Environment & Ecology Quiz: Water Pollution and River Cleaning

The correct answer is B, cadmium pollution. Itai-Itai disease was first identified in Japan among people who ate rice grown with water polluted by cadmium from mining waste. Cadmium damages the kidneys and softens the bones, causing fractures and such severe pain that the Japanese name itai-itai means ouch-ouch. Option A is wrong because mercury pollution causes Minamata disease, also first reported in Japan, which attacks the nervous system and causes loss of coordination and speech. Option C is wrong because arsenic in groundwater causes arsenicosis, marked by skin lesions and pigmentation, a serious problem in parts of West Bengal and Bihar. Option D is wrong because excess nitrate in drinking water causes methaemoglobinemia, the blue baby syndrome, in infants. Learn these four pairs together, since examiners almost always place them in the same question.

The correct answer is B, mercury. Minamata disease takes its name from Minamata Bay in Japan, where a factory discharged mercury compounds that were converted by bacteria into methylmercury, concentrated in fish through biomagnification and then eaten by people. The poison attacks the central nervous system, producing numbness, loss of coordination, impaired speech and vision, and in severe cases death and birth defects. Option A is wrong because lead poisoning causes plumbism, damaging the nervous system and blood, but it is not called Minamata disease. Option C is wrong because cadmium causes Itai-Itai disease, a bone and kidney disorder. Option D is wrong because chromium, especially in its hexavalent form from tanneries and electroplating, causes skin ulcers and is carcinogenic, but again under a different name. Minamata is also the name of the international convention on mercury.

The correct answer is B, a heavy load of organic pollution. Biochemical oxygen demand measures the oxygen that micro-organisms need in order to break down the organic matter present in a sample. The more organic waste, such as sewage, the more oxygen the microbes consume, so a high BOD is a direct sign of heavy organic pollution. Option A is wrong because clean water has a low BOD; a river upstream of a city will show a much lower value than the same river below the sewage outfall. Option C is wrong because high BOD in fact goes with low dissolved oxygen, since the microbes are using the oxygen up; the two move in opposite directions. Option D is wrong because BOD depends on the activity of bacteria, so a high value indicates their presence and vigour rather than their absence. Chemical oxygen demand for the same sample is always higher than BOD.

The correct answer is B, nitrate. Nitrate from fertiliser run-off and from sewage seeps into groundwater; in an infant it is converted to nitrite, which binds to haemoglobin and forms methaemoglobin, a compound that cannot carry oxygen. The child becomes short of oxygen and the skin takes on a bluish tinge, which gives the condition its common name of blue baby syndrome. Option A is wrong because excess fluoride causes fluorosis, mottling the teeth and deforming the bones. Option C is wrong because iron in water chiefly causes taste, colour and staining problems, not this disorder. Option D is wrong because calcium makes water hard, which affects soap and boilers but does not produce methaemoglobinemia. The practical lesson is that agricultural run-off is a leading non-point source of water pollution.

The correct answer is B, eutrophication. When fertilisers, detergents and sewage add nitrates and phosphates to a lake or a slow-moving river, algae multiply into a bloom that covers the surface. Light is cut off from plants below, and when the bloom dies the decomposers use up the dissolved oxygen, so fish and other aquatic animals suffocate. Where human activity is the cause it is called cultural eutrophication. Option A is wrong because biomagnification is the increase in concentration of a persistent poison such as DDT at each higher level of a food chain, a different process altogether. Option C is wrong because salinisation is the build-up of salts in soil or water, usually through over-irrigation in dry regions. Option D is wrong because sedimentation is the settling of suspended solids, which is in fact a step in treating sewage rather than a form of nutrient pollution.

The correct answer is B, 1974. The Water (Prevention and Control of Pollution) Act of 1974 was India’s first comprehensive law on pollution. It created the Central Pollution Control Board and the State Pollution Control Boards, gave them power to lay down effluent standards, and made the consent of the board necessary before any industry may discharge waste water into a stream, well or sewer. Option A is wrong because 1972 is the year of the Wildlife (Protection) Act and of the Stockholm Conference on the Human Environment. Option C is wrong because 1981 is the year of the Air (Prevention and Control of Pollution) Act, which extended the same boards to air quality. Option D is wrong because 1986 is the year of the Environment (Protection) Act, the umbrella law passed after the Bhopal gas tragedy. A related law is the Water Cess Act of 1977.

The correct answer is A, 1985. The Ganga Action Plan was launched in 1985 to intercept, divert and treat the sewage of the towns along the river, and it was the first programme of its kind in India. Its second phase, along with the Yamuna Action Plan, came in 1993. Option B is wrong because 1991 belongs to the economic reforms and has nothing to do with river cleaning. Option C is wrong because 1995 is the year in which the National River Conservation Plan was set up, bringing the Ganga and Yamuna schemes together and extending them to other rivers. Option D is wrong because 2014 is the year the Namami Gange Programme was launched as an integrated conservation mission, the present phase of the effort. The sequence worth memorising is 1985, 1993, 1995, 2008 for the national river declaration, 2009 and 2014.

The correct answer is B, the National Mission for Clean Ganga. The mission, working under the Ministry of Jal Shakti, is the implementing agency of the Namami Gange Programme launched in 2014, and it works through State Ganga Committees and district committees along the river. Option A is wrong because the Central Pollution Control Board, created by the Water Act of 1974, sets and enforces pollution standards and monitors water quality, but it does not run the programme. Option C is wrong because the Central Water Commission deals with water resources development, flood forecasting and dam safety. Option D is wrong because NITI Aayog is a policy think tank without executive responsibility for such a mission. The programme covers sewage treatment, river surface cleaning, industrial effluent monitoring, afforestation, biodiversity and Ganga Grams.

The correct answer is A, terror of Bengal. Water hyacinth is an aquatic weed introduced into India from South America. In water enriched with sewage and fertiliser it grows so fast that it covers the surface, blocks sunlight, cuts the oxygen supply, clogs waterways and provides breeding grounds for mosquitoes; because it spread so violently in the water bodies of Bengal it earned the name terror of Bengal. Options B, C and D are wrong because none of them is a recognised name for this or any other aquatic weed; they are invented distractors placed there to see whether the standard phrase has been learnt. The weed is a textbook illustration of two ideas at once: the effect of eutrophication, and the damage an invasive alien species can do to a native ecosystem.

The correct answer is A, fluoride. A small quantity of fluoride in drinking water protects teeth against decay, but when the concentration rises above the permissible limit it causes fluorosis. Dental fluorosis mottles and discolours the teeth, and skeletal fluorosis stiffens the joints and bends the bones; it is a serious problem in parts of Rajasthan, Gujarat, Andhra Pradesh and Telangana, where the groundwater is naturally rich in fluoride. Option B is wrong because chloride mainly affects the taste of water and at high levels its salinity. Option C is wrong because sulphate in excess has a laxative effect but does not cause fluorosis. Option D is wrong because magnesium, along with calcium, is what makes water hard, affecting soap lather and boilers. The remedy is defluoridation or providing water from an alternative source.