Plants and the Environment

As plants interact with the environment directly by exchanging water and energy, they are very sensitive to storms, droughts and floods.


The Role of Plants in the Environment

Plants are necessary for all life on Earth. Plants provide many things for the sustainability of life on our planet.

As a critical part of the ecosystem, plants provide oxygen for organisms to survive. They are able to reduce the problem of pollution, by using carbon dioxide. Plants are also the basis of most food webs as producers of food for herbivores and ultimately carnivores. Plants also provide shelter for animals, clean and filter water and help prevent soil erosion.

This picture shows some of the more minor ways in which plants interact with their environment. Environmental conditions, such as light intensity, temperature, water availability and wind strength, affect plant growth. Plants also modify the environment around them, they release water which cools the air, breakdown the soil to make it suitable for their roots and for other plants and animals and decrease the speed of the wind.

Photosynthesis:-Probably the most important role of plants in the environment is the production of oxygen (O₂) and the absorption of carbon dioxide (CO₂) from the atmosphere during the process of photosynthesis. Photosynthesis is the basic process for plant life.


We Use Plants in Many Ways
Plants For Food
Nearly 75% of the the world's food supply is based on seven major crops: wheat, rice, maize (corn), potatoes, barley, cassava and sorghum.
Chocolate is made from the fruit of the cocoa tree.Cocoa beans are roasted, shelled and then crushed. Cocoa butter and cocoa powder are separated. Cocoa powder is then mixed with milk to make chocolate.
Canola- 78% of vegetable oil production is from canola.Canola is pressed from the canola seeds and used as salad oil and frying oilIt is used to make margarine, shortening, baked goods, potato chips and french fries.
Seaweed contains iodine and is used in soup broths and sushi.other products from seaweed include: ice cream, chocolate milk, yogurt, whipped cream, pies, jellies and candies.seaweed products are often used to thicken food (alginate, agar, carrageenan).
Sugar half of the world's sugar comes from sugar beets, located in the sugar beets' roots.roots are shredded, heated in running water and the concentrated clear liquid crystallizes to produce sugar similar to sugar cane.
People use plants for things other than food.

Plants for Fibre
Plants also provide fibre, which is the tissue of plants from the stem, leaves, seeds or roots. Plants provide fibres for clothing, paper and shelter. The aboriginal people from the west coast wove cloth from the bark of the western red cedar tree. Much of our clothing today comes from synthetic (manufactured) material, such as polyester and nylon. Natural fibres also provide resources for cloth:
• Cotton - is a natural fibre that absorbs moisture and then allows it to evaporate easily, making it the world's most important non-edible plant. The cotton fibres come from the plant's seeds. The silky fibres are strong, flexible and have a gradual spiral that causes the strans to intelock when twisted, making them ideal for spinning into thread. The second layer of fibers are shorter and are 'fuzzy' - they are used to make cotton batting, rayon and various types of plastic and paper.
• Hemp - Early makers of jeans used hemp, which is the oldest cultivated fibre plant in the world. Other products included the Bible, sails and ropes. Hemp has a less negative effect on the environment, because it uses less land area than trees, can be harvested in a year, lasts longer than paper, can be recycled up to seven times, chokes out weeds naturally and is not prone to insect pests.
• Flax - is a food and fibre crop. The flax fibres, which are smooth and straight, are taken from the stem of the plant are are two to three times stronger than cotton fibres. Flax fibre is used for making linen paper, linseed oil - which is used as a drying oil in paints and varnish - and in products such as klinoleum and printing inks.

Plants for Medicine
An apple a day keeps the doctor away! Many medicines (over 7000) contain ingredients made from plants. Herbal remedies are a common example of how plants are used to prevent illness. Plant medicines include:
• tea (made from ginger root) - is used to soothe an upset stomach
• tea (made from white spruce and hemlock) to prevent scurvy
• white willow bark - is used to ease pain
• kinnikinick (buffalo berry) was used to treat kidney problems
• opium poppy's seed pod - thick milky fluid provides a powerful pain medication - morphine
• codeine is also found in the poppy - it is used in cough medicines
• quinine - which comes from the cinchona tree - is used to prevent malaria.

Plants for Transportation and Construction
Rubber is one of the most important plant products that people use. Natural rubber comes from the Brazilian rubber tree. Synthetic rubber is made from coal and oil by-products - but natural rubber is also an important ingredient. Canoes were carved from trees by Aboriginal people. Lubricants are provided from coconut and castor bean oils. The construction industry in North America uses wood (softwood lumber from British Columbia) as a building material.

Plants for Fuel
Wood or coal (which is a fossil fuel) are used to heat homes. Sugar can be turned into ethanol and wood can provide methanol (wood alcohol). Fuel from plants is economical, but not energy efficient, because a large amount of energy is needed to grow the plants and a lot of the energy is lost when it is converted to fuel.

Saving the Earth
Having now seen how the plant and animal life are tied in this reciprocal relationship it makes us aware of the necessity to take care of the earth for future generations and ourselves. As part of our third grade curriculum on communities, we would be studying the rights and responsibilities of the people and the government in helping to prevent possible problems with the ecology of the earth.

How does pollution affect plants? How Can We Help?
While we are still able to breathe, there are many days when the pollution levels make it difficult. Chemicals and gases in the air that should not be present cause air pollution. Three main environmental problems that affect plants include: Acid Rain, Global Warming, and Ozone Depletion.

Acid rain begins as normal rain but when it falls through clouds of pollution the rain changes into a weak acid. Water vapor sometimes mixes with the exhaust from cars, and factory smoke stacks as it moves over the land. This combination of nitric oxide and sulfur dioxide dissolves in the clouds. This acid can sometimes be as strong as vinegar.This acid is strong enough to damage trees, dissolve marble, and kill fish in ponds and lakes. Small lakes and ponds can be helped temporarily by the addition of baking soda or limestone. The best cure, however, is to control the pollution that is the cause.

Global Warming or the greenhouse affect is connected to the fact that the earth is a closed ecosystem. The temperatures are kept to a certain level so that plant life can thrive. The earth’s temperature is partly the result of the stratosphere that traps gases in the troposphere and stratosphere. Too much heat would make the earth warmer and with hotter temperatures the balance of life would begin to erode. The so-called greenhouse gases ñ carbon dioxide, water vapor, ozone, methane, nitrous oxide, and chlorofluorocarbons - trap heat that is reflected off the earth’s surface. Nature tries to balance itself, but the things that people do upset it. When people burn wood, coal, and oil, more carbon dioxide is released into the air. The carbon dioxide slows down the movement of heat and acts as an insulator. The result is what would happen if the earth were put inside a closed jar.The earth gets increasingly warm from the sun but it cannot cool off. Trees are an important solution to the problem since the trees help to remove carbon out of the air. Saving the rain forests from destruction would help. Some scientists speculate that if the earth’s atmosphere rises a few degrees it could have a devastating affect on the planet. Plant life would be negatively impacted and the polar ice caps would begin to melt. People often confuse the issue of global warming with that of the ozone depletion but they are two separate occurrences though both are major environmental problems.

The ozone is a thin layer of gas that is about 12 miles up in the earth’s stratosphere. This gas helps to protect the earth by filtering the sunlight that hits the earth. Without that layer higher than normal levels of the sun’s ultraviolet radiation would come down and affect the population. These harmful rays mean more skin cancer, cataracts, and lung problems from increased smog levels. Chemicals like the chlorofluorocarbons in refrigerators and air conditioners harm the ozone layer as they rise into the air. Again people can help if they change their buying habits. Don’t purchase foam products that can damage the ozone when they are burned or put in landfills. Use recyclable paper or plastic cups instead of Styrofoam that is also toxic. Refrigerators and freezers should be kept in good running order and if possible limit use of air conditioning or use a fan instead. Scientists measure Ozone depletion by using satellites. The layer is getting thinner, and over places like Antarctica it is completely gone.

We must make sure that our living resources survive and thrive,in order to have them in the future. As we need plants for our survival, they also need care from us.
...................................................................

Radioactive waste: The problem and its management

Radioactive waste, arising from civilian nuclear activities as well as from defence-related nuclear-weapon activities, poses a formidable problem for handling and protecting the environment to be safe to the present and future generations. As nuclear power and arsenal grow, continuous monitoring and immobilization of the waste over several decades and centuries and deposition in safe repositories, assumes great relevance and importance.

Radioactive Waste

Two basic nuclear reactions, namely fission of nuclei like 235U, 239Pu and fusion of elements like hydrogen result in release of enormous energy and radioactive elements. Controlled vast releases of energy are possible in nuclear power plant reactors through the fission reaction. The dream of controlled vast releases of energy through fusion reaction is still to be realized. Uncontrolled vast releases of energy through both these reactions have been possible in ‘atom’ and ‘hydrogen’ (thermonuclear) bombs. As in many other industrial processes, in the nuclear industry also, one gets unusable and unwanted waste products; the residues turn out to be hazardous. Waste that emits nuclear radiation is radioactive waste.

Artificial Radioactivity:- Radioactivity was discovered about a hundred years ago. Following the Second World War and discovery of the fission process, human activity added radioactivity artificially to the natural one. Two main sources have been:

(a) the civilian nuclear programmes, including nuclear power production, medical and industrial applications of radioactive nuclides for peaceful purposes, and

(b) the military nuclear programme, including atmospheric and underground nuclear-weapon testing and weapon production .

The cause for Concern

A>Radiation effects On Humans

Radioactive waste, whether natural or artificial, is a potential harbinger of radioactive exposure to humans through many channels. The routes are direct exposure to materials that are radioactive, inhalation and ingestion of such materials through the air that one breathes or food that one consumes. The quantum of exposure (dose into duration of exposure) decides the deleterious effects that may result. Exposure may occur to particular organs locally or to the whole body. Sufficiently high exposure can lead to cancer.Radiation effects are also classified in two other ways, namely somatic and genetic effects. Somatic effects appear in the exposed person. The delayed somatic effects have a potential for the development of cancer and cataracts. Acute somatic effects of radiation include skin burns, vomiting, hair loss, temporary sterility or subfertility in men, and blood changes. Chronic somatic effects include the development of eye cataracts and cancers. The second class of effects, namely genetic or heritable effects appears in the future generations of the exposed person as a result of radiation damage to the reproductive cells, but risks from genetic effects in humans are seen to be considerably smaller than the risks for somatic effects.

B>Radiation effects On Environment

1>The recent emphasis arises because of concern to the effects on the environment over a very long period of time. High-level radioactive waste is potentially toxic for tens of thousands to millions of years; it is also the most difficult to be disposed safely because of its heat and radiation output. Thermal, chemical and radiological gradients operate on the environment over periods as long as 500,000 years.
2>nuclear power plants are managed subject to several radiation protection control practices. Secondly, one may also note that ‘a 1000 MW electric coal-fired power plant releases into the environment nearly 6 million tonnes of greenhouse gases, 500,000 tons of mixtures of sulphur and nitrogen oxides and about 320,000 tonnes of ashes’. These ashes containing NORMs are potentially capable of subjecting humanity to a collective dose of radiation higher than that attributable to wastes discharged into the environment by nuclear power plants generating the same amount of electricity. In spite of this ground reality, public perception about nuclear wastes is rather skewed against nuclear power in several countries.

Quantifying Nuclear Waste

It is estimated that the nuclear waste, as a result of nuclear power production around the world over the past 50 years, is of the order of 1000 EBq and is growing at the rate of approximately
100 EBq/year. Typically, a large nuclear power plant of generating capacity of 1000 MW electricity produces ‘around 27 tonnes of high-level radioactive waste, 310 tonnes of intermediate-level and 460 tonnes of lowlevel radioactive waste’.

Classification of Radioactive Waste

i)Low-level radioactive waste
ii)High-level radioactive waste

i)Low-level radioactive waste=Large amounts of waste contaminated with small amounts of radionuclides, such as contaminated equipment (glove boxes, air filters, shielding materials and laboratory equipment) protective clothing, cleaning rags, etc. constitute low-level radioactive waste.

ii)High-level radioactive waste=This waste includes uranium, plutonium and other highly radioactive elements created during fission, made up of fission fragments and transuranics. (Note that this definition does not specify the radioactivity that must be present to categorize as high-level radioactive waste.) These two components have different times to decay. The radioactive fission fragments decay to different stable elements via different nuclear reaction chains involving alpha, beta and gama emissions to innocuous levels of radioactivity, and this would take about 1000 years. On the other hand, transuranics take nearly 500,000 years to reach such levels. Heat output lasts over 200 years. Most of the radioactive isotopes in high-level waste emit large amounts of radiation and have extremely long half-lives (some longer than 100,000 years), creating long time-periods before the waste will settle to safe levels of radioactivity.

As a thumb-rule one may note that ‘volumes of lowlevel radioactive waste and intermediate-level waste greatly exceed those of spent fuel or high-level radioactive waste’. In spite of this ground reality, the public concerns regarding disposal of high-level radioactive waste is worldwide and quite controversial.

Radioactive Waste Management

The International Atomic Energy Agency (IAEA) is promoting acceptance of some basic tenets by all countries for radioactive waste management. These include:
(i) securing acceptable level of protection of human health;
(ii) provision of an acceptable level of protection of environment;
(iii) while envisaging (i) and (ii), assurance of negligible effects beyond national boundaries;
(iv) acceptable impact on future generations; and
(v) no undue burden on future generations.

Approaches to Radioactive Waste Disposal

The following options have been aired sometime or the other. Each one of the options demands serious studies and technical assessments:
•Deep geological repositories
•Ocean dumping
Seabed burial
•Sub-seabed disposal
•Subductive waste disposal method
•Transforming radioactive waste to non-radioactive stable waste
•Dispatching to the Sun.

Major problems due to legal, social, political and financial reasons have arisen in execution due to
•Environmental perceptions
•Lack of awareness and education
•‘Not-in-my-backyard’ syndrome
•‘Not-in-the-ocean’ syndrome
•Lack of proven technology.

Geologic Disposal

The deep geological sites provide a natural isolation system that is stable over hundreds of thousands of years to contain long-lived radioactive waste. In practice it is noted that low-level radioactive waste is generally disposed in near-surface facilities or old mines. High-level radioactive waste is disposed in host rocks that are crystalline (granitic, gneiss) or argillaceous (clays) or salty or tuff. Since, in most of the countries, there is not a big backlog of high-level radioactive waste urgently awaiting disposal, interim storage facilities, which allow cooling of the wastes over a few decades, are in place.

Ocean-Dumping

Though this practice has been banned by most of the countries with nuclear programmes, the problem still persists. Russia, which currently controls sixty per cent of the world’s nuclear reactors, continues to dispose of its nuclear wastes into the oceans. According to Russia’s Minister of Ecology, it will continue to dump its wastes into the oceans because it has no other alternative alternative method. It will continue to do so until it receives enough international aid to create proper storage facilities. In response, the United States has pledged money to help Russia, but the problem continues.

Sub-seabed Disposal

Seabed disposal is different from sea-dumping which does not involve isolation of low-level radioactive waste within a geological strata. The floor of deep oceans is a part of a large tectonic plate situated some 5 km below the sea surface, covered by hundreds of metres of thick sedimentary soft clay. These regions are desert-like, supporting virtually no life. The Seabed
Burial Proposal envisages drilling these ‘mud-flats’ to depths of the order of hundreds of metres, such boreholes being spaced apart several hundreds of metres. The high-level radioactive waste contained in canisters, to which we have referred to earlier, would be lowered into these holes and stacked vertically one above the other interspersed by 20 m or more of mud pumped in.

However there are questions that remain to be answered:
•Whether migration of radioactive elements through the ocean floor is at the same rate as that already measured in the laboratories?
•What is the effect of nuclear heat on the deep oceanic- clays?
•What is the import on the deep oceanic fauna and waters above?
•In case the waste reaches the seabed-surface, will the soluble species (for example, Cs, Tc, etc.) be diluted to natural background levels? If so, at what rate?
•What happens to insoluble species like plutonium?
•What is the likelihood of radioactivity reaching all the way to the sea surface?
•In problems of accidents in the process of seabed burial leading to, say, sinking ships, to loss of canisters, etc. how does one recover the waste-load under such scenarios?
•What is the likelihood that the waste is hijacked from its buried location?

Added to these technical problems are others:
•International agreement to consider seabed-burial as distinct from ‘ocean-dumping’.
•This method would be expensive to implement, but its cost would be an impediment to any future plutonium- mining endeavour.

Subductive Waste Disposal Method

Subduction is a process whereby one tectonic plate slides beneath another and is eventually reabsorbed into the mantle. The subductive waste disposal method forms a high-level radioactive waste repository in a subducting plate, so that the waste will be carried beneath the Earth’s crust where it will be diluted and dispersed through the mantle.

Transmutation of High-level Radioactive Waste

This route of high-level radioactive waste envisages that one may use transmutational devices, consisting of a hybrid of a subcritical nuclear reactor and an accelerator of charged particles to ‘destroy’ radioactivity by neutrons.

Solar Option

It is proposed that ‘surplus weapons’ plutonium and other highly concentrated waste might be placed in the Earth orbit and then accelerated so that waste would drop into the Sun. Although theoretically possible, it involves vast technical development and extremely high cost compared to other means of waste disposal. Robust containment would be required to ensure that no waste would be released in the event of failure of the ‘space transport system’.

Concluding Remarks

The problems associated with radioactive waste management on a long-term are major ones that humanity has not been able to come to terms with so far. It is nearly 45 years since the IAEA was founded. Over these years the Agency has deliberated on various issues that confront radioactive waste management and has been providing guidelines and forums for technical and non-technical debates and discussions. As time passes by, new issues crop up, which need to be discussed. One example is how does one ‘plan for retirement of nuclear facilities’, sometimes referred to as ‘decommissioning of facilities’. Similarly changes in concepts of long-term issues on health and safety need to be addressed – ‘dose and risk for a remote time in the future are not believable, since habits of human populations are impossible to be predicted’.

...............................................................

Acid Rain

"Acid Rain" is a broad term referring to a mixture of wet and dry deposition (deposited material) from the atmosphere containing higher than normal amounts of nitric and sulfuric acids. The precursors, or chemical forerunners, of acid rain formation result from both natural sources, such as volcanoes and decaying vegetation, and man-made sources, primarily emissions of Sulphur di oxide (SO2) and Nitrogen Oxides(NOx) resulting from fossil fuel combustion.

      Acid rain occurs when these gases react in the atmosphere with water, oxygen, and other chemicals to form various acidic compounds. The result is a mild solution of sulfuric acid and nitric acid.

Acid Deposition, which has two parts:- wet and dry. 

1>Wet Deposition-It refers to acidic rain, fog, and snow. As this acidic water flows over and through the ground, it affects a variety of plants and animals. The strength of the effects depend on many factors, including how acidic the water is, the chemistry and buffering capacity of the soils involved, and the types of fish, trees, and other living things that rely on the water. -

2>Dry Deposition--Dry deposition refers to acidic gases and particles. About half of the acidity in the atmosphere falls back to earth through dry deposition. The wind blows these acidic particles and gases onto buildings, cars, homes, and trees. Dry deposited gases and particles can also be washed from trees and other surfaces by rainstorms. When that happens, the runoff water adds those acids to the acid rain, making the combination more acidic than the falling rain alone.

The Effects of Acid Rain

Acid rain has been shown to have adverse impacts on forests, freshwaters and soils, killing insect and aquatic life-forms as well as causing damage to buildings and having impacts on human health.

A>Lakes and Rivers:   It is in aquatic habitats that the effects of acid rain are most obvious. Acid rain runs off the land and ends up in streams, lakes and marshes - the rain also falls directly on these areas.

As the acidity of a lake increases, the water becomes clearer and the numbers of fish and other water animals decline. Some species of plant and animal are better able to survive in acidic water than others. Freshwater shrimps, snails, mussels are the most quickly affected by acidification followed by fish such as minnows, salmon and roach. The roe and fry (eggs and young) of the fish are the worst affected, the acidity of the water can cause deformity in young fish and can prevent eggs from hatching properly.

The acidity of the water does not just affect species directly, it also causes toxic substances like aluminium to be released into the water from the soil, harming fish and other aquatic animals.

Lakes, rivers and marshes each have their own fragile ecosystem with many different species of plants and animals all depending on one another to survive. If a species of fish disappears, the animals which feed on it will gradually disappear too. If the extinct fish used to feed on a particular species of large insect, that insect population will start to grow, this in turn will affect the smaller insects or plankton on which the larger insect feeds.

B>Soils  & Forests:  It is thought that acid rain can cause trees to grow more slowly or even to die but scientists have found that it is not the only cause. The same amount of acid rain seems to have more effect in some areas than it does in others.

As acid rain falls on a forest it trickles through the leaves of the trees and runs down into the soil below. Some of it finds its way into streams and then on into rivers and lakes. Some types of soil can help to neutralise the acid - they have what is called a "buffering capacity".

Other soils are already slightly acidic and these are particularly susceptible to the effects of acid rain.

Acid rain can effect trees in several different ways, it may:

• dissolve and wash away the nutrients and minerals in the soil 
which help the trees to grow.

• cause the release of harmful substances such as aluminium into the soil.

• wear away the waxy protective coating of leaves, damaging them 
and preventing them from being able to photosynthesise properly.

A combination of these effects weakens the trees which means that they can be more easily attacked by diseases and insects or injured by bad weather. It is not just trees that are affected by acid rain, other plants may also suffer.

C>Buildings: Every type of material will become eroded sooner or later by the effects of the climate. Water, wind, ice and snow all help in the erosion process but unfortunately, acid rain can help to make this natural process even quicker. Statues, buildings, vehicles, pipes and cables can all suffer. The worst affected are things made from limestone or sandstone as these types of rock are particularly susceptible and can be affected by air pollution in gaseous form as well as by acid rain.

D>Human health Particulates: Acid rain looks, feels, and tastes just like clean rain. The harm to people from acid rain is not direct. Walking in acid rain, or even swimming in an acid lake, is no more dangerous than walking or swimming in clean water. However, the pollutants that cause acid rain—sulfur dioxide (SO₂) and nitrogen oxides (NO_x)—do damage human health. These gases interact in the atmosphere to form fine sulfate and nitrate particles that can be transported long distances by winds and inhaled deep into people's lungs. Fine particles can also penetrate indoors. Many scientific studies have identified a relationship between elevated levels of fine particles and increased illness and premature death from heart and lung disorders, such as asthma and bronchitis.

E>Visibility: Sulfates and nitrates that form in the atmosphere from sulfur dioxide (SO₂) and nitrogen oxides (NO_x) emissions contribute to visibility impairment, meaning we cannot see as far or as clearly through the air.

What We Can Do About Acid Deposition(Prevention methods)

1>Understand acid deposition's causes and effects: To solve the acid rain problem, people need to understand how acid rain causes damage to the environment. They also need to understand what changes could be made to the air pollution sources that cause the problem.

2>Reduce emissions:

• Burning fossil fuels is still one of the cheapest ways to produce electricity so people are now researching new ways to burn fuel which don't produce so much pollution.

• Governments need to spend more money on pollution control even if it does mean an increase in the price of electricity.

• Sulphur can also be 'washed' out of smoke by spraying a mixture of water and powdered limestone into the smokestack.

• Cars are now fitted with catalytic converters which remove three dangerous chemicals from exhaust gases.

3>Find alternative Sources of Energy:

• Governments need to invest in researching different ways to produce energy.

• Two other sources that are currently used are hydroelectric and nuclear power. These are 'clean' as far as acid rain goes but what other impact do they have on our environment?

• Other sources could be solar energy or windmills but how reliable would these be in places where it is not very windy or sunny?

• All energy sources have different benefits and costs and all theses have to be weighed up before any government decides which of them it is going to use.

4>Conserving Resources:

• Greater subsidies of public transport by the government to encourage people to use public transport rather than always travelling by car.

• Every individual can make an effort to save energy by switching off lights when they are not being used and using energy-saving appliances - when less electricity is being used, pollution from power plants decreases.

• Walking, cycling and sharing cars all reduce the pollution from vehicles

5>Take action as individuals: Individuals can contribute directly by conserving energy, since energy production causes the largest portion of the acid deposition problem. For example, you can:

• Turn off lights, computers, and other appliances when you're not using them 
  
• Use energy efficient appliances: lighting, air conditioners, heaters, refrigerators, washing machines, etc.
• Only use electric appliances when you need them.
  Keep your thermostat at 68 F in the winter and 72 F in the summer. You can turn it even lower in the winter and higher in the summer when you are away from home.
• Insulate your home as best you can. 
• Carpool, use public transportation, or better yet, walk or bicycle whenever possible 
• Buy vehicles with low NOx emissions, and maintain all vehicles well. 
• Be well-informed.

Restoring the Damage done by Acid Rain

Lakes and rivers can have powdered limestone added to them to neutralise the water - this is called "LIMING". Liming, however, is expensive and its effects are only temporary - it needs to be continued until the acid rain stops. A major liming programme is currently taking place in Wales.

.................................................................