Oklo in Gabon, Africa is the only known place in the world where what reaction occurs naturally?
"disposal technology. In nature, sixteen repositories were discovered at the Oklo mine in Gabon where natural nuclear fission reactions took place 1.7 billion years ago. The fission products in these natural formations were found to have moved less than 10 ft (3 m) over this period, though the lack of movement may be due more to retention in the uraninite structure than to insolubility and sorption from moving ground water; uraninite crystals are better preserved here than those in spent fuel rods because of a less complete nuclear reaction, so that reaction products would be less accessible to groundwater attack."
"U has a much shorter half-life (700 million years) than U (4.5 billion years), so in the distant past the percentage of U was much higher. About two billion years ago, a water-saturated uranium deposit (in what is now the Oklo mine in Gabon, West Africa) underwent a naturally occurring chain reaction that was moderated by groundwater and, presumably, controlled by the negative void coefficient as the water boiled from the heat of the reaction. Uranium from the Oklo mine is about 50% depleted compared to other locations: it is only about 0.3% to 0.7% U; and the ore contains"
"of radiation in a decay chain that has a half-life of about 4.5 billion years, the storage of this unused uranium and the accompanying fission reaction products have raised public concerns about risks of leaks and containment, however the knowledge gained from studying the Natural nuclear fission reactor in Oklo Gabon, has informed geologists on the proven processes that kept the waste from this 2 billion year old natural nuclear reactor that operated for hundreds of thousands of years, from negatively impacting the surrounding plant and animal life. Natural resources, known as renewable resources, are replaced by natural processes and"
"containers enclosing the waste, other engineered barriers or seals around the containers, the tunnels housing the containers, and the geologic makeup of the surrounding area. The ability of natural geologic barriers to isolate radioactive waste is demonstrated by the natural nuclear fission reactors at Oklo, Gabon. During their long reaction period about 5.4 tonnes of fission products as well as 1.5 tonnes of plutonium together with other transuranic elements were generated in the uranium ore body. This plutonium and the other transuranics remained immobile until the present day, a span of almost 2 billion years. This is quite remarkable in"
"years ago. Although the original Oklo Mine's resources are now depleted, 17 other sites have been found in the same region that once sustained nuclear fission. Half of the reactor zones lack carbonaceous material and in these locations, cesium, rubidium, strontium and boron escaped and were lost. However, in others uraninite is encased in solidified two billion year old bitumen. Some geologists have suggested that this natural bitumen encasement could be a way of storing human produced nuclear waste in permanent geologic disposal sites. The petroleum sector is integral to the Gabonese economy. Oil and gas are produced from the"
"natural geologic barriers to isolate radioactive waste is demonstrated by the natural nuclear fission reactors at Oklo, Africa. During their long reaction period about 5.4 tonnes of fission products as well as 1.5 tonnes of plutonium together with other transuranic elements were generated in the uranium ore body. This plutonium and the other transuranics remained immobile until the present day, a span of almost 2 billion years. This is quite remarkable in view of the fact that ground water had ready access to the deposits and they were not in a chemically inert form, such as glass. Despite a long-standing"
"had operated as a natural fission reactor. Other observations led to the same conclusion, and on September 25, 1972, the CEA announced their finding that self-sustaining nuclear chain reactions had occurred on Earth about 2 billion years ago. Later, other natural nuclear fission reactors were discovered in the region. Neodymium and other elements were found with isotopic compositions different from what is usually found on Earth. For example, Oklo contained less than 6% of the isotope while natural neodymium contains 27%; however Oklo contained more of the isotope. Subtracting the natural isotopic Nd abundance from the Oklo-Nd, the isotopic composition"
"in times past, for example a natural nuclear fission reactor which ran for thousands of years in present-day Oklo Gabon was discovered in the 1970s. It ran for a few hundred thousand years, averaging 100 kW of thermal power during that time. Conventional, human manufactured, nuclear fission power stations largely use uranium, a common metal found in seawater, and in rocks all over the world, as its primary source of fuel. Uranium-235 ""burnt"" in conventional reactors, without fuel recycling, is a non-renewable resource, and if used at present rates would eventually be exhausted. This is also somewhat similar to the"
"must be a critical mass of the relevant isotope present in a certain space under certain conditions. The conditions for the smallest critical mass require the conservation of the emitted neutrons and also their slowing or moderation so that there is a greater cross-section or probability of them initiating another fission. In two regions of Oklo, Gabon, Africa, natural nuclear fission reactors were active over 1.5 billion years ago. Measurements of natural neutrino emission have demonstrated that around half of the heat emanating from the Earth's core results from radioactive decay. However, it is not known if any of this"
"Organic reaction Organic reactions are chemical reactions involving organic compounds. The basic organic chemistry reaction types are addition reactions, elimination reactions, substitution reactions, pericyclic reactions, rearrangement reactions, photochemical reactions and redox reactions. In organic synthesis, organic reactions are used in the construction of new organic molecules. The production of many man-made chemicals such as drugs, plastics, food additives, fabrics depend on organic reactions. The oldest organic reactions are combustion of organic fuels and saponification of fats to make soap. Modern organic chemistry starts with the Wöhler synthesis in 1828. In the history of the Nobel Prize in Chemistry awards have"
"between the Moon and the Earth, the giant impact hypothesis remains more commonly accepted, as it may arguably explain both the similarities and certain differences in the composition of the Moon. Natural nuclear fission reactor A natural nuclear fission reactor is a uranium deposit where self-sustaining nuclear chain reactions have occurred. This can be examined by analysis of isotope ratios. The existence of this phenomenon was discovered in 1972 at Oklo in Gabon by French physicist Francis Perrin. The conditions under which a natural nuclear reactor could exist had been predicted in 1956 by Paul Kazuo Kuroda. The conditions found"
"have had sufficient uranium to support nuclear reactions at that time, but the combination of uranium, water and physical conditions needed to support the chain reaction was unique, as far as is currently known, to the Oklo ore bodies. Another factor which probably contributed to the start of the Oklo natural nuclear reactor at 2 billion years, rather than earlier, was the increasing oxygen content in the Earth's atmosphere. Uranium is naturally present in the rocks of the earth, and the abundance of fissile was at least 3% or higher at all times prior to reactor startup. Uranium is soluble"
"have only moved centimeters in the veins during the last 2 billion years. Studies have suggested this as a useful natural analogue for nuclear waste disposal. The natural reactor of Oklo has been used to check if the atomic fine-structure constant α might have changed over the past 2 billion years. That is because α influences the rate of various nuclear reactions. For example, captures a neutron to become , and since the rate of neutron capture depends on the value of α, the ratio of the two samarium isotopes in samples from Oklo can be used to calculate the"
"the Oklo Fossil Reactors, it was realized that nature had beaten humans to the punch. Large-scale natural uranium fission chain reactions, moderated by normal water, had occurred far in the past and would not be possible now. This ancient process was able to use normal water as a moderator only because 2 billion years before the present, natural uranium was richer in the shorter-lived fissile isotope U (about 3%), than natural uranium available today (which is only 0.7%, and must be enriched to 3% to be usable in light-water reactors). Nuclear fission In nuclear physics and nuclear chemistry, nuclear fission"
"Kasompi, Samboa and the Emmanuel Depot in Kolwezi. Major player is Gécamines, the state mining company. The French conglomerate Areva has an undisclosed contract with Gecamines which is reportedly allows the company to mine unlimited amounts of uranium in the region In Gabon, mining used to occur in Oklo, but the deposits are reported to be exhausted. In 1972, remains of a natural nuclear fission reactor were found at the Oklo deposits. Uranium is produced at Kayelekera mine near Karonga. The mine owned and operated by Australian company, Paladin Energy. As of 2014, the mine is under 'care and maintenance'"
"Lopé National Park Lopé National Park is a national park in central Gabon. Although the terrain is mostly rain forest, in the north the park contains the last remnants of grass savannas created in Central Africa during the last Ice Age, 15,000 years ago. It was the first protected area in Gabon when the Lopé-Okanda Wildlife Reserve was created in 1946. In 2007, the Lopé-Okanda landscape was added to the World Heritage List by UNESCO. The park contains a small research station, named as Mikongo and run by the Zoological Society London, based in the village known as Mikongo, from"
"Goma in Congo, and Gisenyi, Kibuye, and Cyangugu in Rwanda. Lake Kivu is a fresh water lake and, along with Cameroonian Lake Nyos and Lake Monoun, is one of three that are known to undergo limnic eruptions. Around the lake, geologists found evidence of massive local extinctions about every thousand years, presumably caused by outgassing events. The trigger for lake overturns is unknown in Lake Kivu's case, but volcanic activity is suspected. The gaseous chemical composition of exploding lakes is unique to each lake. In Lake Kivu's case, it includes methane and carbon dioxide, as a result of lake water"
"the site remains comparatively underused Ipassa Makokou Biosphere Reserve The Ipassa Makokou Biosphere reserve is situated in Gabon and covers 150.00 km². Situated along the banks of the Ivindo River, Ipassa-Makokou Biosphere Reserve represents an example of the dense tropical rainforest of the Congo-Guinean phytogeographic region. The biosphere reserve is Gabon’s only area where no forest exploitation takes place thus the core area is in a relatively pristine state. Within the 15,000 hectares of the biosphere reserve, more than 2,000 plant species and 600 species of mammals, reptiles, fish, amphibians and birds have been recorded. Among the most threatened plant"
"value of α from 2 billion years ago. Several studies have analysed the relative concentrations of radioactive isotopes left behind at Oklo, and most have concluded that nuclear reactions then were much the same as they are today, which implies α was the same too. Published in 2010, a controversial hypothesis about the origin of the Moon proposes that the Moon may have been formed from the explosion of a natural reactor located along the core-mantle boundary at the equatorial plane of the then-rapidly rotating Earth, 4.5 billion years ago. While this hypothesis would explain in part the compositional similarities"
"in Gabon, Africa about 1.7 billion years ago. At least sixty criticality accidents have been recorded since 1945. These have caused at least twenty-one deaths: seven in the United States, ten in the Soviet Union, two in Japan, one in Argentina, and one in Yugoslavia. Nine have been due to process accidents, and the others from research reactor accidents. Criticality accidents have occurred in the context of production and testing of fissile material for both nuclear weapons and nuclear reactors. There was speculation although not confirmed within criticality accident experts, that Fukushima 3 suffered a criticality accident. Based on incomplete"
"to have taken place approximately 1.7 billion years ago, and ran for a few hundred thousand years, averaging probably less than 100 kW of thermal power during that time. In May 1972 at the Pierrelatte uranium enrichment facility in France, routine mass spectrometry comparing UF samples from the Oklo Mine, located in Gabon, showed a discrepancy in the amount of the isotope. Normally the concentration is 0.72% while these samples had only 0.60%, a significant difference. This discrepancy required explanation, as all civilian uranium handling facilities must meticulously account for all fissionable isotopes to ensure that none are diverted for"
"the time the reactor went critical 1.7 billion years ago, the fissile isotope made up about 3.1% of the natural uranium, which is comparable to the amount used in some of today's reactors. (The remaining 96.9% was non-fissile .) Because has a shorter half-life than , and thus decays more rapidly, the current abundance of in natural uranium is about 0.70–0.72%. A natural nuclear reactor is therefore no longer possible on Earth without heavy water or graphite. The Oklo uranium ore deposits are the only known sites in which natural nuclear reactors existed. Other rich uranium ore bodies would also"
"of a new one in order to release more carbon dioxide. Lake Monoun Lake Monoun is a lake in West Province, Cameroon, that lies in the Oku Volcanic Field . On August 15, 1984, the lake exploded in a limnic eruption, which resulted in the release of a large amount of carbon dioxide that killed 37 people. At first, the cause of the deaths was a mystery, and causes such as terrorism were suspected. Further investigation and a similar event two years later at Lake Nyos led to the currently accepted explanation. Several people reported hearing a loud noise on"
"Loango National Park Loango National Park is a national park in western Gabon. It protects diverse coastal habitat, including part of the 220 km² Iguéla Lagoon, the only significant example of a typical western African lagoon system that is protected within a national park. Situated between the Nkomi and Ndogo Lagoons, Loango National Park is the true jewel of Africa's western coast. The naturalist Mike Fay called Loango 'Africa's Last Eden' and this is where Michael ""Nick"" Nichols from National Geographic took his well-known pictures of surfing hippos. Both men call Loango the 'Land of surfing hippos'. The park’s 1,550"
"an organic molecule. Alkyl groups that are found naturally occurring in the environment are organometallic compounds. Organometallic compounds generally contain a methyl, ethyl, or butyl derivative which is the alkyl group that replaces the hydrogen. Other organic compounds, such as methanol, can provide alkyl groups for alkylation. Methanol is found naturally in the environment in small concentrations, and has been linked to the release from biological decomposition of waste and even a byproduct of vegetation. The following reactions are alkylations of soluble compounds found in creosote preservatives with methanol. The diagram above depicts a reaction between m-cresol and methanol where"
"the Ngorongoro Conservation Area and the Ngorongoro Crater. Just to the south of Lake Natron is Ol Doinyo Lengai (), the world's only active volcano to produce natrocarbonatite lava. To the west of the Crater Highlands lies Serengeti National Park, which is famous for its lions, leopards, elephants, rhinoceroses, and buffalo plus the annual migration of millions of white bearded wildebeest. Just to the southeast of the park is Olduvai Gorge, where many of the oldest hominid fossils and artifacts have been found. Further northwest is Lake Victoria on the Kenya–Uganda–Tanzania border. This is the largest lake in Africa by"
"reaction is catalyzed in nature by a tetramanganese cluster, the oxygen evolving complex. Some synthetic complexes effect the same reaction but usually slowly or with few turnovers. The theme is related to water splitting. Metal aquo complex Metal aquo complexes are coordination compounds containing metal ions with only water as a ligand. These complexes are the predominant species in aqueous solutions of many metal salts, such as metal nitrates, sulfates, and perchlorates. They have the general stoichiometry [M(HO)]. Their behavior underpins many aspects of environmental, biological, and industrial chemistry. This article focuses on complexes where water is the only ligand"
"the British biochemist Robin Hill. He demonstrated that isolated chloroplasts would make oxygen (O) but not fix carbon dioxide (CO). This is evidence that the light and dark reactions happen in different places within the cell. The Hill reaction of photosynthesis was discovered by Robin Hill (1937). He found that isolated chloroplasts from plants can release oxygen when they are illuminated by sunlight in the presence of a suitable electron acceptor such as ferricyanide. To demonstrate the Hill reaction in the laboratory dichlorophenolindophenol (DCPIP) was used as the terminal electron acceptor, replacing NADP which was not available due to the"
"into the oceans through hydrothermal vents. The ""Champagne"" hydrothermal vent, found at the Northwest Eifuku volcano in the Marianas Trench, produces almost pure liquid carbon dioxide, one of only two known sites in the world as of 2004, the other being in the Okinawa Trough. The finding of a submarine lake of liquid carbon dioxide in the Okinawa Trough was reported in 2006. Carbon dioxide is an end product of cellular respiration in organisms that obtain energy by breaking down sugars, fats and amino acids with oxygen as part of their metabolism. This includes all plants, algae and animals and"
"effect on the ozonosphere. It is the world's largest single natural generator of ozone, lending calls for it to be designated a UNESCO World Heritage Site. In the laboratory, ozone can be produced by electrolysis using a 9 volt battery, a pencil graphite rod cathode, a platinum wire anode and a 3 molar sulfuric acid electrolyte. The half cell reactions taking place are: In the net reaction, three equivalents of water are converted into one equivalent of ozone and three equivalents of hydrogen. Oxygen formation is a competing reaction. It can also be generated by a high voltage arc. In"
"rising over above sea level, above the inner part of the graben. The Tanzanian portion includes Mount Kilimanjaro, the highest mountain in Africa, and the huge caldera of Ngorongoro. This portion also contains Ol Doinyo Lengai, the world's only active carbonatite volcano. Lakes in the rift other than Lake Turkana are mostly small and shallow, some with fresh water but many being saline. The thickness of lake sediments is mostly unknown. In Lake Turkana they seem to be at most thick, in the Baringo - Bogoria half-graben from to thick and in the Afar depression up to thick. The first"
"nature reserve, set up by BirdLife International, and home to many rare species. Lake Oku Lake Oku is a crater lake on the Bamenda Plateau in the Northwest Region of Cameroon. It is located at on Mount Oku, and is completely surrounded by cloud forest. The lake lies in an explosion crater formed in the last phase of development of the Oku Massif, a large volcanic field with a diameter of about . Mount Oku is a stratovolcano that rises to . The lake is the subject of many myths among the local people. The lake is the only known"
"world where radioactive material continues to accumulate. Some experts suggest that centralized underground repositories which are well-managed, guarded, and monitored, would be a vast improvement. There is an ""international consensus on the advisability of storing nuclear waste in deep geological repositories"", with the lack of movement of nuclear waste in the 2 billion year old natural nuclear fission reactors in Oklo, Gabon being cited as ""a source of essential information today."" There are no commercial scale purpose built underground high-level waste repositories in operation. However, in Finland the Onkalo spent nuclear fuel repository is under construction as of 2015. The"