both phytoplankton and zooplankton) and nektons (fishes) are the abundant biotic forms of the limnetic zone.
Both littoral and limnetic zones constitute the euphotic zone where light penetrates and production is greater than respiration (P/R > 1).
(c) Profundal zone: The deep water zone present beyond the depth of effective light penetration is the profundal zone. This is also termed as aphotic zone were light does not reach and respiration is greater than production (P/R < 1). Producers are absent and heterotrophs usually inhabit this zone. The consumers are mainly detritus feeders and carnivores. Such profundal zones are usually present in marine and deep freshwater ecosystems, but are usually small or even absent in shallow waterbodies (like ponds).
(d) Compensation level: Between the limnetic and profundal zone lies another strata where production equals respiration (i.e., P/R = 1) is known as compensation level.
(e) Benthic zone: Benthic zone is the bottom region of both littoral and profundal zones. In this zone the dead bodies of plants and animals, organic debris and the materials washed in by inflowing water settle and mainly decomposition takes place. The major community constituents are bacteria, fungi, chironomid larvae, bottom dwelling annelids, clams, etc.

Importance Value Index (IVI): IVI is the sum of the relative frequency, relative density and relative dominance. The relative values are calculated as follows:

Some of the common forms of precipitation are: rain, snow, drizzle, glaze, slet and hail. Snow: Snow is another important form of precipitation. Snow consists of ice crystals which usually combine to form flakes. When fresh, snow has an initial density varying from 0.06 to 0.15 g/cm³ and it is usual to assume an average density of 0.1 g/cm³. In India, snow occurs only in the Himalayan regions.
Sleet: It is frozen raindrops of transparent grains which form when rain falls through air at subfreezing temperature. In Britain, sleet denotes precipitation of snow and rain simultaneously.
Hail: It is a showery precipitation in the form of irregular pellets or lumps of ice of size more than 8 mm. Hails occur in violent thunderstorms in which vertical currents are very strong.

Ocean acidification is affecting the entire world's oceans, including coastal estuaries and waterways. Many economies are dependent on fish and shellfish and people worldwide rely on food from the ocean as their primary source of protein.
Carbonate ions are an important building block of structures such as sea shells and coral skeletons. Decreases in carbonate ions can make building and maintaining shells and other calcium carbonate structures difficult for calcifying organisms such as oysters, clams, sea urchins, shallow water corals, deep sea corals, and calcareous plankton.

Albedo is the measure of the diffuse reflection of solar radiation out of the total solar radiation and measured on a scale from 0. corresponding to a black body that absorbs all incident radiation, to 1, corresponding to a body that reflects all incident radiation. Surface albedo is defined as the ratio of radiosity to the irradiance (flux per unit area) received by a surface. Water surfaces exhibits maximum variation in albedo with respect to the angle of incidence of solar radiations.

Carbon dioxide (CO₂) has contributed the most to climate change. CO₂ remains in the atmosphere longer than the other major heattrapping gases emitted as a result of human activities. It takes about a decade for methane (CH₄) emissions to leave the atmosphere (it converts into CO₂) and about a century for nitrous oxide (N₂O). After a pulse of CO₂ is emitted into the atmosphere, 40% will remain in the atmosphere for 100 years and 20% will reside for 1000 years, while the final 10% will take 10,000 years to turn over. This literally means that the heat-trapping emissions we release today from our cars and power plants are setting the climate our children and grandchildren will inherit.

The variance of a random variable X is a measure of its dispersion around its mean, E(X) defined as:

Malathion has two carboxyester linkages, which are hydrolyzable by carboxylase enzymes to relatively nontoxic products as shown by the following reaction:
The enzymes that accomplish malathion hydrolysis are possessed by mammals, but not by insects, so that mammals can detoxify malathion, whereas insects cannot; therefore, malathion is selectively toxic to insects. Other OP compounds include malathion, which is much less toxic than parathion and is used more in horticulture; dithion, diazinon, hexaethyltetraphosphate (HETP), tetraethylpyrophosphate (TEPP), octamethylpyrophosphamide (OMPA) and demeton are other pesticides of this group.