Environmental protection using Biotechnology – An overview:

Environmental protection using Biotechnology – An overview:

A. The surroundings around us are termed as ‘environment’. Our environment includes the abiotic component (the non living) and biotic component (the living). The abiotic environment includes air, water and soil; and the biotic environment consists of all living organisms such as plants, animals and microorganisms. Environmental pollution broadly refers to the presence of undesirable substances in the environment which are harmful to man and other organisms. There has been a significant increase in the levels of harmful environmental pollution mostly due to direct or indirect human activities in recent past. The major sources of environmental pollution are industries, agricultural and other anthropogenic and biogenic sources etc. The pollutants are chemical, biological and physical in nature.

B. Controlling the environmental pollution and the conservation of environment and biodiversity and controlling environmental pollution are the major focus areas of all the countries around the world. In this context, the importance and impact of biotechnological approaches and the implications of biotechnology has to be thoroughly evaluated. There have been serious concerns regarding the use of biotechnological products and the impact assessment of these products due to their interaction with the environmental factors. A lobby of the environmentalists has expressed alarm on the release of genetically engineered organisms in the atmosphere and have stressed on thorough investigation and proper risk assessment of theses organisms before releasing them in to the environment. The effect of the effluents from biotechnological companies is also a cause of concern for everyone. The need of the hour is to have a proper debate on the safety of the use of the biotechnological products. The efforts are not only on to use biotechnology to protect the environment from pollution but also to use it to conserve the natural resources. As we all know that microorganisms are known natural scavengers so the microbial preparations (both natural as well as genetically engineered) can be used to clean up the environmental hazards.

C. Biotechnology is being used to provide alternative cleaner technologies which help to further reduce the hazardous environmental implications of the traditional technologies. Some of the well known examples and mechanisms are:

(i) Some fermentation technologies have some serious environmental implications. Various biotechnological processes have been devised in which all nutrients introduced for fermentation are retained in the final product, which ensures high conversion efficiency and low environmental impact.

(ii) In paper industry, the pulp bleaching technologies are being replaced by more environmentally friendly technologies involving biotechnology. The pulp processing helps to remove the lignin without damaging valuable cellulosic fibres but the available techniques suffer from the disadvantages of high costs, high energy use and corrosion. A lignin degrading and modifying enzyme (LDM) was isolated from Phanerochaete chrysosporum and was used, which on one hand, helped to reduce the energy costs and corrosion and on the other hand increased the life of the system. This approach helped in reducing the environmental hazards associated with bleach plant effluents.

(iii) In Plastic industry, the conventional technologies use oil based raw materials to extract ethylene and propylene which are converted to alkene oxides and then polymerized to form plastics such as polypropylene and polyethylene. There is always the risk of these raw materials escaping into the atmosphere thereby causing pollution. Using biotechnology, more safer raw materials like sugars (glucose) are being used which are enzymatically or through the direct use of microbes converted into alkene oxides.e.g. Methylococcus capsulatus has been used for converting alkene into alkene oxides.

(iv) Bioremediation is defined as ‘the process of using microorganisms to remove the environmental pollutants where microbes serve as scavengers. The removal of organic wastes by microbes leads to environmental cleanup. The other names/terms used for bioremediation are bio-treatment, bio-reclamation, and bio-restoration. The term “Xenobiotics” (xenos means foreign) refers to the unnatural, foreign and synthetic chemicals such as pesticides, herbicides, refrigerants, solvents and other organic compounds. The microbial degradation of xenobiotics also helps in reducing the environmental pollution. Depending on the method followed to clean up the environment, the bioremediation is carried out in two ways:

(a) In situ bioremediation – involves a direct approach for the microbial degradation of xenobiotics at the site of pollution which could be soil, water etc. The in situ bioremediation is generally used for clean up of oil spillages, beaches etc.;

(b) Ex-situ bioremediation - In this the waste and the toxic material is collected from the polluted sites and the selected range of microorganisms carry out the bioremediation at designed place. This process is an improved method over the in situ bioremediation method.

(v) Pseudomonas which is a soil microorganism effectively degrades xenobiotics. Different strains of Pseudomonas that are capable of detoxifying more than 100 organic compounds (e.g. phenols, biphenyls, organophosphates, naphthalene etc.) have been identified. Some other microbial strains are also known to have the capacity to degrade xenobiotics such as Mycobacterium, Alcaligenes, Norcardia etc.

D. In recent years, efforts have been made to create genetically engineered microorganisms to enhance bioremediation. This is done to overcome some of the limitations and problems in bioremediation. These problems are: a) Sometimes the growth of microorganisms gets inhibited or reduced by the xenobiotics. b) No single naturally occurring microorganisms has the capability of degrading all the xenobiotics present in the environmental pollution. c) The microbial degradation is a very slow process. d) Sometimes certain xenobiotics get adsorbed on to the particulate matter of soil and thus become unavailable for microbial degradation.

E. As the majority of genes responsible for the synthesis of enzymes with biodegradation capability that are located on the plasmids, the genetic manipulations of plasmids can lead to the creation of new strains of bacteria with different degradative pathways. Well known example of genetic manipulations of plasmids is development of ‘Superbug’, which is used for degrading a number of hydrocarbons of petroleum simultaneously such as camphor, octane, xylene, naphthalene etc.

F. We all know that, carbon dioxide (CO2) is the main cause of green house effect and rise in the atmospheric temperature. There is a steady increase in the CO2 content due to continuous addition of CO2 from various sources particularly from industrial processes. It is very clear that the reduction in atmospheric CO2 concentration assumes significance. Biotechnological methods have been used to reduce the atmospheric CO2 content at two levels:

(a) Photosynthesis- Plants utilize CO2 during the photosynthesis which reduces the CO2 content in the atmosphere;

(b) Biological Calcification- Certain deep sea organisms like corals, green and red algae store CO2 through a process of biological calcification. As the CaCO3 gets precipitated, more and more atmospheric CO2 can be utilized for its formation.

G. The sewage is treated to get rid of these undesirable substances by subjecting the organic matter to biodegradation by microorganisms. The biodegradation involves the degradation of organic matter to smaller molecules, such as CO2, NH3, PO4 etc., and requires constant supply of oxygen. The process of supplying oxygen is expensive, tedious, and requires a lot of expertise and manpower. These problems are overcome by growing micro-algae in the ponds and tanks where sewage treatment is carried out. The algae release the O2 while carrying out the photosynthesis which ensures a continuous supply of oxygen for biodegradation. The algae are also capable of adsorbing certain heavy toxic metals due to the negative charges on the algal cell surface which can take up the positively charged metals. The algal treatment of sewage also supports fish growth as algae are a good source of food for fishes.

H. The environmental impact assessment system requires proponents to foresee possible environmental impacts when a development project is being planned, and to conduct an environmental assessment. However, debate continues on exactly what kinds of environmental protection measures are needed and how they should be integrated into a given project to achieve desirable environmental results. Actions to deal with global warming and to prevent ozone layer depletion are gaining momentum, but currently available technologies may not be enough to meet the required targets. Technological advances are needed in order to make progress in solving these issues, as well as with the problem of dioxins. New developments are also needed in technologies for pollution removal and environmental restoration, in cases where environmental pollution has already been generated or is already accumulating in the environment.

Environmental biotechnology – serving the future Like white biotechnology, environmental biotechnology, often referred to as “grey biotechnology”, also focuses on sustainability. For instance, environmental biotechnology deals with the treatment of sewage water, the purification of exhaust gas or the decontamination of soils or ground water using specific microorganisms. The use of organisms for the removal of contamination or pollutants is generally referred to as bioremediation. Originally, bioremediation was mainly used in cleanup operations, including the decomposition of spilt oil or slagheaps containing radioactive waste. In addition, bioremediation is also the method of choice when solvents, plastics or heavy metals and toxic substances like DDT, dioxins or TNT need to be removed. Bioadsorption processes using newly developed bioadsorbers made from renewable materials are currently being developed. These adsorbers function as ion exchangers and are used in the elimination and disposal of toxic heavy metals. The industrial use of mineral resources leads to the drastic accumulation of these pollutants in the biosphere. The new bioadsorbers are used for the elimination of heavy metals and radionuklids from industrial wastewater, ore mine wastewater, seepage water from dumpsites or wastewater from nuclear power stations.

World Environment Day – 5th June, 2008:

World Environment Day – 5^th June, 2008:

Let’s pledge today, on World Environment Day – 5^th June 5, 2008, to change our behavior in order to reduce Air pollution at home as well as on the road. These small steps taken by us would lead to clean our Environment.

A. At Home:

1. Avoid using chemical pesticides or fertilizers in your yard and garden. Many fertilizers are a source of nitrous oxide, a greenhouse gas that contributes to global warming. Try organic products instead.

2. Compost your yard waste instead of burning it. Outdoor burning is not advisable, as it pollutes air. Breathing this smoke is bad for you, your family and your neighbors. Plus, you can use the compost in your garden.

3. If you use a wood stove or fireplace to heat your home, it would be better to consider switching to another form of heat which does not generate smoke. It is always better to use sweater or warm clothing than using fireplace.

4. Be energy efficient. Most traditional sources of energy burn fossil fuels, causing air pollution. Keep your home well-maintained with weather-stripping, storm windows, and insulation. Lowering your thermostat can also help – and for every two degrees Fahrenheit you lower it, you save about two percent on your heating bill.

5. Plant trees and encourage other to plant trees as well. Trees absorb and store carbon dioxide from the atmosphere, and filter out air pollution. During warmer days, trees provide cool air, unnecessary use of energy on air conditioning is avoided, hence the air pollution.

6. Try to stop smoking; at home, at office or at outside. Tobacco smoking not only deteriorates self’s health, it affects others health too.

B. On the Road:

7. Keep your vehicle well maintained. A poorly maintained engine both creates more air pollution and uses more fuel. Replace oil and air filters regularly, and keep your tires properly inflated.

8. Drive less. Walking, bicycling, riding the bus, or working from home can save you money as well as reducing air pollution.

9. Don’t idle your vehicle. If you stop for more than 30 seconds, except in traffic, turn off your engine.

10. Don’t buy more car than you need. Four-wheel drive, all-wheel drive, engine size, vehicle weight, and tire size all affect the amount of fuel your vehicle uses. The more fuel it uses the more air pollution it causes.

Conserve Energy to save our Environment – Few suggestions:

Conserve Energy to save our Environment – Few suggestions:

As discussed earlier, because of the limited amount of non-renewable energy sources on Earth, it is important to conserve our current supply or to use renewable sources so that our natural resources will be available for future generations. Energy conservation is also important because consumption of nonrenewable sources impacts the environment. Specifically, our use of fossil fuels contributes to air and water pollution.

We can help solve these global problems by co-operating among us. Every unit (or kilowatt) of electricity conserved reduces the environmental impact of energy use.

The following concepts can help you evaluate your household energy use and identify ways to conserve energy. These concepts will significantly reduce family utility bill and other energy costs.

* Changing what we use:

(a) Walk, use bicycle, or use mass transit instead of driving; automobile emissions account for about 60 percent of air pollution in our cities.

(b) Install compact fluorescent light bulbs that use less energy and last 10 times longer than incandescent light bulbs.

(c) Air-dry your clothes on a laundry line instead of using a clothes dryer.

(d) Install a programmable thermostat that automatically adjusts the temperature when you are in bed or away.

(e) Buy energy-efficient appliances. There are standard energy use tags attached to most new appliances that can help you determine which appliance will be the most efficient. These appliances may be more costly, but your utility bill savings will quickly make up for the extra cost.

* Changing what we do:

(a) Set the thermostat to 68 °F in winter when you're home and down to 55° F when you go to bed or are away (programmable thermostats can do this automatically).

(b) Insulate the ceiling, walls, and floor of your home.

(c) Plant trees next to a window for shade to reduce the need for air conditioning.

(d) Recycle items such as newspaper, aluminum cans, and plastic bottles; recycling these items requires less energy than producing them from brand new, raw materials.

(e) Wash clothes in cold water and only in full loads.

(f) Use energy-saving settings on washing machines, dishwashers, and clothes dryers.

* Improving our housekeeping:

(a) Turn down the water heater thermostat to 120° F.

(b) Turn off lights when leaving a room.

(c) Close heating vents and close doors to unused rooms.

(d) Close drapes and windows during sunny summer days and after sunset in cooler weather.

(e) Stop air leaks around windows and doors with caulk or weather stripping. Air leaks can rob your house of heat in the winter or make it too humid in the summer. As much as 40 percent of your heating and cooling costs can be due to air leaks.

(f) Clean or change air filters on your air heating system in the winter and on air conditioning units in the summer so that they work more efficiently.

* Educating ourselves and others:

(a) Share knowledge and ideas with family, friends, and neighbors.

(b) Free information on how to evaluate energy efficiency in your house are available in internet or at city community centers. Consult them.

Human health vis-a-vis degradation of global environment:

Human health vis-a-vis degradation of global environment:

Environmental degradation is contributing to human health threats worldwide. We may have several questions in our mind. How much does the environment affect human health? Are air pollution and tainted water shortening our lives and those of our children? These questions have aroused increasing interest in recent years. In the poorest regions of the world an estimated one in five children will not live to see their fifth birthday, primarily because of environment-related diseases. This tragedy translates into more than 11 million childhood deaths a year worldwide, mostly due to malaria, acute respiratory infections or diarrhea, all illnesses that are largely preventable.

* Environmental degradation exerts significant pressure on human health. Exposure to air, water and soil pollution, to chemicals in the environment, or to noise, can cause cancer, respiratory, cardiovascular and communicable diseases, as well as poisoning and neuro-psychiatric disorders.

* Air pollution, in fact, is one obvious environmental health threat in many countries, contributing to a number of illnesses, such as asthma and in some cases leading to premature death. Of particular concern is the fact that children are more vulnerable to air pollution than adults, and increased rates of infant mortality have been recorded in highly polluted areas. Concerns about the impact of air pollution on health and the economy have resulted in measures to mitigate emissions of the most harmful pollutants, such as particle pollution (acids, organic chemicals, metals, and soil or dust particles) and ozone, which affects the respiratory system. Despite national and international interventions and decreases in major pollutant emissions, the health impacts of air pollution are not likely to decrease in the years ahead, unless appropriate action is taken.

* Water is another key environmental health issue – unsafe drinking water and untreated waste water kill thousands of people a year, most of them children. Other health issues associated with emerging environmental hazards, such as chemical products, will also need to be addressed. Chemical products are used in virtually every man-made product and play an important role in the everyday life of people around the world. However, harmful exposure to chemical products can lead to health problems such as skin diseases, chronic bronchitis, nervous system dysfunctions and cancers as well as damaging the environment.

* Environmental degradation has shown an increasing relationship with the rise and spread of human diseases. Genes evolved and became more susceptible to disease to the environmental impacts. The World Health Organization believes that almost one third of global disease can be directly related to environmental risk factors. Antibodies and immune systems have developed in part as a result of environmental change. In fact, environmental change plays a large role in the emergence of infectious disease. In particular, as the human population continues to grow, the population density increases; this leads to an abundance of parasites and infection-forming conditions. Extreme temperatures, climate-related disturbances, and air and water pollution have a direct influence on the spread of infection and disease. Environmental exposures to chemicals and toxins are a major contributor to disease.

* Many of the environmental conditions that impact health are avoidable. Therefore, prevention of health problems through environmental management, rather than simply treating diseases and ailments after they have occurred, is the salient message of environment and health section of various UN charter and various NGOs. These messages offer governments, development agencies, policy-making groups, private businesses, communities and individuals worldwide strategies to slow or even halt further environmental deterioration, averting significant ecological disruption and its possible accompanying economic impacts.

* Improvements must be made in environmental protection. Education is a key process in bettering the conditions. Monitoring of climatic changes help to anticipate outbreaks, as well as changing habits, such as drainage of swamps, screening of houses, and improvements in sanitation and nutrition. Improvement of air quality, water supplies and sanitation, education of the medical community and general public, support of vaccination research, and coordinated restrictions of the use of antibiotics and pesticides would lead to mitigate the problems.

The greatest adverse impact of Deforestation is Greenhouse effect:

The greatest adverse impact of Deforestation is Greenhouse effect:

As described earlier, an approximate area of more than thirty five football grounds of rainforest are deforested all over the world in every minute. The main area attacked for deforestation is the tropical rainforest – situated in on and around equator.

A. The main reason for deforestation is the demand for fuel, wood and paper products, cattle ranching, farming, mining and road construction.

a. Fuel: Half of all the trees cut down in the world are used for fuel. Burning wood is common in developing countries where there are often no readily-available alternatives. Most of the trees cut are not replaced, causing the problems.

b. Wood and Paper Products: The use of wood and paper is a huge factor driving deforestation all over the world. Hardwoods like mahogany are sought after for furniture and are consequently very valuable. Some time, for small number of mahogany, whole forest area is often cut down for those few trees.

c. Cattle-ranching: Areas of rainforest, generally in developing countries, are cleared by cutting down all the vegetation and then burning it. Pastures of grass are then grown and used for grazing cattle. As soon as the cattle are a certain age, they are slaughtered. Although some of the meat goes to the locals, a lot goes to the cheap meat industries in countries such as the UK, USA, and China etc. After a few years, all the nutrients have been removed from the already poor soil and the land is useless, so another area of rainforest has to be cleared.

d. Farming: Large areas of rainforest are cleared for farmland all over the world. In developing countries there are two main types of farming: (i) 'Slash and Burn' and (ii) 'Subsistence Farming'.

(i) Slash and Burn: Areas of forest are cleared to grow crops for a couple of years, then left for a few years for the rainforest to recover, then the process starts again. Slash and burn is the most sustainable of the farming methods, but only if the population in the area is low, because as soon as you get more people in an area, there is less land available for each person and areas of land don't have enough time to recover, so the soil is quickly exhausted. Slash and burn also increases air pollution.

(ii) Subsistence Farming: Small areas of land that have been cleared are farmed. The produce is used to feed the family and provide a small surplus to buy other goods. The problem with this method is that the soil is quickly exhausted of its few nutrients and they are not replaced. This means that the farmers have to rely increasingly on fertilizers before eventually being forced to move.

e. Mining and Infrastructure: Minerals such as gold, bauxite (aluminium ore) and iron ore are often discovered in areas of rainforest. To mine them huge portions of rainforest are cleared, not just the area where the mine is, but also routes for roads and areas for storage of equipment and housing for men. In places where there are large rivers running through rainforest, deforestation often takes place in order to build hydroelectric power stations. The resulting dams cause enormous amounts of flooding behind the walls and large areas of drought downriver.

f. Population Increase: The world population is increasing day by day. With this explosion of population the amount of land needed for humans to live on also increases exponentially. More and more forest areas are being cleared to provide living space. This is known as ‘urbanization’.

B. The adverse effects of deforestation:

(i) Immediate effects of deforestation include the washing away of soil in the monsoon season. This is because trees are no longer anchoring and binding the soil and so mud slides take place. The earth is leached of minerals by the large amounts of water. The lack of vegetation also means that there will be very few animals in the area. The lack of decomposing vegetation and animals means that the nutrients are not replaced and the area quickly becomes infertile.

(ii) Rivers often silt up as soil is moved downriver and deposition takes place. Fish and plants relying on clear water die as the river becomes more and more clogged. This has a knock-on effect through the entire food chain.

(iii) If large areas of rainforest are cleared, the pattern of precipitation may change. This is because less evapotranspiration (evapotranspiration is a term used to describe the sum of evaporation and plant transpiration from the earth's land surface to atmosphere. Evaporation accounts for the movement of water to the air from sources such as the soil, canopy interception, and water bodies) takes place due to the lack of trees. Water is also not delayed before making its way through the ground because of the lack of trees, shrubs, and leaf litter.

(iv) Another very worrying effect of deforestation is global warming (please refer ‘description on global warming’ in the box below). The Earth is made habitable by a process called the greenhouse effect. Gases, mainly carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O) and water vapor (H2O), are found in the atmosphere. The effects of global warming are already showing themselves; the polar ice caps are melting and if this continues we are set for a significant rise in sea level, flooding many places.

C. How to help in mitigating the global warming:

(i) We should turn off the light when we do not require, and to use more energy-efficient bulbs. While energy-efficient bulbs are expensive, they do last longer. Not only will this save money, but it reduces the amount of electricity that needs to be generated and so less fossil fuels have to be burned.

(ii) Use public transport, walk, or cycle if possible. It is said that the bicycle is the most efficient form of transport known to man. Only travel in a car when necessary or share with some body to save petrol. This reduces CO₂ emissions.

(iii) Try to buy paper or wood products that are certified by the Forestry Commission as being from sustainable, managed woodlands. Using recycled paper and its promotion help in reduction of destruction of forest.

(iv) Avoid excess printing of documents from the computer. Print non-presentation documents on the draft ink setting. If possible print on both sides of sheets of paper, thus saving both paper and money.

(v) Recycle as much as possible. This is not just limited to paper, but can include glass, plastic, metal, and a number of other things. Many councils run recycling collection services.

(vi) Encourage people you know to do any or all of the things above.

Description on Greenhouse Effect: Consider a glasshouse in the open air - greenhouse works because of the glass panels that line the roof and walls. The glass is transparent to the visible light from the sun, so sunlight can shine in and warm things inside the greenhouse. Now a body at about 35°C emits mostly infrared radiation. (On the other hand our sun, with a surface temperature of about 5500°C, emits mostly visible light.) The glass panels are opaque to infrared light. The result is that the glass lets the energy of the sun in, but won't let it back out. This keeps the inside of a greenhouse warm. Replace the greenhouse with Earth and glass panels with atmosphere in the above example, and that is how the Earth's greenhouse effect works. Now to show why the greenhouse effect is a very good thing here are examples from our solar system. (i) Mercury: Mercury is the closest planet to the sun, so you would expect it to be hot. It is, but only on the day side. During a Mercurian day temperatures reach 464°C, but because there is no atmosphere to cause a greenhouse effect, temperatures drop to -183°C at night. That's cold enough to warrant an investment in triple-paned windows. (ii) Earth: Our greenhouse effect keeps our night side almost as warm as our day side, allowing life to flourish and keeping the world's collective heating bill manageable. (iii) Venus: Venus is an example of having a greenhouse that is too good at trapping in the heat. Even though Venus is twice as far away from the Sun as Mercury, Venus is the planet with the hottest surface temperature day or night. At about 484°C, lead melts on the surface at any time of the day. The reason why this doesn't happen to Earth is due to the fact that Venus has a much thicker atmosphere with many different kinds of gases. Earth's atmosphere is full of gases that trap infrared radiation (so-called greenhouse gases), but they only trap certain wavelengths at a certain efficiency. In other words, a lot escapes. Venus's atmosphere is more diverse as well as denser, so it traps more wavelengths of infrared radiation at a greater efficiency, making the surface hellishly hot. That is where the greenhouse effect gets its bad reputation. We do not have a lot of carbon dioxide in our atmosphere right now, and if more is released into the atmosphere, more of the infrared radiation that it traps will be held in, making the world warmer than it is. This kind of global warming is a bad thing.

Carbon footprints of power generation using various technologies – Useful for selecting clean technology:

Carbon footprints of power generation using various technologies – Useful for selecting clean technology:

All electricity generation systems have a ‘carbon footprint’, that is, at some points during their construction and operation carbon dioxide (CO2) and other greenhouse gases are emitted to the atmosphere.

To compare the impacts of various different technologies accurately, the total CO2 amounts emitted throughout a system’s life must be calculated. Emissions can be both, direct – arising during operation of the power plant, and indirect – arising during other non-operational phases of the life cycle. Fossil fuelled technologies (coal, oil, gas) have the largest carbon footprints, because they burn these fuels during operation. Non-fossil fuel based technologies such as wind, photovoltaic (solar), hydro, biomass, wave / tidal and nuclear are often referred to as ‘low carbon’ or ‘carbon neutral’ because they do not emit CO2 during their operation. However, they are not ‘carbon free’ forms of generation since CO2 emissions do arise in other phases of their life cycle such as during extraction, construction, maintenance and decommissioning.

A ‘carbon footprint’ is the total amount of CO2 and other greenhouse gases, emitted over the full life cycle of a process or product. It is expressed as grams of CO2 equivalent per kilowatt hour of generation (gCO2eq/kWh), which accounts for the different global warming effects of other greenhouse gases.

Calculating carbon footprints - Carbon footprints are calculated using a method called life cycle assessment (LCA). This method is used to analyze the cumulative environmental impacts of a process or product through all the stages of its life. It takes into account energy inputs and emission outputs throughout the whole production chain from exploration and extraction of raw materials to processing, transport and final use. The LCA method is internationally accredited by ISO 14000 standards.

Carbon footprints:

a. Fossil fuelled technologies - The carbon footprint of fossil fuelled power plants is dominated by emissions during their operation. Indirect emissions during other life cycle phases such as raw material extraction and plant construction are relatively minor.

i) Coal burning power systems have the largest carbon footprint of all the electricity generation systems analyzed here. Conventional coal combustion systems result in emissions of the order of >1,000 gCO2eq/kWh. Lower emissions can be achieved using newer gasification plants (<800gco2eq/kwh),>

ii) Oil accounts for only a very small proportion (about 1%) of the electricity generated in most of the countries. It is primarily used as a back-up fuel to cover peak electricity demand periods. The average carbon footprint of oil-fired electricity generation plants is ~650gCO2eq/kWh.

iii) Current gas powered electricity generation has a carbon footprint around half that of coal (~500gCO2eq/kWh), because gas has a lower carbon content than coal. Like coal fired plants, gas plants could co-fire biomass to reduce carbon emissions in the future.

b. Low carbon technologies - In contrast to fossil fuelled power generation, the common feature of renewable and nuclear energy systems is that emissions of greenhouse gases and other atmospheric pollutants are ‘indirect’, that is, they arise from stages of the life cycle other than power generation.

i) Biomass - Biomass is obtained from organic matter, either directly from dedicated energy crops like short-rotation coppice willow and grasses such as straw, or indirectly from industrial and agricultural by-products such as wood-chips. The use of biomass is generally classed as ‘carbon neutral’ because the CO2 released by burning is equivalent to the CO2 absorbed by the plants during their growth. However, other life cycle energy inputs affect this ‘carbon neutral’ balance, for example emissions arise from fertilizer production, harvesting, drying and transportation.

Biomass fuels are much lower in energy and density than fossil fuels. This means that large quantities of biomass must be grown and harvested to produce enough feedstock for combustion in a power station. Transporting large amounts of feedstock increases life cycle CO2 emissions, so biomass electricity generation is most suited to small-scale local generation facilities,

ii) Photovoltaic (PV) - Photovoltaic (PV), also known as solar cells, are made of crystalline silicon, a semi-conducting material which converts sunlight into electricity. The silicon required for PV modules is extracted from quartz sand at high temperatures. This is the most energy intensive phase of PV module production, accounting for 60% of the total energy requirement. Life cycle CO2 emissions for photovoltaic power systems are currently 58gCO2eq/kWh. However, future reductions in the carbon footprint of PV cells are expected to be achieved in thin film technologies which use thinner layers of silicon, and with the development new semi-conducting materials which are less energy intensive.

iii) Marine technologies (wave and tidal) - There are two types of marine energy devices; wave energy converters and tidal (stream and barrage) devices. Marine based electricity generation is still an emerging technology and is not yet operating on a commercial scale.

iv) Hydro - Hydropower converts the energy from flowing water, via turbines and generators, into electricity. There are two main types of hydroelectric schemes; storage and run-of -river. Storage schemes require dams. In run-of-river schemes, turbines are placed in the natural flow of a river. Once in operation, hydro schemes emit very little CO2, although some methane emissions do arise due to decomposition of flooded vegetation. Storage schemes have a higher footprint, (~10-30gCO2eq/kWh), than run-of-river schemes as they require large amounts of raw materials (steel and concrete) to construct the dam.

v) Wind - Electricity generated from wind energy has one of the lowest carbon footprints. As with other low carbon technologies, nearly all the emissions occur during the manufacturing and construction phases, arising from the production of steel for the tower, concrete for the foundations and epoxy/fibreglass for the rotor blades. Emissions generated during operation of wind turbines arise from routine maintenance inspection trips. This includes use of lubricants and transport. Onshore wind turbines are accessed by vehicle, while offshore turbines are maintained using boats and helicopters. The manufacturing process for both onshore and offshore wind plant is very similar, so life cycle assessment shows that there is little difference between the carbon footprints of onshore (4.64gCO2eq/kWh) versus offshore (5.25gCO2eq/kWh) wind generation.

vi) Nuclear - Nuclear power generation has a relatively small carbon footprints (~5gCO2eq/kWh). Since there is no combustion, (heat is generated by fission of uranium or plutonium), operational CO2 emissions account for <1%>

Adverse Impacts of Road Traffic exhaust on Human Health and Mitigation measures:

Adverse Impacts of Road Traffic exhaust on Human Health and Mitigation measures:

Automotive vehicle engines produce a number of air pollutants that pose risks to human health. Road vehicles such as cars, buses and trucks are a source of air pollution. When their engines burn fuels (gasoline or diesel), they produce large amounts of chemicals that are emitted in engine exhaust. In addition, some of the gasoline used by engines vaporizes into the air without having burned, and this also creates pollution.

A. Recent study shows that those who reside near major highways had worse indoor air pollution than those in more rural settings, with respect to PAHs (polycyclic aromatic hydrocarbons), a class of compounds that contain known cancer-causing toxins.

Although, stringent regulations on engine performance and fuel formulation have brought about a decline in the amount of air pollution produced by individual vehicles, but due to increase in number of vehicles the air pollution level in urban areas have not come down. Automobile exhaust remains a major source of pollution and the pollutants cause local changes in the air quality, which affect the human health adversely.

B. This causes us great concern on health front of public, especially, children who pose risk to various hazards. Children exposed to high levels of air pollution during their initial years of life run a greater risk of developing asthma, pollen allergies, and impaired respiratory function.

Another group of people those are greatly affected due to vehicular exhaust are traffic personnel - men and women. It has also been reported in many countries that, due to high exposure to toxic fumes of vehicular exhaust among traffic personnel, induced impaired reproductive system observed.

C. The following is a summary of the main pollutants produced by road traffic and the way they may affect our health:

Nitrogen oxides: These are created when vehicle engines burn nitrogen that is present in the air and nitrogen compounds found in fossil fuels. Nitrogen oxides can irritate airways, especially your lungs.

Carbon monoxide: This gas is produced by incomplete combustion of gasoline and diesel fuel. All engine exhaust contains a certain amount of carbon monoxide, but the amount will increase if your vehicle engine is poorly maintained. Carbon monoxide decreases the ability of your blood to carry oxygen.

Volatile organic compounds (VOCs): These are a large family of carbon-containing compounds that evaporate easily. Engine exhaust contains a number of different VOCs. Some of them, such as benzene and 1,3-butadiene, are cancer-causing agents, although the risk at current levels in the environment is small.

Fine particulate matter: These tiny particles contain many substances, including metals, acids, carbon, and polycyclic aromatic hydrocarbons. Some of these particles are emitted in vehicle exhaust, while others are formed in the atmosphere through chemical reactions between the various pollutants found in exhaust. Particulates are known to aggravate symptoms in individuals who already suffer from respiratory or cardiovascular diseases.

Ground-level ozone: This is not emitted directly by vehicle engines, but is formed by chemical reactions between nitrogen oxides and VOCs. These reactions are stimulated by sunlight, and this is why concentrations of ground-level ozone are higher during the summer months. Ground-level ozone irritates airways and can trigger reactions in people who have asthma (Ground-level ozone should not be confused with the ozone layer in the stratosphere, which provides protection from the sun's ultraviolet rays.).

The air pollution from road traffic causes two types of effects on health:

Acute Effects: These effects occur rapidly (in a few hours or days) following exposure to high levels of pollutants. In certain cases, air pollution may worsen symptoms for people with existing heart and lung conditions. Scientific research carried out in some countries has shown that the number of deaths and hospitalizations related to respiratory and cardiac conditions increases when the levels of ground-level ozone or fine particulate matter increase.

Chronic Effects: These occur over time following extended exposures (months or years). Scientific studies in Europe have shown that children living in areas with higher traffic density have more respiratory symptoms than other children.

In general, traffic exhaust pollutants are a major source of air pollution especially in urban areas, and are a major source of greenhouse gas emissions as well. Vehicles run on conventional or diesel engines. Although diesel engines are more efficient, they emit more fine particles than conventional engines. According to many, diesel exhaust is responsible for 70 percent of the cancer risk that the average urban population faces from breathing toxic air pollutants.

Potential health effects from being exposed to traffic-exhaust pollutants include respiratory illnesses (including asthma), cardiovascular disease, adverse reproductive outcomes, cancer, and shortening of the life span.

D. We can help to minimize risks by taking steps to reduce traffic-related air pollution. (a) Whenever possible, use public transit, bicycle or walk instead of using your vehicle. (b) Take fuel efficiency into account when you buy a vehicle. (c) Turn off the engine of your car when you stop for more than 10 seconds, unless you are in traffic or at an intersection. (d) Keep your vehicles well maintained. (e) In addition, you can take steps to help minimize your risk of health effects from traffic-related air pollution, such as,

(i) Pay attention to air quality forecasts in your community, and tailor your activities accordingly.

(ii) Avoid or reduce strenuous outdoor activities when air pollution levels are high, especially in the afternoon during summer months when ground-level ozone reaches its peak.

(iii) Choose indoor activities instead.

(iv) Avoid or reduce exercising near areas where traffic is heavy, especially during rush hour.

(v) If you have a problem of heart or lung, consult health care professional about additional ways to protect your health when air pollution levels are high.

E. Governments can encourage the reduction of vehicular use by:

a. Promoting Voluntary abstention,

b. Increase Public Transit - diversify options and limit access to existing roads.

c. Separate commercial and private traffic to increase efficient use of roads,

d. Stop building car-oriented roads and highways,

e. Replace 30% of the existing roads designed for cars with a variety of transportation options,

f. In cities, build more walking paths, bicycle routes and paths for small electric vehicles, g. Reduce commuting - link residence and business activities by rezoning and rebuilding cities,

h. Reward car-pools and car-sharing plans,

i. Redefine road use by defining access privileges - no longer a right,

j. Road Tolls and increased gasoline and vehicle registration taxes,

k. Base car license fees on fuel consumption in the previous year. Use exponential fee rate increase for high fuel consumption individuals,

l. Provide generous development grants and tax incentives for all non-polluting transportation alternatives.

Pollution from Oil refineries:

Pollution from Oil refineries:

Oil refineries pollute our air, water, and land. Oil refineries cause smog and air pollution. Almost all refineries in every country currently pollute at unacceptable, unhealthy levels. Oil refineries emit about 100 chemicals everyday. These include metals like lead which makes it hard for children to learn. They also include very smaller size dust particles that get deep into our lungs and harm our ability to breathe. Finally, refineries emit many gases like sulfur dioxide (SO2), nitrogen oxide (NO2), carbon dioxide, carbon monoxide, methane, dioxins, hydrogen fluoride, chlorine, benzene and others.

Many of the gases emitted by refineries are harmful to humans, and can cause permanent damage and even death. They can cause respiratory problems (such as asthma, coughing, chest pain, choking, bronchitis), skin irritations, nausea, eye problems, headaches, birth defects, leukemia, and cancers. Young children and the elderly are the worst affected.

Sulfur dioxide (SO₂): Crude oil and coal both contain relatively high quantities of sulfur. (Natural gases contain much less sulfur and therefore are safer.) When crude oil or coal is heated at the refinery to produce fuel, the sulfur is converted into a gas called sulfur dioxide. This is a colorless gas with a very strong smell, like rotten eggs.

Bad effects of Sulfur dioxide: Exposure to very high concentrations of SO₂ can result in painful irritation of the eyes, nose, mouth and throat, difficulty in breathing, nausea, vomiting, headaches and even death. Some of the health effects from daily exposure to outdoor levels of SO₂ are tight chests, worsening of asthma and lung disease, and narrowing of air passages in the throat and chest. People with asthma are more sensitive to SO₂. Exposure to SO₂ can provoke asthma attacks. SO₂ mixes easily in water, including moisture in the air to form an acid. Acid rain and early morning dew causes much damage to metals, stones, and the environment.

Fugitive emissions are the air pollution which escapes through leaks in the equipment. Very often the amount of pollution coming from fugitive emissions is higher than the amount coming out of the stacks.

Many of the refineries often use low quality crude oil that has high levels of sulfur. When this is refined it produces higher levels of SO₂ pollution.

Accidental fires, explosions, and chemical and gas leaks are common at refineries. Such accidents cause higher than usual amounts of pollution, which may result in more acute exposure to pollutants and greater health impacts.

Fundamentals of prevention and control of air pollution:

Fundamentals of prevention and control of air pollution:

As mentioned in my earlier discussion, air pollutants can be gaseous or particulate matters. Different techniques for controlling these pollutants are discussed below:

A. Methods of controlling gaseous pollutants -

1. Combustion - This technique is used when the pollutants are in the form of organic gases or vapors. During flame combustion or catalytic process, these organic pollutants are converted into water vapor and relatively less harmful products, such as CO2.

2. Absorption - In this technique, the gaseous effluents are passed through scrubbers or absorbers. These contain a suitable liquid absorbent, which removes or modifies one or more of the pollutants present in the gaseous effluents.

3. Adsorption - The gaseous effluents are passed through porous solid adsorbents kept in suitable containers. The organic and inorganic constituents of the effluent gases are trapped at the interface of the solid adsorbent by physical adsorbent.

B. Methods to control particulate emissions:

1. Mechanical devices generally work on the basis of the following:

(a) Gravity: In this process, the particles settle down by gravitational force.

(b) Sudden change in direction of the gas flow. This causes the particles to separate out due to greater momentum.

2. Fabric Filters: The gases containing dust are passed through a porous medium. These porous media may be woven or filled fabrics. The particles present in the gas are trapped and collected in the filters. The gases freed from the particles are discharged.

3. Wet Scrubbers: Wet scrubbers are used in chemical, mining and metallurgical industries to trap SO2, NH3, metal fumes, etc.

4. Electrostatic Precipitators: When a gas or an air stream containing aerosols in the form of dust, fumes or mist, is passed between two electrodes, then, the aerosol particles get precipitated on the electrode.

C. Apart from the above, following practices also help in controlling air pollution.

(i) Use of better designed equipment and smokeless fuels, hearths in industries and at home.

(ii) Automobiles should be properly maintained and adhere to recent emission-control standards.

(iii) More trees should be planted along road side and houses.

(iv) Renewable energy sources, such as wind, solar energy, ocean currents, should fulfill energy needs.

(v) Tall chimneys should be installed for vertical dispersion of pollutants.

Fundamentals of our environment and environmental problems:

Fundamentals of our environment and environmental problems:

We know that, a living organism cannot live by itself. Organisms interact among themselves. Hence, all organisms, such as plants, animals and human beings, as well as the physical surroundings with whom we interact, form a part of our environment. All these constituents of the environment are dependent upon each other. Thus, they maintain a balance in nature. As we are the only organisms try to modify the environment to fulfill our needs; it is our responsibility to take necessary steps to control the environmental imbalances.

The environmental imbalance gives rise to various environmental problems. Some of the environmental problems are pollution, soil erosion leading to floods, salt deserts and sea recedes, desertification, landslides, change of river directions, extinction of species, and vulnerable ecosystem in place of more complex and stable ecosystems, depletion of natural resources, waste accumulation, deforestation, thinning of ozone layer and global warming. The environmental problems are visualized in terms of pollution, growth in population, development, industrialization, unplanned urbanization etc. Environmental pollution is defined as the undesirable change in physical, chemical and biological characteristics of our air, land and water. As a result of over-population, rapid industrializations, and other human activities like agriculture and deforestation etc., earth became loaded with diverse pollutants that were released as by-products. Pollutants are generally grouped under two classes:

(a) Biodegradable pollutants - Biodegradable pollutants are broken down by the activity of micro-organisms and enter into the biogeochemical cycles. Examples of such pollutants are domestic waste products, urine and faucal matter, sewage, agricultural residue, paper, wood and cloth etc.

(b) Non- Biodegradable pollutants - Non-biodegradable pollutants are stronger chemical bondage, do not break down into simpler and harmless products. These include various insecticides and other pesticides, mercury, lead, arsenic, aluminum, plastics, radioactive waste etc.

Pollution can be classified according to the components of environment that are polluted. These are: (A) Air pollution (B) Water pollution (C) Soil pollution (land degradation).

(A) Air Pollution - Air is mainly a mixture of various gases such as oxygen, carbon dioxide, nitrogen. These are present in a particular ratio. Whenever there is any imbalance in the ratio of these gases, air pollution is caused. The sources of air pollution can be grouped under (i) Natural; such as, forest fires, ash from smoking volcanoes, dust storm and decay of organic matters. (ii) Man-made due to population explosion, deforestation, urbanization and industrializations. Certain activities of human beings release several pollutants in air, such as carbon monoxide (CO), sulfur dioxide (SO2), hydrocarbons (HC), oxides of nitrogen (NOx), lead, arsenic, asbestos, radioactive matter, and dust. The major threat comes from burning of fossil fuels, such as coal and petroleum products. Thermal power plants, automobiles and industries are major sources of air pollution as well. Due to progress in atomic energy sector, there has been an increase in radioactivity in the atmosphere. Mining activity adds to air pollution in the form of particulate matter. Progress in agriculture due to use of fertilizers and pesticides has also contributed towards air pollution. Indiscriminate cutting of trees and clearing of forests has led to increase in the amount of carbon dioxide in atmosphere. Global warming is a consequence of green house effect caused by increased level of carbon dioxide (CO2). Ozone (O3) depletion has resulted in UV radiation striking our earth.

Harmful Effects of air pollution are: (a) it affects respiratory system of living organisms and causes bronchitis, asthma, lung cancer, pneumonia etc. Carbon monoxide (CO) emitted from motor vehicles and cigarette smoke affects the central nervous system. (b) Due to depletion of ozone layer, UV radiation reaches the earth. UV radiation causes skin cancer, damage to eyes and immune system. (c) Acid rain is also a result of air pollution. This is caused by presence of oxides of nitrogen and sulfur in the air. These oxides dissolve in rain water to form nitric acid and sulfuric acid respectively. Various monuments, buildings, and statues are damaged due to corrosion by acid present in the rain. The soil also becomes acidic. The cumulative effect is the gradual degradation of soil and a decline in forest and agricultural productivity. (d) The green house gases, such as carbon dioxide (CO2) and methane (CH4), trap the heat radiated from earth. This leads to an increase in earth’s temperature. (e) Some toxic metals and pesticides also cause air pollution.

(B)Water Pollution - Water is one of the prime necessities of life. With increasing number of people depend on this resource; water has become a scarce commodity. Pollution makes even the limited available water unfit for use. Water is said to be polluted when there is any physical, biological or chemical change in water quality that adversely affects living organisms or makes water unsuitable for use. Sources of water pollution are mainly factories, power plants, coal mines and oil wells situated either close to water source or away from sources. They discharge pollutants directly or indirectly into the water sources like river, lakes, water streams etc. The harmful effects of water pollution are: (a) human beings become victims of various water borne diseases, such as typhoid, cholera, dysentery, hepatitis, jaundice, etc. (b) The presence of acids/alkalies in water destroys the microorganisms, thereby hindering the self-purification process in the rivers or water bodies. Agriculture is affected badly due to polluted water. Marine eco-systems are affected adversely. (c) The sewage waste promotes growth of phytoplankton in water bodies; causing reduction of dissolved oxygen. (d) Poisonous industrial wastes present in water bodies affect the fish population and deprives us of one of our sources of food. It also kills other animals living in fresh water. (e) The quality of underground water is also affected due to toxicity and pollutant content of surface water.

(C) Soil pollution (Land degradation) - Land pollution is due to (i) deforestation and (ii) dumping of solid wastes. Deforestation increases soil erosion; thus valuable agricultural land is lost. Solid wastes from household and industries also pollute land and enhance land degradation. Solid wastes include things from household waste and of industrial wastes. They include ash, glass, peelings of fruit and vegetables, paper, clothes, plastics, rubber, leather, brick, sand, metal, waste from cattle shed, night soil and cow dung. Chemicals discharged into air, such as compounds of sulfur and lead, eventually come to soil and pollute it. The heaps of solid waste destroy the natural beauty and surroundings become dirty. Pigs, dogs, rats, flies, mosquitoes visit the dumped waste and foul smell comes from the waste. The waste may block the flow of water in the drain, which then becomes the breeding place for mosquitoes. Mosquitoes are carriers of parasites of malaria and dengue. Consumption of polluted water causes many diseases, such as cholera, diarrhea and dysentery.