Weak coupling between sulfate reduction and the anaerobic oxidation of methane in methane-rich seafloor sediments during ex situ incubation     

Marshall W. Bowles 《Geochimica et cosmochimica acta》2011,75(2):500-519

We investigated coupling between sulfate reduction (SR) and anaerobic oxidation of methane (AOM) by quantifying pore water geochemical profiles, determining rates of microbial processes, and examining microbial community structure at two sites within Mississippi Canyon lease block 118 (MC118) in the Northern Gulf of Mexico. Sediments from the northwest seep contained high concentrations of methane while sediments from the southwest seep contained methane, gaseous n-alkanes and liquid hydrocarbons and had abundant surficial accumulations of gas hydrate. Volumetric (21.5 μmol cm⁻³ day⁻¹) and integrated (1429 mmol m⁻² day⁻¹) rates of SR at MC118 in ex situ incubations are the highest reported thus far for seafloor environments. AOM rates were small in comparison, with volumetric rates ranging from 0.1 to 12.6 nmol cm⁻³ day⁻¹. Diffusion cannot adequately supply the sulfate required to support these high SR rates so additional mechanisms, possibly biological sulfide oxidation and/or downward advection, play important roles in supplying sulfate at these sites. The microbial communities at MC118 included sulfate-reducing bacteria phylogenetically associated with Desulfobacterium anilini, which is capable of complex hydrocarbon degradation. Despite low AOM rates, the majority of archaea identified were phylogenetically related to previously described methane oxidizing archaea. To evaluate whether weak coupling between SR and AOM occurs in habitats lacking the complex hydrocarbon milieu present at MC118, we compiled available SR and AOM rates and found that the global median ratio of SR to AOM was 10.7:1 rather than the expected 1:1. The global median integrated AOM rate was used to refine global estimates for AOM rates at cold seeps; these new estimates are only 5% of the previous estimate.  相似文献   

Earthshaking science: what we know (and don't know) about earthquakes by Susan Elizabeth Hough. Princeton University Press,Princeton, NJ, 2002. No. of pages: 238 (hardback). ISBN 0 691 05010 4     

Kenneth Burke 《Geological Journal》2005,40(1):121-121

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Two observed consequences of penetration electric fields     

C.Y. Huang  W.J. Burke  C.S. Lin 《Journal of Atmospheric and Solar》2009,71(16):1614-1622

The influence of penetration electric fields (PEF) on storm-time energetic particles in the inner magnetosphere and on the stability of plasma in the low-latitude ionosphere is widely recognized. We describe two consequences of PEFs, regularly observed during magnetic storms that indicate their persistence throughout the main phases. These are (1) the presence of equatorial plasma bubbles (EPB) across the evening local time sector during main phases and their absence throughout recovery, and (2) detections of low-energy ion precipitation in the dawn sector equatorward of the auroral electron boundary.  相似文献   

Storm surge computations in estuarine and near-coastal regions: the Mersey estuary and Irish Sea area     

John Eric Jones  Alan Marshall Davies 《Ocean Dynamics》2009,59(6):1061-1076

An unstructured grid storm surge model of the west coast of Britain, incorporating a high-resolution representation of the Mersey estuary is used to examine storm surge dynamics in the region. The focus of the study is the major surge that occurred during the period 11–14 November 1977, which has been investigated previously using uniform grid finite difference models and a finite element model of the west coast of Britain. However, none of these models included the Mersey estuary. Comparison of solutions in the eastern Irish Sea with those computed with these earlier models showed that, away from the Liverpool Bay region, the inclusion of the Mersey estuary had little effect. However, at the entrance to the Mersey, its inclusion did influence the solution. By including a detailed representation of the Mersey estuary within the model, it was possible to conduct a detailed study of storm surge propagation in the Mersey, which had never previously been performed. This detailed study showed for the first time that the surge’s temporal variability within the estuary is influenced by surge elevation at its entrance. This varies with time as a function of spatial and temporal variations of wind stress over the west coast of Britain. Within the Mersey, calculations show that the spatial variability is mainly determined by changes in bottom topography, which had not been included in earlier finite difference models. However, since water depth is influenced by variations in tidal elevation, this, together with tide surge interaction through bottom friction and momentum advection, influences the surge. The ability of the finite element model to vary the mesh in near-shore regions to such an extent that it can resolve the Mersey and hence the impact of the Mersey estuary upon the Liverpool Bay circulation shows that it has distinct advantages over earlier finite difference models. In the absence of detailed measurements within the Mersey at the time of the surge, it was not possible to validate predicted surge elevations within the Mersey. However, significant insight into physical processes influencing the surge propagation down the estuary, its reflection and spatial/temporal variability could be gained.  相似文献   

TAOS – The Taiwanese‐American Occultation Survey     

M. J. Lehner  C. Alcock  T. Axelrod  F. Bianco  Y.‐I. Byun  W.‐P. Chen  K. H. Cook  R. Dave  I. de Pater  J. Giammarco  S.‐K. King  T. Lee  J. Lissauer  S. L. Marshall  S. Mondal  T. Nihei  J. Rice  M. Schwamb  A. Wang  S.‐Y. Wang  C.‐Y. Wen  Z.‐W. Zhang 《Astronomische Nachrichten》2006,327(8):814-817

The Taiwanese‐American Occultation Survey (TAOS) seeks to determine the number and size spectrum for small (∼3 km) bodies in the Kuiper Belt. This will be accomplished by searching for the brief occultations of bright stars (R ∼ 14) by these objects. We have designed and built a special purpose photometric monitoring system for this purpose. TAOS comprises four 50 cm telescopes, each equipped with a 2048 × 2048 pixel CCD camera, in a compact array located in the central highlands of Taiwan. TAOS will monitor up to 2 000 stars at 5 Hz. The system went into scientific operation in the autumn of 2005. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

The whaling issue: [Marine Policy 2000;24(3):179–91]     

William Aron  William Burke  Milton M.R. Freeman 《Marine Policy》2000,24(6):501

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The radio galaxy RC J1148+0455     

Yu. N. Pariiskii  N. S. Soboleva  A. I. Kopylov  O. V. Verkhodanov  A. V. Temirova  O. P. Zhelenkova  J. Winn  A. Fletcher  B. Burke 《Astronomy Letters》2000,26(7):423-427

Based on data from the MIT-GB-VLA 4850-MHz survey, we investigate the radio structure of RC J1148+0455 with a steep radio spectrum (α=?1.04) from the COLD catalog. The radio source consists of two components, each having a complex structure. We analyze an optical identification of the source by using 6-m telescope images. The centroid of the radio source falls on a group of eight galaxies at a 24 ^m level in R.  相似文献   

Made in Japan: The Japanese market and herring roe production and management in Canada's southern Gulf of St. Lawrence     

Lenore Burke  John Phyne 《Marine Policy》2008

The herring roe fishery in Canada's southern Gulf of St. Lawrence is a productive fishery that lies outside the confines of privatized arrangements. Yet, this fishery is compromised by its dependence on the Japanese seafood market. Consideration of the efficiency of this fishery needs to account for the role assumed by this market in setting fishing practices. A more ecologically and economically efficient use of the herring resource requires greater attention to supply chain integration by local harvesters, processors and buyers prior to engaging with distant markets. This is necessary regardless of the property rights regime that is in place.  相似文献   

Corrigendum to “Climatological mean and decadal change in surface ocean pCO₂, and net sea–air CO₂ flux over the global oceans” [Deep Sea Res. II 56 (2009) 554–577]     

Taro Takahashi  Stewart C. Sutherland  Rik Wanninkhof  Colm Sweeney  Richard A. Feely  David W. Chipman  Burke Hales  Gernot Friederich  Francisco Chavez  Christopher Sabine  Andrew Watson  Dorothee C.E. Bakker  Ute Schuster  Nicolas Metzl  Hisayuki Yoshikawa-Inoue  Masao Ishii  Takashi Midorikawa  Yukihiro Nojiri  Arne Krtzinger  Tobias Steinhoff  Mario Hoppema  Jon Olafsson  Thorarinn S. Arnarson  Bronte Tilbrook  Truls Johannessen  Are Olsen  Richard Bellerby  C.S. Wong  Bruno Delille  N.R. Bates  Hein J.W. de Baar 《Deep Sea Research Part I: Oceanographic Research Papers》2009,56(11):2075-2076

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Dives into outer Coronado Canyon System     

Francis P. Shepard  Neil F. Marshall 《Marine Geology》1975,18(5):313-323

Dives in Lockheed's submarine “Deep Quest” followed the floor of the fan valley and outer gorge of Coronado Canyon, southwest of the California—Baja California border. Both the fan valley and outer gorge have meandering courses. Basin depressions and intermittent steep descents characterize the outer gorge. No indications were found of recent activity of turbidity currents at either location, but a sand layer 30 cm below the surface is interpreted as related to a lower stand of sea level at the close of the last ice age. Abundant organisms were seen on the valley floor and in the overlying water.  相似文献