Eutrophication is excessive richness of nutrients in a fresh water bodies like lake, pond frequently due to run-off from the land, which causes a dense growth of plant life Answer : (d)

exposure to arsenic via drinking-water has been shown to cause a severe disease of the blood vessels, which leads to gangrene, known as 'black foot disease'. Itai-itai disease is caused by cadmium (Cd) exposure, and this condition was first recognised in Japan in the 1960s. Itai-itai disease is characterised by osteomalaecia with severe bone pain and is associated with renal tubular dysfunction. Skeletal fluorosis is a bone disease caused by excessive accumulation of fluoride in the bones. Minamata disease, sometimes referred to as Chisso-Minamata disease, is a neurological syndrome caused by severe mercury poisoning. Symptoms include ataxia, numbness in the hands and feet, general muscle weakness, narrowing of the field of vision and damage to hearing and speech. Blue baby syndrome can also be caused by methemoglobinemia. Methemoglobinemia can be acquired in infancy from a number of exposures, including certain drugs or nitrates in drinking water. Nitrates from polluted drinking water form compounds in the body that change haemoglobin to methemoglobin, decreasing the ability of blood to carry oxygen. Answer : (a)

Nuclear blast can cause the release of radiations which can cause cancer and the radioactive materials can lead to soil pollution. Deforestation results in soil erosion and the quality of soil is degraded in which the plants cannot grow. The biopollutants are the natural microbes which act as pollutants when there is an increase in the number. Ozone layer is present in the stratosphere over the Earths surface. This is a protective layer which prevents the entry of the harmful UV rays from the sun into the atmosphere. Answer : (c)

Anthracosis (anthrac- meaning coal, carbon + -osis meaning condition) is defined in Bioline as, “the asymptomatic, milder type of pneumoconiosis as caused by the accumulation of carbon in the lungs due to repeated exposure to air pollution or inhalation of smoke or coal dust particles” Answer : (b)

Bioaccumulation is the gradual accumulation of substances, such as pesticides or other chemicals, in an organism. Biomagnification, also known as bioamplification or biological magnification, is any concentration of a toxin, such as pesticides, in the tissues of tolerant organisms at successively higher levels in a food chain. This happens because a toxic substance accumulated by an organism cannot be metabolised or excreted, and is thus passed on to the next higher trophic level. DDT reach man by this process. Bioremediation is a process used to treat contaminated media, including water, soil and subsurface material, by altering environmental conditions to stimulate growth of microorganisms and degrade the target pollutants Eutrophication, distrophication or hypertrophication, is when a body of water becomes overly enriched with minerals and nutrients which induce excessive growth of algae. This process may result in oxygen depletion of the water body Answer : (b)

UV rays act on chloroflurocarbons (CFC) releasing Cl atoms. Cl degrades ozone releasing molecular oxygen, with these atoms acting merely as catalysts; Cl atoms are not consumed in the reaction. Answer : (a)

UN designates 5 June as World Environment Day in 1972; two years later, the day is celebrated for the first time under the slogan “Only One Earth.” Answer : (c)

Aerosols are chlorofluoro-hydrocarbon compounds released into air with force in the form of vapour. Main source of aerosols is the emission of jet planes, where fluorocarbons are used. Answer : (d)

Answer : (a)

Biochemical oxygen demand is the amount of dissolved oxygen needed by aerobic biological organisms to break down organic material present in a given water sample at certain temperature over a specific time period.he BOD value is most commonly expressed in milligrams of oxygen consumed per litre of sample during 5 days of incubation at 20 °C and is often used as a surrogate of the degree of organic pollution of water. Answer : (a)

Biomagnification refers to increase in concentration of the toxicant at successive trophic levels. This happens because a toxic substance accumulated by an organism cannot be metabolised or excreted, and is thus passed on to the next higher trophic level. This phenomenon is wellknown for mercury and DDT. Answer : (d)

Hydrogen cyanide stops the transport of oxygen around the body and may also cause sudden loss of consciousness, weakness, headache, confusion, nausea, vomiting, irritation and eye infections. Breathing in hydrogen fluoride at high levels or in combination with skin contact can cause death from an irregular heartbeat or from fluid buildup in the lungs. At low levels, hydrogen sulfide causes irritation of the eyes, nose, and throat. Moderate levels can cause headache, dizziness, nausea, and vomiting, as well as coughing and difficulty in breathing. Higher levels can cause shock, convulsions, coma, and death. Answer : (d)

Water chlorination is the process of adding chlorine or chlorine compounds such as sodium hypochlorite to water. This method is used to kill certain bacteria and other microbes in tap water as chlorine is highly toxic. Answer : (b)

El Nino is a warm ocean surge of Peru current (flowing north from Antarctic along the west coast of South America to S. Ecuador, the west). It recurs every 5-8 years ot so in the E. Pacific off South America. Answer : (a)

The Montreal Protocol on Substances that Deplete the Ozone Layer is the landmark multilateral environmental agreement that regulates the production and consumption of nearly 100 man-made chemicals referred to as ozone depleting substances (ODS). Answer : (d)

Oxides of sulphur and nitrogen, oxides of carbon, hydrocarbons, hydrogen sulphide, ozone and other oxidants gaseous along with particulate pollutants like fumes, dust, smoke, etc. are the air pollutants that are responsible for severe air pollution Answer : (b)

Secondary treatment or Biological treatment : The primary effluent is passed into large aeration tanks where it is constantly agitated mechanically and air is pumped into it. This allows vigorous growth of useful aerobic microbes into flocs (masses of bacteria associated with fungal filaments to form mesh like structures). While growing, these microbes consume the major part of the organic matter in the effluent. This significantly reduces the BOD (biochemical oxygen demand) of the effluent. The sewage water is treated till the BOD is reduced. Answer : (c)

Nitrous oxide, like CFCs, is stable when emitted at ground level, but breaks down when it reaches the stratosphere to form other gases, called nitrogen oxides, that trigger ozone-destroying reactions Answer : (a)

Due to ozone depletion, UV radiation is not absorbed by Earth’s atmosphere. UV-B damages DNA and mutation may occur. It causes aging of skin,damage to skin cells and various types of skin cancers. In human eye, cornea absorbs UV-B radiation, and a high dose of UV-B causes inflammation of cornea, called snow-blindness, cataract, etc. Such exposure may permanently damage the cornea. Answer : (d)

Discharge of domestic and industrial effluent wastes, agricultural discharges, leakage from water tanks, marine dumping, radioactive waste and atmospheric deposition are major causes of water pollution. Answer : (d)

All the options except carbon dioxide are pollutant. Carbon dioxide is a green house gases and cannot be considered as pollutant. Answer : (b)

DDT is non-biodegradable and presist in environment in active form for 22-25 years. This is the reason why DDT is a major pollutant. Answer : (d)

Carbon dioxide contributes to 60% of global warming. methane contributes to 20% of global warming. CFC conrtibutes to 14% of global warming N2O conrtibutes to 6% of global warming. These are all green house gases. Answer : (d)

livestock enteric fermentation and manure management, paddy rice farming, land use and wetland changes, leading to higher methane atmospheric concentrations. Agricultural activities, including the use of fertilizers, that lead to higher nitrous oxide (N2O) concentrations. Answer : (a)

Answer : (a)

Carbon dioxide, methane, nitrous oxide and CFC are green house gases. Answer : (a)

Biodegradable” refers to the ability of things to get disintegrated (decomposed) by the action of micro-organisms such as bacteria or fungi biological (with or without oxygen) while getting assimilated into the natural environment. Sewage is an biogedradable pollutant. Answer : (c)

In India, the Air (Prevention and Control of Pollution) Act came into force in 1981, but was amended in 1987 to include noise as an air pollutant. Answer : (c)

Ultraviolet radiation may inactivate enzymes in numerous biologic systems by producing alterations in proteins. Peptide bonds may be split, photochemical oxidations may occur, sulfide and disulfide bonds may be altered, and DNA may be photochemically changed. Answer : (a)

In stratosphere, UV rays act on chloroflurocarbon (CFCs) releasing Cl atoms. Cl degrades ozone releasing molecular oxygen, with these atoms acting merely as catalysts; Cl atoms are not consumed in the reaction. Answer : (b)