Radioactive gas Radon may affect the people of Ranchi city in India.

Radon problem cannot be ruled out in the houses of Ranchi city in India.

by

Dr. Nitish Priyadarshi

Fig. House build on the rocks in Ranchi city.

Earth has many ways to kill us. We keep on the lookout, and rightly so, for volcanic eruptions, earthquakes, landslides, flooding, cosmic impacts, climate change and falling rocks on the highway. Should we still worry about radon?
You remember radon—that radioactive gas that comes up from the soil and collects in basements and ground floors, sometimes in well water. Radon is a prominent villain in many countries. Blamed for tens of thousands of deaths from lung cancer. Like asbestos, radon was looked at more kindly when it was new, and today it too is more feared than it deserves.

Radon Geology:
To the geologist, radon is interesting, not worrisome. For one thing, radon starts with uranium, which is worth knowing about for its energy content and its important role in the Earth's heat budget.

Uranium turns to lead via a long, slow cascade of nuclear decay, and radon sits at an important point in that process.

Not only does the radon nuclide decay quickly, with a half-life less than four days, but the next four nuclides in the cascade decay with a combined half-life less than an hour. In other words, radon packs a powerful dose of radioactivity, and because it is a gaseous element, it can drift out of the minerals where it forms into the air. Thus it's a good signal of uranium, even for buried deposits.

Humans have always been exposed throughout their period of existence to naturally occurring ionising radiation. Specifically, naturally occurring radionuclides are present in variable amounts in our environment. To assess radiological health hazards, naturally occurring radionuclides are being measured in soil, sand, marble, bricks etc throughout the world.

Terrestrial radiation comes from radioactive elements that were present at the time the earth was formed. They continue to decay and form additional radioactive materials.
Unusual soil composition has increased background radiation twenty-five fold or more in a few areas in the world. Locations with high background radiation in the soil, mainly from uranium, include the Rocky Mountains, Kerala India, coastal regions of Brazil, granite rock areas of France, and the northern Nile Delta.

Seeing the rock types and its mineral composition Radon problem cannot be ruled out in the houses of Ranchi city of Jharkhand State in India. This fact was justified by a published report of Research Reactor Institute, Kyoto University, Japan. According to the report Air-gamma dose rate was 0.30 μSv/h on the surface in the densely populated area in the city. In Ranchi the concentration of K-40 (potassium-40) and thorium is high. Concentration of Radium-226 was 75 Bq/Kg in the soils.

Very interesting thing in the Ranchi city is that name of one of its major road is RADIUM ROAD. Till today no body knows from where did this name came from. Name of this road exists from the British rule in India i.e. before 1947.

Seeing the presence of apatite, sphene and zircon in the Ranchi rocks, presence of Uranium cannot be ruled out. According to the report Uranium concentration is also high in Ranchi. All these concentrations are of natural origin. Radioactivity in the bricks made by the local soil may pose threat to the people living in the houses made by these bricks.

When Uranium is there, presence of Radon cannot be ruled out. It is radioactive gas that comes up from the soil and collects in basements and ground floors, sometimes in well water. Radon is a prominent villain in the United States, blamed for tens of thousands of deaths from lung cancer.
Even the granites of the Daltonganj area of Jharkhand state contain anomalous uranium values. Uranium mineralization has also been observed in the granitic rocks comprising the southern periphery of the Hutar basin of Daltonganj area. The Proterozoic granitoids, forming the provenance for the Hutar and Auranga subbasin, have been analyzed which revealed uranium content up to 520 ppm. ( Virnave, 1999).
The radon in home indoor air can come from two sources, the soil or water supply. The radon in water supply poses an inhalation risk and an ingestion risk. Research has shown that risk of lung cancer from breathing radon in air is much larger than the risk of stomach cancer from swallowing water with radon in it. Most of the risk from radon in water comes from radon released into the air when water is used for showering and other household purposes.
Radon in home water in not usually a problem when its source is surface water. A radon in water problem is more likely when its source is ground water, e.g., a private well or a public water supply system that uses ground water.
From last several years people of Ranchi are becoming more dependent on ground water for their daily uses. Indiscriminate deep borings are rampant in the granite rocks of Ranchi city. People are going more and more deeper for search for water.
People of Jharkhand state are unaware of danger from Radon gas.
Radon loves fractures because they set it free. Solid mineral grains are a pretty good trap for gases, but break the grains and the gas escapes. So just having rocks rich in uranium is not enough—they must be fractured, too.
Ranchi rocks are filled with fractures and joints. Ground waters are mined through these fractures and joints. So threat of Radon Poisoning looms large in Ranchi city.

Even the houses build on the rocks filled with cracks and fractures are under threat of Radon poisoning inside the house. Most of the radon indoors is contributed by the ground underneath buildings.
The amount of radon entering buildings from the ground is influenced by the following four factors.

a) Radon concentrations in soil gas: This depends on the concentration of the immediate precursor of Rn-222, Ra-226, in rocks and soils. Elevated levels of radium are found in some granites, limestone's and sandstone's and other geologies.

b) Permeability of the ground: This depends on the nature of the rock and soil under the building Disturbed ground can have greatly increased permeability. Usually the radon comes from the ground within a few metres of the building, but if the ground is particularly permeable or fissured it may come from a greater distance.

c) Entry routes into homes: Concrete floors often have cracks around the edges and gaps around services entries such as mains water supply, electricity or sewage pipes. If homes have suspended timber floors the gaps between the floorboards are the major route of entry. Pathways for soil gas to enter houses are often concealed, and vary between apparently identical houses.

d) Under-pressure of homes: Atmospheric pressure is usually lower indoors than outdoors owning to the warm indoor air rising; this creates a gentle suction at ground level in the building through the so-called `stack effect'. Wind blowing across chimneys and windows can also create an under-pressure (the `Bernoulli effect'). The result is that the building draws in outside air, typically at the rate of one air change per hour. Most of this inflow comes through doors and windows, but perhaps 1% or so comes from the ground. In an average house, this amounts to a couple of cubic metres of soil gas entering the house each hour. The radon concentration in a building depends on the rate of entry of the radon and the rate at which it is removed by ventilation. Increasing the ventilation rate will not always decrease the radon concentrations, however, because ventilation rate and under-pressure are related, and some ways of increasing ventilation, such as the use of extract fans or opening upstairs windows, can also increase the under-pressure.

Recently high concentrations of radioactive gas radon have been detected in Bengalooru’s groundwater, which means a higher risk of stomach cancer for those who drink it.A team from the Bangalore University and the Baba Atomic Research Centre in Mumbai collected 78 samples of water from bore wells, shallow wells, surface water and the supplied drinking water in Bengalooru. More than half the samples contained radon in concentrations up to a thousand times the permissible limit of 11.1 Becquerel per litre.

In the case of Bengalooru (old name Bangalore) it is the large reserves of granite that is causing the problem. Being highly soluble, radon easily dissolves in groundwater. The rate at which radon is released from rocks depends on the porosity of the rocks and the intensity of water flow.
Radon is a cancer-causing natural radioactive gas that we can’t see, smell or taste. Its presence in the home can pose a danger to family's health. Radon is the leading cause of lung cancer among non-smokers. Radon is the second leading cause of lung cancer in America and claims about 20,000 lives annually.
Any home can have a radon problem. This means new and old homes, well-sealed and drafty homes, and homes with or without basements. In fact, people and their family are most likely to get greatest radiation exposure at home. That is where they spend most of their time. Jharkhand government should come forward to analyze the amount of Radon present in groundwater and in the air inside the house.
Sources:
Virnave, S.N. Nuclear Geology and Atomic Mineral Resources. Bharati Bhawan, Patna. 169.
http://www.epa.gov/iaq/radon/
http://www.epa.gov/radon/healthrisks.html
http://www.epa.gov/radon/pubs/hmbyguid.html#6.
http://www.radonguide.com/sources-of-radon-in-buildings.html
http://www.downtoearth.org.in/full6.asp?foldername=20090215&filename=news&sec_id=4&sid=21

Plant more trees to reduce carbon dioxide.

Carbon dioxide on the rise.

by

Dr. Nitish Priyadarshi
Carbon is found in all living things –plants, animals, and humans- and nearly everywhere on the Earth. It is found in the atmosphere in the gas carbon dioxide, and dissolved in water in oceans and lakes. It is also found in soil, fossil fuels stored deep in ground, certain types of rocks, and in the shells of animals.

The carbon cycle is a complex cycle that circulates carbon between plants, animals and soils. The exchange of carbon between living and non-living things is very closely balanced. About 100 gigatonnes of carbon is captured by plants and oceans each year and about the same amount is released back into the environment. But this natural balance is disturbed by human activities such as burning fossil fuels and deforestation. Burning fossil fuels releases more carbon dioxide into the air. Deforestation or thin forest cover on the other hand, results in less carbon being removed from the atmosphere. It is clear from the pictures below where more carbon concentration (in Red colour) is seen in the atmosphere on the areas (Northern Hemisphere) where the forest cover is thin as compared to southern hemisphere where forest covers are sufficient. Green plants are known as carbon sinks. This means that they remove carbon from the atmosphere and store it.

Fig. 1. [Picture showing the forest cover on our Earth in green colours]
source: NASA's Terra satellite.

Fig.2. [Red colour is the concentration of carbon dioxide. Concentration of CO2 is high where forest cover is thin.]

An international team of scientists, including researchers from CIFOR, have discovered that rainforest trees are getting bigger, storing more carbon from the atmosphere and slowing climate change.

According to the findings, tropical trees in undisturbed forests around the world are absorbing nearly a fifth of the carbon-dioxide (C02) released by burning fossil fuels. That is significantly more than the greenhouse gas emissions produced by the world’s transport sector.

The researchers estimate that remaining tropical forests remove a massive 4.8 billion tonnes of CO2 emissions from the atmosphere each year. This includes a previously unknown carbon sink in Africa, mopping up 1.2 billion tonnes of CO2 each year.

Published on February 19 in Nature, the 40-year study of African tropical forests, which account for one third of the world’s total tropical forest, shows that over decades each hectare of intact African forest has trapped an extra 0.6 tonnes of carbon per year.

Over the past 140 years, forest clearing and fossil-fuel burning have pushed up the atmosphere’s CO2 level by nearly 100 parts per million. The average surface temperature of the Northern Hemisphere has mirrored the rise in CO2. the 1990s was the warmest decade since the mid- 1800s, and 1998 the warmest year.

While all living plant matter absorbs CO2 as part of photosynthesis, trees process significantly more than smaller plants due to their large size and extensive root structures. In essence, trees, as kings of the plant world, have much more “woody biomass” to store CO2 than smaller plants, and as a result are considered nature’s most efficient “carbon sinks.”
According to the U.S. Department of Energy (DOE), tree species that grow quickly and live long are ideal carbon sinks.

Forests are carbon stores, and they are carbon dioxide sinks when they are increasing in density or area.

As the human population increases, forests are cleared for land and to provide firewood and timber to build houses. Today, almost all of the forests in Europe and North America have been cleared. The forests that remain are mostly in tropical areas like the Amazon region of Brazil and Southeast Asia.

The terrifying fact is that tropical forests are also being destroyed across the planet at accelerating rates. Current estimates indicate that as much as 17 million hectares of tropical forests are being destroyed each year, with up to six million hectares alone of that destruction taking place in the Brazilian Amazon. Saranda forest (one of the biggest forest area of Asia} of Jharkhand State of Eastern India is also being destroyed due illegal iron ore mining which is rampant in the area.

These forests are disappearing at an alarming rate. Data obtained from satellites show that the rate of destruction in these places has increased to between 64,000 square kilometres and 204,000 square kilometres. Scientists estimate that by 2030, 80 percent of the world’s forest will be lost forever. As wood decomposes or is burned for fuel, the carbon stored in trees goes back into the atmosphere as carbon dioxide. According to the scientists, deforestation accounts for about 20 per cent of the increase in the release of human related carbon dioxide since the beginning of the Industrial Revolution.

In the mid-1700s, people began to invent machines to help them do work. Like vehicles today, these machines burned fossil fuels for energy, which released green house gases into the atmosphere. More and more machines were built and used. In less than 200 years, the amount of carbon dioxide in the atmosphere increased from 280 parts per million to 360 parts per million. This means that if we divided a sample of air into a million parts, 360 of those parts would be carbon dioxide.

Forest scientists have come to a surprising conclusion regarding old growth forests and their majestic, mature trees: They’re not just relaxing in their arboreal old age, but are still actively taking in carbon dioxide from the atmosphere. The new study suggests that protecting old growth forests may be just as important as planting new trees in efforts to reduce carbon dioxide levels and fight global warming.

Previously, researchers believed that only young, fast-growing trees absorbed enough carbon dioxide to be considered significant “carbon sinks.” Old, crowded forests don’t allow for much new growth: The only new growth occurred in the small spaces that opened up when large old trees died and decomposed, releasing their accumulated carbon. The forests at large were therefore considered to be carbon neutral, and accounted as such in climate models [Nature News]. But the new study shows that the slow but continuous growth of old trees means that they continue to suck up more carbon than they release. These forests need to be protected not just because they help to absorb carbon dioxide, but also because destroying them could release huge stores of greenhouse gases.
Already we have pumped out enough greenhouse gases to warm the planet for many decades to come. We have created the environment in which our children and grandchildren are going to leave.

Sources:

Bunyard, P.,1999. Eradicating the Amazon rainforests will wreak havoc on climate. The Ecologist. Volume.29, no.2.

National Geographic Magazine, September,2004.

Our Warming Planet, 2004. Times Editions, Singapore.

http://blogs.discovermagazine.com/80beats/2008/09/11/want-to-capture-carbon-protect-old-trees/

Diamonds are also found as placers deposit.

Diamonds are also found as placers deposit.
by
Dr. Nitish Priyadarshi
Diamond, a gem amongst gems the crystallized carbon and the hardest mineral known is a rare gift from mother earth to humanity. With admantine luster and twinkling habit it fascinated men and women from time immemorial. To win diamonds temples have been profaned, palaces looted, thrones torn to fragments, princes tortured, women strangled, guests poisoned and slaves disemboweled. No strain of fancy in an Arabian Tale has outstripped the marvels of fact in the diamond’s history. So wrote Garner Williams, the General Manager of the renowned Diamond Company De Beers in 1890.

Pliny (A.D.100) described diamond as the king of the stones known only to the kings and to them superficially only as decorative objects. Now diamonds can be possessed by those who are not necessarily kings. It is estimated that about three hundred million women own at least a piece of diamond as jewellery today. Wannenburgh in the year 1990 in his book diamond people, mentioned that each year, men and women spend almost forty billion dollars on about sixty million pieces containing some fifteen million carats of diamonds.

Diamonds occurs in nature in (1) primary form in igneous rocks like kimberlite, lamproites (2) secondary in conglomerates, grits and similar sedimentary rocks, (3) in Quaternary to Recent placers and (4) extra-terrestrial, as in meteorites. Of these different sources most of the diamonds in the world are recovered from the first and the third type.
Minerals which are more abundant than diamond and act as pathfinders to locate diamondiferous source rocks are considered as indicator minerals in exploration for diamonds. These are formed along with diamond in the upper mantle and brought up to the surface as xenocrysts in the kimberlite and lamproite magma. Indicator minerals useful in diamond exploration are pyrope garnet, picro- ilmenite, chrome-diopside, chromite, spinel and micro diamond.
Diamonds as placers deposit:
In geology, a placer deposit or placer is an accumulation of valuable minerals formed by deposition of dense mineral phases in a trap site Placer mining. (pronounced "plass-er") refers to the mining of alluvial deposits for minerals. This may be done by open-pit (also called open-cast mining) or by various forms of tunneling into ancient riverbeds. Excavation may be accomplished using water pressure (hydraulic mining), surface excavating equipment or tunneling equipment.
The name derives from Spanish, placera, meaning "alluvial sand." It refers to mining the precious metal deposits (particularly diamonds, gold and gemstones) found in alluvial deposits—deposits of sand and gravel in modern or ancient stream beds.
The simplest technique to extract diamond or gold from placer ore is panning. In panning, some mined ore is placed in a large metal or plastic pan, combined with a generous amount of water, and agitated so that the gold particles, being of higher density than the other material, settle to the bottom of the pan. The lighter gangue material such as sand, mud and gravel are then washed over the side of the pan, leaving the precious stones behind.

Fig. Aeolian diamond placers of Namibian desert in Africa

The disintegration of primary rock due to weathering, transportation and deposition along with valuable minerals like diamond, gold, tin ore etc., give rise to placers. If the placers are very close to the source, they are known as “eluvial placers”. If shifted down the hill or slope they get grouped as “deluvial placers”. If the material gets accumulated at the foot of the hill due to gravity action it is called “colluvial placers”. The material transported by water, streams and rivers for longer distance deposited away from the source is called “alluvial placers”. Deposition along the shores of the sea results in “beach placers” and in deserts when deposition takes place by wind it is called “aeolian placers”.
The secondary deposits are formed by the weathering of the kimberlite and the lamproite. The diamonds are released from the rock and then, they are transported hundreds of kilometres away to be found in river beds, beach sands, old river beds (sometime found on top of hills deep jungle forest, deserts, etc... Diamonds may also have been transported by glaciers and if the journey has been hard, rough and long, they are not to be found as they have been broken and grinded into near dust.
There is no single, universally applicable method of target selection for alluvial diamond deposits. Climatic and geomorphic history, stratigraphy, structure and tectonic history are important factors that require study and need to be understood for each alluvial diamond province prior to target selection. What is appropriate in one part of the world may be entirely inappropriate in another, but there are some basic principles which must be followed in planning and executing any alluvial diamond exploration program.
Before starting field exploration, it is important to have a comprehensive knowledge of (i) the regional geology of the drainage basin under revue; (ii) the constituent lithologies of the gravel being prospected for; (iii) the geomorphic and climatic factors which have affected the exploration area; (iv) the type of deposit to be sought; and (v) any post-depositional processes which may have affected the alluvial deposits being considered for exploration.

World diamond occurrences were found in first in placer deposits which later led to the discovery of many primary kimberlite source rocks. Understanding the mechanism of formation of placers will help in locating areas of concentration of diamond in placers deposits.
Historically diamonds were known to be found only in alluvial deposits in southern India. India led the world in diamond production from the time of their discovery in approximately the 9th century BCE to the mid-18th century AD, but the commercial potential of these sources had been exhausted by the late 18th century and at that time India was eclipsed by Brazil where the first non-Indian diamonds were found in 1725.

Diamondiferous residual rubble and clay found on the mainland of Tanzania developed over weathered kimberlite pipe is a typical example of eluvial placer deposit. Diamondiferous placer of Namibian desert in Africa is a classic example of aeolian placer.
Precambrian diamond bearing conglomerate of Diamantina in Brazil, diamondiferous moraines of Michigan and Wisconsin in United States of America are example of glacial placers.
The diamantiferous gravels of the Belgian Congo, which yield about two-thirds of the world production, are former stream gravels, and the diamonds probably came originally from weathered kimberlite pipes, several of which are known within the Congo. Some diamonds also occur in the Lulua, Zambesi, and other basins.
The Orange River forms a geographic dividing-line between the nations of South Africa and Namibia. For the last hundred million years, the Orange has been carrying eroded diamondiferous kimberlite material from its source on the Kaapvaal Craton, in central South Africa and Botswana.
Diamond-bearing material was deposited in river bank gravels and alluvium as it traveled westward towards the Atlantic Ocean. Other diamondiferous material was re-distributed by wind action, settling to form eluvial deposits in the desert. Material that completed the journey was deposited in beach terrace sediments, or redistributed by northerly ocean currents, to off-shore marine deposits on the sea floor.
These secondary alluvial land and marine deposits are Namibia's only source for diamonds, but the Orange River has left an enormous amount of diamondiferous material in the vast drainage basin stretching 150 miles from Oranjemund to Elizabeth Bay. As the sea-level receded, diamond-bearing sediments were exposed, and eventually covered by blowing sand. Land-based secondary deposits must be excavated from this sedimentary layer that lies beneath a deep layer of surface sand.
In Jharkhand state of India diamonds were reported in Chotanagpur area (ancient name Kokrah) in the Brahmani, Sankh and Koel river basins as mentioned in old records. Records show that near Simah in Palamau district in the Sankh River, near Rajadera (Rajadera is a saucer shaped village, is situated 19 km from Chainpur and about 26 km south of Netarhat) and in Sadni falls originating point of Sankh River, active diamond mines existed. These mines are stated to have yielded in the sixteenth and the seventeenth centuries many large and fine stones especially from Sankh River. Diamonds were washed from the sands and gravels of river Gouel. The river is probably North koel, a tributary of Son. On the banks of this river an ancient township Semah/Semelpur existed. According to the old reports about 8000 people are stated to have worked in these mines.
Raigarh in the upper reaches of Mahanadi river, west of Hirakud, Orissa in India, is also known to have been active in diamond mining since ancient times. Local tribals carry out small scale panning and recover diamonds from alluvial and colluvial placers.
Mr. T.K. Rau of Geological survey of India recovered micro-and macro diamonds from the heavy mineral concentrates of beach samples from the southern tip of India. The diamonds exhibit varied tints of which white, pink and yellow are prominent.

Reference:
· Babu, T.M. Diamonds in India. 1998. Geological Society of India, Bangalore, India.
· Bateman, A.M. 1955. Economic Mineral Deposits, John Wiley and Sons, New York.
· Rau, T.K., 2006. Incidence of diamonds in the beach sands of the Kanyakumari Coast, Tamil Nadu, Journal of the Geological Society of India, vol.67, no1, pp.11-16.
· http://en.wikipedia.org/wiki/Diamonds#Mining.2C_sources_and_production
· http://en.wikipedia.org/wiki/Placer_deposit
· http://en.wikipedia.org/wiki/Placer_mining