Radioactivity:
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Radioactivity is the phenomenon of spontaneous emission of particles or waves from the unstable nuclei of some elements.
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There are three types of radioactive emissions: Alpha, Beta and Gamma.
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Alpha particles are positively charged He (Helium) atoms, beta particles are negatively charged electrons and gamma rays are neutral electromagnetic radiations.
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Radioactive elements are naturally found in the earth’s crust.
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Uranium, thorium and actinium are three NORM (Naturally Occurring Radioactive Materials) series that contaminate water resources.
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A small amount of radiation is found in nature but the extended amount of radiation is harmful to human health.
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Radioactivity is measured in Becquerel (SI unit) or in Curie.
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The unit Sievert measures the quantity of radiation absorbed by human tissues.
Sources of Radioactivity:
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Natural Sources:
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Radiotoxic Elements in Aquatic System: Radium, a descendant of the NORM series, is one of the radiotoxic elements found in aquatic systems and can be penetrated into groundwater via:
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aquifer rock dissolution
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decaying of 238U and 232Th,
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desorption processes.
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Radium is a radionuclide formed by the decay of uranium (U) and thorium (Th) in the environment.
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Magma: Sometimes, magma also releases radioactive gases into the environment.
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Soil Sediments: Percolation of NORM from the soil sediments to the aquifer causes groundwater contamination.
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Atmospheric Deposition of Cosmogenic Radionuclides:
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Atmospheric deposition (both dry and wet) of cosmogenic radionuclides add radioactive nuclei in the surface water.
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Cosmogenic radionuclides are radioactive isotopes which are produced by natural processes and distributed within the Earth system.
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Anthropogenic:
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Nuclear Reactors and Warheads:
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Nuclear reactors and nuclear warhead experiments are the key sources of human-induced radionuclides discharge.
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Nuclear reactors produce radioisotopes (Cobalt-60, Iridium-192, etc) that hand out as sources of gamma radiation in radiotherapy and numerous industrial appliances.
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Nuclear power plants placed at the coastal regions add to the radiological contaminants in the marine water by releasing atomic wastes.
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Water is also used as coolants in these powerhouses, which also get contaminated.
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Dumping of Radioactive Waste:
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The application of radioactive elements in nuclear weapons, X-rays, MRI and other medical equipment causes their exposure to human beings. Dumping of these radioactive wastes in surface water bodies causes water pollution.
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Mining:
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Mining activities of radioactive elements like uranium and thorium also pollute surface and groundwater.
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Nuclear Accidents:
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Radioactive pollution due to nuclear submarine accidents and sinking have been reported.
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The Rocky Flats plant in Colorado, Fukushima and the Chernobyl nuclear disaster are some examples of such nuclear accidents.
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Effects of radioactive pollution on health:
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Radiation Syndrome:
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Human tissues absorb radiation through polluted water and foodstuff, which can cause serious health risks.
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High doses of radiation can cause acute radiation syndrome or dermal radiation injury.
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Disorders in Human Physiology:
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Exposure to radiation causes various disorders in human physiology, including cancer, leukaemia, genetic mutations, cataracts, etc.
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Mutation and Structural Alteration:
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Genetic effects ionizing radiation induces mutations in germ cells (male sperm cells and female egg cells), resulting in structural alteration in germ cell DNA that is passed onto offspring.
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Hereditary disorders can lead to premature death and severe mental illness.