Role of geology in interpreting Paleoclimate of the earth.

 Rock types as indicators of ancient climate.

by

Dr. Nitish Priyadarshi

The Earth’s climate has changed dramatically over the eons, as the atmosphere continuously interacts with oceans, lithosphere, and biosphere over a wide range of timescales. Efforts to place recent climate observations into a longer-term context have been stimulated by concern over whether the twentieth century global warming trend is part of natural climate variability or linked to increasing anthropogenic inputs of greenhouse gases into the atmosphere. The ability to decipher past climates has expanded in recent years with an improved understanding of present climatic processes and the development of more sophisticated analytical tools. 

Scientists know the Earth's average temperature has increased approximately 1°F since 1860. Is this warming due to something people are releasing into the atmosphere or natural causes? Many people today are quick to blame the greenhouse effect for global warming, but the temperature increases may have a natural cause, for example, from elevated volcanic activity. Gases in the earth’s atmosphere which trap heat, and cause an increase in temperature cause the greenhouse effect. Carbon dioxide (CO2), water vapour, and other gases in the atmosphere absorb the infrared rays forming a kind of blanket around the earth. Scientists fear that if humans continue to place too much carbon dioxide in the atmosphere, too much heat will be trapped, causing the global temperature to rise and resulting in devastating effects. Some scientists speculate that natural events like volcanic eruptions or an increase in the sun's output, may be influencing the climate. Perhaps the temperature rise is a natural trend that is part of a long-term cycle. Obviously, using only the weather data scientists have collected in the past 140 years will not be sufficient to answer these questions, so scientists use paleoclimactic studies to determine if today’s warming climate has occurred anytime in the past. Through past climate studies, scientists can predict what future climates and trends may occur.

Paleoclimate studies focus on both determining the climate states of the earth during the geological past and understanding how the climate system worked to produce those ancient environments. The careful observation, collection and interpretation of geological evidence from as many independent sources as possible is the most reliable way of determining details of ancient climate states. For many geological periods, paleoclimatic data are still new, and more rigorous methods for interpreting the data that we already have are needed ( Francis, 1998). The most exciting aspect of this geological research is that we can study unique environments that existed on earth in the past that are no longer present in our modern world, such as forests and dinosaurs living in warm climates in the polar regions and the extreme environments inn continental interiors on supercontinental landmasses such as Pangaea. 

Over Earth history, the climate has changed a lot. For example, during the Mesozoic Era, the Age of Dinosaurs, the climate was much warmer and carbon dioxide was abundant in the atmosphere. However, throughout the Cenozoic Era (65 Million years ago to today), the climate has been gradually cooling. How do we know about past climates? Geologists use proxy indicators to understand past climate. A proxy indicator is a biological, chemical, or physical signature preserved in the rock, sediment, or ice record that acts like a “fingerprint” of something in the past . Thus they are an indirect indicator of something like climate. 

The study of climates during the geological past, is one of the most topical areas of research in the geosciences at present. The threat of future climate change caused by higher levels of greenhouse gases, which would drastically alter many aspects of our environment, has prompted research to try to understand how our complex climate system works. Only by understanding how climate has evolved over millions of years can we identify important climate cycles with a frequency in excess of the short climate records we possess.  These climate cycles have the potential to have a profound effect on our environment. Earth's climate has shifted dramatically and frequently during the last few million years, alternating between ice ages, when vast glaciers covered northern Europe and much of North America, and interglacials — warm periods similar to the present. Geoscientists use "proxies", or indirect means to reconstruct climates that existed long before the invention of thermometers, barometers, or other meteorological instruments: tree rings, pollen grains, animal and plant fossil assemblages. Understanding our climate history in the geological past is also important for climatologists trying to construct accurate numerical computer models of our present climate system to use for predicting future climate change.

Minerals also furnish important clues about ancient climates. At Earth's surface, minerals interact closely with water and the atmosphere. Most useful are those deposited under relatively narrow climatic ranges or within specific environmental settings. These include evaporites, low temperature minerals such as ikaite and hydrohalite, minerals of residual soils (e.g., in bauxites or laterites), and some clay minerals like kaolinite.The formation of some rock types is directly influenced by aspects of climate. Some of the most useful are coals, evaporates, glacial deposits and carbonates.

Evaporites

Evaporite minerals form by evaporation of seawater or lakes in narrow basins, rift valleys (like the East African Rift Valley), and coastal lagoons under extremely hot and dry climates. Their distribution closely matches that of deserts. As water evaporates from the basin, salts precipitate in a sequence usually starting with carbonates, sulfates, and ending with the more soluble chloride salts. Typical evaporite minerals include gypsum, anhydrite, halite (rock salt), borax, and nitrates, such as saltpeter or niter (potassium nitrate). Major deposits of rock salt occur in the Gulf Coast, the Austrian Alps, the Dead Sea, upstate New York, Michigan, and elsewhere.

Climate Clues from Soils and Sediments

Clay minerals form by the chemical break-down of rocks near Earth's surface. The detritus is removed by water erosion and accumulates in lakes, estuaries, and the sea. Clays also occur in terrestrial soils and airborne dust. The types of clay minerals and their relative abundances are closely related to climate, although the composition of the source rocks can also influence their development. Kaolinite, for example, is created by intense chemical weathering in warm, humid climates where silica is leached out, leaving soils enriched in alumina. Chlorite and illite, on the other hand, tend to form in soils dominated by mechanical weathering, both in colder, often formerly glaciated regions, but also in hot, dry climates.

Bauxite.

 

Bauxite is a residual soil that forms by intense chemical weathering of rocks in wet, tropical climates where the average rainfall is 60 inches/year. The extreme leaching destroys most silicates and even resistant minerals such as quartz, leaving insoluble aluminum minerals, such as gibbsite, and boehmite, with lesser quantities of diaspore, kaolinite, and iron oxides. Laterite and bauxite peaks were coeval with times of global high warmth and precipitation, elevated atmospheric carbon dioxide, oceanic anoxia, exceptional fossil preservation, and mass extinction.

Coal.

Just as evaporates indicate hot and dry climates, occurrences of coal in the geologic record suggest hot and wet climates. The presence of coal, initially formed from the accumulation of plant materials as peat, is generally taken to indicate warm and wet humid climates ideal for lush plant growth, and where the rainfall is higher than the rate of evaporation, such as in equatorial regions. However, rainfall is a more important factor than temperature, as are high water tables and waterlogged swamps which are required to preserve the peat.

In the past, the most abundant coal deposits were formed during the Carboniferous when large subsiding continental areas were situated in low latitudes and experienced hot and humid climate.

Carbonates.

Coral reefs provide paleoclimatologists with important proxy data. Coral reefs have been a part of the Earth's oceans for millions of years and are very sensitive to changes in climate. Scientists can use indicators from corals to study weather conditions from the past hundreds or even thousands of years to determine trends in climate. Corals form skeletons by extracting calcium carbonate from the ocean waters. When the water temperature changes, calcium carbonate densities in the skeletons also change. Coral formed in the summer has a different density than coral formed in the winter. This creates seasonal growth rings on the coral (like rings on a tree). Scientists can study these rings to determine the temperature of the water, and the season in which the coral grew. By using these growth bands, scientists can date the coral samples to an exact year and season.

Glacial deposits.

Varves 

Evidence for glaciation and the presence of thick ice sheets can be obtained from a variety of sources. The most convincing are striated pavements, that is surfaces of bedrock with the grooves scratched by debris frozen into the base of moving ice glaciers. The orientation of ice movement and therefore in some cases the position of glacial centres can also be determined. For example, studies of Carboniferous and Permian glacial deposits in the Southern Hemisphere enabled Crowell and Frakes ( 1975) to reconstruct the location of ice centres over Gondwana continents and to determine the direction of movement of ice lobes from these centres.

Glacial tillites can provide information about ice passage but, in the absence of other glacial features, tillites can sometimes be hard to distinguish from other diamictites, such as debris flow deposits, which may have formed under totally different conditions. Ice –rafted dropstones and varves indicate that ice formed, at least seasonally, and produced dumps of ice carried debris or seasonal lake sediments. In addition, glendonite nodules have also been used as evidence for cold climates, particularly for the Permian from which sequences they were originally described.

Reference:

Crowell, J.C. , Frakes, L.A. 1975. The Late Palaeozoic glaciation. In Campbell, K.S. (ed.) Gondwana Geology. Australian National University Press, Canberra, 313-331.

Francis, J.E. 1998. Interpreting Palaeoclimates. In Peter, D. and Matthew R.B. (ed.) Unlocking the Stratigraphical Record. Advances in Modern Stratigraphy. John Wiley & Sons, 471-490.

https://www.giss.nasa.gov/research/briefs/gornitz_08/

https://geo.libretexts.org/Bookshelves/Geology/Book%3A_An_Introduction_to_Geology_(Johnson_Affolter_Inkenbrandt_and_Mosher)/15%3A_Global_Climate_Change/15.04%3A_Prehistoric_Climate_Change

https://pubs.geoscienceworld.org/segweb/economicgeology/article-abstract/105/3/655/128205/Lateritization-and-Bauxitization-Events?redirectedFrom=fulltext

https://www.marine.usf.edu/pjocean/packets/sp00/sp00u1le4.pdf

Presence of Arsenic in different geological environment.

In modern parlance, arsenic is viewed as being synonymous with “toxic”.
by
Dr. Nitish Priyadarshi

As old as recorded history, arsenic has existed through the centuries as a curative, a pigment, a cosmetic, on mirrors, part of alchemical lore, and most notoriously, the deadliest of poisons. In its various forms- as tasteless and odorless arsenic trioxide, the gold-bearing yellow arsenic sulfide, the deadly gas arsine, the practical alloy copper-arsenic, common pesticide white arsenic, and the electronics staple gallium arsenide-arsenic has served with fascinating ease human impulses both noble and wicked.

The long history of arsenic in science, medicine and technology has been over shadowed by its notoriety as a preferred poison in homicides. In modern parlance, arsenic is often viewed as being synonymous with “toxic”.

Widespread arsenic contamination of groundwater has led to a massive epidemic of arsenic poisoning in India and Bangladesh and neighbouring countries. Presently 42 major incidents around the world have been reported on groundwater arsenic contamination. It is estimated that approximately 57 million people are drinking groundwater with arsenic concentrations elevated above the World Health Organization's standard of 10 parts per billion.

The notoriety and lingering concern about the potential effects of arsenic on various fauna and flora has inevitably engendered a lot of research on the many facets of this element in the environment. This paper represents an attempt to bring together the key research results from the different geological work.

Arsenic is considered to be a rare but ubiquitous element of the upper lithosphere. Arsenic is occasionally observed in the native state in nature. However it is more frequently found combined with sulfur, selenium, tellurium and also as sulfo salts and arsenides of various heavy metals such as copper, iron, nickel and cobalt. It also forms a number of pentavalent arsenate minerals that bear a close geochemical relationship with phosphates and vandates with which it can form some isomorphic compounds.

Arsenopyrite, which is the most abundant and widespread mineral of arsenic, is found in pegmatites but more frequently in high temperature gold-quartz veins, high temperature tin-veins, and in contact with metamorphic sulfide deposits.

The numerous oxidic minerals of arsenic observed in nature are a result of the oxidation of sulfide and arsenide deposits in contact with the free oxygen of the atmosphere. The arsenate mineral are the most preponderant of the oxide minerals. Some arsenate minerals have been observed in metamorphic rocks deep in the earth.

It is not surprising to find that there has been increased interest in coals, together with work on rocks, soils, plants and waste materials, probably because of possible adverse health effects of high concentrations. Arsenic with some other environmentally sensitive elements, coal tends to be seen as a major source of arsenic, whereas, where as it only contributes 1.8 % of the total emissions to the atmosphere, which is about the same as wood fuel. There is a wide range of values from less than 1 ppm to several hundred ppm, sometimes enrichment being related to nearly arsenic rich ores. Arsenic has similar chemical properties to phosphorus (P), the element immediately below arsenic on the periodic chart. During coal combustion, arsenic oxidizes and forms gaseous As2 O3 and enters the atmosphere. This volatilization causes concerns for governments of many countries because of environmental pollution due to extensive use of coal.

Although it has been stated categorically that arsenic is present in coal as arsenopyrite and that ‘little exists in any other form’, the only good evidence for the nature of the association of arsenic with pyrite has come from a detailed study of an eastern U.S. coal. It was found that the arsenic was most likely to be present in solid solution in the pyrite, and it was noted that the arsenic was predominantely in fractures in the coal and in microfractures in the pyrite. Arsenic was also detected at isolated points in some pyrite grains, perhaps because small arsenic and selenium bearing minerals inclusions formed and were incorporated into the pyrite at the time of crystallization. However, not all high pyrite coals contain high arsenic, an observations that has also been made in respect of many Australian bituminous coals. This probably means that some coals contain arsenic in other forms, for example organically associated, associated with clays, perhaps as arsenate ions or with phosphate minerals, where (As04)3- could replace some (PO4)3-. Studies need to be carried out on a variety of coals, in order to clarify the nature of the mineral association of arsenic in coals. The extent of organically associated of arsenic is not clear, although organic bonding has been suggested for many Bulgarian coals, for some low rank Canadian coals and for some low sulfur Siberian coals. For most coals, arsenic seems to be mainly associated with the mineral matter, with varying smaller amounts being associated with organic matter.

Many researchers recognize arsenic as a sulphophile element. The occurrence of arsenic in coal is chiefly associated with sulfide minerals, pyrite in particular , and subordinately with organic matter. Therefore, there is commonly a positive correlative relationship between arsenic and total sulfur content in coal.

The distribution of arsenic in a coal - bearing basin appears to have been profoundly modified by the combined effects of many factors , such as the diagenesis of arsenic matter derived from vegetal matter , or the surrounding rocks , the geochemistry of peat formation including pH and Eh conditions of the basin and many other variables. Syn- depositional tectonic activities also exert an impact on peat accumulation and on the quality of coal as well.

A high coal bearing index indicates a relative balance between the rate of basin subsidence and the compensative peat accumulation over a long period of deposition. The weaker the tectonic disturbance, the higher the coal – bearing index and the lower the arsenic concentration in the coal. High concentration of arsenic in coals reflects the relatively vigorous tectonic activities during deposition.

Under the geological and geochemical conditions described above, the secondary arsenic enrichment occurs in part of coal beds. Because the secondary arsenic enrichment results from deuterogenic tectonic (mainly faults ) and hydrothermal activities, the enrichment is local in extent. Thus within the same mining area, the arsenic distribution in coal can be divided into two major distribution types : synsedimentary and secondary.

Deuterogenic arsenic concentration in coal is controlled to some extent by the original sulfur content of the coal. This is manifested by the apparent strong positive correlation of arsenic and total sulfur in the coal.

According to different geo-scientists basalts and diabases contain an average of 2.0ppm arsenic and gabbros 1.4ppm. At present a value of 1.5ppm arsenic may be assigned to basaltic rocks. Fifty-six individual samples of granitic rocks analyzed by different workers gave an average of 1.6ppm arsenic. The average for granitic rocks may be taken as 1.5ppm. Thus the granitic average does not differ enough from the basaltic and gabbroic averages (1.5 and 1.4ppm, respectively). Rhyolitic rocks and silicic glasses are higher in arsenic than other common rock types. The average content of arsenic in igneous rocks may be taken as 1.5ppm arsenic based on the average for granitic rocks, basalts and gabbros.

In nonmarine carbonaceous shales and near shore marine shales and claystones , the arsenic content is not related to the organic carbon content of the samples. However, in offshore marine samples arsenic is concentrated in high carbon – samples. Arsenic occurs in some samples in syngenetic pyrite but also is present in relatively large amount in samples that contain little pyrite. In general, arsenic is present in iron sulfides, clay minerals ( possibly in adsorbed form), organic matter etc in shales. Because of the wide variation of arsenic among the shales, it is not easy to obtain a precise average. At present the average for shales may be taken as 13ppm arsenic. A tentative average for sandstones may be taken as 1ppm arsenic. Analysis of many sandstone samples from the various parts of the world are desirable. Cherts usually contain about 1ppm arsenic. An average of 1ppm arsenic may be given for limestones and dolomites.

Data on the arsenic content of metamorphic rocks are not abundant, and therefore, behavior of arsenic is metamorphic reactions is not well known. Arsenic is likely to be lost in the transformation of slates and graywackes into schists and gneiss in regional metamorphism. In metamorphosed sedimentary iron ores containing coarsely crystalline hematite the arsenic seemed to have been removed by some leaching process.

Many arsenic compounds are water soluble and hence arsenic contamination of water can occur readily. Water is the major means of transport of arsenic in the environmental compartments. Sedimentation of arsenic in association with iron and aluminium may sometimes be considerable. Rivers and lakes generally contain less than 0.01 mg/1.arsenic. The concentration in ground water depends on the arsenic content of the bedrock. Where ever arsenic is present in natural waters, it is most often found as the anion, either as arsenate or arsenite.

The solubility of arsenic oxide in water is 2.05 g. As2 O3 per 100 g. of water at 25 0 C. The solubility of arsenic sulfide As2 S3 in water in extremely low.

Arsenic as a tendency to become precipitated in the hydralyzates. It is more concentrated near the surface than deep in the sediments. It is enriched in oxidate sediments, chiefly by absorption on ferric hydroxide. The manganese – rich oxidates are lower in arsenic than the iron rich type.

Arsenic is present in air mainly in the particulate form as inorganic arsenic. Though both tri and pentavalent forms occurs in air, the pentavalent form is more predominant than the trivalent form. Methylarsenic is also present in small amounts in air of suburban , urban and industrial areas.

Data on the arsenic content of soils were summarized by different scientists. Their results showed that about 30% of the soils contained less than 5ppm arsenic, about 50% contained 5 to 10ppm and about 20% contain more than 10ppm (parts per million). Most of the recent data on arsenic in various soils give less than 10ppm arsenic. The average value of arsenic in soils probably lies in the range of 5 to 10ppm arsenic. Thus soils are enriched in arsenic compared to igneous rocks.

Arsenic, in small quantities, is a universal contaminant of plants and animals and may sometimes be notably concentrated in organisms, e.g. in land plants growing in soil rich in arsenic and in marine and fresh – water organisms , such as fishes , mollusks , crustaceans , plankton , and some brown algae.

Though organic arsenic compounds are beneficial as a growth stimulant for animals and arsenic compounds have been used as medicines , there is no firm evidence that arsenic in any form is essential to man. In fact arsenic compounds are proved to be toxic. The toxicity of arsenic compounds depends on the chemical and physical form of the compound, the route by which it enters the body and dose and duration of exposure. In man, subacute and chronic arsenic poising may be insidious and pernicious. The symptoms of mild chronic poisoning are fatigue and lot of energy. In more severe intoxication the following symptoms may be observed: kidney degeneration, tendency to edema , liver cirrhosis , bone marrow injury , gastrointestinal catarrh , polyneuritis , exfoliate dermatitis and altered skin pigmentation.

No true tolerance of arsenic has ever been demonstrated. During chronic exposure, trivalent arsenic accumulates mainly in bone , muscle , and skin and to a lesser degree in the liver and kidneys.

A W.H.O task group, applying the linear non-threshold model estimated that a life time exposure to arsenic in drinking water at a concentration of 0.2 mg/1 gave a 5% risk of getting cancer of the skin.

Distribution of Uranium in world coals.

Jharkhand coal contains trace amount of Uranium in North Karanpura coal field.

by

Dr. Nitish Priyadarshi

Coal is largely composed of organic matter, but it is the inorganic matter in coal—minerals and trace elements— that have been cited as possible causes of health, environmental, and technological problems associated with the use of coal. Some trace elements in coal are naturally radioactive. These radioactive elements include uranium (U), thorium (Th), and their numerous decay products, including radium (Ra) and radon (Rn). Although these elements are less chemically toxic than other coal constituents such as arsenic, selenium, or mercury, questions have been raised concerning possible risk from radiation.


Uranium association with coal has a long history. There is a continuing interest in uranium in coal, because it is a source of radioactivity and because it may be an economic source of uranium. It is just 200 years since the discovery of uranium by M.H. Klaproth. The first detection in coal was by Berthoud (1875) who found up to 2% uranium in coal from near Denver, USA. The samples were collected from a mineralized section of the coal-bed. This mine was soon abandoned.

Subsequent field studies have proven several areas with high uranium coals, especially in the United States, mainly in the Dakotas, Wyoming, Montana, Colorado and New Mexico (Vine,1956). It seems that uranium is carried into the coal swamp in solution as carbonate complexes (Breger, et. al. 1955), which then release uranyl ions to form uranyl-organic complexes. In many coals, especially low-U coals, Uranium is predominantly organically bound.

After World War II, a very intensive uranium search was initiated. The measurement of coal radioactivity were performed in many countries; however only a few are documented. For example, in year 1967 scientists have measured uranium concentration in lignites from Spain (Huesca, Lerida, Ternel, Galicia, Murcia) and reported concentration values 20 to 1200 parts per million (ppm).

Gott (1952) has determined uranium distribution in lignites, shales, and limestones from throughout the US, and a possible mechanism for uranium accumulation in lignites was suggested. Highest uranium concentrations were prevalent in lignites from the Dakotas, Wyoming, and Montana (0.01%), and from high ash Nevada lignite which contained up to 0.05 % uranium. It was postulated that uranium was possibly concentrated in lignite by the action of percolating surface waters after having been leached from volcanic ash.

Uranium bearing coal in the Red Desert area in Wyoming has been studied by Masursky; his findings are documented in several reports. In the first report in year 1952, core and channel samples taken from the Red Desert area in Wyoming were used to investigate the origin of uranium in the coal of the region. Specific uraniferous zones examined included the Sourdough, Monument, Battle, and Luman zones. Areas which were topographically higher and in which coal was overlain by conglomerate showed the highest uranium concentration. Studies of core samples revealed that uranium concentration in the coal beds correlates well with the degree of permeability of adjacent rocks. Where coal beds are overlain or underlain by sandstone, the greatest concentrations of uranium occur at the top and / or bottom of the bed.

J.R. Gill and others in the year 1959 have studied uranium bearing lignite in South Dakota and Montana. They have reported some lignite deposits containing as much as 0.1% uranium.

Coal samples were analyzed for uranium concentration in the coals from the Western United States and approximately 300 coals from the Illinois Basin. In the majority of samples, concentrations of uranium fall in the range from slightly below 1 to 4 parts per million (ppm). Coals with more than 20 ppm uranium are rare in the United States (http://energy.er.usgs.gov/products/databases/ CoalQual/intro.htm).



Results for the uranium in world coals are as follows (Swaine,1990):

Australia- 0.01-4.5 ppm
Brazil- 2.7-19 ppm
Canada- 0.2-7.2 ppm
China- 0.16-21 ppm
Germany West- less than 1 – 13 ppm
India- 1.1-3.6 ppm.
New Zealand- 0.015-0.46 ppm
South Africa- 1.2- 7.3 ppm
Turkey- 1.4-6.4 ppm
UK- 1.1- 3.0 ppm.

Traces of uranium have been also found in the Permian coals of Jharkhand State of India. Areas are KDH, Dakra, Rohini, and Rai Bachra in the North Karanpura coalfield. Channeled samples were analyzed with the help of XRF instrument.

Occurrence of uranium in coals:

Three hypotheses advanced to explain the occurrence of uranium in some coals were described by Denson (1959) as follows.

1. Syngenetic: Uranium was deposited from surface waters by living plants or in dead organic matter in swamps prior to coalification.
2. Diagenetic: Uranium was introduced into the coal during coalification by waters bringing the uranium from areas marginal to the coal deposits or from the consolidating enclosing sediments.
3. Epigenetic: Uranium was introduced in the coal after coalification and after consolidation of the enclosing sediments by groundwater deriving uranium from hydrothermal sources or from unconformably overlying volcanic rocks.

Uranium is associated with clays, zircon and phosphates and may also be organically bound in coal. The accumulation of uranium in coal may vary markedly from place to place, and the occurrence of uranium in each deposit should be interpreted in relation to the geologic history of the region. Field evidence favors the epigenetic hypothesis of the origin of uranium in U.S. western coals. Secondary concentration of uranium in coal may occur when solution of small quantities of uranium by groundwater from overlying volcanic rocks is followed by downward percolation of these waters through previous strata until the uranium is taken up and retained by the highest of the underlying lignite beds. Application of this theory led to the discovery of uranium-bearing coal in Wyoming, Montana, Idaho and New Mexico.

Most thorium in coal is contained in common phosphate minerals such as monazite or apatite. In contrast, uranium is found in both the mineral and organic fractions of coal. Some uranium may be added slowly over geologic time because organic matter can extract dissolved uranium from ground water. In fly ash, the uranium is more concentrated in the finer sized particles. If during coal combustion some uranium is concentrated on ash surfaces as a condensate, then this surface-bound uranium is potentially more susceptible to leaching. However, no obvious evidence of surface enrichment of uranium has been found in the hundreds of fly ash particles examined by USGS researchers.

Most coal also contains potassium-40, lead-210, and radium-226. The total levels are generally about the same as in other rocks of the Earth's crust. Most emerge from a power station in the light flyash, which is fused and chemically stable, or the bottom ash. Some 99% of flyash is typically retained in a modern power station (90% is some older ones), and this is buried in an ash dam.

The amounts of radionuclides involved are noteworthy. In Victoria, 65 million tonnes of brown coal is burned annually for electricity production. This contains about 1.6 ppm uranium and 3.0-3.5 ppm thorium, hence about 100 tonnes of uranium and 200 tonnes of thorium is buried in landfill each year in the Latrobe Valley. Australia exports 235 Mt/yr of coal with 1 to 2 ppm uranium and about 3.5 ppm thorium in it, hence up to 400 tonnes of uranium and about 800 tonnes of thorium could conceivably be added to published export figures (http://www.world-nuclear.org/info/inf30.html).

Other coals are quoted as ranging up to 25 ppm U and 80 ppm Th. In the USA, ash from coal-fired power plants contains on average 1.3 ppm of uranium and 3.2 ppm of thorium, giving rise to 1200 tonnes of uranium and 3000 tonnes of thorium in ash each year (for 955 million tonnes of coal used for power generation). Applying these concentration figures to world coal consumption for power generation (7800 Mt/yr) gives 10,000 tonnes of uranium and 25,000 tonnes of thorium per year(http://www.world-nuclear.org/info/inf30.html).

Reference:
Berthoud, E.L. 1875. on the occurrence of uranium, silver, iron etc., in the Tertiary Formation of Colorado Territory. Proc. Nat. Acad. Sci., Philadelphia, 27, 363-365.
Breger, I.A., Deul, M. and Meyrowitz, R. 1955. Geochemistry and mineralogy of a uraniferous subbituminous coal. Econ. Geol., 50, 610-624.
Bouska, V. 1981. Geochemistry of Coal. Elsevier Scientific Publishing Company, New York.
Denson, N.M., 1959. Uranium in coal in the Western United States, U.S. Geological Survey Bull. 1055.
Gill, J.R. 1959. Reconnaissance for uranium in the Ekalaka Lignite field, Carter County, Montana. US Geological Survey, Bull. 1055.
Gott, G.B. 1952. Uranium in black shales, lignites and limestones in the United States. Selected papers on uranium deposits in the United States. U.S. Geological Survey, Circ.220,Washington. 31-35.
Swaine, D.J. 1990. Trace elements in coal. Butterworths, London.
Valkovic, V. 1983. Trace elements in coal. CRC Press, Inc. Florida.
Vine, J.D. 1956. Uranium-bearing coal in the United States. US Geol. Surv. Prof. Pap., No 300, 405-41.

Fire erupted in National Highway in Jharkhand State of India.

Coal supply and environment are going to be badly affected.
Explosions are being heard.

By.

Dr. Nitish Priyadarshi

Ramgarh district administration of Jharkhand state of India on Friday (August 7,2009) suspended the movement of vehicles on the 35 Km stretch of National Highway (NH) 33 between Ranchi (capital of Jharkhand) and Patna (capital of Bihar). The underground fire erupted violently on 750 metre –stretch on highway on Friday. Explosions are also being heard.
Supplies of coal from this area to other parts of the country are going to be badly affected due to this fire and closure of the most important road. Other than environmental it is also going to affect the supply of the food grains to other parts of drought affected area of the Jharkhand state.
For detail story please scroll down this blog.