Radioactive Kerala: Element Causing Pollution Revealed

Kerala, India, has the world's highest level of natural radioactivity in a densely populated area. The coastal belt of Karunagappally, in particular, is known for its high radiation from black sand containing radioactive elements. These elements include thorium, monazite, radium, and uranium. While the background radiation levels in Kerala are high, studies have shown that they do not pose a significant health risk to the local population.

Radioactive elements in black sand

Kerala, India, is known for having the world's highest level of natural radioactivity in a densely populated area. The coastal belt of Karunagappally, in particular, is known for its high radiation from black sand containing radioactive elements. These radioactive elements include thorium, monazite, and radium.

Thorium is a naturally occurring radioactive element that is silvery in colour and can turn black when exposed to air, forming thorium oxide. It is hard, malleable, and has a high melting point. It is also reactive and can ignite in the air when finely divided. Thorium is one of only three radioactive elements that still occur naturally in large amounts, the other two being bismuth and uranium.

Monazite is a radioactive mineral that is often found in heavy mineral sands, such as those in Kerala. It is indicative of its formation within metamorphic rock, and the degree of metamorphism dictates the quantity of thorium present. In addition to monazite, beach placer deposits may also contain zircon, ilmenite, rutile, and garnet.

Radium is another radioactive element present in the black sand in Kerala. It is a highly radioactive metal that was discovered by Marie and Pierre Curie in 1898. Radium is formed from the decay of uranium and can be further decayed into stable lead.

The presence of these radioactive elements in the black sand of Kerala has led to increased levels of background radiation in the region. This has raised concerns about the potential health risks for the local inhabitants, as long-term exposure to radiation can lead to diseases such as cancer. Studies have been conducted to assess the impact of elevated radiation levels on the residents of Kerala, and protective measures have been suggested to mitigate the risks associated with exposure to radioactive black sand.

High background radiation areas

Kerala, India, is known for having the world's highest level of natural radioactivity in a densely populated area. The coastal belt of Karunagappally, in particular, is known for its high radiation from black sand containing radioactive elements. These include thorium, monazite, and uranium. The Chavara-Neendakara region in Kerala ranks second in the world's High Background Radiation Areas (HBRAs) due to the presence of heavy minerals like monazite in the local black sand.

The high background radiation in Kerala is caused by the presence of radioactive minerals in the soil and sand. Monazite is a prominent example, which is indicative of its formation within metamorphic rock. The degree of metamorphism dictates the quantity of thorium present in such rock. India's extensive coastline has been reported to contain placer deposits of monazite sand. In addition, beach placer deposits may also contain zircon, ilmenite, rutile, and garnet. The Chavara region in the Kollam district of Kerala was found to have the highest radiation exposure in a 1986 study, at 3,002 nGy/year. A more recent study found that the levels in the Kollam district were 9,562 nGy/hr, or about three times more.

The background radiation levels in Kerala are high, but studies have shown that they do not pose a significant health risk. The gamma radiation in the researched region does not present significant carcinogenic risks or likelihoods of cancer development for local residents. However, long-term exposure to high levels of radiation may lead to diseases like cancer. It is important to continue monitoring radiation levels in areas with higher levels of natural background radiation and to update estimates periodically.

There are several factors that influence the variation in the external dose of terrestrial radiation received. These include the geomagnetic field, altitude, and solar cycle. Locations situated in high-altitude regions have 10–12% more background radiation than lowlands. Additional sources, such as urbanisation, industrial waste, weapon testing, and radioactive waste, also contribute to the background radiation level. The design of buildings, such as the lack of proper ventilation, can also impact the indoor radiation dose.

Radioactive minerals in soil and sand

Kerala has the world's highest level of natural radioactivity in a densely populated area. The coastal belt of Karunagappally, Kerala, is known for its high radiation from black sand, which contains radioactive elements. These include thorium, monazite, apatite, and radium. The Chavara-Neendakara region in Kerala ranks second in the world for High Background Radiation Areas (HBRAs) due to the presence of heavy minerals like monazite in the local black sand. The degree of metamorphism dictates the quantity of thorium present in such rock.

The radioactivity of uranium minerals is usually more than that of pure uranium due to the presence of radium. Radioactive equilibrium is established in a uranium mineral between radium and uranium atoms in a 1:28 ratio. Uranium is one of only three radioactive elements that still occur naturally in large amounts, along with thorium and bismuth.

The coastal landscape of Kerala primarily consists of paddy fields interlinked by rivers and canals. Coastal areas are vulnerable to natural hazards such as landslides. Sand samples collected from the Kavvayi coastal region showed activity concentrations of 226Ra, 232Th, and 40K. These radiological elements were found to be moderately above the average values proposed by the UNSCEAR 2000 report for India and the world. However, the gamma radiation in the researched region does not present significant carcinogenic risks or likelihoods of cancer development for local residents.

While Kerala's background radiation levels are high, studies have found no elevated health risk. The body is believed to be accustomed to higher doses of radiation. However, it is important to continue monitoring radiation levels in areas with higher levels of natural background radiation and to update estimates periodically.

Radioactive decay of natural uranium

Kerala has the highest level of natural radioactivity in a densely populated area in the world. The radioactive elements in the black sand of its coastal belt, mainly thorium and monazite, are responsible for this.

Radioactive decay is the emission of energy in the form of ionizing radiation. It occurs in unbalanced atoms called radionuclides, which are elements with unstable forms that emit ionizing radiation. Uranium is a naturally occurring radioactive element and Uranium-238 is the most common isotope of uranium found in nature, with a relative abundance of 99%. Uranium-238 is minimally radioactive, but its decay products, such as thorium-230, radium-226, and radon-222, are highly radioactive and can cause severe health effects, including cancer of the bone or liver, if there is significant exposure. The decay chain that begins with Uranium-238 eventually leads to Lead-206, passing through several intermediates, including Uranium-234, Thorium-230, Radium-226, and Radon-222. Each decay product is radioactive until the final, stable atom in the chain, which is Lead-206.

Uranium-238 is also used as a radiation shield, as its alpha radiation can be easily stopped by a non-radioactive casing, and its high atomic weight and number of electrons make it highly effective in absorbing gamma rays and X-rays. It is about five times better as a gamma-ray shield than lead.

Radioactive decay occurs until the atom reaches a stable state and is no longer radioactive. The majority of radionuclides only decay once before becoming stable, but some decay in multiple steps, and these are called series radionuclides. Each radionuclide has a specific decay rate, or half-life, which is the time required for half of the radioactive atoms present to decay or transform. Uranium-238 has a half-life of 4.468 billion years, while the most stable isotope of thorium, Thorium-232, has a half-life of 14.05 billion years.

Radioactivity in coastal landscape

Kerala, India, is known for having the world's highest level of natural radioactivity in a densely populated area. The state's flat coastal landscape consists of paddy fields interlinked by rivers and canals. The coastal belt of Karunagappally, in particular, is known for its high radiation levels due to the presence of black sand containing radioactive elements. These radioactive elements are mainly thorium, monazite, and uranium. The Chavara-Neendakara region in Kerala ranks second in the world's High Background Radiation Areas (HBRAs) due to the presence of heavy minerals like monazite in the local black sand.

Radioactivity in the coastal landscape of Kerala is a cause for concern, especially considering the potential health risks associated with long-term exposure to radiation. The radiation in the region is primarily due to the presence of radioactive minerals in the soil and sand. Monazite, a radioactive mineral, is found in significant quantities in the beach sands of Kerala. The degree of metamorphism dictates the quantity of thorium present in such rock. The thorium concentration in monazite from placer deposits also varies across different sites. India's extensive coastline has been reported to harbour these placer deposits containing monazite sand. In addition to monazite, beach placer deposits may also contain zircon, ilmenite, rutile, and garnet.

The high levels of radioactivity in Kerala's coastal areas have been a subject of study for several years. A recent pan-India study by scientists at the Bhabha Atomic Research Centre (BARC) found that background radiation levels in parts of Kerala are nearly three times more than previously assumed. However, it is important to note that these elevated radiation levels do not translate to an elevated health risk. The study found no major birth defects or increased rates of cancer or mortality in areas with high natural radiation. The body of individuals living in these areas seems to have adapted to higher doses of radiation.

Despite the apparent lack of direct health risks, the long-term effects of radiation exposure remain a concern. The gamma radiation in the researched region may not present significant carcinogenic risks for local residents, but other potential health risks, such as genetic mutations, cannot be ruled out. Additionally, the impact of radiation on the local environment, including flora and fauna, needs to be studied further. Adequate measures, such as efficient ventilation in homes, are necessary to reduce indoor radiation exposure and potential ill effects.

The government of India has taken steps to address the issue of radioactivity in Kerala's coastal areas. The country heavily relies on nuclear energy for power generation, and thorium is a fertile material that can be converted into nuclear fuel. Southern India's higher levels of radiation from uranium deposits are due to the presence of granite and basaltic volcanic rock. India is constructing several new nuclear power plants to utilise this energy source sustainably.

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