The Arctic Coastal Dynamics Database: A New Classification Scheme and Statistics on Arctic Permafrost Coastlines     

Hugues Lantuit  Pier Paul Overduin  Nicole Couture  Sebastian Wetterich  Felix Aré  David Atkinson  Jerry Brown  Georgy Cherkashov  Dmitry Drozdov  Donald Lawrence Forbes  Allison Graves-Gaylord  Mikhail Grigoriev  Hans-Wolfgang Hubberten  James Jordan  Torre Jorgenson  Rune Strand ?deg?rd  Stanislav Ogorodov  Wayne H. Pollard  Volker Rachold  Sergey Sedenko  Steve Solomon  Frits Steenhuisen  Irina Streletskaya  Alexander Vasiliev 《Estuaries and Coasts》2012,35(2):383-400

Arctic permafrost coasts are sensitive to changing climate. The lengthening open water season and the increasing open water area are likely to induce greater erosion and threaten community and industry infrastructure as well as dramatically change nutrient pathways in the near-shore zone. The shallow, mediterranean Arctic Ocean is likely to be strongly affected by changes in currently poorly observed arctic coastal dynamics. We present a geomorphological classification scheme for the arctic coast, with 101,447?km of coastline in 1,315 segments. The average rate of erosion for the arctic coast is 0.5?m? year^?1 with high local and regional variability. Highest rates are observed in the Laptev, East Siberian, and Beaufort Seas. Strong spatial variability in associated database bluff height, ground carbon and ice content, and coastline movement highlights the need to estimate the relative importance of shifting coastal fluxes to the Arctic Ocean at multiple spatial scales.  相似文献   

Seasonal and Annual Fluxes of Nutrients and Organic Matter from Large Rivers to the Arctic Ocean and Surrounding Seas   总被引：3，自引：0，他引：3  

Robert Max Holmes  James W. McClelland  Bruce J. Peterson  Suzanne E. Tank  Ekaterina Bulygina  Timothy I. Eglinton  Viacheslav V. Gordeev  Tatiana Y. Gurtovaya  Peter A. Raymond  Daniel J. Repeta  Robin Staples  Robert G. Striegl  Alexander V. Zhulidov  Sergey A. Zimov 《Estuaries and Coasts》2012,35(2):369-382

River inputs of nutrients and organic matter impact the biogeochemistry of arctic estuaries and the Arctic Ocean as a whole, yet there is considerable uncertainty about the magnitude of fluvial fluxes at the pan-Arctic scale. Samples from the six largest arctic rivers, with a combined watershed area of 11.3?×?10⁶?km², have revealed strong seasonal variations in constituent concentrations and fluxes within rivers as well as large differences among the rivers. Specifically, we investigate fluxes of dissolved organic carbon, dissolved organic nitrogen, total dissolved phosphorus, dissolved inorganic nitrogen, nitrate, and silica. This is the first time that seasonal and annual constituent fluxes have been determined using consistent sampling and analytical methods at the pan-Arctic scale and consequently provide the best available estimates for constituent flux from land to the Arctic Ocean and surrounding seas. Given the large inputs of river water to the relatively small Arctic Ocean and the dramatic impacts that climate change is having in the Arctic, it is particularly urgent that we establish the contemporary river fluxes so that we will be able to detect future changes and evaluate the impact of the changes on the biogeochemistry of the receiving coastal and ocean systems.  相似文献   

The Deposition and Chronology of Cenote T’isil: A Multiproxy Study of Human/Environment Interaction in the Northern Maya Lowlands of Southeast Mexico     

Lance Wollwage  Scott Fedick  Sergey Sedov  Elizabeth Solleiro‐Rebolledo 《Geoarchaeology》2012,27(5):441-456

Cenotes (natural wells or sinkholes) comprise the most common landscape features in the northern Maya Lowlands of the Yucatán Peninsula, México. Detailed study of dated soil‐sedimentary sequences, recovered from a cenote at the archaeological site T’isil and nearby wetlands, allows a partial reconstruction of environmental variability at the site for the last 2000 years. Biogenic calcite sedimentation and Calcisol development occur during three intervals of increased inundation in cenote and wetland environments, ca. A.D. 300, A.D. 1000, and A.D. 1300. Periods of increased inundation in the cenote and wetlands correlate with wetter climatic intervals, and periods of Maya occupation at sites in the Yalahau region. Evidence for Maya modification of the cenote environment may relate to regional wetland agricultural practices.  相似文献   

Onset of Hydraulic Fracture Initiation Monitored by Acoustic Emission and Volumetric Deformation Measurements   总被引：2，自引：1，他引：1  

Sergey Stanchits  Aniket Surdi  Patrick Gathogo  Eric Edelman  Roberto Suarez-Rivera 《Rock Mechanics and Rock Engineering》2014,47(5):1521-1532

In this paper, the results of laboratory studies of fracture initiation, early propagation and breakdown are reported. Three experiments were conducted on a low permeability sandstone block, loaded in a polyaxial test frame, to representative effective in situ stress conditions. The blocks were instrumented with acoustic emission (AE) and volumetric deformation sensors. In two experiments, fluids of different viscosity were injected into the wellbore, fluid injection was interrupted soon after the breakdown pressure had been reached. This allowed us to investigate hydraulic fracture initiation. In the third test, fracture initiation criteria were applied to stop hydraulic fracture propagation significantly earlier, prior to breakdown, and as it propagated a short distance from the wellbore. The analysis of AE results shows an increase in AE activity and a change in the AE spatial correlation, during the fracture initiation. This early stage of fracturing correlates strongly with the onset of rock volumetric deformation, and is confirmed by the analysis of ultrasonic transmission monitoring. The rock microstructure, after the test, was investigated by analysis of scanning electron microscope images. These indicated the development of leak-off zone near the wellbore and a dry hydraulic fracture at the farther distance from the wellbore.  相似文献   

Uranium in Saline Lakes of Mongolia and Adjacent Areas     

Vitaly ISUPOV  SODOV Ariunbileg  Svetlana SHATSKAYA  Marina KOLPAKOVA  Ljudmila RAZVOROTNEVA  Alexander VLADIMIROV  Stepan SHVARTSEV  Leonid KUIBIDA  Sergey KRIVONOGOV  Ekaterina MOROZ 《《地质学报》英文版》2014,88(Z1):137-138

正1 Introduction Increasing demand for uranium raw materials for the nuclear industry has stimulated interest in non-traditional sources,including hydromineral ones[Qin,2009].Those are saline lakes located in the uranium ore districts.Accumulation of uranium in such lakes results from the leaching of uranium from the rocks by surface and ground  相似文献   

Mesoscale and Nutrient Conditions Associated with the Massive 2008 Cochlodinium polykrikoides Bloom in the Sea of Oman/Arabian Gulf     

Adnan R. Al-Azri  Sergey A. Piontkovski  Khalid A. Al-Hashmi  Joaquim I. Goes  Helga do R. Gomes  Patricia M. Glibert 《Estuaries and Coasts》2014,37(2):325-338

Cochlodinium polykrikoides formed large blooms in the coastal waters of Oman from October 2008 through mid-January 2009, and satellite images from Aqua-MODIS and region-wide reports suggest that this bloom was found throughout the Arabian Gulf and Sea of Oman for more than 10 months. The unusual occurrence of this species appears to have supplanted the more regularly occurring bloom species, Noctiluca scintillans, in 2008–2009. For the first 2 weeks of the coastal Omani bloom, C. polykrikoides abundance was near monospecific proportions, with cell densities ranging from 4.6?×?10³ to 9?×?10⁶ cells L^?1 and very high levels of chlorophyll a (78.0 μg L^?1) were also recorded. The regional progression of the bloom likely began with stronger than normal upwelling along the Iranian and northern Omani coasts during the southwest monsoon in late summer, followed by discharge of unusually warm coastal plume water along the coast of Oman with the reversal of monsoonal winds in late October. The occurrence and persistence of high densities of C. polykrikoides in Oman coastal water were also significantly influenced by an elevated nutrient load and warmer than normal temperatures. Concentrations of nutrients, especially NH₄ ⁺, urea, PO₄ ^3?, and organic nitrogen and phosphorus, were manyfold higher than observed in the year prior or since. These findings suggest that mesoscale features were important in bloom dynamics more regionally, but locally the bloom was sustained by nutrient enrichment supplemented by its mixotrophic capabilities.  相似文献   

Time-series analysis of subsidence associated with rapid urbanization in Shanghai,China measured with SBAS InSAR method     

Shaochun Dong  Sergey Samsonov  Hongwei Yin  Shujun Ye  Yanrong Cao 《Environmental Earth Sciences》2014,72(3):677-691

River delta plains (deltas) are susceptible to subsidence producing undesirable environmental impact and affecting dense population. The City of Shanghai, located in the easternmost of Yangtze Delta in China, is one of the most developed regions in China that experiences the greatest land subsidence. Excessive groundwater withdrawal is thought to be the primary cause of the land subsidence, but rapid urbanization and economic development, mass construction of skyscrapers, metro lines and highways are also contributing factors. In this paper, a spatial–temporal analysis of the land subsidence in Shanghai was performed with the help of the Small Baseline Subset Interferometric Synthetic Aperture Radar. Twenty l-band ALOS PALSAR images acquired during 2007–2010 were used to produce a linear deformation rate map and to derive time series of ground deformation. The results show homogeneous subsidence within the research area, but exceptionally rapid subsidence around skyscrapers, along metro lines, elevated roads and highways was also observed. Because groundwater exploitation and rapid urbanization responsible for much of the subsidence in the Shanghai region are expected to continue, future subsidence monitoring is warranted.  相似文献   

Magmatic evolution of the ultramafic–mafic Kharaelakh intrusion (Siberian Craton, Russia): insights from trace-element, U–Pb and Hf-isotope data on zircon     

Kreshimir Nenadovitch Malitch  Elena A. Belousova  William L. Griffin  Inna Yu Badanina  Norman J. Pearson  Sergey L. Presnyakov  Evgeniya V. Tuganova 《Contributions to Mineralogy and Petrology》2010,159(6):753-768

The ultramafic–mafic Kharaelakh intrusion in the northwestern part of the Siberian Craton (Russia) hosts major economic platinum-group-element (PGE)–Cu–Ni sulphide deposits. In situ U–Pb, REE and Hf-isotope analyses of zircon from these rocks, combined with detailed study of crystal morphology and internal structure, identify four zircon populations. U–Pb ages of these populations cover a significant time span (from 347 ± 16 to 235.7 ± 6.1 Ma) suggesting multiple magmatic events that cluster around 350 and 250 Ma, being consistent with two recognised stages of active tectonism in the development of the Siberian Craton. The oldest zircon population, however, represents previously unknown stage of magmatic activity in the Noril’sk area. Epsilon-Hf values of +2.3 to +16.3 in the analysed zircons reflect a dominant role of mantle-derived magmas and suggest that juvenile mantle material was the main source for the ultramafic–mafic Kharaelakh intrusion. A significant range in initial ¹⁷⁶Hf/¹⁷⁷Hf values, found in zircons that cluster around 250 Ma, indicate mixing between mantle and crustal magma sources. Our findings imply that economic intrusions hosting PGE–Cu–Ni deposits of the Noril’sk area have a far more complex geological history than is commonly assumed.  相似文献   

WSO-UV progress and expectations     

Boris Shustov  Ana I. Gómez de Castro  Mikhail Sachkov  Alexander Moisheev  Evgeny Kanev  Javier López-Santiago  Oleg Malkov  Dmitry Nasonov  G. Belén Perea  Néstor Sánchez  Igor Savanov  Andrey Shugarov  Sergey Sichevskiy  Oleg Vlasenko  Javier Yañez 《Astrophysics and Space Science》2014,354(1):155-161

The World Space Observatory Ultraviolet (WSO-UV) is the space mission that will grant access to the ultraviolet (UV) range in the post Hubble epoch. WSO-UV is equipped with instrumentation for imaging and spectroscopy and it is fully devoted to UV astronomy. In this article, we outline the WSO-UV mission model and present the current status of the project.  相似文献   

Regulatory control of vehicle and power plant emissions: how effective and at what cost?     

Sergey Paltsev  Valerie Karplus  Henry Chen  Ioanna Karkatsouli  John Reilly  Henry Jacoby 《Climate Policy》2013,13(4):438-457

Passenger vehicles and power plants are major sources of GHG emissions. While economic analyses generally indicate that a broader market-based approach to GHG reduction would be less costly and more effective, regulatory approaches have found greater political success. We evaluate a global regulatory regime that replaces coal with natural gas in the electricity sector and imposes technically achievable improvements in the efficiency of personal transport vehicles. Its performance and cost are compared with other scenarios of future policy development including a no-policy world, achievements under the Copenhagen Accord, and a price-based policy to reduce global emissions by 50% by 2050. The assumed regulations applied globally achieve a global emissions reduction larger than projected for the Copenhagen agreements, but they do not prevent global GHG emissions from continuing to grow. The reduction in emissions is achieved at a high cost compared to a price-based policy. Diagnosis of the reasons for the limited yet high-cost performance reveals influences including the partial coverage of emitting sectors, small or no influence on the demand for emissions-intensive products, leakage when a reduction in fossil use in the covered sectors lowers the price to others, and the partial coverage of GHGs. If these regulatory measures are in part correcting other barriers or behavioural limitations consumers face, the benefits of overcoming these could offset at least some of the costs we estimate. The extent of any efficiency gap – the difference between engineering estimates of best practice and what actually happens – is highly contested, and offers an important avenue for future research.

Policy relevance

While analysts concerned with national cost of GHG control have long advocated a GHG pricing policy, by a cap-and-trade system or a tax, covering all emissions sources and gases, governments more often pursue sectoral policies and technology standards. Given these political realities, the regulations represent a more politically practical approach to GHG reductions, focusing on solutions that are within reach and that do not depend on technological breakthroughs. If regulations are imposed as a way to get started on larger emissions reductions, and then combined with a broader GHG pricing policy pursuing a deep global cut in emissions, its requirements will eventually be overtaken by the pricing policy. The remaining higher costs of the regulatory targets become diluted so that in later years the difference in average cost per ton between a least-cost approach and one preceded by a period of regulatory action becomes very small.  相似文献