Ozone Depletion

OZONE DEPLETION Adriana Orjuela, Ansar Mustafa, Yohana Shum (Francis Lewis High School), Adam de Delva, Nandini Seepersaud (Math, Science Research, And Technology High school ) This project has the objective of informing the audience about why the ozone layer is so important to preserve life on Earth and why we must remain committed to protecting it. Ozone layer arose naturally as a by-product of the evolution of photosynthesis and the rise of atmospheric oxygen. It is very fragile which can be destroyed by various catalytic cycles involving elements such as nitrogen, chlorine and bromine. Today it is being threatened by chemicals released into the atmosphere by anthropogenic activities. It is a serious problem and significant steps have been taken to reduce the impact. Effects on life UVA/UVB & UVC rays- ,[object Object],[object Object],[object Object],The tropospheric ozone layer is a vital part of the earth’s atmosphere that helps life flourish on earth. It’s effect is relatively straightforward: absorbing harmful UVB and UVC rays before they make it to the earth’s surface. Numerous atmospheric researchers have concluded that anthropogenic ozone depleting sources are at fault for recent ozone depth decreases. This poster covers exactly what has been happening to the ozone layer within recent decades and how it specifically affects life on earth. The ozone layer consists of O3 molecules that are created by UV photons in a special part of the troposphere. Scenarios in which the ozone layer is nonexistent will be discussed as well as what we can do to stop ozone depletion from occurring. Humans can quickly make crucial adaptations to increased UV-B radiation by staying out of the sun, protecting their skin with clothing, and applying sunscreens. However, plants and other animals that help support us and other forms of life can’t make such changes except through the long process of biological evolution. The Montreal Protocol and many others wanted to lower the abundance of stratospheric chlorine; it shows the concentrations under the various international agreements and the absence of them (No protocol). With no protocol, stratospheric chlorine would have been expected to have risen quite rapidly over the new few decades. With the Beijing 1999 Accord the outlook is much more improved. Scientists and experts expect that the hole will disappear by 2060, when the stratospheric chlorine should be back down to about 2 ppb. They hope that within the following century, stratospheric chlorine should reach the background level of 0.6 ppb Montreal Protocol in 1987: placed strict limits on amount of Freons and halons that could be realeased into the atmosphere by any country. Sources & Sinks of Ozone depleting compounds Atmospheric chemists have been searching for reasons as to why the amounts of Ozone in the atmosphere have been depleting and now feel that they have found the main culprits to this phenomenon. The gasses that damage the ozone layer by using O 3 ) as a catalyst which reduces the availability of Ozone. Two Catalytic cycles known as the Nitrogen and Chlorine catalytic cycles react with ozone to break it back down into O 2 . The Nitrogen Catalytic cycle quickly reacts with O 3 ) to create Nitric oxide and Oxygen as well as nitrogen dioxide. The Chlorine catalytic cycle is one that humans directly contribute to with industrial activity. This cycle is much faster than the nitrogen cycle because it shoots the Chlorine directly into the troposphere and is shifted upward to the stratosphere by winds and eddies. The usage of Freons rapidly damaged the Ozone layer because of its reactivity with O 3 molecules. Bromine has a very similar effect to O 3 molecules because of the way that they break down O 3 into O 2 Professor: Kimmy Szeto (Queens College) Classification of UV Radiation Why is ozone depletion getting worse? Though there are many other factors that come into play, human activity predominantly deals with the depletion of the ozone layer. Chlorofluorocarbons (CFCs) and hydro fluorocarbons (HCFCs) that are released into the atmosphere are broken down by ultraviolet radiation. After being broken down, chlorine atoms are then released, causing a reaction with ozone which ultimately enhances the effects of ozone depletion. Simple everyday activities, such as driving a car affect the atmosphere greatly. The car exhaust together with certain compounds in the air such as carbon tetrachloride and halons, continue to worsen the ozone layer. Like CFCs and HCFCs, methyl bromide and halons are broken down, releasing bromine atoms which pose a bigger threat to the ozone than chlorine atoms. Other factors such as aerosols and coal burning merely exacerbate the ozone. Chlorofluorocarbons (CFCs) are produced in high percentages since they are commonly used as refrigerants, spray cans, foam packaging, and home insulation which we use every day. CFC-12 is used in cosmetics and medical products such as inhalers. Along with CFC-12, CFC-11 is used for air conditioning and refrigeration. CFC-113 is used in metal cleaning and dry-cleaning. The continuous or increased use of these substances will only deplete the ozone further. Why is ozone depletion over the Arctic and Antarctic? Mainly occurring in the winter, the thinning of the ozone layer in the Arctic and Antarctic is known as the “ozone hole”. The main cause of the ozone hole is from the atmospheric conditions in the Antarctic. Polar stratospheric clouds (PSCs) are created as a result of the very low stratospheric temperatures. Low stratospheric temperatures such as those in the Antarctic are not the same in the Arctic. PSCs form a chemical reaction what forms reactive bromine and chlorine reactions. Most PSCs have nitric acid which they remove from the ozone in a process called denitrification. Through denitrification, there is less nitric acid, which enables reactive chlorine gas to remain active for a longer period of time. These reactions then react to ultraviolet light during the Spring in the Antarctic, producing the ozone hole. Through the Montreal Protocol, the production of CFCs and other ozone depleting substances were banned in certain countries. Nevertheless, the ozone hole continues to get worse. The Antarctic ozone hole was at its largest in September 2006. What are the types of ozone? GROUND LEVEL OZONE This form of ozone has rather detrimental effects to humans in highly populated cities with numerous motor vehicles such as New York City, Los Angeles and Miami. Ground level ozone is formed in the troposphere when motor vehicles, power plants refineries and many other nitrogen oxide emitting activities discharge these and other chemical compounds. After reacting with sunlight they form a unique compound that we refer to as ground level ozone. Breathing in high amounts of ozone on hot summer days has a direct correlation to future lung complications, heart disease, and asthma. The environment is directly impacted from an excess of ground level ozone. It affects the starches found in plant life and increases the onset of global warming by damaging the plants that reduce global CO2 concentrations. Ground level ozone can produce smog which is a combination of fog, ozone and compounds produced by car emissions. Inhaling smog for prolonged periods of time can cause lung cancer, chest pains and has drastic effects on nearby ecosystems. HIGH-ALTITUDE OZONE This type of ozone occurs in the stratosphere and high altitudes in the earth. In the stratosphere, ozone is constant. This means that it is created and destroyed at a constant rate. This type of ozone also protects us from the suns UV Rays. In the stratosphere, the ozone is being depleted. This happens when chlorine molecules are broken apart due to the suns UV rays. These harmful molecules destroy our ozone layer and allow more harmful substances to enter the earth, such as radiation. We can face some health problems such as more skin cancer cases, increase the level of carbon dioxide in the atmosphere. GROUND –LEVEL OZONE • Keep your car tuned-up and well maintained. • Carpool to reduce driving. • Be careful not to spill gas • Make sure your tires are properly inflated • Participate in energy conservation programs. • Seal containers with household cleaners, and garden chemicals to prevent these from evaporating into the air. How is it produced? Ozone O3 is created when oxygen molecules interact with ultraviolet light. It is also known as photolysis. Photolysis is basically when UV radiation splits a molecule. Ozone is created when there is a combination of oxygen and covalent oxygen. This is also possible with the help of sunlight. O3 + UV, visible light -> O + O2 What can we do? High Altitude Ozone: • Have air conditioner units and refrigerator checked for leaks. • Properly dispose of refrigeration or air conditioning equipment • Protect yourself against the sun to shield yourself from harmful rays Why is the Ozone depleting? As we know, the ozone layer is a layer in earth’s atmosphere which contains a fair amount of high concentrations of ozone (O3). This layer then absorbs 97-99% of the sun’s frequency ultraviolet light, which can cause great damage to life on earth. It is located at the lower portion of the stratosphere, around (10-30) miles above earth. Since the 1970’s two distinct yet very similar topics were observed. One being a steady decline of 4-5% within every ten years in the total volume of the ozone in earth’s stratosphere; and due to that a decrease in springtime in the stratospheric ozone over earth’s Polar Regions. This is referred to as the ozone hole. The main cause of the ozone depleting would be due to the production and the release of CFC’s (chlorofluorocarbons). CFC which was discovered way back in the 1930’s has been extremely useful in the industry. CFC came to be used in refrigerators, home insulation, plastic foam, and throwaway food containers. The reason why it is so harmful is due to the fact that the chlorine atom within it is removed from the CFC and then it goes ahead and attracts one of the three oxygen atoms in the ozone molecule located in the ozone layer. A single chlorine atom can destroy over 100,000 molecules of ozone. CFC would first enter into the atmosphere, and then make its way up into the stratosphere. Every time a small amount of the ozone layer is lost, more ultraviolet light is able to reach the earth. The increase in UV-B rays on earth surface, can cause an increase in skin cancer, also there will be an increase rate of malaria and other infectious diseases. Other effects to this would be the cycles of plants which will change and disrupt the food chain. Microscopic organisms living in the ocean such as plankton may not be able to survive, causing other animals above the plankton in the food chain to die out as well. Wind patterns could change, as a result of climatic changes throughout the world. As the years go on the ozone continues to deplete more and more. Effects of life UVA/UVB/UVC radiation: Ultraviolet light is an electromagnetic radiation that consists of a wavelength shorter than visible light, but longer than x-rays. It got its name because the spectrum consists of waves with very high frequencies. Higher than those that humans identify as the color violet. Despite the fact it is invisible to the naked eye, people are still aware of the effects it can bring, for instance sunburn. But UV rays also have many other effects that goes both ways, beneficial and damaging, to humans. UVA which is also known as black light is capable of causing damage to collagen fibers and destroying vitamins A and D in our skin. Whereas UVB and UVC, cause direct damage to our DNA ultimately leading to skin cancer. UVB also benefits humans, as its exposure creates the production of vitamin D in the skin of humans. It has regulatory roles in calcium metabolism, immunity, cell proliferation, insulin secretion, and blood pressure. Too little UVB can lead to a lack of vitamin D but too much can lead to DNA damage, skin burn and skin cancer. UVC is usually filtered out by the atmosphere and never reaches us. Almost all of the sun radiation at sea level is UVA, but it is UVB that causes the most problems to humans, which relates to sun exposure such as aging, wrinkles, cancer and so on. UVA are also responsible for most people vision problems on earth. Excessive sun bathing can lead to the weakening of human’s immune system, this is caused because UV radiation changes the function of WBC which plays an active role in fighting diseases, for up to 24 hours after sun exposure, and the more people do it, the more damage that is being done to their immune system. Something that many people tend to get is tans. What tans really are is the skins reaction when it is being injured. Tanning occurs when the UV rays get into contact with the skin’s layer and causes the skin to produce more of its natural pigment as a response to being injured. The sun is most beneficial during the mornings or evenings, not mid day. There are many effects that UV rays brings upon humans, both beneficial and harmful to us. Range (nm) Name Biological Effects 320-400 UVA Relatively harmless; causes tanning but not burning 290-320 UVB Harmful; causes sunburn, skin cancer and other disorders 200-290 UVC Extremely harmful but almost completely absorbed by the ozone

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Ozone Depletion

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