Geological Cycle Research Articles

Is late Quaternary climate change governed by self-sustained oscillations in atmospheric CO2?

A simple earth system model is developed to simulate global carbon and phosphorus cycling over the late Quaternary. It is focused on the geological cycling of C and P via continental weathering, volcanic and metamorphic degassing, hydrothermal processes and burial at the seabed. A simple ocean model is embedded in this geological model where the global ocean is represented by surface water, thermocline and deep water boxes. Concentrations of dissolved phosphorus, dissolved inorganic carbon, and total alkalinity are calculated for each box. The partial pressure of CO2 in the atmosphere (pCO2A) is determined by exchange processes with the surface ocean and the continents. It serves as key prognostic model variable and is assumed to govern surface temperatures and global sea-level. The model is formulated as autonomous system, in which the governing equations have no explicit time-dependence. For certain parameter values, the model does not converge towards a steady-state but develops stable self-sustained oscillations. These free oscillations feature pCO2A minima and maxima consistent with the ice-core record when vertical mixing in the ocean is allowed to vary in response to pCO2A-controlled temperature change. A stable 100-kyr cycle with a rapid transition from glacial to interglacial conditions is obtained when additional non-linear equations are applied to calculate deep ocean mixing, iron fertilization and the depth of organic matter degradation as function of pCO2A-controlled surface temperature. The δ13C value of carbon in the ocean/atmosphere system calculated in these model runs is consistent with the benthic δ13C record. However, the simulated 13C depletion in the glacial ocean is not driven by the decline in terrestrial carbon stocks but by sea-level change controlling the rates of organic carbon burial and weathering at continental margins. The pCO2A- and δ13C oscillations develop without any form of external Milankovitch forcing. They are induced and maintained by sea-level change generating persistent imbalances in the marine carbon and phosphorus budgets. Stable oscillations are also obtained when sea-level change is allowed to lag temperature with a realistic time scale for ice-sheet adjustment.

Controls upon biomass losses and char production from prescribed burning on UK moorland

Prescribed burning is a common management technique used across many areas of the UK uplands. However, there are few data sets that assess the loss of biomass during burning and even fewer data on the effect of burning on above-ground carbon stocks and production of char. During fire the production of char occurs which represents a transfer of carbon from the short term bio-atmospheric cycle to the longer term geological cycle. However, biomass is consumed leading to the reduction in litter formation which is the principal mechanism for peat formation. This study aims to solve the problem of whether loss of biomass during a fire is ever outweighed by the production of refractory forms of carbon during the fire. This study combines both a laboratory study of char production with an assessment of biomass loss from a series of field burns from moorland in the Peak District, UK.The laboratory results show that there are significant effects due to ambient temperature but the most important control on dry mass loss is the maximum burn temperature. Burn temperature was also found to be linearly related to the production of char in the burn products. Optimisation of dry mass loss, char production and carbon content shows that the production of char from certain fires could store more carbon in the ecosystem than if there had been no fire. Field results show that approximately 75% of the biomass and carbon were lost through combustion, a figure comparable to other studies of prescribed fire in other settings. Char-C production was approximately 2.6% of the carbon consumed during the fire.This study has shown that there are conditions (fast burns at high temperatures) under which prescribed fire may increase C sequestration through char production and that these conditions are within existing management options available to practitioners.

Resource quality affects carbon cycling in deep-sea sediments

Deep-sea sediments cover ~70% of Earth's surface and represent the largest interface between the biological and geological cycles of carbon. Diatoms and zooplankton faecal pellets naturally transport organic material from the upper ocean down to the deep seabed, but how these qualitatively different substrates affect the fate of carbon in this permanently cold environment remains unknown. We added equal quantities of (13)C-labelled diatoms and faecal pellets to a cold water (-0.7 °C) sediment community retrieved from 1080 m in the Faroe-Shetland Channel, Northeast Atlantic, and quantified carbon mineralization and uptake by the resident bacteria and macrofauna over a 6-day period. High-quality, diatom-derived carbon was mineralized >300% faster than that from low-quality faecal pellets, demonstrating that qualitative differences in organic matter drive major changes in the residence time of carbon at the deep seabed. Benthic bacteria dominated biological carbon processing in our experiments, yet showed no evidence of resource quality-limited growth; they displayed lower growth efficiencies when respiring diatoms. These effects were consistent in contrasting months. We contend that respiration and growth in the resident sediment microbial communities were substrate and temperature limited, respectively. Our study has important implications for how future changes in the biochemical makeup of exported organic matter will affect the balance between mineralization and sequestration of organic carbon in the largest ecosystem on Earth.

3.8 Ga zircons sampled by Neogene ignimbrite eruptions in Central Anatolia

Dating the oldest terrestrial rocks and minerals allows constraining the age and formation conditions of the ancient basement of our present-day continents. The oldest terranes, with ages ranging from 3.8 Ga to 4.0 Ga, have been identified in Canada, while Australian zircon crystals dated at 4.4 Ga represent the oldest dated minerals on Earth. The exceptional resistance of zircon grains to repeated geological cycles has allowed dating 3.3–3.9 Ga crystals in several Archean cratons worldwide. Identifying new, scarce but essential witnesses to this primitive Earth is still a challenging goal. Ignimbrites are silicic pyroclastic deposits produced by large-scale explosive eruptions. During magma residence and ascent, basement enclaves may be scavenged and mixed with the rhyolitic magma. Here we show that an ignimbrite eruption from Central Anatolia (Turkey) dated at 5.4 Ma has sampled Proterozoic and Archean zircons ranging from 2.3 Ga to 3.8 Ga in age. This is the first documented occurrence of Early Archean zircon crystals sampled by a recent volcanic event. These Central Anatolian zircon grains are among the oldest discovered on Earth and imply the presence at depth of remnants of an Early Archean basement that was hitherto unknown in Eurasia.

Global Rates of Geologic Cycling: Tectonic Diffusion of Upper Crustal Lithosomes

AbstractAge frequency distributions of various rock types now exposed at Earth's surface primarily reflect characteristic crustal depths at which they originate and the cumulative influence of vertical tectonic movements that displace them. Abundances of mid- to upper-crustal lithosomes increase rapidly to some modal age and then gradually decrease with increasing age. Paucity of exposures younger than the modal age reflects an intrinsic interval of geologic time needed for tectonic movements to exhume rock units, while increasing rarity of exposures older than the modal age reflects the overall dispersion (uplift and erosion, subsidence and burial) from initial lithosome positions relative to Earth's surface. We develop a random-walk model that describes the geologic cycling of crustal rock as a tectonically driven diffusive system because, at a globally averaged spatial and temporal scale, tectonic subsidence/burial and uplift/erosion are essentially random processes. From this, we produce solutions to ...

Magma to mud to magma: Rapid crustal recycling by Permian granite magmatism near the eastern Gondwana margin

Early Permian (Cisuralian) S-type monzogranites of the Bundarra Supersuite, New England Orogen (NEO), eastern Australia, have chemical and isotopic compositions indicative of their being derived from young, weathered, volcanogenic sedimentary source rocks. High δ18Ozrn values of zircon precipitated from the melt phase of the magma (ca. 11.5‰) confirm that the previously measured high granite whole-rock values (δ18OWR) are a primary magmatic feature. Abundant inherited detrital zircon cores with a range of dates (360–300Ma) and distinctly lower δ18Ozrn values (ca. 5–10‰) were derived from mostly young (Carboniferous) volcanogenic source rocks that became less primitive and more isotopically diverse with time. The age difference between the youngest inherited zircon population and the earliest zircon growth during magma genesis is about 15Ma. An arc-related volcanogenic sedimentary pile built up over about 50Ma was weathered, buried, and partially melted, producing voluminous peraluminous magmas within no more than ca. 15Ma of the youngest source sediment being deposited. The time interval between the initiation of melting and post-emplacement magma crystallization was about 5Ma. The S-type Bundarra Supersuite in the NEO is a rare case in which the entire geologic cycle has been captured by zircon. Recognizing this is uniquely possible because of the relatively simple populations of inherited and newly-grown zircon, and their distinctive oxygen isotopic compositions.

Major geological cycles substantiated by U–Pb ages and εHfi of detrital zircon grains from the Lower Rhine Basin

Detrital zircon grains of the Cenozoic Lower Rhine Basin were dated by the U–Pb method and simultaneously analyzed for initial Hf signatures to (1) identify distinct geodynamic events recorded in the W-European basement and cover rocks and (2) estimate the addition of juvenile crust in relation to these. Approximately 350 zircon grains extracted from 4 Miocene to Quaternary sand samples were investigated by back-scattered electron (BSE) and cathodoluminescence (CL) imaging. One third of these zircons were found to be sufficiently homogeneous for laser ablation U–Pb dating, which was performed by two individual and spatially well separated laser-spot analyses on the same grain, substantiating zircons have identical ages for the two intra-grain analyses. Approximately 40 zircons showed different ages. Our U–Pb dating results document distinct periods of primary magmatic zircon growth between 2.7 and 0.03Ga. These ages correspond to worldwide known subduction–collision cycles. The oldest terrains exposed today along the Rhine River and the Alps belong to the Variscan cycle. Therefore, all zircon grains older than ca. 0.4Ga must have been extracted from Paleozoic or Mesozoic–Cenozoic cover rocks containing detrital grains inherited from pre-Variscan basement; only the Cenozoic zircons require direct transport to the basin.From the dated homogeneous zircons 34 grains were selected for Hf isotope analysis, showing large variations in initial Hf isotope ratios (εHfi) between −10.9 and +15.2. Twelve of the 13 Precambrian grains yield positive or zero εHfi values, with a single 1025-Ma old grain having a negative value of −10.9. For the 21 zircon grains younger than 0.6Ga, a series of 9 grains yield positive or zero εHfi, whereas the remaining 12 zircons have negative values as low as −5.8. Approximately 60% of the zircon crystals reflect addition of juvenile crust having positive or zero εHfi being extracted from the mantle around the time indicated by their U–Pb ages. For some cases, juvenile crust addition may be somewhat older than indicated by the U–Pb ages because zircon growth may occur during later differentiation of rocks originally devoid of zircon. For such cases, εHfi values are necessarily less positive than that of the juvenile magma, depending on the Lu/Hf and crustal residence times of the zircon-free rock. A few εHfi values between +11.4 and +15.2 corroborate the existence of highly fractionated, Lu-enriched and Hf-depleted asthenospheric mantle in Mid-Proterozoic times. In agreement with earlier detrital zircon studies, our new data demonstrate that crustal recycling during continent collision events significantly increased in Phanerozoic times, being relatively rare during Precambrian times where intra-plate plume activity and oceanic arc attachment were dominant.

Les princi peseneraux tie toute theorie globale del' ecorceter restre

Theories considering the local phenomena on/in the earth's crust — formation of a mountain chain, eruption of a volcano, accumulation of sediments, a.s.o. —, and theories considering the earth's crust as a whole on the way of studying the successions of states of this crust. 1. Cyclic successions ( cycles ) and non-closed successions. 2. Exemples of cyclis successions (figures 1-A, 2-A, 3-A, 4-A), their graphic represesentations (figures 1-B, 2-B, 3-B, -t-B).3. Manifest existence of the cycles during the geologic history of the earth and absolute necessity of getting these cycles as a corollary of every theory of earth's crust. Practical impossibility of obtaining these consequences from the existing theories, and the causes of this impossibility.4. Three kinds of the mechanic theories in general and of the mechanic theories of earth's crust particulary: A. The exact continuous theories;B. The continuous theories which consider in first approximation the earth's crust a whole, and C. The theories considering the earth's crust as a whole in the full sense of these words. Examples. Astonishing fact that the theories of earth's crust of the kind C are non-existent till today. Hence the purpose of this article: the establishment of the general principles ofthese theories (— of the kind C). 5. Choice and definition of the quantities caracterising the states of the earth's crust. Definitive table of these quantities).6. Hypotheses necessary to build the system of differential equations of our problem. Simplifications which can be introduced. Pinal system of fundamental equations [2], Some remarks to resolving of [2], 7. Solutions [3] and [4] of the fundamental equations. Remarkable coincidence of these forms with the existing geological cycles.8. Different kinds of solutions [3] and [4]: I. Exactly periodic; II. Nearly periodic, and III. Aperiodic. Their geological meaning. On the choice of the constants in the fundamental equations [2].9. Some mechanical-geological analogies. Remarks about the number of the necessary constant. Conclusion.

The Global Biogeochemical Silicon Cycle

Silicon is one of the most important elements in the current age of the anthropocene. It has numerous industrial applications, and supports a high-tech multi-billion Euro industry. Silicon has a fascinating biological and geological cycle, interacting with other globally important biogeochemical cycles. In this review, we bring together both biological and geological aspects of the silicon cycle to provide a general, comprehensive review of the cycling of silicon in the environment. We hope this review will provide inspiration for researchers to study this fascinating element, as well as providing a background environmental context to those interested in silicon.

Peculiarity and consequence of geological subsurface water circulation

The geological mass current of free and connected ground waters is estimated. This is where waters go under the continental crust during the processes of continental drift and subduction, form the hydrothermal systems, participate in volcanic eruptions, and constitute a descending current reaching the lowest part of the Earth’s crust and the uppermost mantle layer. The mass of this current, throughout the entire time of the tectonic process, is conducted, and a geological circle is carried out, amount ~0.95 × 10 24 g, and can be compared with the water mass contained in the mantle, which equals 1 × 10 24 g. The suggestion that the geological circle of ground waters is the mechanism for mantle dehydration compensation and keeping the water contained in the mantle at a level sufficient for convection to occur has been made. The most important peculiarity of ground waters in the Earth’s crust is that they are mobile components; i.e., virtually every system in the Earth’s crust is seen as an open one due to constant water transfer. Subsurface water transfer within the thickness of the Earth’s crust, determined by the combined influence of solar radiation and the thermal and gravitational fields of the Earth, occurs constantly during the process of crust evolution with a number of cycles, ranging from active water exchange in the uppermost crust to slow processes in the deep zones of the Earth’s crust. The refined quantitative model of subsurface water mass fluxes within the whole thickness of the Earth’s crust is shown in Table 1, which includes the following: (1) hydrogeological mass fluxes of free gravitational subsurface waters in active and slow water exchange zones of the continental block of the Earth’s crust which are totally controlling modern exogenic processes; (2) lithogenic metamorphic subsurface water mass fluxes in continental and subcontinental blocks of the Earth’s crust, determined mostly by release of physically connected waters in clayey strata being sunk and pressured, and also by sequential hydration of rocks, chemically connected water transfer, and dehydration of the former when sinking in the course of regional metamorphism; (3) geological lithospheric subsurface water mass fluxes in the oceanic crust, in the zones of crust adjunction with island arcs and active continental margins during the subduction process; these fluxes are formed by physically connected waters of the I seismic sedimentary layer of the oceanic crust and by chemically connected waters of the II volcanogenic and III basaltic layers of the oceanic crust. The geological role of free, chemically and physically connected waters, dragging under the continental crust in the course of continental drift and subduction; i.e., the geological subsurface water cycle with a total mass flux of 1.294 × 10 15 g/yr is extremely high. They generate hydrothermal systems, participate in volcanic eruptions, and form the descending water flux, reaching the lowest layer of the Earth’s crust and the uppermost mantle and equal to ~0.38 × 10 15 g/yr (Table 2). I.D. Ryabchikov [3] points out the high role of the geological cycle’s deep branches (down to 400 km), being able to the reach transit zone and control the beginning of mantle rock melting. The subsurface waters of the Earth’s crust, like the whole hydrosphere of the Earth, had passed the stage of protoplanetic substance degassing in their evolution. Contrary to other mobile components, the main part of the water mass did not leave the planet, and joined the Earth’s solid phase during degassing processes in the early stages of the planet’s development. The water content in the hypothetical primitive mantle is estimated by Ryabchikov [3] at ~0.1% of its mass, which is about 4 × 10 24 g. He also concluded that the H 2 O content in MORB glasses (190 g/t) corre

Supercontinent: ten billion years in the life of our planet

To understand continental drift and plate tectonics, the shifting and collisions that make and unmake continents, requires a long view. The Earth, after all, is 4.6 billion years old. This book extends our vision to take in the greatest geological cycle of all--one so vast that our species will probably be extinct long before the current one ends in about 250 million years. And yet this cycle, the grandest pattern in Nature, may well be the fundamental reason our species--or any complex life at all--exists. This book explores the Supercontinent Cycle from scientists' earliest inkling of the phenomenon to the geological discoveries of today--and from the most recent fusing of all of Earth's landmasses, Pangaea, on which dinosaurs evolved, to the next. Chronicling a 500-million-year cycle, Ted Nield introduces readers to some of the most exciting science of our time. He describes how, long before plate tectonics were understood, geologists first guessed at these vanishing landmasses and came to appreciate the significance of the fusing and fragmenting of supercontinents. He also uses the story of the supercontinents to consider how scientific ideas develop, and how they sometimes escape the confines of science. Nield takes the example of the recent Indian Ocean tsunami to explain how the whole endeavor of science is itself a supercontinent, whose usefulness in saving human lives, and life on Earth, depends crucially on a freedom to explore the unknown.

Chemical kinetic model for the lower atmosphere of Venus

A self-consistent chemical kinetic model of the Venus atmosphere at 0–47 km has been calculated for the first time. The model involves 82 reactions of 26 species. Chemical processes in the atmosphere below the clouds are initiated by photochemical products from the middle atmosphere (H 2SO 4, CO, S x ), thermochemistry in the lowest 10 km, and photolysis of S 3. The sulfur bonds in OCS and S x are weaker than the bonds of other elements in the basic atmospheric species on Venus; therefore the chemistry is mostly sulfur-driven. Sulfur chemistry activates some H and Cl atoms and radicals, though their effect on the chemical composition is weak. The lack of kinetic data for many reactions presents a problem that has been solved using some similar reactions and thermodynamic calculations of inverse processes. Column rates of some reactions in the lower atmosphere exceed the highest rates in the middle atmosphere by two orders of magnitude. However, many reactions are balanced by the inverse processes, and their net rates are comparable to those in the middle atmosphere. The calculated profile of CO is in excellent agreement with the Pioneer Venus and Venera 12 gas chromatographic measurements and slightly above the values from the nightside spectroscopy at 2.3 μm. The OCS profile also agrees with the nightside spectroscopy which is the only source of data for this species. The abundance and vertical profile of gaseous H 2SO 4 are similar to those observed by the Mariner 10 and Magellan radio occultations and ground-based microwave telescopes. While the calculated mean S 3 abundance agrees with the Venera 11–14 observations, a steep decrease in S 3 from the surface to 20 km is not expected from the observations. The ClSO 2 and SO 2Cl 2 mixing ratios are ∼10 −11 in the lowest scale height. The existing concept of the atmospheric sulfur cycles is incompatible with the observations of the OCS profile. A scheme suggested in the current work involves the basic photochemical cycle, that transforms CO 2 and SO 2 into SO 3, CO, and S x , and a minor photochemical cycle which forms CO and S x from OCS. The net effect of thermochemistry in the lowest 10 km is formation of OCS from CO and S x . Chemistry at 30–40 km removes the downward flux of SO 3 and the upward flux of OCS and increases the downward fluxes of CO and S x . The geological cycle of sulfur remains unchanged.

Earth cycles: a historical perspective

Humans have tried to figure out what formed the landscape of the earth for thousands of years. How were mountains created? Where did lakes and rivers come from? What lies under the surface of the earth? And one concept that greatly aided the scientific advance of the earth sciences was that of geological cycles. Once scientists understood that many geological actions are cyclic, the scientific knowledge of the earth exploded. These ideas are central to the nature of the earth sciences, and appreciating how scientists arrived at these ideas is essential for understanding the nature of the earth sciences.

The Chemical Element: A Historical Perspective (Greenwood Guides to Great Ideas in Science) (Andrew Ede)

This book has been published as part of a new series that focuses on fundamental scientific concepts such as the gene, the quantum, geological cycles, planetary motion, etc.

Incorporation of Geologic Cycles in Establishing Geologic Time Scales: Exercise Notes

The main goal is to introduce some of the technical methods of time series analysis and cyclostratigraphy, with the overall focus to enable interested scientists with little experience in time series analysis to “get their hands dirty” while analysing their own data sets. The course notes make use of example data sets, and provide pointers to additional methods and software to conduct the basic steps of analysis of geological data that appear to show evidence of cyclicity. The short course notes presented here were originally developed as teaching material for advanced undergraduate and postgraduate students at the University of Cambridge and Stockholm University. The original notes were modified and enhanced, and aim to supplement the presentation during the Paleontological Society Short Course 2006.

Hydrogen, carbon, and oxygen isotope ratios from the Archean Pibara Block: Constraints on geological cycles

Hydrogen, carbon, and oxygen isotope ratios from the Archean Pibara Block: Constraints on geological cycles

SATELLITE TECHNOLOGIES IN FUNCTION OF EUROPEAN CONCEPTOF SUITABLE DEVELOPMENT IN AGRICULTURE

Development of modern cosmical technology made it possible to record electromagnetic spectrum, not only for cosmical research, but also for Earth research needs. Satellite research of regional geological structure, hydro geological cycle, hydro geochemical, biogeochemical and climate processes increasingly take part in global monitoring of the whole planet. Satellite observing and certain issue noting should play an important and necessary role in plans of development and rational natural resources management process. Planning and optimal usage of space is an important factor of each country and each society, where remote detection and management have not only a very important part, but also rationality of ecological and financial aspect. The data obtained from satellite observing and recording, have become essential in geography, agriculture, forestry, waterpower engineering, oceanography, ecology and other segments of human civilization. Multidisciplinary and functional processing and satellite scanning data make a good start for planning the space in ecologically and economically rational model of developing new societies.

TCF selenium preconcentration in geological materials for determination at sub-μg g −1 with INAA (Se/TCF-INAA)

In geological samples, Se concentration ranges from 1 × 10 −9 g g −1 up to 1 × 10 −3 g g −1. The analytical difficulty at low concentration (<1 μg g −1), is one of the main reasons why the geological cycle of Se is poorly known. The analytical method that consisted of preconcentration of Se with thiol cotton fiber (TCF) followed by graphite furnace atomic absorption spectrometry (GFAAS) has been modified by finishing with instrumental neutron activation analysis (INAA). The modified technique involves sample dissolution (HF–HNO 3–H 2O 2) and evaporation to dryness at low temperature (55–60 °C) to avoid selenium volatilization. Se VI is converted to Se IV by adding 6 M HCl to the dry residuum and the solution is then heated in a covered boiling bath (95–100 °C). The solution is diluted to obtain 0.6 M HCl and then collected on TCF. The TCF is placed in a polyethylene vial for irradiation in the SLOWPOKE II reactor (Montréal) for 30 s at a neutron flux of 10 15 m −2 s −1. The 162 keV peak of 77mSe (half-life 17.36 s) is read for 20 s after a decay of 7 s. The amount of sample to be dissolved is controlled by two competing effects. To obtain low detection limits, a larger amount of sample should be dissolved. On the other hand, the TCF could become saturated with chalcophile elements when large sample is used. Sulfur is a good indicator of the amount of Se and chalcophile elements present. In S poor sample (<100 μg g −1) 3.0 g of sample was used and the L D was ∼2 ng g −1. In S high samples (>1.5% S) 0.05 g of sample was used and the L D was ∼120 ng g −1. The present work also includes suggested Se concentration for eight international geological reference materials (IGRM) that compare favorably with literature values.

The Evolution of Biological Carbon and Nitrogen Cycling--a Genomic Perspective

Carbon and nitrogen are essential to all living organisms, owing to their abundance and remarkable characteristics when participating in chemical bonds. Their essentiality dates back to the very origin of life, where current theories hypothesize either a prebiotic abundance of organic compounds rich in carbon and nitrogen, or an ability to assimilate them inorganically through abiotic reactions that might have been catalyzed on ancient mineral surfaces. This chapter details the core reactions essential to the assimilation of these elements in biologically useful forms—the so-called fixation of carbon and nitrogen—focusing on recent literature and insights from comparative genomics and phylogenetics. Though considerable debate continues on the antiquity of these pathways, especially whether or not they might have been present in the last common ancestor (LCA) of modern organisms, it is clear that carbon and nitrogen fixation pathways were of crucial importance to the primitive ancestors of extant life. Furthermore, the biological assimilation of inorganic carbon (autotrophy) and atmospheric nitrogen (diazotrophy) represent pivotal juxtapositions of biological and geological cycles. It is thought that atmospheric CO2 concentrations have decreased substantially since the proposed origin of life some 3.8 billion years ago, due in large part to either primary (fixation) or secondary (e.g., weathering) influence by biota (Hayes 1994; Rye et al. 1995; Des Marais 1997; Lowe and Tice 2004). Though the biosphere accounts for a relatively small fraction of the total carbon on Earth, the rate of carbon flux through the biosphere far exceeds that through any geological reservoirs (Des Marais 1997). Biological carbon fixation is closely balanced to carbon recycling through biological oxidation, and the future stability of this and other CO2 reservoirs (and our ability to influence or understand them) depends critically on these biological underpinnings (e.g., Falkowski et al. 2000). Conversely, nitrogen, especially the …

Long-Term Energy Solutions: The Truth Behind the Silent Lie

Paul Weisz’s article on long-term energy supplies (Physics Today, Physics Today 0031-9228 57 7 2004 47 https://doi.org/10.1063/1.1784302. July 2004, page 47 ) states that uranium resources with breeder reactors could provide the world’s energy needs for “hundreds of years.” That is a gross underestimate. The world’s energy needs could be provided by uranium-fueled breeder reactors for the full billion years that life on Earth will be sustainable, without the price of electricity increasing by more than a small fraction of 1% due to raw fuel costs. 1 1. B. L. Cohen, Am. J. Phys. 51, 75 (1983). The error in Weisz’s calculation is that he is referring to uranium available at its present price, $10–20 per pound. But in breeder reactors, 100 times as much energy is derived from a pound of uranium as in present-day light water reactors, so we could afford to use uranium that is 100 times as expensive.The cost of extracting uranium from its most plentiful source, seawater, is about $250 per pound—the energy equivalent of gasoline at 0.13 cent per gallon! The uranium now in the oceans could provide the world’s current electricity usage for 7 million years. But seawater uranium levels are constantly being replenished, by rivers that carry uranium dissolved out of rock, at a rate sufficient to provide 20 times the world’s current total electricity usage. In view of the geological cycles of erosion, subduction, and land uplift, this process could continue for a billion years with no appreciable reduction of the uranium concentration in seawater and hence no increase in extraction costs.REFERENCESection:ChooseTop of pageREFERENCE <<1. B. L. Cohen, Am. J. Phys. 51, 75 (1983). Google ScholarCrossref© 2004 American Institute of Physics.