From UPSC perspective, the following things are important :
Prelims level : Raidioactivity
Mains level : Water Pollution
Radioactive pollution of water is newly emerging but is of grave concern for water pollution and human health.
Quick recap: Radioactivity
- Radioactivity is the phenomenon of spontaneous emission of particles or waves from the unstable nuclei of some elements.
- There are three types of radioactive emissions: Alpha, Beta and Gamma.
- Alpha particles are positively charged He atoms, beta particles are negatively charged electrons and gamma rays are neutral electromagnetic radiations.
- Radioactive elements are naturally found in the earth’s crust.
Radioactive contamination of Water
- Natural: Percolation of naturally occurring radioactive materials (NORM) from the soil sediments to the aquifer causes groundwater contamination.
- Man-made: Anthropogenic sources of such pollution include- nuclear weapon investigation, nuclear calamities, nuclear powerhouses and dumping of radioactive waste.
Various contaminant elements
- Uranium, thorium and actinium are three NORM series that contaminate water resources.
- A number of radionuclides are found in surface and subsurface waters, among which 3H, 14C, 40K, 210Pb, 210Po, 222Rn, 226Ra, 228Ra, 232Th and 234,235,238U are common.
- Strontium-90, Caesium-137, etc are also formed by nuclear reactors, along with numerous unnecessary radioisotopes wastes.
- 40K and 7Be are the most commonly found radioactive elements in the sludge generated in sewage treatment plants.
- Nuclear reactors produce radioisotopes (Cobalt-60, Iridium-192, etc) that hand out as sources of gamma radiation in radiotherapy and numerous industrial appliances.
- Oceans and seas are the natural repositories of naturally occurring uranium. It is found in the form of uranyl carbonate ion.
- A significant concentration of uranium is supposed to be found in the greater salinity of the marine water.
- 40K (Radioactive Potassium) is also found in considerable concentration in the marine environment.
Measuring radioactive pollution
- Radioactivity is measured in Becquerel (SI unit) or in Curie.
- Energy absorbed per unit mass is measured by Gray, while the unit Sievert measures the quantity of radiation absorbed by human tissues.
- A small amount of radiation is found in all types of water but the extended amount of radiation is harmful to human health.
- Radioactivity in drinking water can be determined by a gross alpha test.
Hazards of such pollution
- Radioactive elements have an effect on the environment and can cause a risk to human healthiness if inhaled, injected or exposed.
- Human tissues absorb radiation through polluted water and foodstuff, which can cause serious health risks.
- High doses of radiation can cause acute radiation syndrome or cutaneous radiation injury.
- Exposure to radiation causes various disorders in human physiology, including cancer, leukaemia, genetic mutations, osteonecrosis, cataracts and chromosomal disruption.