My Science School

• The Himalayan yew is a medium-sized evergreen coniferous tree growing up to 30 mt tall. It is native to the Himalayas and parts of south-east Asia, and found at altitudes of 2100-3400 mt. In forests, it tends to be present as a low canopy tree and in open areas, it usually forms a large and wide shrub. The leaves are thin, flat, slightly sickle-shaped. They are arranged spirally on the shoots, but twisted at the base. Male and female cones are found on separate plants. The seed cones and berry-like, with a single scale developing into a soft, juicy red aril, containing a single dark brown seed. The pollen cones are globose, produced on the undersides of the shoots.


• The species is currently classified as endangered by the IUCN.


• The Himalayan yew has been subject to heavy exploitation for their use in ayurvedic and Tibetan medicine. The Himalayan yew is used in the production of anti-cancer drugs and as fuelwood by the local communities.

 

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• White-bellied heron is a species of large heron found in Bangladesh and Myanmar and on the foothills of the Himalayas in India and Bhutan. It is mostly a dark grey with a white throat and underparts. The bill is black, greenish near the base and the tip, and the face is a greenish grey. On the ground, it walks slowly, looking from side to side. The usual call is a deep croak. At 127 cm in height, it is the second largest heron on Earth, after the Goliath heron. It is mostly solitary and occurs in undistributed riverside or wetland habitats.


• It has been listed as Critically Endangered on the IUCN Red List, because the global population is estimated at less than 300 mature individuals.


• The threats include habitat degradation and human activities such as large-scale infrastructure development. It is under grave threat of extinction in Bhutan due to the development of large-scale hydro-power projects in the basin. Rising water levels force the nesting birds to search extensively for fish, leaving the eggs or chicks exposed to predators.

 

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• The Himalayan quail, also called the mountain quail, belongs to the pheasant family. The male of the species is a dark grey with black speckles and a white forehead. The female is brownish, with dark streaks and a grayish brow. The red or yellow bill, long covert tail and prominent white spots around the eyes distinguish it from other quail species.


• The species has been known from only two locations in the western Himalayas in Uttarakhand. It was last sighted in 1876 near the hill station of Mussoorie. It is listed as critically endangered by the ICUN. A 2015 study suggested that the species might still be extant and that there might be some locations around Mussoorie where intensive surveys could be attempted.


• The Himalayan quail was a popular game bird. It was sought by British for their leisure hunting. Mass killing of the bird probably led to its decline around the 1870s, say scientists.

 

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• The Gee’s golden langur belongs to the Old World monkey family. Golden langurs were first brought to the attention of the western world by naturalist E.P. Gee in the 1950s, and hence the name. They are found in a small region of western Assam, and in neighbouring Bhutan. These monkeys have a cream to golden-coloured coat, a black face and a long tail. On the face and chest, the hair is darker and often rust-coloured. These langurs are mostly arboreal, living on the top part of the trees, and eating fruits, leaves, seeds, buds and flowers. Gee’s golden langurs live in troops, consisting of four to 22 members.


• With only about 6,500 individuals in the wild, Gee’s golden langurs are listed as Endangered by the IUCN.


• Due to habitat destruction, the populations of this species are restricted to fragmented forest pockets. Human-animal conflict, hunting by dogs, deforestation and inbreeding are the major threats, according to the IUCN.

 

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• The red panda is a mammal species belonging to the genus Ailurus and family Ailuridae. Red pandas are native to the eastern Himalayas and southwestern China. Though found in China, remember, they are not genetically related to the giant panda. Red pandas have reddish-brown fur, a long, bushy tail, which they use like wraparound blankets in the chilly mountains. Red planets grow roughly to the size of a domestic cat. However, they have a longer body and are heavier. Their belly and limbs are black, and they have white markings on the sides of the head. The animals predominantly tree-dwelling and feed on bamboo, eggs, birds and insects. They are solitary, active at night and sedentary during the day.


• Red panda is listed as Endangered on the IUCN Red List. The population is estimated as fewer than 10,000 mature individuals and continues to decline.


• Habitat loss and fragmentation, poaching and inbreeding are the major threats to the species.

 

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• The Himalayan brown bear is a subspecies of the brown bear, native to the region in North-western and central Himalayas, including Pakistan, India, Nepal, Tibet and Bhutan. It is a large bear with thick fur, usually sand-coloured or reddish-brown. Himalayan brown bears eat grasses, roots and other plants as well as insects and small mammals. They are diurnal and are usually solitary. The bears go into hibernation in a cave or dug-out den around October, emerging in April or May.


• While the brown bear as a species is classified as Least Concern by the International Union for Conservation of Nature (IUCN), this subspecies is critically endangered. Overall, the population is in decline.


• Habitat loss and killing by livestock herders are a major threat for the bears. They are also poached for their fur and claws, used in the making of ornaments. Their body parts are used for medicine. In Pakistan, they face the additional threat of bear baiting, a sport where bears are pitted against other animals.

 

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If you removed everything from your home that contained plastic, how much would be left? Many kitchens would be almost bare. Most carpets and rugs would go, many clothes and perhaps the curtains would vanish. There would certainly be no telephone, hi-fi or television.

And think of all the other things made of plastic, such as riot shields, credit cards, artificial snow and hip joints. Now Australians are even buying their plastic goods with plastic banknotes.

The term ‘plastics’ covers a wide range of materials man-made from two basic ingredients: carbon and hydrogen. By adding extra chemicals, plastics can be given special properties like extra strength, heat-resistance, slipperiness and flexibility.

There is almost no end to the number of plastics that can be created by combining chemicals in different ratios and patterns. Scientists are already trying to develop a plastic as tough as steel, as clear and waterproof as glass and as cheap as paper.

Plastics are made up of large molecules called polymers, which are formed by smaller molecules joining together in long chains. These chains become tangled, giving plastic its strength – considerable force is needed to pull the chains apart.

When most plastics – called thermoplastics – are heated to about 3900ºF (2000ºC) the chains stay intact but move apart enough to slide over one another. This allows thermoplastics to be repeatedly heated and moulded into new shapes. Once the plastic has cooled it holds its neew shape and maintains its strength.

However, there are other plastics which, once moulded, remain hard and keep their shape even when reheard. These are thermosetting plastics.

The process of getting small molecules to join up and form larger ones, called polymerization , differs from one plastic to another. But it often involves high pressures and the use of special agents, called catalysts, to encourage the small molecules to link up.

The carbon and hydrogen atoms that form the base of all plastics come from crude oil. Oil consists of hydrocarbons – hydrogen and carbon molecules bonded together. Hydrocarbons range from simple molecules like methane (a gas made up of one hydrogen atom combined with four carbon atoms) to tars and asphalts, which may have hundreds of atoms.

In the process of refining crude oil many different hydrocarbons are produced, one of them is the gas ethane (two carbon and six hydrogen atoms) which can be converted to another gas, ethylene, and then polymerized to make polyethylene (polythene). Similarly, propane gas becomes polypropylene. These two plastics are used to make bottles, pipes and plastic bags.

PVC – polyvinyl chloride – is chemically similar to polythene, but its hydrogen atom is replaced by a chlorine atom. This slight change makes PVC ‘flame retardant’, making it safer to use in the home. If four fluorine atoms are used rather than the chlorine atom, polytetrafluoroethylene, PTFE, is made. This, known as Teflon, is used for nonstick frying pans and bearings.

Many polymers have been made in the laboratory, but only those with the most useful qualities, like polystyrene, PTFE and nylon, are produced industrially.

 

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One of the advantages of plastic is that it does not rust or rot. But this can also be a problem – plastic cups, bags, wrappers and containers litter the countryside and beaches all over the world. Unless they are picked up, they go on accumulating year after year.

To deal with the problem, various forms of degradable plastic have been developed. The secret is to incorporate into the plastic a chemical that can be attacked by light, bacteria or other chemicals.

Biodegradable plastics can be made by adding starch. If the plastics are buried, bacteria that feed on starch will gradually break them up into tiny pieces that disappear harmlessly into the soil.

Chemically degradable plastics can be broken up by spraying them with a solution that causes them to dissolve. They can be used, for example, as a protective waxy covering for new cars, and washed off at the dealer’s garage by a specially formulated spray. This reacts with one of the components in the plastic and causes it dissolve into harmless materials which can be flushed down the drain.

One of the most successful uses of degradable plastics is in surgery, where stitches are now often made using plastics which dissolve slowly in body fluids, saving the patient the anxiety of having the stitches removed. Drugs are often prescribed in plastic capsules which dissolve slowly, releasing the rug into the bloodstream at a controlled rate.

Photodegradable plastics contain chemicals that slowly disintegrate when exposed to light. In France, strips of photodegradable plastic about 3ft (1m) wide are used in the fields to retain heat in the soil and produce early crops. They last for between one and three years before rotting into the soil. But they have to be used in a country with a consistent amount of sunshine so they decay at a predictable speed.

In the USA, about one-quarter of the plastic ‘yokes’ that link beer cans in a six-pack are made of a plastic called Ecolyte, which is photodegradable. But to stop them decaying too early they must be stored away from direct sunlight, which can be an inconvenience for the retailer.

Degradable plastic has other problems. For example, it cannot be recycled because there is no easy way to measure its remaining life span. The biggest drawback has been the cost of producing it, but Japanese scientists believe they will soon be able to produce a much cheaper multipurpose biodegradable plastic.

 

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High-level radioactive waste is lethal and it remains dangerous for thousands of years. If someone were to stand 30ft (9m) away from a small amount of fresh waste from a nuclear reactor for ten minutes, he would have only a 50 per cent chance of living. A nuclear reactor’s spent fuel contains a deadly cocktail of radioactive products, like plutonium, strontium and caesium.

Fortunately the volume of high-level nuclear waste is small. A typical plant, generating 1000 megawatts of electricity, produces about two and a half cubic yards (two cubic metres) of waste a year.

Storage methods vary. In the USA, some processed waste is stored in double-walled stainless-steel tanks surrounded by 3ft (1m) thick concrete cladding. But most is immersed in special pools near the nuclear plants, in the form of spent fuel rods still inside the original cladding. Unfortunately this is not a long-term solution.

In Britain the waste is stored as a liquid, the colour of strong tea, in steel tanks encased in concrete, similar to those used in America. The waste generates hear as the radioactive atoms decay, so the tanks have to be cooled to prevent the liquid boiling dry, which could eventually cause a radioactive leak. Cold water is pumped through coils inside the tanks.

However, although they have already been used for 40 years, tanks are also only a temporary storage solution.

Possibly the best answer at the moment is to fuse the waste into glass cylinders to be stored deep underground. A demonstration plant in Marcoule, France, has been carrying out this process since 1978.

The waste is dried and reduced to a solid residue by heating it inside a rotating drum. It is then mixed with silica and boron, and other glass-making materials, poured through a vertical chamber and heated to  ( . A stream of molten glass emerges from the bottom, to be cast into stainless-steel containers about twice the size of an old-fashioned milk churn. A year’s output from a 1000 megawatt plant fills 15 of these canisters. After the glass has solidified, the lids are welded on.

The canisters are stored in special ‘pits’ in a neighbouring building at Marcoule. Each consider produces 1.5 kilowatts of heat and is cooled by air. The British and the Americans are also beginning to adopt this process. The waste is safe so long as it is monitored, but ultimately it should be put where it can remain without further human intervention.

One proposal is to surround the canisters with a jacket cast iron or copper, and then store them in underground caverns. The canisters would be placed in holes or trenches, then covered with concrete or a clay called bentonite, which absorbs escaping radioactive material.

The canisters should last up to 1000 years before they become corroded and let any radioactivity escape. After 500 years the radioactivity will have dropped to about the level of the original uranium ore. Experts believe that as long as the caverns are well suited and sufficiently deep – several hundred metres – it would take a million years before any material could seep to the surface, and by that time all but the tiniest traces of the radioactive waste would have decayed. The areas chosen for the ‘dumps’ should contain no valuable minerals; in case some future civilization should stumble across the waste while mining. Eventually the caverns could be sealed off and forgotten. The waste would be sealed behind so many barriers that escape in any imaginable time scale would be impossible.

The difficulty is finding sites where local people agree to have nuclear waste stored. Nobody relishes the idea of a nuclear dump close to their home. In the end, the nuclear waste authorities may well be forced to drill caverns beneath existing reprocessing facilities, or under the sea, rather than try to find new sites on land.

 

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Recycling rubbish is not only makes economic sense – it also helps the environment. Pollution created by burning rubbish is reduced and valuable resources are saved. Some 75,000 tress would be spared every week just by recycling the Sunday edition of the New York Times.

Many countries encourage recycling new technology allows more and more waste to be reprocessed. Most of the world’s rubbish can be reused – paper, metals, glass, even some plastics.

Plastic is one of the most difficult substances to recycle, because it comes in so many varieties. A plastic tomato-ketchup bottle, for example, consists of six layers of different plastics, each designed to give the bottle certain qualities – shape, strength, flexibility. And as yet there is no simple way to turn an old plastic bottle into a new one.

Plastic can only be turned into a product of lower quality – a plastic lemonade bottle might be cleaned, shredded and used to stuff seat cushions or insulate sleeping bags. A mixture of plastic waste can be recycled into plastic ‘timber’ and used to make durable fencing. But a lot of plastic waste still has to be thrown away because its value as scrap is so low.

Metals are different. Any car on the road today will consist, in part, of earlier cars that have been scrapped and recycled into new steel and other metals.

The more valuable the metal, like gold and silver, the more it pays to recycle it. Aluminium is worth recycling because extracting it from bauxite consumes a huge amount of electricity. Largely thanks to recycling programmes the energy used to make aluminium has fallen by a quarter since the early 1970s.

More than 70 billion canned drinks are bought in America every year, and all the cans are made of aluminium. About half are remelted after use and within six weeks they have been made into new tins and are back on the supermarket shelves.

Glass is worth recovering. The most sensible method is to use glass bottles as often as possible. The average British milk bottle makes about 30 trips to and from the dairy.

Many countries now have compulsory deposit schemes to make people return bottles to shops. When such a law was passed in the state of New York in 1983, it was estimated that within two years it had saved $50 million on rubbish collection, $19 million on waste disposal costs, and about $50 million in energy costs.

Some supermarkets now have machines that accept glass bottles and aluminium cans and give cash or redeemable vouchers to the customer. They read the computer codes on the containers to work out how much to pay.

Broken glass, known as ‘cullet’, can also be recycled, and many countries have bottles banks depend on people’s goodwill. The success of bottle banks varies widely from country to country. The Swiss and Dutch recover 50 per cent of their glass, while in Britain only 12 per cent is recovered.

Glass is best separated by colour, since cullet of mixed colours can be used only to make green glass. Broken glass can be remelted in furnaces and then it can easily be shaped into new bottles or other objects.

Half the world’s waste consists of paper. Many countries import waste paper rather than new pulp for their paper mills. The waste is pulped, cleaned and bleached to remove most of the ink and dirt, before it is turned into new paper in the same way as wood pulp or rags. Japan now makes half its paper by recycling.

 

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Every year Americans throw away 250 million tons of rubbish. New York alone generates almost 10 million tons a year. It has been estimated that America’s garbage could provide as much energy as 100 million tons of coal. However, most of it is buried, and never used.

About half of the world’s domestic waste is paper, while kitchen waste makes up a quarter and plastics less than a tenth. Only a fifth will not burn and most of that can be recycled.

Western Europe has more than 200 plants which burn rubbish to produce electricity. A large plant at Edmonton in London, which opened in 1974, burns about 400,000 tons of refuse a year. The burning refuse heats water to create steam which powers the electric generators. Within ten years the plant has saved a million tons of coal.

In Dusseldorf, West Germany, six similar plants supply steam to generate electricity for district heating schemes.

In Peekskill, New York, a plant has been built to handle 2250 tons of refuse a day, generating 60 megawatts of electricity – enough to supply 70,000 people.

Rubbish can also be burned by factories instead of coal or oil, but it must be treated first. The rubbish is separated by feeding it though a vibrating screen which sifts out the fine organic particles to be turned into compost for treating land. In Sweden a quarter of all solid waste is turned into compost and recycled.

Next the heavy part of the rubbish, mainly metals, must be sorted out and removed, leaving mainly paper and textile waste. These are pressed into cylindrical pellets and sold as fuel.

Even rubbish dumped in the ground can be used as a source of fuel. As it begins to rot, it produces methane gas – identical to the natural gas found in pockets under the Earth’s crust. Each ton of refuse can produce over 8000 cubic feet (227 cubic metres) of methane. Left alone, the gas will find its way to the surface and escape, sometimes causing explosions. But it can be tapped very cheaply and used to generate heat or electricity. There are more than 140 such schemes in operation in 15 countries, saving a total of at least 825,000 tons of coal a year. In England, for example, a large tip has been drilled with wells to extract the gas, which is piped to a brickworks where it replaces coal.

Other plants use the gas on site to generate electricity by burning it in simple gas engines. This allows all the gas to be used, rather than trying to match output to the fluctuating demands of a factory.

In the future, production of gas in rubbish tips may be improved by ‘seeding’ the tips with bacteria. Some strains of bacteria break down refuse faster than others. By introducing the best mix of bacteria for the particular waste in a tip, the maximum amount could be produced.

 

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• Dumping of medical waste in the open or disposal of untreated waste can be dangerous.


• A host of infectious diseases is linked to toxic medical waste while garbage collectors, along with those living close to medical centres, are especially at risk.


• The disposal of untreated waste in landfills can lead to the contamination of drinking, surface and ground water if those landfills are not properly constructed.


• The disposal of untreated waste in landfills can cause diseases in animals as well. Animals may consume infected waste and eventually, these infections can be passed on to humans who come in contact with them.


• It is often found that biomedical waste is dumped into the ocean, where it eventually washes up on shore.


• The treatment of healthcare waste with chemical disinfectants can result in the release of chemical substances into the environment if those substances are not handled properly.


• Inadequate incineration or the incineration of unsuitable materials results in the release of pollutants, including carcinogens (cancer-causing chemicals) into the air.


• Incineration of medical devices with heavy metals (in particular lead, mercury and cadmium) can lead to the spread of toxic in the environment.


• If safety measures are not followed, health workers, laboratory personnel and transport workers will also be affected.

 

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• As of 2016, India was generating about 484 tonnes of bio-medical waste per day, from its 1,60,000 health-care centres. It was estimated that the country would generate 77.5 tonnes of medical waste per day by 2022. A 100-bed hospital generates 100-200 kg of hospital waste every day, according to a study.


• Of the total amount of waste generated by health-care activities, 15% is considered hazardous that may be infectious, toxic or radioactive.


• Segregation, treatment and transportation, depends on the type of bio-medical waste. Incineration, deep burial, local autoclaving, microwaving, chemical disinfection, mutilation and shredding and discharge into the drains, followed by disinfection are some of the ways that medical wastes are managed in India.


• Colour-coded containers are used for disposal of biomedical waste.


• India’s bio-medical waste management is ruled by the Bio-medical Waste Management Rules 2016. According to the rules, blood samples and microbiological waste should be pre-treated on-site before being disposed of. It also planned to introduce a bar-coding system, where all biomedical waste containers or bags are going to be tracked by the government. This is to ensure that the movement from its manufacturing to treatment facilities is monitored.


• Common bio-medical waste treatment facilities (CBWTFs) are involved in managing waste. According to the 2016 rules, a CBWTF within 75 km of a healthcare centre has to ensure that waste is collected routinely and regularly.


• The ruling also extends to vaccination camps, blood donation centres and surgical camps.

 

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Infectious medical waste: These are waste materials that can pose a risk of infection to humans, animals, and the overall environment. This includes blood-stained bandages, surgical waste, human or animal body parts, cultures and swabs.

Sharps waste: This includes syringes, needles, disposable scalpels and blades.

Chemical waste: Solvents and re-agents used for laboratory preparations, disinfectants, metals such as mercury in devices such as broken thermometers and batteries.

Pharmaceutical waste: Unused, expired and contaminated medicines.

Radioactive waste: Products contaminated by radionuclides, including radioactive diagnostic material or radiotherapeutic materials.

 

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Morning walkers of Clifton Beach, Karachi, Pakistan, were in for a shock recently as the golden sand was covered in garbage, which included a large amount of bio-medical waste. The tide had brought with it several blood vials and open syringes to the shoreline. Pakistani media criticised the government for going easy on hospitals and research centres that continue to dump toxic waste in the open or directly into water bodies.

To story is not different in India. Despite regulations against the dumping of medical waste in the open, loads of them are disposed of in landfills along with other garbage every day. Other rules of segregation and safety measures are also flouted in some places. Coming in contact with such waster or open burning can prove harmful to the environment and our health.

Waste generated during the diagnosis, treatment or immunisation of human beings or animals in hospitals and clinics and during experiments in research labs are all biomedical waste. It includes used syringes, blood-stained cotton bandages, used I-V tubes, scalpels, blades, glass, microbiological cultures, discarded gloves, and linen. It also includes human or animal tissues, organs and body parts and fluids. Biomedical waste may be solid or liquid.

 

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