ENVIRONMENTAL STUDIES-II

Transcription

1 ENVIRONMENTAL STUDIES-II MODULE I ENVIRONMENTAL POLLUTION LECTURE 7 THERMAL & RADIOACTIVE POLLUTION

2 CONTENTS Causes of Thermal Pollution Effects of Thermal Pollution Control of Thermal Pollution Sources of Radioactive Pollution Effects of Radioactive Pollution Control of Radioactive Pollution

3 Thermal Pollution An increase in the optimum temperature of the water by industrial process ( Steel factories, electric power houses, atomic power plants etc.) is called thermal pollution. Industries uses water to cool the generators and this hot water is released in to adjoining streams causing warming of the water. If the adjoining streams are slow flowing permanent increase in the temperature may result. 3

4 Effects: Many organisms are killed instantly due to hot water. The eggs of the aquatic animals may hatch early or fail to hatch at all. It may change the behaviour and metabolic response of the aquatic organisms. It leads to unplanned migration of aquatic animals. Aquatic flora may also be changed. 4

5 Decrease in the level of dissolved oxygen. High mortality of aquatic flora and fauna. Change in the micro flora and microfauna of the aquatic body. 5

6 Causes or source of thermal pollution: Coal fired Power Plants. Industrial Effluents. Nuclear Power Plants. Hydro Electric Power. Domestic sewage. 6

7 Control of thermal pollution: Cooling ponds: Cooling towers: Artificial lakes: 7

8 Nuclear or Radio active Pollution Radioactive pollution is the physical pollution of the air, water and soil by radioactive material like Uranium, Radium, Thorium etc. Radioactive material released from nuclear explosion and nuclear power plant pose a serious risk to living organism. 8

9 Ionizing radiation comes in three flavors: alpha particles, beta particles and gamma rays. 1. Alpha particles are the least dangerous in terms of external exposure. Each particle contains a pair of neutrons and a pair of protons. They don't penetrate very deeply into the skin, if at all in fact, clothing can stop alpha particles. Unfortunately, alpha particles can be inhaled or ingested, usually in the form of radon gas. Once ingested, alpha particles can be very dangerous. However, even then they don't typically cause radiation sickness instead, they lead to lung cancer

10 2. Beta particles are electrons that move very quickly that is, with a lot of energy. Beta particles travel several feet when emitted from a radioactive source, but they're blocked by most solid objects. A beta particle is about 8,000 times smaller than an alpha particle and that's what makes them more dangerous. Their small size allows them to penetrate clothing and skin. External exposure can cause burns and tissue damage, along with other symptoms of radiation sickness. If radioactive material enters food or water supplies or is dispersed into the air, people can inhale or ingest beta particle emitters unknowingly. Internal exposure to beta particles causes much more severe symptoms than external exposure.

11 3. Gamma rays are the most dangerous form of ionizing radiation. These extremely high energy photons can travel through most forms of matter because they have no mass. It takes several inches of lead -- or several feet of concrete to effectively block gamma rays. If you're exposed to gamma rays, they pass through your entire body, affecting all of your tissues from your skin to the marrow of bones. This causes widespread, systemic damage.

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13 Source of radioactive pollution: Natural sources: These include cosmic rays which are fast moving and highly energetic radiation reaching the earth from outer space. The intensity of cosmic ray in the biosphere is low and so they are not a health hazard but they cause major hazard in the space. The terrestrial radiations from radioactive elements present in the rock soil and water also constitute the natural source of the radio active pollution 13

14 Man Made sources: Man cause radiation pollution by testing the nuclear weapons, establishing the nuclear power plants, mining and processing of thorium and plutonium etc. A large number of radioactive isotopes such as I-125, C-14, P-32 find their use in scientific research. The waste water from these institute contain varying amount of radioactive materials. When this waste water reaches the different water sources it cause water pollution. 14

15 Other sources: Medical treatments like X ray, CT scan etc. Effect of radioactive pollution: At 5 Sv (sievert) and up, radiation can damage skin so severely that it doesn't heal properly. Hair falls out. High dose of radiation can cause instant death whereas in lower dose it can impair the functioning of the body It results in to the mutation Development of tumour and cancer Mental retardation Leukaemia Sterility Defective eyesight 15

16 Control of radioactive pollution: Radiation exposure protection: Three principle of radiation protection are distance, time to exposure and shielding. In case of occupational exposure the total exposure should be kept below maximum dose. Use of shielding: by using some material as a barrier between source and surrounding. Avoid routine X- rays. Use of X -ray equipment of high quality. 16

17 Radiation Contamination Protection: Radioactive material are highly hazardous if inhaled. This can be minimized by using laboratory hoods, air filters and specially designed suits (protective clothing), using respirator. Avoiding eating and smoking in the area where radioactive material was used. Air also contain large amount of radioactive substances after nuclear explosion 17

18 Controlled area: Area which cause or permit exposure to radiation are required to have controlled accessibility and should be marked restricted area or radiation zone etc. Level of radiation pollutant should be checked regularly in high risk areas. Radiation resistant cases or walls should be constructed for screening workers from radioactive materials. 18

19 Collection, storage and disposal: Radioactive waste should be changed in to harmless form or stored in to the deeper layer of the lithosphere where their gradual decay can take place. Special techniques like disposal of low and high activity radioactive substance in specialized containers made of durable glass. Disposal in deeper part of the sea, mines and deep wells etc. 19

20 Case of hazards A Physicist Harry K. Daghlian, suffered a 5.1 Sv exposure in 1945 while working on a plutonium core. He suffered severe burns to his hands and died 25 days after the accident. Another physicist, Louis Slotin, suffered a similar accident using the exact same core just one year later. Slotin was exposed to a 21 Sv dose, which is a massive amount of radiation. He vomited immediately, and then suffered through nine days of horrific symptoms before dying. The incident that killed Slotin was so intense that the air in the lab itself became ionized, causing a clear blue glow and a visible wave of heat. His symptoms were very similar to those seen in victims of the atomic bomb attacks on the Japanese cities of Hiroshima and Nagasaki.

21 Nuclear BLAST IN JAPAN In 1945, sufficient amount of Plutonium was extracted and a bomb was made. The bomb was exploded on 16 July 1945 in a desert in Mexico. The 30M tower on which the bomb was placed completely melted, sand over several sq. km melted. The blinding light that spread for a few minutes turned the sun into a pale ball.

22 Frightened to the core by the resulting blast, scientist vehemently opposed using it on Japan. President Truman, to save a few American soldier who might be the casualties in war with Japan, ordered dropping of the bomb on Japan. Little boy the Uranium bomb was dropped on Hiroshima on 6 th August 1945 which shook Japan and 1 lakh people were burnt in minutes like moths near a lamp. Just three days latter, a Plutonium bomb called Fat man reduced Nagasaki into a desert with dead bodies strewn allover. Japan surrendered on 14 th August

23 The consequences of a bomb blast were: 1. Enormous amount of heat creating a temperature where any life cannot exist. 2. Devastating shock waves making earth quake look like pygmies before them 3. Deadly gamma radiation The nuclear plants cause thermal pollution the waste heat from the plants heat up the environment and release highly dangerous radiation into the environment. The radio active products cause serious problem of disposal. If any accident occur in the plant, mass destructions of people in the neighborhood is inevitable. High dosage of radiation destroys tissues. Smaller radiation does produce malignancy years after exposure. 23

24 Genetic effects are visible in future generations. The cells which are constantly replaced are more susceptible to these radiations. The bone marrow is most important one in this case. Damage of reproductive cells show abnormality in future generations. B) April 27, 1986 was a tragic day in the history of nuclear power generation as a major accident occurred at an atomic reactor at Chernobyl in the Ukraine area of former Soviet Union. This had resulted in clouds of radioactive smoke over a large area in Scandinavian countries about 2000 km away and in the Russian region itself. During the first 10 days after the explosion, over 400 million people were exposed to the radiation. 24

25 Approximately 1000 were treated for radiation burns and sickness over a people were evacuated from an area inside a 30 km range of explosion. The radiation level in western Europe reached 100 times of the normal resulting in misery and panic death. The exposure caused ulcerate skin, loss of hair, nausea and anemia. The death toll was expected to be more than The explosion in the atomic reactor and the subsequent fire was caused by failure of emergency cooling system in the light water graphite reactor, due to human error. The explosion and hot fire (about 2500 degree C) below large amount of redionuclides high into the atmosphere. It is expected that heavy fall out from the mishap could damage Soviet agricultural output for years to come. 25

26 The intense radiation has already killed several fields, trees, shrubs. Plants etc. The immediate damage was put at 10% of the crop. The chronic health defects noted include blood abnormalities, hemorrhagic disease, thyroid change, mutagenic and somatic alterations, bone narosis, skin cancer and lung changes. 26