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Sample records for coalfields southern north

  1. Geology and potential hydrocarbon play system of Lower Karoo Group in the Maamba Coalfield Basin, southern Zambia

    NASA Astrophysics Data System (ADS)

    Phiri, Cryton; Wang, Pujun; Nyambe, Imasiku Anayawa

    2016-06-01

    This study attempts to augment geology and potential hydrocarbon play system database not only in the Maamba Coalfield basin of southern Zambia but in other similar continental non-marine Karoo rift basins in the region as well. Geological analyses were conducted through extensive outcrops and exposures and subsurface boreholes. Six (6) major lithofacies (diamictites, conglomerates, sandstones, siltstones, coal and mudstones) represents Lower Karoo Group sequence. Four (4) mudstone core samples were prepared for thin section petrography. In addition, six (6) samples of sandstones obtained from outcrops, exposures and cores were impregnated with blue epoxy before thin sectioning in order to facilitate easy recognition of porosity. Quantification of framework grain composition and porosity was achieved by point counting a total of 300 points per thin section. The identification of diagenetic constituents and pore types was made possible by the use of scanning electron microscopy (SEM). Rock-Eval pyrolysis analyses utilised 35 core samples of mudstones and coal. According to results of the analyses, three (3) deposition settings which include; alluvial, fluvial-lacustrine and lacustrine setting are envisaged. . Fluvial-lacustrine deposits are host to mudstones and coal source rocks and sandstone reservoir rocks. Mudstones and coal source rocks gave the total organic carbon (TOC) that is well above the recommended thresholds of 0.5 wt % and 2.5 wt % of gas and oil generation respectively. The hydrogen index (HI) values are mostly below 200 mg HC/g TOC, indicating fair quantities of type III kerogen. The thermal maturity readings measured by temperature Tmax range from 440 to 485 °C in agreement with calculated vitrinite reflectance (Rocalc) range of 0.76-1.57% indicating mature to post mature stages. This maturation is attributed to the burial temperatures and near-surface heat flows by faults. Production Index (PI) values are less than 0.1 suggesting some hydrocarbon

  2. Abandoned mine drainage in the Swatara Creek Basin, southern anthracite coalfield, Pennsylvania, USA: 2. performance of treatment systems

    USGS Publications Warehouse

    Cravotta, Charles A., III

    2010-01-01

    A variety of passive and semi-passive treatment systems were constructed by state and local agencies to neutralize acidic mine drainage (AMD) and reduce the transport of dissolved metals in the upper Swatara Creek Basin in the Southern Anthracite Coalfield in eastern Pennsylvania. To evaluate the effectiveness of selected treatment systems installed during 1995–2001, the US Geological Survey collected water-quality data at upstream and downstream locations relative to each system eight or more times annually for a minimum of 3 years at each site during 1996–2007. Performance was normalized among treatment types by dividing the acid load removed by the size of the treatment system. For the limestone sand, open limestone channel, oxic limestone drain, anoxic limestone drain (ALD), and limestone diversion well treatment systems, the size was indicated by the total mass of limestone; for the aerobic wetland systems, the size was indicated by the total surface area of ponds and wetlands. Additionally, the approximate cost per tonne of acid treated over an assumed service life of 20 years was computed. On the basis of these performance metrics, the limestone sand, ALD, oxic limestone drain, and limestone diversion wells had similar ranges of acid-removal efficiency and cost efficiency. However, the open limestone channel had lower removal efficiency and higher cost per ton of acid treated. The wetlands effectively attenuated metals transport but were relatively expensive considering metrics that evaluated acid removal and cost efficiency. Although the water-quality data indicated that all treatments reduced the acidity load from AMD, the ALD was most effective at producing near-neutral pH and attenuating acidity and dissolved metals. The diversion wells were effective at removing acidity and increasing pH of downstream water and exhibited unique potential to treat moderate to high flows associated with storm flow conditions.

  3. Resource and potential reclamation evaluation of Rattlesnake Butte study area, Dickinson coalfield, North Dakota: summary. Final report 1978-82

    SciTech Connect

    Westman, G.H.; Parish, L.M.

    1982-06-01

    The purpose of this investigation was to collect baseline data for establishing reclamation objectives and lease stipulations. The report includes data on climate, physiography, geology, coal resources, and overburden. The study area, located in Southwestern North Dakota, lies within the unglaciated portion of the Great Plains Physiographic Province.

  4. 2. GENERAL VIEW LOOKING NORTH, SHOWING THE SOUTHERN FACADE OF ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. GENERAL VIEW LOOKING NORTH, SHOWING THE SOUTHERN FACADE OF THE NORTHERN-MOST CAR BARN (CONSTRUCTED 1893) AT CENTRAL AVENUE AND BOND STREET - Johnstown Passenger Railway Company, Car Barns, 726 Central Avenue, Johnstown, Cambria County, PA

  5. Thermal history of the Sabero Coalfield (Southern Cantabrian Zone, NW Spain) as revealed by apatite fission track analyses from tonstein horizons: implications for timing of coalification

    NASA Astrophysics Data System (ADS)

    Botor, Dariusz; Anczkiewicz, Aneta A.

    2015-10-01

    Apatite fission track (AFT) central ages from Carboniferous (Stephanian) tonsteins of the Sabero Coalfield, NW Spain, range from 140.8 ± 7.5 to 65.8 ± 8.1 Ma (Cretaceous), with mean c-axis projected track length values ranging from 12.5 to 13.4 μm. Mean random vitrinite reflectance ( R r) of these samples ranges from 0.91 to 1.20 %, which can be translated into maximum palaeotemperatures of ca. 130 to 180 °C. All analysed samples experienced substantial post-depositional annealing. The considerably younger AFT ages compared to the depositional ages of the samples and R r data indicate the certainty of the occurrence of at least one heating event after the deposition of strata. The unimodal track length distributions, the relatively short mean track length, and the rather low standard deviation (SD) (1.0-1.6 μm) indicate a relatively simple thermal history that could be related to the post-Late Variscan heating event followed by prolonged residence in the apatite partial annealing zone (APAZ). Geological data combined with thermal models of AFT data indicate that Stephanian strata reached the maximum palaeotemperatures in the Permian period, which was therefore the major time of the coalification processes. The Permian magmatic activity was responsible for a high heat flow, which, with the added effect of sedimentary burial, could account for the resetting of the AFT system. It appears that the fault-related hydrothermal activity could have redistributed heat in areas of significant subsidence. Cooling occurred in the Triassic-Cretaceous times after a high heat flow Permian regime. A post-Permian maturation of the Stephanian organic matter is not very likely, since there is no evidence of a high Mesozoic burial that was sufficient to cause a significant increase in the palaeotemperatures. Finally, exhumation and associated erosion rates may possibly have been faster in the Tertiary, causing the present exposure of the studied rocks.

  6. The Southern Cone: A critical element in North American geology

    SciTech Connect

    Dalziel, I.W.D. . Inst. for Geophysics)

    1993-02-01

    The Pacific and Atlantic-Gulf of Mexico continental margins converge towards southern Mexico, delimiting the Southern Cone of North American. The margins are controlled by late Precambrian to early Paleozoic rift systems. The Neoproterozoic rifts along the Pacific margin truncate the 1.3--1.0 Ga Grenville-Llano front and still older structural boundaries within the craton, such as the Snowbird line. The Atlantic margin originated by separation from another continent within the Grenville orogen near the time of the Precambrian-Cambrian boundary. The Gulf of Mexico margin was initiated with rifting at that time, but appears to truncate the Ordovician Taconian orogen in Georgia. The continental margins of the Southern Cone may prove critical in understanding the origin of North America as a discrete continent. A possible continuation of the Grenville-Llano front has now been identified along the Pacific margin of the East Antarctic craton; the opposite side of the Grenville orogen may be present in South America and East Antarctic; a southern continuation of the Taconic Appalachians may have been identified in southern South American and Antarctica (L. Dalla Salda et al., Geology, 1992 a;b: I. Dalziel, Geology, 1991, and GSA Today, 1992; P. Hoffman, Science, 1991; E. Moores, Geology, 1991). Thus the geology of the Southern Cone of North America provides opportunities for critical testing of these globally important hypotheses, notably through geochronometry, isotope geochemistry, stratigraphy, and paleobiogeography. Conversely, East Antarctica, southern Africa, and the proto-Andean margin of South America may offer exciting opportunities to further understanding of pre-Pangea geology across southern North America.

  7. 2. Southern Light Tower and Northern Light Tower, view north, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. Southern Light Tower and Northern Light Tower, view north, south sides - Kennebec River Light Station, South side of Doubling Point Road, off State Highway 127, 1.8 miles south of U.S. Route 1, Arrowsic, Sagadahoc County, ME

  8. North Carolina and the Southern Regional Education Board, December 2014

    ERIC Educational Resources Information Center

    Southern Regional Education Board (SREB), 2014

    2014-01-01

    This document details North Carolina's participation in Southern Regional Education Board (SREB) programs and services from December 2013 through November 2014. Appropriations from member states support SREB's core operations and general services. SREB leverages the long-standing commitment of member states to attract external funding for an array…

  9. 14. This view, looking north east from the southern approach ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    14. This view, looking north east from the southern approach to the bridge, is a detail of the southeast abutment. It shows the sequence of concrete castings which were necessary to achieve the curb, curb coping, the balustrade and its coping. A portion of the original concrete bridge deck is visible. - Vigo County Bridge No. 139, Spanning Sugar Creek at Seventy-fourth Place, Terre Haute, Vigo County, IN

  10. "The Lady Is Not Returning!": Educational Precarity and a Social Haunting in the UK Coalfields

    ERIC Educational Resources Information Center

    Bright, N. Geoffrey

    2016-01-01

    Drawing on research in de-industrialised coal-mining communities in the north of England, this article focuses on how experiences of some young people might be approached through a notion of precarity linked to the idea of a "social haunting" of the coalfields. Concentrating on data gathered in the period after the 2010 change of UK…

  11. Shallow gas in Cenozoic sediments of the Southern North Sea

    NASA Astrophysics Data System (ADS)

    Trampe, Anna F.; Lutz, Rüdiger; Franke, Dieter; Thöle, Hauke; Arfai, Jashar

    2013-04-01

    Shallow petroleum systems in the southern North Sea are known for several decades but they were not actively explored for a long time. In recent years these unconventional shallow petroleum systems are studied in greater detail and one shallow gas field (A-12) is in production in the Netherlands. Additionally, oil was encountered in Miocene sandstones in the southern Danish North Sea (Lille John well) just north of the Danish-German border. Seismic amplitude anomalies are an indication for hydrocarbons in sediments. Therefore we have mapped the occurrence of seismic amplitude anomalies in the German North Sea based on more than 25.000 km of 2D seismic data and around 4.000 km2 of 3D seismic data. Amplitude anomalies are ubiquitous phenomena in the study area. These anomalies are not only caused by hydrocarbons but also by changing lithologies e.g. peat or fluid migration. Therefore several classes of seismic anomalies, e.g. bright spots, chimneys, blanking areas and velocity pull-down were mapped. Examples for these classes were studied with AVO (amplitude variation with offset) analyses to verify the existence or non-existence of gas in the sediments. Shallow gas can be produced and transported through the dense pipeline grid of the southern and central North Sea or it could be burned offshore close to wind parks in small power plants and the electric energy then transported through the existing power connections of the wind parks. Thus enabling a continuous energy supply during calm wind periods. This study is carried out within the framework of the project "Geoscientific Potential of the German North Sea (GPDN)" in which the Cenozoic sedimentary system was mapped in great detail. A detailed model of delta evolution (Baltic river system) was developed which serves as a structural framework. The studied interval is time equivalent to the Utsira formation which is used offshore Norway for sequestration of CO2. These different possibilities of using or exploiting

  12. Spatial Organization of Decadal and Bidecadal Rainfall On Southern North America and Southern South America

    NASA Astrophysics Data System (ADS)

    Lucero, O. A.; Rodriguez, N. C.

    The spatial organization of decadal and bidecadal components (fluctuations) of annual rainfall is identified in this research for two regions: 1) southern South America, and 2) southern North America (conterminous USA, southeastern Canada and northern and central Mexico). Findings indicate that these decadal and bidecadal components have highly-coherent wave-like spatial organization. Two types of organization of decadal and bidecadal components of annual rainfall were identified: a train of propagating fluctuations, and quasi-standing fluctuations. For decadal components, such patterns alternate in time. A widespread change in the spatial organization of decadal com- ponents of annual rainfall took place simultaneously in both continents in 1932. The bidecadal component is organized as standing fluctuations in southern North Amer- ica, and as travelling fluctuations in southern South America. The spatial pattern of decadal fluctuations of annual rainfall has 12- and 13-year cycle; and the spatial pat- tern of bidecadal fluctuations has predominantly 21- and 22-year cycles. Correspond- ing author's email: omarabellucero@yahoo.com

  13. How North Atlantic cooling alters Southern Ocean wind

    NASA Astrophysics Data System (ADS)

    Schultz, Colin

    2011-07-01

    At least seven times during the last ice age, large portions of the polar glaciers crumbled, sending rafts of ice floating into the North Atlantic Ocean. When these icebergs melted, the resultant injection of cold freshwater was enough to drive down ocean temperatures by as much as 12°C. These so-called Heinrich events are associated with rising atmospheric carbon dioxide (CO2) levels, but a mechanism to explain the connection convincingly has yet to arise. One proposed explanation sees the melting-iceberg-triggered North Atlantic cooling tied to increases in CO2 venting from the Southern Ocean, which surrounds Antarctica, through increased wind-driven upwelling. To test this hypothesis, which was initially proposed by researchers in 2009 based on paleoclimate evidence, Lee et al. ran ocean-atmosphere coupled climate simulations to determine the physical mechanism that could support this cross-hemisphere connection. (Paleoceanography, doi:10.1029/ 2010PA002004, 2011)

  14. Seasonality of floc strength in the southern North Sea

    NASA Astrophysics Data System (ADS)

    Fettweis, Michael; Baeye, Matthias; Zande, Dimitry; Eynde, Dries; Joon Lee, Byung

    2014-03-01

    The suspended particulate matter (SPM) concentration in the high turbidity zones of the southern North Sea is inversely correlated with chlorophyll (Chl) concentration. During winter, SPM concentration is high and Chl concentration is low and vice versa during summer. This seasonality has often been associated with the seasonal pattern in wind forcing. However, the decrease in SPM concentration corresponds well with the spring algal bloom. Does the decrease of SPM concentration caused by changing wind conditions cause the start of algae bloom, or does the algae bloom decrease SPM concentrations through enhanced flocculation and deposition? To answer the question, measurements from 2011 of particle size distribution (PSD), SPM, and Chl concentrations from the southern North Sea have been analyzed. The results indicate that the frequency of occurrence of macroflocs has a seasonal signal, while seasonality has little impact upon floc size. The data from a highly turbid coastal zone suggest that the maximum size of the macroflocs is controlled by turbulence and the available flocculation time during a tidal cycle, but the strength of the macroflocs is controlled by the availability of sticky organic substances associated with enhanced primary production during spring and summer. The results highlight the shift from mainly microflocs and flocculi in winter toward more muddy marine snow with larger amounts of macroflocs in spring and summer. The macroflocs will reduce the SPM concentrations in the turbidity maximum area as they settle faster. Consequently, the SPM concentration decreases and the light condition increases in the surface layer enhancing algae growth further.

  15. Coal bed methane research in West Virginia's northern coalfield

    SciTech Connect

    Repine, T.E. Jr.; Blake, B.M. Jr.; Ashton, K.C.; Schwietering, J.F.; Grady, W.C. )

    1991-03-01

    Production of coal bed methane from virgin coal beds within the northern West Virginia coalfield is presently limited to several small fields in Wetzel County. Approximately 50 years of periodic activity have yielded wells with reported initial productions of between 30 and 60 mcf per day from the 500-ft-deep Pittsburgh and slightly shallower Sewickley coal beds. Current exploration within this region is focused on multiple-seam completions, utilizing the more predictable areal geology of the Sewickley and Pittsburgh coal beds (Upper Pennsylvanian/Monongahela Group), plus the assumed higher methane potential of the more deeply buried and less well studied Freeport and Kittanning (Middle Pennsylvanian/Allegheny Formation) and the undivided Pottsville Group (Lower to Middle Pennsylvanian) coal beds. Regional gas contents indicate moderately gassy (generally less than 200 ft{sup 3} of gas per ton of coal) coal beds. The West Virginia Geological and Economic Survey is using a Gas Research Institute grant to review available data describing the occurrence of coal, oil, gas, and water in West Virginia's northern coalfield. Subdrainage overburden maps, which eliminate the impact of topography on overburden calculations, have been constructed to assist both regional and local exploration. Limited core samples are available to study the relationship between vitrinite reflectance and gas contents. Similar studies involving gas content versus ash content of in-seam benches are planned. Preliminary coal isopleth maps indicate a greater frequency of occurrence of coal beds in the southern portion of the study area.

  16. Marine litter ensemble transport simulations in the southern North Sea.

    PubMed

    Neumann, Daniel; Callies, Ulrich; Matthies, Michael

    2014-09-15

    The drift of marine litter in the southern North Sea was simulated with the offline Lagrangian transport model PELETS-2D. Assuming different source regions, passive tracer particles were released every 28 h within a nine-year period. Based on pre-calculated hourly wind and ocean current data, drift simulations were carried out forward and backward in time with and without the assumption of extra wind forces influencing particle movement. Due to strong variability of currents, backward simulations did not allow for the identification of particular source regions influencing given monitoring sites. Neither accumulation regions at open sea could be identified by forward simulations. A seasonal signal, however, could be identified in the number of tracer particles that reached the coastal areas. Both particle drift velocity and variability of drift paths further increased when an extra wind drift was assumed. PMID:25125287

  17. Comparison of survival patterns of northern and southern genotypes of the North American tick Ixodes scapularis (Acari: Ixodidae) under northern and southern conditions

    USGS Publications Warehouse

    Ginsberg, Howard S.; Rulison, Eric L.; Azevedo, Alexandra; Pang, Genevieve C.; Kuczaj, Isis M.; Tsao, Jean I.; LeBrun, Roger A.

    2014-01-01

    Conclusions: Our results suggest that conditions in southern North America are less hospitable than in the north to populations of I. scapularis. Southern conditions might have resulted in ecological or behavioral adaptations that contribute to the relative rarity of I. scapularis borne diseases, such as Lyme borreliosis, in the southern compared to the northern United States.

  18. Comparison of survival patterns of northern and southern genotypes of the North American tick Ixodes scapularis (Acari: Ixodidae) under northern and southern conditions

    USGS Publications Warehouse

    Ginsberg, Howard S.; Rulison, Eric L.; Azevedo, Alexandra; Pang, Genevieve C.; Kuczaj, Isis M.; Tsao, Jean I.; LeBrun, Roger A.

    2014-01-01

    Our results suggest that conditions in southern North America are less hospitable than in the north to populations of I. scapularis. Southern conditions might have resulted in ecological or behavioral adaptations that contribute to the relative rarity of I. scapularis borne diseases, such as Lyme borreliosis, in the southern compared to the northern United States.

  19. Upper carboniferous gas indications and Zechstein features in southern North Sea

    SciTech Connect

    Jenyon, M.K.

    1984-05-14

    Seismograph Service's recent nonproprietary marine survey in the Southern basin of the North Sea indicates the possible presence of gas in the Upper Carboniferous region. At the southern margin of the Northern Salt basin, north of the Mid North Sea High, hydrocarbon accumulations have been found in fractured and vuggy Zechstein carbonates in the Auk and Argyll fields. To date, no hydrocarbon accumulations of any importance have been produced from either shelf Zechstein or Upper Carboniferous to the south of these fields, although gas and condensate shows have been logged in wells in the southern part. Certain structural features seen in the Zechstein interval, which lies unconformably upon the Upper Carboniferous, make this North Sea basin a very promising area for more detailed study. These Zechstein features may include porous carbonate intervals containing gas.

  20. Suspended particulate matter in the Southern North Sea: Application of a numerical model to extend NERC North Sea project data interpretation

    NASA Astrophysics Data System (ADS)

    Puls, Walter; Pohlmann, Thomas; Sündermann, Jürgen

    1997-09-01

    A numerical SPM (suspended particulate matter) transport model for the North Sea is used for supporting the interpretation of SPM data collected during the British NERC North Sea Project (NSP) in the southern North Sea. This interpretation applies to (i) the assessment of the spatial and temporal representativity of the measured data, (ii) the presentation of the SPM's origin in the southern North Sea and (iii) the estimation of SPM fluxes.

  1. The influence of Southern Ocean winds on the North Atlantic carbon sink

    NASA Astrophysics Data System (ADS)

    Bronselaer, Ben; Zanna, Laure; Munday, David R.; Lowe, Jason

    2016-06-01

    Observed and predicted increases in Southern Ocean winds are thought to upwell deep ocean carbon and increase atmospheric CO2. However, Southern Ocean dynamics affect biogeochemistry and circulation pathways on a global scale. Using idealized Massachusetts Institute of Technology General Circulation Model (MITgcm) simulations, we demonstrate that an increase in Southern Ocean winds reduces the carbon sink in the North Atlantic subpolar gyre. The increase in atmospheric CO2 due to the reduction of the North Atlantic carbon sink is shown to be of the same magnitude as the increase in atmospheric CO2 due to Southern Ocean outgassing. The mechanism can be described as follows: The increase in Southern Ocean winds leads to an increase in upper ocean northward nutrient transport. Biological productivity is therefore enhanced in the tropics, which alters the chemistry of the subthermocline waters that are ultimately upwelled in the subpolar gyre. The results demonstrate the influence of Southern Ocean winds on the North Atlantic carbon sink and show that the effect of Southern Ocean winds on atmospheric CO2 is likely twice as large as previously thought in past, present, and future climates.

  2. Strain in southern California: Measured uniaxial north-south regional contraction

    USGS Publications Warehouse

    Savage, J.C.; Prescott, W.H.; Lisowski, M.; King, N.

    1978-01-01

    The plate tectonics model of the Pacific moving northwest relative to North America implies that the regional strain in California should be simple shear across a vertical plane striking N45??W or equivalently equal parts of north-south contraction and east-west extension. Measurements of the strain accumulation at seven separate sites in southern California in the interval 1972 through 1978 indicate a remarkably consistent uniaxial north-south contraction of about 0.3 part per million per year; the expected east-west extension is absent. It is not clear whether the period from 1972 through 1978 is anomalous or whether the secular strain in southern California is indeed a uniaxial north-south contraction.

  3. 1. View north from StanleyBostitch property toward southern boundary/stone wall ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. View north from Stanley-Bostitch property toward southern boundary/stone wall of Joseph Fry Farm with South County Trail/Route 2 to the east (right) - Joseph Fry Farm Landscape, 2153 South County Trail Road (U.S. Route 2), East Greenwich, Kent County, RI

  4. Biochemical characterization of the eelgrass Zostera marina at its southern distribution limit in the North Pacific

    USGS Publications Warehouse

    Cabello-Pasini, Alejandro; Munoz-Salazar, R.; Ward, D.H.

    2004-01-01

    The eelgrass Zostera marina L. is distributed along the Baja California Peninsula (Mexico) where it is exposed to a wide range of irradiances and temperatures that could promote changes in its biochemical composition. Consequently, the objective of this study was to characterize the variations in the levels of chlorophyll, carbohydrates, proteins, fiber, ash and calories in the shoots of Z. marina from the north (San Quintin) and south (Ojo de Liebre and San Ignacio lagoons) of the peninsula. Temperature in the southern lagoons was 5-6??C higher than in the northern lagoon; likewise, in situ irradiance was two-fold greater in the south than in the north. As a result of the lower irradiance levels, the concentration of chlorophyll in the shoots of Z. marina was twice as high (1.7 mg gWW-1) in the northern lagoon than in the southern ones (0.8 mg gWW-1). Similar to chlorophyll levels, the concentration of soluble carbohydrates in the shoots was greater in the northern lagoon than in the southern ones, suggesting that the high levels of chlorophyll are enough to compensate for the low irradiance levels and to maintain a positive carbon balance at San Quintin. On the other hand, the levels of proteins in the shoots from the north of the peninsula were slightly lower than those from the southern populations. In general, these results suggest that the different environmental conditions to which Z. marina is exposed along the peninsula impact its biochemical composition.

  5. The response of southern North Sea elevations to oceanographical and meteorological forcing

    NASA Astrophysics Data System (ADS)

    Thompson, K. R.

    1981-09-01

    Relationships between the daily mean sea levels, air pressure, wind, density and currents of the southern North Sea are examined, using data recorded during September and October 1973 as part of the Joint North Sea Data Acquisition Programme. The sea level fluctuations are highly coherent through space. Principal component analysis shows that 88% of the variance can be accounted for by changes in the overall level of the southern North Sea. Seven per cent of the variance can be accounted for by an east-west tilting of sea level. Variations of the overall level are negatively correlated with air pressure changes. Cross-spectral analysis shows that the response of Southend sea level (i) lags the inverted barometer effect by 14 h and (ii) depends on the frequency of air pressure forcing. A qualitative explanation for these results is given. Wind stress is the most important influence on the daily mean surface topography of the southern North Sea, causing slopes in excess of 80 cm (100 km) -1. The largest slopes due to bottom stress, Coriolis acceleration and advection are 59 cm (100 km) -1, 34 cm (100 km) -1 and 13 cm (100 km) -1 respectively. The contributions of the equilibrium tide, local acceleration density and air pressure are small. It is shown that the sea surface topography, computed for a quiet period of several days, may be used to define accurately an equipotential surface at the tide gauge sites. A procedure for the estimation of depth-mean currents from sea level, air pressure and wind data is described. Reasonable agreement is obtained between observed and estimated currents at one position in the southern North Sea.

  6. Southern Hemisphere water mass conversion linked with North Atlantic climate variability.

    PubMed

    Pahnke, Katharina; Zahn, Rainer

    2005-03-18

    Intermediate water variability at multicentennial scales is documented by 340,000-year-long isotope time series from bottom-dwelling foraminifers at a mid-depth core site in the southwest Pacific. Periods of sudden increases in intermediate water production are linked with transient Southern Hemisphere warm episodes, which implies direct control of climate warming on intermediate water conversion at high southern latitudes. Coincidence with episodes of climate cooling and minimum or halted deepwater convection in the North Atlantic provides striking evidence for interdependence of water mass conversion in both hemispheres, with implications for interhemispheric forcing of ocean thermohaline circulation and climate instability. PMID:15774752

  7. Multiple-stage deformation along the southern flank of the North Chukchi High, Chukchi Sea, Alaska

    SciTech Connect

    Johnson, P.P. )

    1990-05-01

    Structural and stratigraphic relations along the southern edge of the North Chukchi high provide insights into the timing and mechanics of Late Cretaceous and Cenozoic tectonic events in the northern Chukchi Sea. In this area, the easternmost strand of the north-trending Hanna wrench fault zone is deflected to the northeast and terminates in a series of reverse faults along the southern edge of the high. Areas east of the Hanna fault zone were characterized by tectonic stability during this period of time. Within the fault zone, east-west-trending box folds and reverse faults accompanied uplift of the North Chukchi high and erosion of the entire Ellesmerian sequence along its southern margin. Stratigraphic and structural relations indicate that this compressional deformation began during the Early Cretaceous (Albian ) but ceased prior to the Late( ) Cretaceous. During the early Cenozoic( ), the northern part of the Hanna fault zone was reactivated as an extensional systems which controlled the development of a local basin. Some faults which showed an early history of reverse displacement were reactivated as normal faults during this late-stage tectonic event. This data is consistent with a model for Early Cretaceous impingement of adjacent blocks at a constrained corner near the North Chukchi high during the rift opening of the North Chukchi basin. The compressional deformation ceased prior to the Cenozoic when the opposing blocks in the constrained corner finally escaped past each other. Continued rifting and subsidence of the North Chukchi basin resulted in late-stage extensional overprinting of earlier compressional structures.

  8. North-South contraction of the mojave block and strike-slip tectonics in southern california.

    PubMed

    Bartley, J M; Glazner, A F; Schermer, E R

    1990-06-15

    The Mojave block of southern California has undergone significant late Cenozoic north-south contraction. This previously unappreciated deformation may account for part of the discrepancy between neotectonic and plate-tectonic estimates of Pacific-North American plate motion, and for part of the Big Bend in the San Andreas fault. In the eastern Mojave block, contraction is superimposed on early Miocene crustal extension. In the western Mojave block, contractional folds and reverse faults have been mistaken for extensional structures. The three-dimensional complexity of the contractional structures may mean that rigid-block tectonic models of the region based primarily on paleomagnetic data are unreliable. PMID:17747526

  9. Incursions of southern-sourced water into the deep North Atlantic during late Pliocene glacial intensification

    NASA Astrophysics Data System (ADS)

    Lang, David C.; Bailey, Ian; Wilson, Paul A.; Chalk, Thomas B.; Foster, Gavin L.; Gutjahr, Marcus

    2016-05-01

    The circulation and internal structure of the oceans exert a strong influence on Earth's climate because they control latitudinal heat transport and the segregation of carbon between the atmosphere and the abyss. Circulation change, particularly in the Atlantic Ocean, is widely suggested to have been instrumental in the intensification of Northern Hemisphere glaciation when large ice sheets first developed on North America and Eurasia during the late Pliocene, approximately 2.7 million years ago. Yet the mechanistic link and cause/effect relationship between ocean circulation and glaciation are debated. Here we present new records of North Atlantic Ocean structure using the carbon and neodymium isotopic composition of marine sediments recording deep water for both the Last Glacial to Holocene (35-5 thousand years ago) and the late Pliocene to earliest Pleistocene (3.3-2.4 million years ago). Our data show no secular change. Instead we document major southern-sourced water incursions into the deep North Atlantic during prominent glacials from 2.7 million years ago. Our results suggest that Atlantic circulation acts as a positive feedback rather than as an underlying cause of late Pliocene Northern Hemisphere glaciation. We propose that, once surface Southern Ocean stratification and/or extensive sea-ice cover was established, cold-stage expansions of southern-sourced water such as those documented here enhanced carbon dioxide storage in the deep ocean, helping to increase the amplitude of glacial cycles.

  10. Southern Ocean Evidence for Reduced Export of North Atlantic Water During Heinrich Event 1

    NASA Astrophysics Data System (ADS)

    van de Flierdt, T.; Robinson, L. F.

    2008-12-01

    Deep-sea corals form unique, high-resolution archives of ocean circulation that can be dated using the decay of uranium to thorium. They are abundant in the Southern Ocean, and can provide unprecedented insights into ocean circulation and ocean chemistry on sub-millennial time-scales in areas where traditional paleoceanographic proxies are fraught with difficulties. Here we present the first coupled neodymium (Nd) isotope and radiocarbon data from deep-sea corals in the Drake Passage (Southern Ocean) adding new constraints on ocean circulation during the last Heinrich event (H-1; 16,700 years ago). The modern day Drake Passage water column is homogeneous with respect to Nd isotopes (expressed in epsilon units; ɛNd). The seawater value of close to -9.0 is largely controlled by the mixture of North Atlantic Deep Water and Pacific waters. The aragonite of modern Drake Passage corals reflects this water-column value. In contrast, a fossil coral from H-1 is significantly higher at -6.4 ±0.4. We interpret this ~2.5 epsilon unit shift as a reduction in the influence of North Atlantic-sourced Nd in the Southern Ocean during H1. This interpretation is supported by a series of radiocarbon analyses on the same sample, and is consistent with a two-fold or greater slow down in export of North Atlantic waters from the Atlantic Basin. This shift has important implications for the evaluation of lower latitude paleo-ɛNd reconstructions that have been used to assess the mixing ratio of northern to southern waters in the past.

  11. Recent Population Trends in North Carolina and the Southern Region: 1970-1975. Progress Report Soc. 64, 1977.

    ERIC Educational Resources Information Center

    Clifford, William B.

    Estimates of population change and the components of change for North Carolina and its counties were made for the 1970-75 period. Attention was given to the growth patterns in the metropolitan and nonmetropolitan areas of North Carolina and the southern region. Data showed that the state's population grew at a faster rate during this period than…

  12. Detecting storm surge loading deformations around the southern North Sea using subdaily GPS

    NASA Astrophysics Data System (ADS)

    Geng, Jianghui; Williams, Simon D. P.; Teferle, Felix N.; Dodson, Alan H.

    2012-09-01

    A large storm surge event occurred on 2007 November 2009 in the southern North Sea where strong winds caused the sea level to rise drastically by up to 3 m within several hours. Based on the Proudman Oceanographic Laboratory storm surge model, the predicted loading displacements at coastal stations can reach a few centimetres in the vertical and several millimetres in the horizontal directions. In this study, we used two-hourly global positioning system (GPS) positions at 26 stations around the southern North Sea to identify the loading displacements caused by this storm surge event. We find that the mean rms of the differences between the estimated and predicted displacements are 4.9, 1.3 and 1.4 mm, which are insignificant compared to the one-sigma GPS positioning errors of 5.1, 2.0 and 2.4 mm for the Up, East and North components, respectively. More interestingly, in both vertical and horizontal directions, the estimated displacements successfully tracked the temporal evolution of the storm surge loading effects. In addition, within the whole of 2007 November, we used the predicted displacements to correct the two-hourly GPS positions, and consequently reduced the rms of the estimated displacements on average from 9.3, 3.0 and 2.9 mm to 7.8, 2.8 and 2.8 mm for Up, East and North components, respectively. Therefore, subdaily loading effects due to storm surges should be paid attention to in the GPS positioning that contributes to crustal-motion studies around shallow seas such as the North Sea, the Baltic Sea and the Gulf of Mexico.

  13. Tracing back nutrients from Southern North Sea eutrophicated areas up to the watersheds

    NASA Astrophysics Data System (ADS)

    Dulière, Valérie; Gypens, Nathalie; Lancelot, Christiane; Thieu, Vincent; Luyten, Patrick; Lacroix, Geneviève

    2015-04-01

    The Southern North Sea faces eutrophication problems. They result from growing anthropogenic pressure in the river watersheds, and subsequent increase in nutrients (nitrogen and phosphorus) loading to the sea. Establishing the link between human activities and eutrophication problems requires the identification of the major nutrient sources and the ecological response of the coastal ecosystem to these nutrient alterations. This information is crucial to mitigate eutrophication in coastal zones by applying appropriate dual-nutrient reduction strategies, therefore achieving the Good Environmental Status of EU marine waters by 2020. The marine biogeochemical model (MIRO&CO) has been coupled to a newly developed generic watershed model (PyNuts) based on Riverstrahler model. A nutrient tracking approach has been adapted and implemented in MIRO&CO. The transboundary nutrient transport method has been used to track the nutrients in the sea, and trace back their sources (river, ocean, and atmosphere). Here, the relative contributions of the different nutrient sources will be presented. Results show that the nitrogen contribution from atmospheric deposition is not negligible and that the nutrients released by French rivers reach the Southern North Sea in significant proportions. This work has done in the framework of the EMoSEM EU project (http://www.odnature.be/emosem/) that aims at providing support to eutrophication management in the North Atlantic Ocean, using state-of-the-art modelling tools.

  14. North Pecan Island field: a mature trend discovery in Miocene of southern Louisiana

    SciTech Connect

    Bauer, A.G.; McCormick, J.A.

    1985-02-01

    The Exxon 1 M.J. Epley discovery well for North Pecan Island field was completed in early 1982 as a discovery of significant new gas and condensate reserves in the mature Miocene trend of south Louisiana. The field is located in Vermilion Parish within a large megablock between 2 major down-to-the basin growth-fault systems and is on the southern end of a south-plunging structural nose. Traps in 2 fault segments are formed in southeasterly dipping beds upthrown to 2 north dipping, sealing faults. Six separate Robulus chambersi sandstones contain gas and condensate reserves. Major gas and condensate reserves from sandstone reservoirs in the R. chambersi section were discovered in the mid-1960s 3.3 mi. west in the Pecan island field and in the North Freshwater Bayou field, 5 mi northeast of the North Pecan Island field discovery. Several earlier dry holes just north of the discovery were drilled seeking to extend production from the upstructure Fire Island field (3 mi north), which produced a limited amount of gas and condensate from R. chambersi sandstones. Extensive structural and isopach mapping, aided by new high-resolution seismic data, revealed the North Pecan Island prospect to be structural high to production at Pecan Island and that the prospective section was deposited over a growing paleostructure. Four wells have been completed to date in the field, with flow rates as high as 30 MMCFGB. Current estimates place the new field recoverable at approximately 250 bcf of gas and 6 million bbl condensate.

  15. Shoreline responses to storm impacts: North Norfolk coast, southern North Sea

    NASA Astrophysics Data System (ADS)

    Brooks, Sue; Spencer, Thomas

    2016-04-01

    Recent phases of enhanced mid-latitude storminess (e.g. NW European winter of 2013 - 14) have led to a growing awareness of the considerable impacts of storms on coastal landscapes and their communities. Using aerial photography, bi-annual cross-shore profiles, detailed alongshore ground survey, and offshore/inshore wave buoy and regional tide gauge datasets, this paper considers storm impacts on the barrier coastline of North Norfolk, UK. Firstly, at Scolt Head Island, we show that the barrier dune crest has been progressively set back landwards since 2006 in three storm-related phases, with each shoreline translation being of the order of 5-8 m. However, a fourth storm produced no significant shoreline change, demonstrating that the threshold for morphological change is a function of the combined effects of still water level and wave height at the shore, the magnitude and duration of these components, and the timing of their interaction. Secondly, we consider recovery times in the system against periods of quiescence and heightened storm activity on this coast. Thirdly, it has been argued that future changes in extreme water level will be governed by mean sea level rise. Long-term rates of North Norfolk barrier retreat (1.15 m a-1, 1891-2013) have occurred under a regional rate of relative sea level rise over the 20th century of 2.7 ± 0.4 mm a-1 (Lowestoft tide gauge, 1900-2014). If there is a broad correlation between rates of barrier retreat and sea level rise, then recent increases in the rate of regional sea level rise (4.4 ± 1.1 mm a-1, 1993-2011) imply a considerable acceleration in the rate of barrier migration over the remainder of the 21st century.

  16. Comparison of Archean and Phanerozoic granulites: Southern India and North American Appalachians

    NASA Technical Reports Server (NTRS)

    Mcsween, Harry Y., Jr.; Kittleson, Roger C.

    1988-01-01

    Archean granulites at the southern end of the Dharwar craton of India and Phanerozoic granulites in the southern Appalachians of North America share an important characteristic: both show continuous transitions from amphibolite facies rocks to higher grade. This property is highly unusual for granulite terranes, which commonly are bounded by major shears or thrusts. These two terranes thus offer an ideal opportunity to compare petrogenetic models for deep crustal rocks formed in different time periods, which conventional wisdom suggests may have had different thermal profiles. The salient features of the Archean amphibolite-to-granulite transition in southern India have been recently summarized. The observed metamorphic progression reflects increasing temperature and pressure. Conditions for the Phanerozoic amphibolite-to-granulite transition in the southern Appalachians were documented. The following sequence of prograde reactions was observed: kyanite = sillimanite, muscovite = sillimanite + K-feldspar, partial melting of pelites, and hornblende = orthopyroxene + clinopyroxene + garnet. The mineral compositions of low-variance assemblages in mafic and intermediate rocks are almost identical for the two granulite facies assemblages. In light of their different fluid regimes and possible mechanisms for heat flow augmentation, it seems surprising that these Archean and Phanerozoic granulite terranes were apparently metamorphosed under such similar conditions of pressure and temperature. Comparison with other terrains containing continuous amphibolite-to-granulite facies transitions will be necessary before this problem can be addressed.

  17. Recent trends in Sea ice in the southern and western Baltic and the North Sea

    NASA Astrophysics Data System (ADS)

    Holfort, Jürgen; Schmelzer, Natalija; Schwegmann, Sandra

    2016-04-01

    We analyzed sea ice charts and observations of a 50 year long period starting in 1961 to produce two climatological ice atlases, one for the western and southern Baltic and one for the German Bight and Limfjord. As the year to year variability is large we subdivided the 50 year into three overlapping 30 year periods (1961-1990, 1971-2000 and 1981-2010) to look for trends in the sea ice. In the southern and western Baltic as well as in the North Sea there was a clear decrease in the total frequency of ice occurrence. Other parameters like begin and end of the ice season, ice thickness, etc. did not show such clear signal and also showed larger regional differences. The ice conditions mainly changed in accordance with the changes in air temperature in the same period, although some more regional changes in some parameters were most probably also influenced by other factors like the deepening of fairways.

  18. Characterization of Phaeocystis globosa (Prymnesiophyceae), the blooming species in the Southern North Sea

    NASA Astrophysics Data System (ADS)

    Rousseau, Véronique; Lantoine, François; Rodriguez, Francisco; LeGall, Florence; Chrétiennot-Dinet, Marie-Josèphe; Lancelot, Christiane

    2013-02-01

    Despite significant research dedicated to the marine genus Phaeocystis, which forms large blooms in the coastal waters of the Southern North Sea, some aspects of the taxonomy and biology of this species still suffer from a sketchy knowledge. It is currently admitted that P. globosa is the species that blooms in the Southern North Sea. This has however, never been confirmed by SSU rDNA sequencing which constitutes nowadays, together with the morphology of the haploid flagellate, a reliable taxonomic criterion to distinguish between Phaeocystis species. Also, although the fine morphology of the haploid scaly flagellate is well known, there is a lack of comparable and harmonized description of the other cell types, i.e. colonial cells and diploid flagellates, previously identified within the Phaeocystis life cycle. In this study, we used SSU rDNA sequencing, light and electron scanning microscopy and flow cytometry to identify and characterize three cell types produced in controlled and reproducible manner from two strains of Phaeocystis isolated from the Belgian coastal zone. Our morphometry and sequencing data confirm unambiguously that P. globosa is the species that blooms in the Southern North Sea, but suggest in addition that both strains are representative of the original P. globosa Scherffel. Our study compares, for the first time since the species description, the fine morphometry and ploidy features of diploid colonial cells, diploid and haploid flagellates originating from same strains, providing therefore unambiguous identification criteria for distinguishing them from each other. The diploid stage, colonial or flagellated cell, is thus characterized by a naked surface, has a size range nearly twice that of the haploid flagellate and do not produce the chitinous filaments specific of the haploid stage. Colonial cells lack flagella and haptonema but possess on their apical side two appendages, which elongate to form the flagella of the diploid flagellate.

  19. Quantification of tertiary exhumation in the United Kingdom southern North Sea using sonic velocity data

    SciTech Connect

    Hillis, R.R.

    1995-01-01

    Sonic velocities from the Upper and Middle Chalk (Upper Cretaceous), the Bunter Sandstone and the Bunter Shale (both Lower Triassic) were used to independently quantify apparent exhumation (height above maximum burial depth) in the United Kingdom (UK) southern North Sea. Apparent exhumation is the displacement, on the depth axis, of a given velocity/depth trend from the normal (unaffected by exhumation) trend. Apparent exhumation results derived from the Upper and Middle Chalk, the Bunter Sandstone, and the Bunter Shale are statistically similar. The consistency of results from carbonate and clastic units suggests that, at a formational and regional scale, over-compaction (i.e., anomalously high sonic velocity) in all three units analyzed reflects previously greater burial depth, rather than sedimentological and/or diagenetic processes, and validates the use of lithologies other than shale in maximum burial depth studies. The consistency of results from units of Early Triassic to Late Cretaceous age suggests that Tertiary exhumation was of sufficiently great magnitude to mask any earlier Mesozoic periods of exhumation, and the maximum Mesozoic-Cenozoic burial depth in the southern North Sea was attained prior to Tertiary exhumation. The proposed magnitudes of exhumation are generally greater than those previously published for the southern North Sea, but they are consistent with recent estimates from apatite fission track analysis. Cretaceous-Tertiary burial prior to exhumation must have been of great magnitude and more rapid than suggested by the preserved stratigraphy. The effect of this extra burial and subsequent exhumation on sedimentary rock decompaction procedure and thermal maturation modeling is illustrated for the Cleethorpes-1 and 44/7-1 wells, and must also be incorporated in modeling reservoir diagenesis. The regional, Tertiary tectonic uplift associated with exhumation must have had a thick-skinned origin.

  20. Basin-edge diapirism and updip salt flow in Zechstein of southern North Sea

    SciTech Connect

    Jenyon, M.K.

    1985-01-01

    Some unusual and interesting structural geometries have been recognized on seismic lines recorded in the United Kingdom sector of the southern Permian basin of the North Sea. They seem to be the result of diapirism at the northern edge of the (Upper Permian) Zechstein salt basin, and involve the preservation of a 75 km (47 mi) long prism of a younger Mesozoic sequence replaced elsewhere by the widespread Jurassic/Cretaceous late Kimmerian unconformity. It is suggested that the diapiric features described are due to the movement of salt toward the basin edge having been dammed by a change in facies from basinal halite to shelf lithologies over a short distance.

  1. Basin-edge diapirism and updip salt flow in Zechstein of southern North Sea

    SciTech Connect

    Jenyon, M.K.

    1985-12-01

    Some unusual and interesting structural geometries have been recognized on seismic lines recorded in the United Kingdom sector the southern Permian basin of the North Sea. They seem to be the result of diapirism at the northern edge of the (Upper Permian) Zechstein salt basin, and involve the preservation of a 75 km (47 mi) long prism of a younger Mesozoic sequence replaced elsewhere by the widespread Jurassic/Cretaceous late Kimmerian unconformity. It is suggested that the diapiric features described are due to the movement of salt toward the basin edge having been dammed by a change in facies from basinal halite to shelf lithologies over a short distance. 13 figures.

  2. A simulation of the Southern North Sea in comparison with measurements from the North Sea Project. Part 1: Temperature

    NASA Astrophysics Data System (ADS)

    Holt, Jason T.; James, Ian D.

    1999-06-01

    The accurate simulation of the annual cycle and vertical structure of temperature is crucial to biological and water quality modelling in shelf-seas. As a precursor to these applications, we present a three-dimensional baroclinic simulation of the southern North Sea at the time of the North Sea Project (NSP), with density controlled by a prognostically evolving temperature field forced by surface heat fluxes from bulk formulae. The model results are compared, on a point for point basis, with CTD data from the NSP. The annual cycles in mean temperature, mean surface to bed temperature difference and mean thermocline depth, and the extent of the summer stratification are found to be in good agreement. Overall, the correlation between modelled and observed temperature is r2=0.95 for the depth mean component and r2=0.64 for the depth varying component. The rms deviation is about 1 degree. We assess the sources of these errors and the performance of the Mellor-Yamada level 2.5 turbulence closure as implemented in this model.

  3. Dimethylsulfoniopropionate (DMSP) cell quota of key Southern North Sea spring diatoms and Phaeocystis globosa.

    NASA Astrophysics Data System (ADS)

    Speeckaert, Gaëlle; Gypens, Nathalie; Lancelot, Christiane; Borges, Alberto V.

    2015-04-01

    Dimethylsulfide (DMS) in the ocean results of complex transformations of dimethylsulfoniopropionate (DMSP) produced by phytoplankton under different controls, including microbial transformation pathways. The phytoplankton composition is an important factor of variability due to the species dependence of the DMSP production and conversion to DMS. To better appraise the link between phytoplankton diversity and the DMS(P) cycling in the Southern North Sea we present measurements of the DMSP cell quota of key spring phytoplankton species (Skeletonema costatum, Thalassiosira rotula, Rhizosolenia delicatula, Asterionella glacialis, Nitzschia closterium, Chaetoceros debilis, Chaetoceros socialis and Phaeocystis globosa) isolated from the North Sea and maintained in non-limiting and axenic laboratory culture conditions. Results are discussed with regards to literature data and hypothesis currently used in DMS(P) biogeochemical models.

  4. Modelling survival and connectivity of Mnemiopsis leidyi in the southern North Sea and Scheldt estuaries

    NASA Astrophysics Data System (ADS)

    van der Molen, J.; van Beek, J.; Augustine, S.; Vansteenbrugge, L.; van Walraven, L.; Langenberg, V.; van der Veer, H. W.; Hostens, K.; Pitois, S.; Robbens, J.

    2014-06-01

    Three different models were applied to study the reproduction, survival and dispersal of Mnemiopsis leidyi in the Scheldt estuaries and the southern North Sea: a high-resolution particle tracking model with passive particles, a low resolution particle tracking model with a reproduction model coupled to a biogeochemical model, and a dynamic energy budget (DEB) model. The results of the models, each with its strengths and weaknesses, suggest the following conceptual situation: (i) the estuaries possess enough retention capability to keep an overwintering population, and enough exchange with coastal waters of the North Sea to seed offshore populations; (ii) M. leidyi can survive in the North Sea, and be transported over considerable distances, thus facilitating connectivity between coastal embayments; (iii) under current climatic conditions, M. leidyi may not be able to reproduce in large numbers in coastal and offshore waters of the North Sea, but this may change with global warming - however this result is subject to substantial uncertainty. Further quantitative observational work is needed on the effects of temperature, salinity and food availability on reproduction and on mortality at different life stages to improve models such as used here.

  5. Reduced North Atlantic Deep Water flux to the glacial Southern Ocean inferred from neodymium isotope ratios

    PubMed

    Rutberg; Hemming; Goldstein

    2000-06-22

    The global circulation of the oceans and the atmosphere transports heat around the Earth. Broecker and Denton suggested that changes in the global ocean circulation might have triggered or enhanced the glacial-interglacial cycles. But proxy data for past circulation taken from sediment cores in the South Atlantic Ocean have yielded conflicting interpretations of ocean circulation in glacial times--delta13C variations in benthic foraminifera support the idea of a glacial weakening or shutdown of North Atlantic Deep Water production, whereas other proxies, such as Cd/Ca, Ba/Ca and 231Pa/230Th ratios, show little change from the Last Glacial Maximum to the Holocene epoch. Here we report neodymium isotope ratios from the dispersed Fe-Mn oxide component of two southeast Atlantic sediment cores. Both cores show variations that tend towards North Atlantic signatures during the warm marine isotope stages 1 and 3, whereas for the full glacial stages 2 and 4 they are closer to Pacific Ocean signatures. We conclude that the export of North Atlantic Deep Water to the Southern Ocean has resembled present-day conditions during the warm climate intervals, but was reduced during the cold stages. An increase in biological productivity may explain the various proxy data during the times of reduced North Atlantic Deep Water export. PMID:10879531

  6. Comparisons of The Habitat Utilization Of Top Predators In The Southern Ocean And The North Pacific

    NASA Astrophysics Data System (ADS)

    Costa, D. P.; Robinson, P.; Huckstadt, L. E.; Crocker, D. E.; Goebel, M. E.

    2010-12-01

    Northern and Southern elephant seals (Mirounga angustirostris, M. leonina) separated some 4 MYA. While these congeners are physiologically very similar and thus have the potential to forage in similar ways they inhabit very different habitats. While southern elephant seals (SES) are distributed throughout the southern ocean, northern elephant seals (NES) are limited to the Northeast Pacific Ocean and range over lower latitudes than SES. In order to compare and contrast the physiological capability and response to different habitats we compared the foraging behavior of 167 adult female northern elephant seals (Año Nuevo and San Benitos Islands) and 55 southern elephant seals (Livingston Island, Antarctic Peninsula) using satellite telemetry and dive recorders. As expected both species carried out very similar dive depths (NES 509m ± 166 vs SES 345m±79) and dive durations (NES 23.0 min ± 6.7; SES 22.5 min ± 5.0). However, there were significant differences in their foraging pattern that we attribute to differences in the availability of continental shelf and suitable foraging habitat. While 85% of NES females foraged offshore, the dominant strategy for SES was benthic foraging on the continental shelf. Even with the differences in habitat, the fundamental components of their foraging patterns remained the same as when they foraged pelagically they both species relied on persistent large scale oceanographic features where mixing enhances productivity such as the North Pacific Transition zone (NES) and the Southern Antarctic Circumpolar Current Front (SES). Given the very different habitats and prey species consumed by these two species their overall foraging behavior is surprisingly similar suggesting that as a mesopelagic predator the elephant seal design is rather robust.

  7. Relating Cenozoic North Sea sediments to topography in southern Norway: The interplay between tectonics and climate

    NASA Astrophysics Data System (ADS)

    Anell, Ingrid; Thybo, Hans; Stratford, Wanda

    2010-11-01

    About 482 000 km 3 of sediment (ca 24 m/Ma) accumulated in the North Sea during the Cenozoic. Early Cenozoic sedimentation was likely due to uplift of the circum North Atlantic landmasses related to continental break-up. Kilometre-scale transient uplift, and in some areas permanent uplift, generated sources for progradational influx of clastic sediments from Scotland, the Shetland platform and, to a lesser degree, southwestern Norway. The Eocene sedimentation pattern was similar to the Palaeocene, with lower rates of accumulation associated with flooding and tectonic quiescence. Sediment influx from the Shetland platform continued throughout the Cenozoic while supply from southern Norway increased markedly around the Eocene-Oligocene, coeval with the greenhouse-icehouse transition. Mass balance calculations of sediment and eroded rock volumes suggest that while some topography along the western margin of Norway may be pre-Cenozoic, significant uplift of the main Paleic surface in southern Norway occurred around the early Oligocene. Sedimentation rates were almost ten-fold higher than the Cenozoic average in the Plio-Pleistocene, slightly higher than the global average. Mass balance calculations indicate that Plio-Pleistocene erosion over-deepened a pre-existing topography.

  8. Offshore Windfarm Impact on Pelagic Primary Production in the Southern North Sea

    NASA Astrophysics Data System (ADS)

    Slavik, Kaela; Zhang, Wenyan; Lemmen, Carsten; Wirtz, Kai

    2016-04-01

    As society struggles to find solutions to mitigate global warming, the demand for renewable energy technology has increased. Especially investment in offshore wind energy has proliferated in the European Union, with projections over the next 15 years estimating an over 40 fold increase in total offshore wind electricity. Though built with the goal of reducing the environmental impacts associated with traditional energy production, the long-term ecological impacts of offshore windfarm structures is not yet well understood. The consequences are of particular importance in the southern North Sea, where the expansion of offshore windfarms is focused. Our study investigates how the gradual accumulation of epifaunal biomass on submerged substrate at offshore windfarms impacts ecosystem services in the southern North Sea. Biofouling is governed predominately by the filter feeder Mytilus edulis, which, as an ecological engineer, will further alter the surrounding benthic and pelagic environment. We reconstruct the distribution of benthic filter feeders in the SNS and generate scenarios of increased potential distribution based on available information of Mytilus edulis settlement at turbines and of turbine locations. These maps are coupled through the MOSSCO (Modular Coupling System for Shelves and Coasts) to state-of-the-art and high resolution hydrodynamic and ecosystem models. We find a substantial change in pelagic primary production as a result of additional Mytilus edulis growth at offshore windfarms.

  9. Tertiary Sequences And Quaternary Glacial Sediments Of The Southern North Sea, Europe

    NASA Astrophysics Data System (ADS)

    Hermann, K.; Lutz, R.; Christoph, G.; Ruediger, L.; Michael, W.

    2004-12-01

    The southern North Sea with a focus on the German exclusive economic zone was surveyed by multichannel seismic (airgun) and shallow seismic (boomer and sparker). The seismic lines, with their special focus on the shallow subsurface, complement data sets of varying quality of scientific (e.g., 2D seismic and wells of the EC Southern North Sea Project) and commercial origin (2D/3D seismic and wells of hydrocarbon exploration). The different data sets were integrated in a digital interpretation system. Interpretation was supported by numerous shallow (6 m) cores targeted at key sites. On a large scale, key reflectors are mapped below and above the prominent Middle Miocene unconformity leading to a better understanding of the prograding Eridanos delta throughout the Tertiary. Also a first subdivision of the Quaternary sequence has been achieved. The most prominent structures in the shallow subsurface are widespread ramified subglacial valleys of likely Elsterian age (~400 kyr BP), which can be up to 400 m deep and which generally have a complex infill. Another prominent feature is a shallow depression of the sea floor starting NW of Heligoland and spanning far north into Danish waters. This elongated depression ("Elbe-Urstromtal" Figge, 1980) is interpreted to be eroded by periglacial rivers running southward and westward of the ice sheet. On a regional scale, some studied 3D-seismic volumes allow the identification of more subtle structures in time slices like widespread iceberg keel scours and ice sheet scours. Also remnants of the morphology of the glacial landscapes seem to be preserved represented by contrasting seismic facies of patchy, rough moraines and more uniform planes. The planes are incised by up to 4 intersecting systems of gullies, channels, and valleys that are of supposed fluvial and subglacial origin. Recurrent seismic anomalies with exceptional high amplitudes may indicate shallow gas in subsurface sediments.

  10. Holocene Pacific - North American plate interaction in southern Alaska: implications for the Yakataga seismic gap.

    USGS Publications Warehouse

    Lahr, J.C.; Plafker, G.

    1980-01-01

    The St. Elias, Alaska, earthquake (magnitude 7.1 MS) on February 28, 1979, occurred along the complex Pacific-North American plate boundary between Yakutat Bay and Prince William Sound, rupturing only a fraction of the seismic gap identified in that region. To aid in evaluating the potential for, and likely site of, a future earthquake occurring in the remainder of the gap, we have formulated a kinematic model of neotectonic deformation in southern Alaska from available geologic and seismic data. In this model the part of the North American plate bordering on the Gulf of Alaska is divided into three subblocks, which are partially coupled to the Pacific plate. On the basis of the model, the gap-filling rupture or ruptures would most likely be along the north-dipping thrust faults of the Pamplona zone between Icy Bay and the eastern end of the Aleutian Trench. If the accumulated strain of 3.8 m postulated for this region were released suddenly in one event involving the remainder of the gap, the result would be an earthquake as large as magnitude 8. -Authors

  11. Salt-influenced structures in the mesozoic-tertiary cover of the southern North Sea, U.K.

    SciTech Connect

    Coward, M.; Stewart, S.

    1996-12-31

    A structural model encompassing the southern North Sea Basin west of the Central Graben has been developed that combines gravity gliding of the postsalt cover with basement tectonics. The basin differs from many salt basins in that it forms a closed system. Section construction and balancing through the cover of the North Sea need to take into account thin-skinned and thick-skinned extensions and contractions. The North Sea salt formed in Permian time in two large oval basins separated by the Mid North Sea High. The shape of these basins reflects variable patterns of thermal subsidence. Subsequent salt tectonics was governed by local graben structures and by regional uplift and subsidence. Rifting initiated during the Triassic and allowed reactive and locally passive diapirs to develop in the post-salt cover. In the southern North Sea, the Dowsing graben system in the cover is offset from the Dowsing fault zone below the salt. This offset in extensional structures probably relates to the salt thickness and to the position of the surface hinge line that controlled the onset of gravity gliding in the postsalt section. Gravity gliding of the cover into the Triassic-Jurassic Sole Pit trough and away from zones of rift flank uplift was associated with Late Jurassic-Early Cretaceous extension in the Central North Sea; gliding caused asymmetric compressional pillows to develop downslope. Gravity spreading of the cover during the Late Cretaceous-early Tertiary was associated with tilting during thermal subsidence of the southern North Sea Basin, enhanced by pulses of tectonic inversion in the southern North Sea basement. The resultant glide tectonics formed new small grabens upslope and compressional pillows downslope. Where the compressional pillows were eroded sufficiently or faulted later, the salt broke through the thinned cover to produce new active and then passive diapirs, which drained the pillows to produce new rim synclines.

  12. Early arrival of Southern Source Water in the deep North Atlantic prior to Heinrich event 2

    NASA Astrophysics Data System (ADS)

    Gutjahr, Marcus; Lippold, JöRg

    2011-06-01

    The Atlantic Meridional Overturning Circulation (AMOC) plays an important role in the Northern Hemisphere climate system. Significant interest went into the question of how excessive freshwater input through melting of continental ice can affect its overturning vigor and, hence, heat supply, to higher northern latitudes. Such forcing can be tested by investigating its behavior during extreme iceberg discharge events into the open North Atlantic during the last glacial period, the so-called Heinrich events (HE). Here we present neodymium (Nd) isotope compositions of past seawater, a sensitive chemical water mass tag, extracted from sediments of Ocean Drilling Program Site 1063 in the western North Atlantic (Bermuda Rise), covering the period surrounding HE 2, the Last Glacial Maximum, and the early deglaciation. These data are compared with a record of the kinematic circulation tracer (231Pa/230Th)xs extracted from the same sediment core. Both tracers indicate significant circulation changes preceding intense ice rafting during HE 2 by almost 2 kyr. Moreover, the Nd isotope record suggests the presence of deeply ventilating North Atlantic Deep Water early during Marine Isotope Stage 2 until it was replaced by Southern Source Water at ˜27 ka. The early switch to high (Pa/Th)xs and radiogenic ɛNd in relation to intensified ice rafting during HE 2 suggests that ice rafting into the open North Atlantic during major HE 2 was preceded by an early change of the AMOC. This opens the possibility that variations in AMOC contributed to or even triggered the ice sheet instability rather than merely responding to it.

  13. Abandoned mine shafts and levels in the British coalfields

    NASA Astrophysics Data System (ADS)

    Davies, Christopher S.

    1988-07-01

    Industrial dereliction is a concern to all societies. In the United Kingdom the British government is trying to make its abandoned coalfields more attractive to new industry through a combination of land reclamation and job incentive programs. The most ambitious of these projects occurs in the South Wales Coalfield, which records 200 years of land defilement and the highest unemployment amplitudes in mainland Britain. In returning this area to a semblance of its previous state, problems arise over how best to fill and cap the many derelict pit shafts and abandoned shallow mines that riddle this region. This analysis reports on the methods of treatment used to achieve this end, along with the procedures used to minimize ground subsidence, water pollution, noxious gas emission, and the potential for physical injury. These environmental controls have application to the United States and Western Europe, where pockets of industrial blight are also symptomatic of a troubled local economy.

  14. Siting of USArray Seismic Stations in North Carolina and southern Virginia: Experience of NC-1 Team

    NASA Astrophysics Data System (ADS)

    Martin, P.; Howard, J.; Horne, T.

    2012-12-01

    The USArray component of the EarthScope, a transportable array of 400 seismometers installed in a grid about 70 km apart, is in the next two years entering its final stage with station deployment along the Atlantic coast of the United States. Here, we present the experience of the student-faculty team from North Carolina Central University (NCCU) in finding and documenting the suitable sites for the twenty five USArray stations in North Carolina and southern Virginia. The ideal sites are easily accessible yet far from traffic and other sources of noise, with good cell phone coverage, sun exposure and out of flood-prone areas. Although the initial selection of potential locations was done using geospatial mapping and analysis software provided by EarthScope, finding and finalizing the sites involved driving more then 1,000 miles each week for over two months inspecting possible site locations. Aside from driving, the majority of time was spent talking about the EarthScope project and hosting of USArray stations to mostly reluctant landowners. In addition to facing various challenges in finding appropriate sites due to land use issues, such as suburban sprawl of central North Carolina, or topography factors, such as low lying flood prone coastal areas, by far the major challenge was finding the landowners willing to host the seismic station for the necessary three years. In addition to involving students from an HBCU in seismology related project and increasing the visibility of NCCU geophysics program in the University and local community through publicity releases in local media and on university web site, the project had an important outreach component. As North Carolina is located along the seismically quiet, passive Atlantic margin, most residents are not familiar with earthquakes and seismology and the siting experience provided students an opportunity to practice explaining the earthquake research to the general public. The dialog also highlighted science

  15. Surface Forcing from CH4 at the North Slope of Alaska and Southern Great Plains Sites

    NASA Astrophysics Data System (ADS)

    Collins, W.; Feldman, D.; Turner, D. D.

    2014-12-01

    Recent increases in atmospheric CH4 have been spatially heterogeneous as indicated by in situ flask measurements and space-borne remote-sensing retrievals from the AIRS instrument, potentially leading to increased radiative forcing. We present detailed, specialized measurements at the DOE ARM North Slope of Alaska (NSA) and Southern Great Plains (SGP) sites to derive the time-series of both CH4 atmospheric concentrations and associated radiative implications at highly-contrasting natural and anthropogenic sources. Using a combination of spectroscopic measurements, in situ observations, and ancillary data for the atmospheric thermodynamic state from radiosondes and cloud-clearing from active sounders, we can separate out the contribution of CH4 to clear-sky downwelling radiance spectra and its infrared surface forcing. The time-series indicates year-to-year variation in shoulder season increases of CH4 concentration and forcing at NSA and large signals from anthropogenic activity at SGP.

  16. A model for tides and currents in the English Channel and southern North Sea

    USGS Publications Warehouse

    Walters, Roy A.

    1987-01-01

    The amplitude and phase of 11 tidal constituents for the English Channel and southern North Sea are calculated using a frequency domain, finite element model. The governing equations - the shallow water equations - are modifed such that sea level is calculated using an elliptic equation of the Helmholz type followed by a back-calculation of velocity using the primitive momentum equations. Triangular elements with linear basis functions are used. The modified form of the governing equations provides stable solutions with little numerical noise. In this field-scale test problem, the model was able to produce the details of the structure of 11 tidal constituents including O1, K1, M2, S2, N2, K2, M4, MS4, MN4, M6, and 2MS6.

  17. North american--pacific relative plate motion in southern california from interferometry.

    PubMed

    Lyzenga, G A; Golombek, M P

    1986-09-12

    Very long baseline interferometry measurements of baselines crossing the San Andreas fault zone in southern California have provided observational constraints on rates of elastic tectonic strain accumulation. The single site located near this fault (the Jet Propulsion Laboratory site) moves in a direction concordant with the Pacific plate motion vector but at approximately half the net rate relative to North America. This motion agrees approximately in amount with geologically determined displacement rates on the San Andreas fault alone but not with the local strike of the fault. When considered together with complementary geodetic data, these results suggest a complex relation between the short-term accumulation of elastic strain and its permanent accommodation on existing faults. PMID:17756870

  18. Priority volatile organic compounds in surface waters of the southern North Sea.

    PubMed

    Huybrechts, Tom; Dewulf, Jo; Van Langenhove, Herman

    2005-01-01

    The occurrence of 25 volatile organic compounds (VOCs) was studied from April 1998 to October 2000 in the southern North Sea. Target VOCs were selected from lists of priority pollutants for the marine environment and included, e.g., chlorinated short-chain hydrocarbons (CHCs), monocyclic aromatic hydrocarbons (MAHs), and chlorinated monocyclic aromatic hydrocarbons (CMAHs). Water samples were taken from the Channel, the Belgian Continental Shelf, the mouth of the Scheldt estuary and the Southern Bight, and were analysed by purge-and-trap and high-resolution gas chromatography-mass spectrometry. All data were produced by analyses deemed 'in control' by a rigorous quality assurance/quality control program provided by QUASIMEME (Quality Assurance of Information for Marine Environmental Monitoring in Europe). Chloroform and trichloroethene were commonly detected at concentrations up to 1900 and 270 ng l(-1), respectively. The other CHCs were generally found below 5 ng l(-1), and rarely exceeded 10 ng l(-1). Concentrations of MAHs were at least one order of magnitude higher than those of the CHCs. The higher levels were attributed to anthropogenic emissions from oil-related activities in coastal areas. CMAHs, except chlorobenzene and 1,4-dichlorobenzene, were hardly detected in North Sea waters. The levels of several CHCs and MAHs were shown to decrease compared to previous investigations in 1994-1995, probably as a result of on-going emission reduction efforts. The occurrence of 1,1,1-trichloroethane, for instance, was substantially reduced since the Montreal Protocol was implemented in 1995. PMID:15519456

  19. Anisotropy from SKS splitting across the Pacific-North America plate boundary offshore southern California

    NASA Astrophysics Data System (ADS)

    Ramsay, Joseph; Kohler, Monica D.; Davis, Paul M.; Wang, Xinguo; Holt, William; Weeraratne, Dayanthie S.

    2016-07-01

    SKS arrivals from ocean bottom seismometer (OBS) data from an offshore southern California deployment are analyzed for shear-wave splitting. The project involved 34 OBSs deployed for 12 months in a region extending up to 500 kilometers west of the coastline into the oceanic Pacific plate. The measurement process consisted of removing the effects of anisotropy using a range of values for splitting fast directions and delay times to minimize energy along the transverse seismometer axis. Computed splitting parameters are unexpectedly similar to onland parameters, exhibiting WSW-ENE fast polarization directions and delays between 0.8 and 1.8 s, even for oceanic plate sites. This is the first SKS splitting study to extend across the entire boundary between the North America and Pacific plates, into the oceanic part of the Pacific plate. The splitting results show that the fast direction of anisotropy on the Pacific plate does not align with absolute plate motion (APM), and they extend the trend of anisotropy in southern California an additional 500 km west, well onto the oceanic Pacific plate. We model the finite strain and anisotropy within the asthenosphere associated with density-buoyancy driven mantle flow and the effects of APM. In the absence of plate motion effects, such buoyancy driven mantle flow would be NE-directed beneath the Pacific plate observations. The best-fit patterns of mantle flow are inferred from the tomography-based models that show primary influences from foundering higher-density zones associated with the history of subduction beneath North America. The new offshore SKS measurements, when combined with measurements onshore within the plate boundary zone, indicate that dramatic lateral variations in density-driven upper mantle flow are required from offshore California into the plate boundary zone in California and western Basin and Range.

  20. Southern Ocean forcing of the North Atlantic at multi-centennial time scales in the Kiel Climate Model

    NASA Astrophysics Data System (ADS)

    Martin, Torge; Park, Wonsun; Latif, Mojib

    2015-04-01

    Internal multi-centennial variability of open ocean deep convection in the Atlantic sector of the Southern Ocean impacts the strength of the Atlantic Meridional Overturning Circulation (AMOC) in the Kiel Climate Model. The northward extent of Antarctic Bottom Water (AABW) strongly depends on the state of Weddell Sea deep convection. The retreat of AABW results in an enhanced meridional density gradient that drives an increase in the strength and vertical extent of the North Atlantic Deep Water (NADW) cell. This shows, for instance, as a peak in AMOC strength at 30°N about a century after Weddell Sea deep convection has ceased. The stronger southward flow of NADW is compensated by an expansion of the North Atlantic subpolar gyre and an acceleration of the North Atlantic Current, indicating greater deep water formation. Contractions of the North Atlantic subpolar gyre enable warm water anomalies, which evolved in response to deep convection events in the Southern Ocean, to penetrate farther to the north, eventually weakening the AMOC and closing a quasi-centennial cycle. Gyre contractions are accompanied by increases in sea level of up to 20 cm/century in some areas of the North Atlantic. In the Southern Ocean itself, the heat loss during the convective regime results in a sea surface height decrease on the order of 10 cm/century, with a maximum of 30 cm/century in the Weddell Sea. Hence, the impact of the Southern Ocean Centennial Variability (SOCV) on regional as well as North Atlantic sea level is of the same order of magnitude as the rise of global average sea level during the 20th century, which amounts to about 15-20 cm. This suggests that internal variability on a centennial time scale cannot be neglected a priori in assessments of 20th and 21st century AMOC and regional sea level change.

  1. Long-term variability of the southern Adriatic circulation in relation to North Atlantic Oscillation

    NASA Astrophysics Data System (ADS)

    Shabrang, L.; Menna, M.; Pizzi, C.; Lavigne, H.; Civitarese, G.; Gačić, M.

    2016-02-01

    The interannual variability of the South Adriatic Gyre and its relation to the wind vorticity and the large-scale climatic pattern (North Atlantic Oscillation - NAO) was studied using the time series of satellite altimetric data and ocean surface wind products. The cyclonic circulation observed in the southern Adriatic area was partly sustained by the local wind forcing, as suggested by the positive correlation between the rate of change of the current vorticity and the wind-stress vorticity. Nevertheless, the influence of vorticity advection from the adjacent area (northern Ionian Sea) cannot be ignored and it is more significant during the anticyclonic phase of Adriatic-Ionian Bimodal Oscillation System. The geostrophic current vorticities of the southern Adriatic and northern Ionian seas are correlated with a time lag of 14 months, which approximately corresponds to an advection speed of ˜ 1 cm s-1. The different wind patterns observed during two NAO phases in the winter revealed a stronger positive vorticity during the negative NAO phase. Conversely, during the wintertime positive NAO phase the wind vorticity is characterized by lower positive or slightly negative values. Despite a statistically significant negative correlation between the NAO index and the wind vorticity, no unequivocal relationship between large climatic system and the interannual variability of the South Adriatic Gyre intensity was found due to additional effects of the vorticity advection from the Ionian. This can be explained by the fact that the Ionian circulation mode does not depend on the NAO variations. Therefore, the main result of this study is that the interannual variability of the southern Adriatic cyclonic circulation is a result of the combined influence of the vorticity advection from the Ionian and the local wind-curl effect.

  2. "Narrow and Filthy Alleys of the City?": The Residential Settlement Patterns of Black Southern Migrants to the North.

    ERIC Educational Resources Information Center

    Tolnay, Stewart E.; Crowder, Kyle D.; Adelman, Robert M.

    2000-01-01

    Analysis of the 1970 Neighborhood Characteristics Public Use Microdata Sample indicates that recent (1965-70) southern Black migrants to the North resided in the "best" neighborhoods (less poverty, segregation, and family instability), while earlier Black migrants lived in the worst neighborhoods. Recent migrants also received the greatest…

  3. Participatory Research in North America; A Perspective on Participatory Research in Latin America; Participatory Research in Southern Europe.

    ERIC Educational Resources Information Center

    Gaventa, John; And Others

    1988-01-01

    The authors present perspectives on the employment of participatory research techniques in three areas: (1) North America (Gaventa); (2) Latin America (de Souza); and (3) Southern Europe (Orefice). Discussion focuses on participatory research strategies for popular groups, purposes and considerations regarding participatory research, and the role…

  4. Integrated pest management of the southern green stinkbug, Nezara viridula (Hemiptera: Pentatomidae) on tomato in North Florida

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Southern Green Stinkbug, Nezara viridula is a serious insect pest of tomatoes in north Florida. We evaluated three trap crops and three refuge crops to investigate their potential for IPM of N. viridula. The experimental trap crops and refuge crops were, striped sunflower, WGF sorghum and brown ...

  5. Species assemblages of pelagic fish embryos in the southern North Sea between 1984 and 2000

    NASA Astrophysics Data System (ADS)

    von Westernhagen, Hein; Dethlefsen, Volkert; Bade, Tim; Wosniok, Werner

    2002-02-01

    The occurrence and abundance of the pelagic eggs of southern North Sea spring-spawning fish were analysed between 1984 and 2000. Species number varied between six (1986) and 14 (1999) and was positively correlated with sea surface temperature. With one exception, dab eggs were always the most abundant and usually highly dominant. Ranking of species depended on temperature, but no significant differences in ranking between years was discernible. Although with the increase in temperature in the 1990s a change in species assemblage was evident [species belonging to the boreal-Mediterranean (Lusitanian) group became more apparent in the species assemblage] this did not lead to an increased species diversity (Shannon Index) or a change in other community parameters. It appears that the recent developments regarding spawning stock biomass of commercial North Sea fish is reflected in the declining egg abundance of the respective commercial and larger species (i.e. cod, flounder, plaice) and an increase in abundance of the eggs of small species (i.e. long rough dab, rockling) over the years.

  6. Are the birch trees in Southern England a source of Betula pollen for North London?

    NASA Astrophysics Data System (ADS)

    Skjøth, C. A.; Smith, M.; Brandt, J.; Emberlin, J.

    2009-01-01

    Birch pollen is highly allergenic. Knowledge of daily variations, atmospheric transport and source areas of birch pollen is important for exposure studies and for warnings to the public, especially for large cities such as London. Our results show that broad-leaved forests with high birch tree densities are located to the south and west of London. Bi-hourly Betula pollen concentrations for all the days included in the study, and for all available days with high birch pollen counts (daily average birch pollen counts >80 grains/m3), show that, on average, there is a peak between 1400 hours and 1600 hours. Back-trajectory analysis showed that, on days with high birch pollen counts ( n = 60), 80% of air masses arriving at the time of peak diurnal birch pollen count approached North London from the south in a 180 degree arc from due east to due west. Detailed investigations of three Betula pollen episodes, with distinctly different diurnal patterns compared to the mean daily cycle, were used to illustrate how night-time maxima (2200-0400 hours) in Betula pollen counts could be the result of transport from distant sources or long transport times caused by slow moving air masses. We conclude that the Betula pollen recorded in North London could originate from sources found to the west and south of the city and not just trees within London itself. Possible sources outside the city include Continental Europe and the Betula trees within the broad-leaved forests of Southern England.

  7. Advection of North Atlantic Deep Water from the Labrador Sea to the southern hemisphere

    NASA Astrophysics Data System (ADS)

    Rhein, Monika; Kieke, Dagmar; Steinfeldt, Reiner

    2015-04-01

    Recently formed Labrador Seawater (LSW) and overflow water from Denmark Strait (DSOW) are main components of the Atlantic Meridional Overturning Circulation. Both exhibit a distinct chlorofluorocarbon (CFC) maximum. Here we use 25 years of CFC observations in the Atlantic to study the main features of the circulation of LSW and DSOW. From the CFC data, the age and fraction of young deep water are inferred. Due to the superior spatial data resolution compared to former attempts, regional differences in the spreading velocity and pathways of young deep water become evident, dependent on the regional circulation. The observed distributions of young LSW and DSOW showed that the DWBC is the fastest pathway to reach the southern hemisphere. The downstream decrease of the fractions of young LSW in the DWBC is slower compared to model studies. From 47°N to 42°N, DWBC transports of young LSW and DSOW decrease by 44% and 49%, respectively. At 26°N, the DWBC transport of young water is still 39% of the LSW formation rate and 44% of the DSOW overflow transport. Interior pathways also exist, especially in the subpolar North Atlantic and in the transition zone between the subpolar and subtropical gyre. Compared to DSOW, the distributions indicate a higher tendency for LSW to follow additional interior pathways. North of 45°N the major part of LSW is younger than 20 years. The general weakening of new LSW formation since the 1990s worked toward a homogenization between the LSW in the western and the eastern subpolar North Atlantic.

  8. Interannual sedimentary effluxes of alkalinity in the southern North Sea: Model results compared with summer observations.

    NASA Astrophysics Data System (ADS)

    Paetsch, Johannes; Kuehn, Wilfried; Six, Katharina

    2016-04-01

    Alkalinity generation in the sediment of the southern North Sea is the focus of several recent studies. One motivation for these efforts is the potentially enhanced buffering capacity of anthropogenic CO2 invasion into the corresponding pelagic system. An adaptation of a global multilayer sediment model (Heinze et al., 1999) in combination with a pelagic ecosystem model for shelf sea dynamics was used to study the benthic reactions on very different annual cycles (2001 - 2009) including the River Elbe summer flooding in 2002. The focus of this study is the efflux of alkalinity, their different contributors (aerobic respiration, denitrification, net sulfate reduction, calcite dissolution, nitrification) and their seasonal and interannual cycles. Similar to the observations covering the southern North Sea (Brenner et al., 2015) the model results show large horizontal gradients from the near-shore high productive areas with benthic remineralization up to Rmin = 10.6 mol C m‑2 yr‑1 and TA generation RTA = 2 mol C m‑2 yr‑1 to off-shore moderate productive areas with mean Rmin = 2.5 mol C m‑2 yr‑1 and mean TA generation RTA = 0.4 mol C m‑2 yr‑1. Beside calcite dissolution, aerobic respiration (producing ammonium) and denitrification are the largest contributors to alkalinity generation. Nitrification is reducing alkalinity in the sediment. Due to low regenerated primary production in summer, the year 2001 exhibits the lowest input of particulate organic matter into the sediment (POCexp=2.3 mol C m‑2 yr‑1), while the year 2003 exhibits the highest export production (POCexp=2.6 mol C m‑2 yr‑1). The biogeochemical reactions and the effluxes from the sediment follow these pelagic amplitudes with a time lag of about one year with damped amplitudes. References Brenner, H., Braeckman, U., Le Guitton, M., Meysman, F.J.R., 2015. The impact of sedimentary alkalinity release on the water column CO2 system in the North Sea. Biogeosiences Discussion, 12

  9. Benthic remineralisation rates in southern North Sea - from point measurements to areal estimates

    NASA Astrophysics Data System (ADS)

    Neumann, Andreas; Friedrich, Jana; van Beusekom, Justus; Naderipour, Céline

    2015-04-01

    The southern North Sea is enclosed by densely populated hinterland with intensive use by agriculture and industry and thus substantially affected by anthropogenic influences. As a coastal subsystem, this applies especially to the German Wadden Sea, a system of back-barrier tidal flats along the whole German Bight. Ongoing efforts to implement environmental protection policies during the last decades changed the significance of various pollutants such as reactive nitrogen or phosphate, which raises the desire for constant monitoring of the coastal ecosystem to assess the efficiency of the employed environmental protection measures. Environmental monitoring is limited to point measurements which thus have to be interpolated with appropriate models. However, existing models to estimate various sediment characteristics for the interpolation of point measurements appear insufficient when compared with actual field measurements in the southern North Sea. We therefore seek to improve these models by identifying and quantifying key variables of benthic solute fluxes by comprehensive measurements which cover the complete spatial and seasonal variability. We employ in-situ measurements with the eddy-correlation technique and flux chambers in combination with ex-situ incubations of sediment cores to establish benthic fluxes of oxygen and nutrients. Additional ex-situ measurements determine basic sediment characteristics such as permeability, volumetric reaction rates, and substrate concentration. With our first results we mapped the distribution of measured sediment permeability, which suggest that areas with water depth greater than 30 m are impervious whereas sediment in shallower water at the Dogger Bank and along the coast is substantially permeable with permeability between 10-12 m2 and 10-10 m2. This implies that benthic fluxes can be estimated with simple diffusion-type models for water depths >30 m, whereas estimates especially for coastal sediments require

  10. Pliocene palaeotemperature reconstruction for the southern North Sea Based on Ostracoda

    NASA Astrophysics Data System (ADS)

    Wood, A. M.; Whatley, R. C.; Cronin, T. M.; Holtz, T.

    The development of a large northeastern Atlantic shelf ostracod database has confirmed that an intrinsic relationship exists between watermass temperature and the spatial (latitudinal) distribution of benthonic shelf Ostracoda. A second Pliocene ostracod database, using assemblages from four boreholes in The Netherlands and a number of localities from the East Anglian Neogene succession has also been constructed. A quantitative method of modern analogues and the Squared Chord Distance dissimilarity coefficient has been employed as a means of calculating the level of similarity between Recent and Neogene assemblages and, therefore, to aid in the reconstruction of palaeotemperatures in the southern North Sea Basin during the Pliocene. The results, in the form of contoured dissimilarity values, indicate the presence of at least seven palaeoceanographical climatic phases between ca. 5.2 and 1.6 Ma BP. An early Pliocene cooling phase (ecozone A), in which the fauna is dominated by the cryophilic species; Palmenella limicola (Norman), Elofsonella concinna (Jones), Robertsonites tuberculatus (Sars), Neomonoceratina tsurugasakensis (Tabuki) and Acanthocythereis dunelmensis (Norman), supervenes a period of stable subtropical conditions in the Miocene. A 'mid' Pliocene warming phase (ecozone B), which has been documented throughout the North Atlantic, can be recognized in the faunal composition of the sublittoral ostracod assemblages of both The Netherlands and East Anglia. A hiatus between the Coralline and Waltonian crags is thought to be associated with a deterioration in climatic conditions. Recent analogues to The Netherlands faunas of ecozone C (first phase late Pliocene cooling, ca. 2.9 Ma BP) indicate a decrease of approximately 5-6°C in mean summer surface temperatures. A return to elevated temperatures, of a Mauritanian aspect, can be seen in the fauna of the FA2 zone and Waltonian Crag. This amelioration of climate occurred prior to the Praetiglian cold phase

  11. Learning to Labour: Elementary Education in the Leicestershire and South Derbyshire Coalfields c. 1840-1870.

    ERIC Educational Resources Information Center

    Griffin, Colin

    2002-01-01

    Discusses education issues in 1840-1870 for children of coalfield workers. Focuses on the Leicestershire and Derbyshire (England) coalfield children. Describes gender education strategies, mining legislation that considered youth as a labor source, and coalmine owners' goal to produce an educated workforce. States education had positive effects on…

  12. Evolution and genesis of permafrost peatlands in southern limit of cryolithozone in Europen North-East

    NASA Astrophysics Data System (ADS)

    Pastukhov, Alexander; Kaverin, Dmitry; Marchenko-Vagapova, Tatiana

    2015-04-01

    The North-East of the European part of Russia is currently experiencing a degradation of permafrost due to climate warming. Permafrost peat plateaus extending only about 20% of the territory contain almost 50% of stocks of soil organic carbon (Pastukhov & Kaverin, 2013). Currently in the region extreme southern limit of the permafrost zone with permafrost temperature 0 ... -1 ° C is the far north taiga. Sporadic island permafrost is preserved only in peat plateaus, which are an ideal object for assessing climate change impacts in the event of further thawing of permafrost. On the basis of the macrofossil, palynological and 14C data of peat, Holocene evolution and current state of permafrost peatlands were studed in the extreme southern limit of the East European Cryolithozone. Palynological and radiocarbon data provides evidence of the start of peat accumulation in the early Holocene, about 8000 years ago, in the late Boreal (BO-2). Then the accumulation of peat first significantly slowed down, and then almost stopped between 2500-850 years ago. I.e. about 2500 years ago permafrost was aggradated, which manifested itself in the heave of peatland mounds and a sharp decline in peat accumulation due to dry conditions in raised surface peat. There was the formation of permafrost peat plateaus of modern appearance. Fens occurred from the late-modern Subatlantic (SA-3-SA-R) Holocene period, i.e. after the Little Ice Age and the beginning of the small climatic optimum (about 850 years ago), when the permafrost partially degraded, and formed non-permafrost sphagnum bogs. At the same time (SA-3-SA-R), the gradual and slower peat accumulation proceeded. Vegetation of peat mounds prevents permafrost thawing in the current climate warming. As mounds surface dry out, lichens succeed mosses and bare peat circles are formed. But dry peat has higher insulating properties and prevents from further thawing. Thawing of permafrost peatlands starting from the surface occurs only as

  13. Grassland vegetation and bird communities in the southern Great Plains of North America

    USGS Publications Warehouse

    Chapman, R.N.; Engle, David M.; Masters, R.E.; Leslie, David M., Jr.

    2004-01-01

    Structure and composition of vegetation and abundance of breeding birds in grasslands seeded to Old World bluestem (Bothriochloa ischmaeum) were compared to native mixed prairie in the southern Great Plains of North America. Abundance of birds was determined using fixed-radius point counts. Detrended correspondence analysis was used to compare plant community composition and canonical correspondence analysis was used to examine the relationships between plant species composition and vegetation structure with the bird community. Plant species composition differed distinctly between seeded grassland and native mixed prairie, but the differences were not reflected in habitat structure, bird community composition, or abundance of bird species. Seeded grassland was inferior to native mixed prairie in terms of diversity of plant species, but that difference did not translate into meaningful differences in structure that drove habitat selection by breeding birds. Conservation programs that promote establishment of seeded grassland and do not allow for suitable disturbance regimes will selectively benefit a narrow suite of birds regardless of plant species composition. ?? 2004 Elsevier B.V. All rights reserved.

  14. On the formation, ventilation, and erosion of mode waters in the North Atlantic and Southern Oceans

    NASA Astrophysics Data System (ADS)

    Trossman, D. S.; Thompson, L.; Mecking, S.; Warner, M. J.

    2012-09-01

    The mean residence times, subduction rates, and formation rates of Subtropical Mode Water (STMW) and Subpolar Mode Water (SPMW) in the North Atlantic and Subantarctic Mode Water (SAMW) in the Southern Ocean are estimated by combining a model and observations of chlorofluorocarbon-11 (CFC-11) via Bayesian Model Averaging (BMA), a statistical technique that weights model estimates according to how close they agree with observations. Subduction rates are estimated in two different ways to investigate the non-advective contribution to thermocline ventilation, which in turn are compared to formation rate estimates. One subduction rate estimate is based on entrainment/detrainment velocities and the other subduction rate estimate allows ventilation to be both an advective and diffusive process instead of a purely advective one by using transit-time distributions (TTDs). It is found that the subduction of all three mode waters is mostly an advective process, but up to about one-third of STMW subduction likely owes to non-advective processes. Also, while the formation of STMW is mostly due to subduction, the formation of SPMW is mostly due to other processes. About half of the formation of SAMW is due to subduction and half is due to other processes. A combination of air-sea flux, acting on relatively short timescales, and turbulent mixing, acting on a wide range of timescales, is likely the dominant SPMW erosion mechanism. Air-sea flux is likely responsible for most STMW erosion, and turbulent mixing is likely responsible for most SAMW erosion.

  15. Generation of seiches by cold fronts over the southern North Sea

    NASA Astrophysics Data System (ADS)

    de Jong, M. P. C.; Holthuijsen, L. H.; Battjes, J. A.

    2003-04-01

    Seiches affecting the Port of Rotterdam are generated in the Southern North Sea. Their generation is investigated with observations and numerical simulations. A wavelet analysis of the observations, both at sea and in the harbor, shows that low-frequency energy (0.1-2.0 mHz) does indeed occur at sea prior to each seiche event in Rotterdam. An analysis of 6 years of weather charts indicates that all 51 seiche events in this period (with amplitude exceeding 0.25 m) coincided with the passage of a low-pressure weather system. Some of these low-pressure systems included a sharp cold front (classical or ana), whereas others included a more diffuse cold front (split or kata). Numerical simulations with a hydrodynamic model driven by meteorological observations reproduced the seiches for situations with the sharp cold fronts correctly. The seiches that were simulated for situations with the gradual cold fronts do not agree with the observations, which is ascribed to the inadequate atmospheric forcing of the hydrodynamical model.

  16. The impact of coastal defence structures (tetrapods) on decapod crustaceans in the southern North Sea.

    PubMed

    Wehkamp, Stephanie; Fischer, Philipp

    2013-12-01

    Although the use of coastal defence structures is expected to increase, little is known about the ecological impact of such structures on the natural environment. In particular, the temporal and spatial patterns of communities in association with artificial substrate are still poorly understood. This study examined possible effects of experimental tetrapod fields on the decapod crustacean community in a subtidal hard-bottom area in the southern North Sea. We performed in situ studies in the fields and along transects oriented away from the tetrapod fields. Species composition and abundances were assessed before and after the introduction of the artificial material. The study revealed a significant decrease of smaller, less vagile species (Pisidia longicornis, Pilumnus hirtellus, Galathea squamifera) over the entire study area in the years following the tetrapod introduction. For 2 species, Hyas araneus and Homarus gammarus, the tetrapods appeared to be highly attractive as habitat and shelter because their abundance increased over time. No distinct spatial or temporal effects were observed for mobile predatory crabs, such as Cancer pagurus and Liocarcinus spp. The results of the study demonstrate that possible effects of artificial structures on macro-invertebrates in temperate hard-bottom areas are highly species-specific and depend on the size, lifestyle and ecological requirements of the species. This work highlights the importance of long-term studies. Our findings clearly indicate that more time is needed to distinguish between natural and anthropogenic influences on species distributions. PMID:24041979

  17. Late Holocene saltmarsh accretion among sand ridges, West Bay, southern Pamlico Sound, North Carolina

    NASA Astrophysics Data System (ADS)

    Barber, D. C.; Woodson, A. L.; Newbern, E. H.

    2011-12-01

    The ongoing Late Holocene sea-level rise has inundated a series of low (< 2m above sea level) relict sand ridges on Cedar Island, in southern Pamlico Sound on the central North Carolina coast (35.00°N, 76.34°W). The ridges likely represent shorelines formed during a previous (Pleistocene) sea-level highstand by a combination of longshore transport and eolian dune processes. Saltmarsh peat comprising primarily the remains of the high marsh plant Juncus gerardii has accumulated between the ridges, yielding a continuous record of transgression over at least the last 2,000 years. The protected depositional setting between the ridges, the small tidal amplitude (< 25 cm) in southern Pamlico Sound, and the smoothly varying topography of the underlying sand surface provide the opportunity to acquire basal saltmarsh peat samples from a range of elevations for sea-level reconstruction. We obtained cores of the marsh peat and sand deposits using various techniques (hand auger, Russian and dutch peat corers, vibracore) to generate an overview of the stratigraphy in the study area. We visually logged the cores and analyzed samples for organic carbon content, particle size and magnetic susceptibility. In the marsh peat, plant macrofossils were identified and agglutinated foraminiferal assemblages were counted. Saltmarsh foraminifera species identified in the cores include Trochammina inflata, Ammoastuta inepta, Jadammina macrescens, Tiphotroca comprimata and Milliamina fusca. Radiocarbon dates on plant material provide chronological control. Marsh core elevations were referenced to NAVD88 by total station surveys to the NGS benchmark on Cedar Island. We have acquired marsh cores as deep as 3.25 m below local mean sea level (MSL), but thus far the deepest saltmarsh peat sample found to contain saltmarsh foraminifera is from 2.16 m below MSL. The marsh deposits are laterally consistent in the upper 1.5 m of core transects, but minor downcore variations in organic content

  18. Analyses and descriptions of geochemical samples, central part of the Southern Nantahala Wilderness, Rabun and Towns Counties, Georgia, and Clay and Macon Counties, North Carolina

    SciTech Connect

    Adrian, B.M.; Peper, J.D.; Fairfield, R.J.; Laudon, L.S.; Edwards, C.A.

    1989-01-01

    A U.S. Geological Survey report is presented giving analyses and descriptions of geochemical samples, central part of the southern Nantahala Wilderness, Rabun and Towns Counties, Georgia, and Clay and Macon Counties, North Carolina.

  19. Avalonian crustal controls on basin evolution: implications for the Mesozoic basins of the southern North Sea

    NASA Astrophysics Data System (ADS)

    Smit, Jeroen; van Wees, Jan-Diederik; Cloetingh, Sierd

    2015-04-01

    Little is known of the Southern North Sea Basin's (SNSB) Pre-Permian basement due to a lack of outcrop and cores. The nature and structure of the East Avalonian crust and lithosphere remain even less constrained in the absence of deep seismic (refraction) lines. However, various studies have hinted at the importance of the Reactivation of the Early Carboniferous fault network during each consecutive Mesozoic and Cenozoic tectonic phase, demonstrating the key role of weak zones from the Early Carboniferous structural grain in partitioning of structural deformation and vertical basin motions at various scales. Although the older basin history and the basement attract increasing attention, the Pre-Permian tectonics of the SNSB remains little studied with most attention focused on the Permian and younger history. The strong dispersal of existing constraints requires a comprehensive study from Denmark to the UK, i.e. the East Avalonian microplate, bordered by the Variscan Rheïc suture, the Atlantic and Baltica. Based on an extensive literature study and the reinterpretation of publicly available data, linking constraints from the crust and mantle to stratigraphic-sedimentological information, we complement the map of Early Carboniferous rifting of East Avalonia and propose a new tectonic scenario. From the reinterpretation of the boundary between Avalonia and Baltica we propose a new outline for the Avalonian microplate with implications for the tectonics of the North German Basin. Furthermore, we highlight the nature and extent of the major crustal/lithospheric domains with contrasting structural behaviour and the major boundaries that separate them. Results shed light on the effects of long lived differences in crustal fabric that are responsible for spatial heterogeneity in stress and strain magnitudes and zonations of fracturing, burial history and temperature history. The geomechanical control of large crustal-scale fault structures will provide the constraints

  20. A hydrographic time series station in the Wadden Sea (southern North Sea)

    NASA Astrophysics Data System (ADS)

    Reuter, Rainer; Badewien, Thomas H.; Bartholomä, Alexander; Braun, Axel; Lübben, Andrea; Rullkötter, Jürgen

    2009-04-01

    In the tidal inlet between the East Frisian islands of Langeoog and Spiekeroog, southern North Sea, a time-series station was set up in autumn 2002 as part of the research programme BioGeoChemistry of Tidal Flats run by the University of Oldenburg. The purpose of the station is to provide continuous data on physical, biological and chemical parameters. In addition to instruments recording basic hydrographic and meteorological parameters, the time-series station is equipped with acoustic Doppler profilers for measuring surface waves and current profiles. Compact optical spectrometers are being used for spectral measurements of seawater transmission and for daylight reflectance. Additional sensors were installed for measuring oxygen, nutrients and methane in the seawater. The data shall help to quantify the flux of dissolved and suspended matter between the backbarrier tidal flat and the open sea and to characterise the material transformation in the tidal flat area by biogeochemical processes over the tidal cycle. Due to its novel design, operation of the station is also possible during winter and under extreme weather conditions (gales, storm surges, and sea ice) when data sampling with conventional platforms such as research vessels, buoys, or smaller poles could not be performed in the past. In this way, time series of data are obtained, which include events that are most relevant to the evolution of this coastal area. The performance of the station and its equipment are presented with data covering 6 years of operation. Time series of air and water temperature as well as seawater salinity demonstrate the multiyear dynamics of these parameters in the East Frisian Wadden Sea. Hydrographic data collected under specific meteorological conditions such as gales and storm surges exemplify the all-weather capabilities of the station and its value for studying hydrographic processes in the Wadden Sea.

  1. Acoustic bottom detection and seabed classification in the German Bight, southern North Sea

    NASA Astrophysics Data System (ADS)

    Bartholomä, Alexander

    2006-09-01

    To investigate the hydrodynamic activity of the seabed in the German Bight, underwater remote sensing was carried out over an area of 32 km2 located 20 km northeast of Helgoland island in the southern North Sea in January, May and August 2001. On the basis of acoustic seabed classification, six seabed types have been identified by the combined evaluation of side-scan sonar records, wave-shape analysis of echo-sounder data, and 100 grab samples. In five seabed types, the acoustic classes can be distinguished on the basis of sediment characteristics, comprising size components ranging from coarse pebbles to fine sand. The sixth seabed type corresponds to large pebbles and cobbles which are completely overgrown with brown algae. Statistically, the complex spatial patchiness of the six classes varied significantly in the course of the study period. During the winter period (January 2001), the study site was dominated by coarse material, except for a small area of finer sediment in the centre. With the onset of more moderate weather conditions in spring (May 2001), a general fining trend in sediment composition was observed, especially in the deeper western parts of the study area. In summer (August 2001), finer sediments still dominated but a slight increase in signal roughness suggests an overprint by coarser lag deposits and/or denser coverage by benthic organisms (e.g. Lanice conchilega) which then were found more frequently in grab samples, in association with finer sand. These findings demonstrate that the distribution of seafloor sediments and their benthic fauna in the deeper part of the German Bight region are controlled largely by seasonal changes in hydrodynamic conditions. These changes are reflected in correspondingly high variability in the complex patchiness of sediment distribution patterns, which would not have been adequately resolved by any standard sampling procedure.

  2. Participatory planning in river catchments, an innovative toolkit tested in Southern Africa and North West England.

    PubMed

    Tippett, J

    2005-01-01

    The European Union Water Framework Directive (WFD) offers an unparalleled opportunity for improving river basin management. Active participation is essential for its delivery. "End-of-pipe" solutions will not deliver the improvements needed to achieve its ambitious goals. This research tested DesignWays, a toolkit for participatory planning, as a mechanism for maximizing the long-term social and environmental benefits of such stakeholder and community participation. It examined the emerging role of "planning for sustainability" in the context of river catchments. Sustainable management of water requires integration, and recognition of interconnections between systems at different levels of scale. This is an endeavour in which systems thinking provides useful tools. The development of DesignWays was a conscious attempt to embed 'new paradigm' living systems metaphors into a practical planning tool. This paper begins with a description of DesignWays and its development in Southern Africa. An outline of the context of the action research in North-West England is followed by a description of the stages of the process, with highlights of the outcomes. This research had two major outcomes: a contribution to theory through an in-depth exploration of the theoretical basis of participatory, ecologically informed design; and a contribution to practice through investigating DesignWays' potential to meet key challenges of the WFD. This research points to the importance of understanding participatory planning as a societal process, aiming to make the process engaging and meaningful. It has pointed to the need to see participatory planning and education for sustainability as an integrated process. It demonstrated the benefits of an iterative process in which planning at the landscape level of scale informs, and is informed by, work at the site level. It has shown that an approach consistent with a living systems paradigm can contribute to the development of more integrated

  3. A discovery of extremely-enriched boehmite from coal in the Junger Coalfield, the northeastern Ordos Basin

    USGS Publications Warehouse

    Dai, S.; Ren, D.; Li, S.; Chou, C.

    2006-01-01

    The authors found an extremely-enriched boehmite and its associated minerals for the first time in the super-thick No. 6 coal seam from the Junger Coalfield in the northeastern Ordos Basin by using technologies including the X-ray diffraction analysis (XRD), scanning electron microscope equipped with an energy dispersive X-ray spectrometer, and optical microscope. The content of boehmite is as high as 13.1%, and the associated minerals are goyazite, zircon, rutile, goethite, galena, clausthalite, and selenio-galena. The heavy minerals assemblage is similar to that in the bauxite of the Benxi Formation from North China. The high boehmite in coal is mainly from weathering crust bauxite of the Benxi Formation from the northeastern coal-accumulation basin. The gibbsite colloidstone solution was removed from bauxite to the peat mire, and boehmite was formed via compaction and dehydration of gibbsite colloidstone solution in the period of peat accumulation and early period of diagenesis.

  4. Response of the western North Atlantic to seasonal variability in the Southern Ocean

    NASA Astrophysics Data System (ADS)

    Ivchenko, V.; Sinha, B.; Wells, N.; Blaker, A.

    2009-04-01

    The huge seasonal variability in Antarctic sea ice distribution and concentration is well known. As a result the air-sea fluxes of heat, freshwater and momentum fluxes are strongly modified seasonally. In this study we conduct two experiments with the NEMO ocean general circulation model at 1 degree horizontal resolution. The first is a control run between January 1989 and December of 1994 forced at the surface by NCEP reanalysis. The second experiment was run for the same period of time as the control run, but all external fluxes from/to the atmosphere south of 30S are replaced by annual mean fluxes. The difference between the two experiments results in anomalies of temperature, salinity and other variables. The anomalies south of 30S are created by differences in the surface fluxes. The anomalies north of 30S are created by the influence of the Southern Ocean (SO) on the northern domain (ND). The SO anomalies can affect the ND in two ways (disregarding possible atmosphere influence): (i) slow propagation of the anomaly signal by currents and turbulence (ii) fast wave-like propagation of the anomaly signal. The propagation speed of such waves could be high. For example the barotropic Rossby waves have a wave speed of about 40 m/s. The results from the experiments show that the anomaly signal starts propagation in the South Atlantic as a barotropic planetary wave, reaching the equator within the first two days and reaching the North Atlantic in a few days. After the wave reflects from the western boundary temperature anomalies (TA) appear quickly, but with very low amplitude. However, the amplitude of the TA increases with time. Maximum values of TA occur in an area adjacent to the coast over the Southeast Newfoundland Rise (SNR). The highest values of TA can be observed after two or three years at depths between 90 and 200m: usually between 0.3 to 0.6C and occasionally even above that, up to 0.8C and 1.0C. Mesoscale patches appear after approx. 5 months with

  5. Rayleigh phase velocities in the upper mantle of the Pacific-North American plate boundary in southern California

    NASA Astrophysics Data System (ADS)

    Escobar, L.; Weeraratne, D. S.; Kohler, M. D.

    2013-05-01

    The Pacific-North America plate boundary, located in Southern California, presents an opportunity to study a unique tectonic process that has been shaping the plate tectonic setting of the western North American and Mexican Pacific margin since the Miocene. This is one of the few locations where the interaction between a migrating oceanic spreading center and a subduction zone can be studied. The rapid subduction of the Farallon plate outpaced the spreading rate of the East Pacific Rise rift system causing it to be subducted beneath southern California and northern Mexico 30 Ma years ago. The details of microplate capture, reorganization, and lithospheric deformation on both the Pacific and North American side of this boundary is not well understood, but may have important implications for fault activity, stresses, and earthquake hazard analysis both onshore and offshore. We use Rayleigh waves recorded by an array of 34 ocean bottom seismometers deployed offshore southern California for a 12 month duration from August 2010 to 2011. Our array recorded teleseismic earthquakes at distances ranging from 30° to 120° with good signal-to-noise ratios for magnitudes Mw ≥ 5.9. The events exhibit good azimuthal distribution and enable us to solve simultaneously for Rayleigh wave phase velocities and azimuthal anisotropy. Fewer events occur at NE back-azimuths due to the lack of seismicity in central North America. We consider seismic periods between 18 - 90 seconds. The inversion technique considers non-great circle path propagation by representing the arriving wave field as two interfering plane waves. This takes advantage of statistical averaging of a large number of paths that travel offshore southern California and northern Mexico allowing for improved resolution and parameterization of lateral seismic velocity variations at lithospheric and sublithospheric depths. We present phase velocity results for periods sampling mantle structure down to 150 km depth along the

  6. Geology of the fushun coalfield, Liaoning Province, People's Republic of China

    USGS Publications Warehouse

    Johnson, E.A.

    1990-01-01

    The Fushun coalfield is located in Liaoning Province 45 km east of Shenyang in a relatively small east-west-trending exposure of Mesozoic and Cenozoic rocks surrounded by Precambrian terrane. The coal is included in a sequence of early Tertiary rocks consisting of Paleocene basalt and tuff, and Eocene coal, oil shale and mudstone. These units have been folded into a syncline that plunges gently to the east. The overturned north limb of this fold has been partly removed by a thrust fault. The principal coal beds are low-sulfur subbituminous and bituminous in rank, are of limnic origin, and are contained in the 55-m-thick Eocene Guchengzi Formation. The field, which has been active since the turn of the century, has both open pit and underground mines. The largest operation is the West Open Pit mine, which measures 2.0 km wide, 6.6 km long, and 300 m deep. Coal is mined by means of power shovels, trucks, and an electric rail system. Oil shale from the Eocene Jijuntun Formation is also mined. ?? 1990.

  7. Making a World of Difference. Dimension: Language '91. Selected Papers from the Joint Meeting of the Southern Conference on Language Teaching and the Foreign Language Association of North Carolina (Research Triangle Park, North Carolina, 1991).

    ERIC Educational Resources Information Center

    Terry, Robert M., Ed.

    Papers from the 1991 joint Southern Conference on Language Teaching (SCOLT)/ Foreign Language Association of North Carolina (FLANC) conference are presented. Because the state of North Carolina is in the forefront of state-mandated foreign language education in the elementary schools (FLES), 4 of the 10 articles in this volume address FLES…

  8. Surface CO 2 measurements in the English Channel and Southern Bight of North Sea using voluntary observing ships

    NASA Astrophysics Data System (ADS)

    Padin, X. A.; Vázquez-Rodríquez, M.; Ríos, A. F.; Pérez, F. F.

    2007-06-01

    Ships of opportunity have been used to investigate ocean-atmosphere CO 2 fluxes in the English Channel and Southern Bight of the North Sea. Continuous underway measurements of the fugacity of seawater carbon dioxide ( fCO 2sw), chlorophyll, temperature and salinity have been performed along 26 transects during the spring and autumn periods. The spatial fCO 2sw distribution along the Channel and Southern Bight is modulated by the photosynthetic activity, temperature changes and water mixing between inputs from the North Atlantic Ocean and riverine discharges. The seasonal variability of fCO 2sw is assessed and discussed in terms of the biology and temperature effects, these having similar impacts. The variation of fCO 2sw shows similar interannual patterns, with lower values in spring. The annual average of air-sea CO 2 fluxes places the English Channel as neutral area of CO 2 uptake. The spring and autumn data allow differentiating between distal and proximal continental areas. The Southern Bight shows a tendency towards net CO 2 uptake on the distal continental shelf, whereas the Scheldt and Thames Plumes show a CO 2 source behaviour on the proximal continental shelves.

  9. Pelagimonas varians gen. nov., sp. nov., isolated from the southern North Sea.

    PubMed

    Hahnke, Sarah; Tindall, Brian J; Schumann, Peter; Simon, Meinhard; Brinkhoff, Thorsten

    2013-03-01

    A heterotrophic, Gram-stain-negative, aerobic bacterium, designated strain SH4-1(T), was obtained from a seawater sample collected from the southern North Sea during a phytoplankton bloom. The 16S rRNA gene sequence comparison revealed affiliation to the Roseobacter clade (class Alphaproteobacteria) with Sulfitobacter marinus SW-265(T) as the most closely related characterized strain, showing 97.2 % 16S rRNA gene sequence similarity. Calculation of phylogenetic trees based on 16S rRNA gene sequences indicated, however, that members of the genus Roseobacter, Roseobacter denitrificans Och 114(T) and Roseobacter litoralis Och 149(T) (95 % and 96 % sequence similarity, respectively) fall between strain SH4-1(T) and the Sulfitobacter cluster including Oceanibulbus indolifex HEL-45(T) (≥95.4 % sequence similarity). Cells of strain SH4-1(T) are irregular rods with at least one flagellum. Optimal growth occurred between 28 and 32 °C and at a pH between 7.0 and 8.5. Cells require the vitamin nicotinic acid amide as well as sodium ions for growth. The DNA G+C content was 55.1 mol%. The fatty acids (>1 %) comprised C10 : 0 3-OH, C12 : 1, C14 : 1 3-OH, C16 : 0, C18 : 0, C18 : 2, C18 : 1ω7c and 11-methyl C18 : 1ω7c. The polar lipid pattern indicated the presence of phosphatidylcholine, phosphatidylglycerol, phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylmonomethylethanolamine, an unidentified aminolipid, one unidentified phospholipid and one other unidentified lipid. On the basis of phenotypic, chemotaxonomic and phylogenetic differences, strain SH4-1(T) represents a novel species in a new genus within the family Rhodobacteraceae, for which we propose the name Pelagimonas varians gen. nov., sp. nov. The type strain of the type species is SH4-1(T) ( = DSM 23678(T) = LMG 26343(T) = CIP 110297(T)). PMID:22611199

  10. A 408 MHz all-sky continuum survey. I - Observations at southern declinations and for the North Polar region

    NASA Astrophysics Data System (ADS)

    Haslam, C. G. T.; Klein, U.; Salter, C. J.; Stoffel, H.; Wilson, W. E.; Cleary, M. N.; Cooke, D. J.; Thomasson, P.

    1981-07-01

    The observation, data reduction and calibration of two large area radio continuum surveys at 408 MHz are described in detail. The resolution of both is close to 0.85 deg. One covers the complete southern sky, the other the north polar regions and, together with existing observations, they form the data-base for the first all-sky continuum survey of better than one degree resolution. Sample maps of astronomical interest are presented and possible uses of the 408 MHz survey are discussed. The full set of maps will appear in a companion all-sky atlas.

  11. Biogeochemical consequences of vertical and lateral transport of particulate organic matter in the southern North Sea: A multiproxy approach

    NASA Astrophysics Data System (ADS)

    Le Guitton, M.; Soetaert, K.; Damsté, J. S. Sinninghe; Middelburg, J. J.

    2015-11-01

    Vertical and lateral transports are of importance in continental shelf systems such as the North Sea and play a major role in the processing of organic matter. We investigated the biogeochemical consequences of these transports on particulate organic matter at the molecular level in the southern North Sea. We analysed suspended particulate matter and surface sediments for organic carbon, pigments and phospholipid derived fatty acids at 10 stations sampled in September 2011 along the particle transport route. The particulate organic matter in both suspended particulate matter and surface sediment was mainly from marine phytoplankton origin but of fresher quality in the water column. Particulate organic matter quality did not change from south to north in the suspended particulate matter, whereas it clearly decreased towards the north in the surface sediments, reflecting a decreased intensity of benthic-pelagic coupling. However, we also observed strong deposition of fresh organic matter in the northern station denoting that occasionally, intense benthic-pelagic coupling can occur. Finally, our study highlights the necessity to use a multiproxy approach covering multiple characteristic time scales, when investigating both suspended particulate matter and surface sediments.

  12. 75 FR 53687 - Southern Montana Electric Generation & Transmission Cooperative, Inc. v. NorthWestern Corporation...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-01

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Southern Montana Electric Generation & Transmission Cooperative, Inc. v... Electric Generation & Transmission Cooperative, Inc. (Complainant) filed a complaint against...

  13. Assessing surface sediment dynamics along the north-west coast of Marsa Dhouiba (Tunisia, southern Mediterranean)

    NASA Astrophysics Data System (ADS)

    Khiari, Nouha; Atoui, Abdelfattah; Brahim, Mouldi; Sammari, Chérif; Charef, Abdelkrim; Aleya, Lotfi

    2016-04-01

    An investigation was conducted from summer 2012 to winter 2013 at 25 stations along the Tunisian coast near Kef Abbed at Marsa Dhouiba (north-east Mediterranean Sea) to analyse grain size, sediment mineralogy and currents. Particle-size analysis shows that sand deposits at shallow depths are characterised by S-shaped curves, indicating a degree of agitation and possible transport by rip currents near the bottom. At greater depths (between 10 and 30 m), the bottom is covered by coarse sand and gravel. A current was observed transporting sediment eastward along the coast; another seaward current was also noted. Generated by wind, swell and especially waves from west to north-west, the two currents transport clay and silt-sized sediment seaward. An Acoustic Doppler Current Profiler showed Marsa Dhouiba's coastal current to follow a direction 175° East, with its main axis running north/north-west parallel to the coast and its minor axis also running north/north-west. Analysis of current components indicates that the velocities u and v are oriented north to south. Sediment evolution in shallow waters is dependent on detrital inputs from streams and winds. The coarse fraction of surface sediments in Marsa Dhouiba presents 87% of total sediments and is located at depths of 10-30 m. Sediment dynamics in the Marsa Dhouiba region are closely related to the west/north-west swell.

  14. ESR dating of Neogene marine sands from the southern North Sea basin, NE Belgium: first results

    NASA Astrophysics Data System (ADS)

    Iacovo, Serena; Jivanescu, Mihaela; Beerten, Koen; Stesmans, Andre; Vandenberghe, Noël

    2013-04-01

    Quantifying Neogene and Quaternary geodynamic processes requires reliable age control on the geological record from which the rate and intensity of these processes are usually derived. The nature and geometry of marine sediments preserved in the southern North Sea basin, NE Belgium, are influenced by geodynamic processes such as tectonic movements and eustatic sea level changes. Yet, the geochronology of these sediments is almost entirely based on micropalaeontological analyses and subsequent correlations with widely accepted geological boundaries. In recent years, the electron spin resonance (ESR) dating method has been applied to buried sediments that range in age between ~ 100 ka and several Ma. The method is based on the measurement of accumulated radiation damage in quartz crystals during burial, and can thus in theory be applied to obtain absolute numerical age control on any quartz-rich sediment given several conditions are met. The most important of these is sunlight bleaching of pre-existing radiation damage prior to burial. In this case study, we present preliminary ESR dating results of three samples from a cored borehole in Miocene glauconite-rich sands, which are biostratigraphically estimated as between 7 Ma and 11 Ma (Tortonian). Following chemical and physical purification of the samples (taken at 107 m, 135 m and 147 m depth), quartz grains (100-200 µm) were irradiated by Co-60 gamma rays to doses between 1-150 kGy. Individual aliquots (each weighting several 100 mg) were measured at cryogenic temperatures in a JEOL X-band ESR spectrometer operating at a microwave frequency of ~ 9.2 GHz. Defect densities were derived by integration of relevant ESR spectra, and making use of a comounted defect density calibrated marker sample. Subsequently, the equivalent dose was calculated using the thus constructed dose curves (including the natural, unirradiated, aliquot). Finally, dose rates were determined using high resolution gamma ray spectrometry in the

  15. Fishing mortality in North Carolina's southern flounder fishery: direct estimates of instantaneous fishing mortality from a tag return experiment

    USGS Publications Warehouse

    Smith, William E.; Scharf, Frederick S.; Hightower, Joseph E.

    2009-01-01

    Estimation of harvest rates is often a critical component of fishery stock assessment and management. These assessments are often based on catch-at-age data sets generated over many years, but estimates of instantaneous fishing mortality (F) can also be obtained from a shorter-term tag return study. We conducted a 2-year tag return experiment to generate direct estimates of F for southern flounder Paralichthys lethostigma in a North Carolina estuary. The southern flounder supports lucrative commercial and recreational fisheries within the state and has experienced heavy fishing pressure for more than a decade. During 2005 and 2006, fish were captured and tagged with the assistance of commercial harvesters in the New River estuary. Tag returns were used to generate monthly estimates of F, which demonstrated a clear seasonal pattern that was consistent between years. Several important assumptions of the tag return model were accounted for through the use of double-tagged individuals, the distribution of both high- and standard-reward tags, and the completion of an independent controlled experiment to evaluate mortality related to tagging. Annual estimates of F exceeded the short-term management target in both years. Residual patterns suggest that the estimates may actually have been biased low, possibly due to delayed mixing of tagged fish. Thus, despite recently amended fishery regulations, F in the North Carolina southern flounder gill-net fishery still has the potential to greatly exceed targeted levels, which may delay stock recovery. Tag return studies can provide reliable (and nearly real-time) information about F and natural mortality as long as the experimental design addresses specific assumptions related to tagging-induced mortality, tag shedding, and nonreporting of tags.

  16. The Effects of Mountaintop Mines and Valley Fills on Aquatic Ecosystems of the Central Appalachian Coalfields (2011 Final)

    EPA Science Inventory

    This report assesses the state of the science on the environmental impacts of mountaintop mines and valley fills (MTM-VF) on streams in the central Appalachian coalfields. These coalfields cover about 48,000 square kilometers (122 million acres) in West Virginia, Kentucky, Virgi...

  17. Evaluation of numerical models by FerryBox and Fixed Platform in-situ data in the southern North Sea

    NASA Astrophysics Data System (ADS)

    Haller, M.; Janssen, F.; Siddorn, J.; Petersen, W.; Dick, S.

    2015-02-01

    FerryBoxes installed on ships of opportunity (SoO) provide high-frequency surface biogeochemical measurements along selected tracks on a regular basis. Within the European FerryBox Community, several FerryBoxes are operated by different institutions. Here we present a comparison of model simulations applied to the North Sea with FerryBox temperature and salinity data from a transect along the southern North Sea and a more detailed analysis at three different positions located off the English East coast, at the Oyster Ground and in the German Bight. In addition to the FerryBox data, data from a Fixed Platform of the MARNET network are applied. Two operational hydrodynamic models have been evaluated for different time periods: results of BSHcmod v4 are analysed for 2009-2012, while simulations of FOAM AMM7 NEMO have been available from MyOcean data base for 2011 and 2012. The simulation of water temperatures is satisfying; however, limitations of the models exist, especially near the coast in the southern North Sea, where both models are underestimating salinity. Statistical errors differ between the models and the measured parameters, as the root mean square error (rmse) accounts for BSHcmod v4 to 0.92 K, for AMM7 only to 0.44 K. For salinity, BSHcmod is slightly better than AMM7 (0.98 and 1.1 psu, respectively). The study results reveal weaknesses of both models, in terms of variability, absolute levels and limited spatial resolution. In coastal areas, where the simulation of the transition zone between the coasts and the open ocean is still a demanding task for operational modelling, FerryBox data, combined with other observations with differing temporal and spatial scales serve as an invaluable tool for model evaluation and optimization. The optimization of hydrodynamical models with high frequency regional datasets, like the FerryBox data, is beneficial for their subsequent integration in ecosystem modelling.

  18. Lung dust and lung iron contents of coal workers in different coalfields in Great Britain

    PubMed Central

    Bergman, I.; Casswell, C.

    1972-01-01

    Bergman, I., and Casswell, C. (1972).Brit. J. industr. Med.,29, 160-168. Lung dust and lung iron contents of coal workers in different coalfields in Great Britain. Lung dust analyses from seven coalfields are studied and it is found that the average dust composition varies significantly with the rank of coal. The higher the rank, the higher the coal percentage and the lower the quartz percentage of the lung dust. This holds for all coalfields except in Scotland, where the lung dust contains mainly soot instead of coal. Samples of airborne dust collected at the coalface in different coalfields show a similar but small variability of composition with rank of coal, and the results from Scotland are in good agreement with the results from other coalfields. The amount of iron in simple pneumoconiosis lungs is related to their mineral and coal contents and to the factor `years underground'. The strongest relationship is with coal and mineral for coalface workers from England. For pit accident cases (all simple pneumoconiosis) mineral is important as well as years underground, while for simple pneumoconiosis cases from Scotland, years underground is the most important factor. PMID:4336667

  19. Miners wives: Gender, culture, and society in the south Wales coalfields, 1919-1939

    SciTech Connect

    Gier, J.J.

    1993-01-01

    This study addresses the absence of historical research on the role of women in Welsh coalfield society through the use of oral history testimony, folk culture sources, literature, newspapers, union records and comparative data from other British and Australian coalfield regions. The thesis identifies the ways in which the domestic ideology and the vernacular culture of coalfield society influenced gender roles and relations in Welsh mining communities during the interwar period. Since the myth of the Miner and the Mining Mam signified the pervasive influence of both the domestic ideology and the vernacular culture, the aim of the study was to dismantle these ideals in order to reconstruct a history of miners' wives. To further this goal a life-cycle approach was used; the thesis examined courtship an marriage practices, domestic culture in the mining household, women's customary role in ritual surrounding birth and death, and their role in mining strikes and other forms of collective action. The study concludes that while the traditions of rural Wales tended to support a broader role for women in coalfield society, the domestic ideology denied the miner's wife her identity as a worker, and thus limited her participation in class struggle and obscured her role in the history of coalfield society.

  20. Renifer aniarum (Digenea: Reniferidae), an introduced North American parasite in grass snakes Natrix natrix in Calabria, southern Italy.

    PubMed

    Santoro, Mario; Tkach, Vasyl V; Mattiucci, Simonetta; Kinsella, John M; Nascetti, Giuseppe

    2011-07-12

    Over the past decades, as a result of various human activities involving intentional or unintentional movement of animals, many helminth species have been introduced to new regions with several ecological and epidemiological implications for the native species. A high prevalence of infection with an introduced digenean Renifer aniarum, previously known only from North America, was found in the grass snake Natrix natrix in the Calabria region, southern Italy. Morphological and molecular comparison with North American R. aniarum has confirmed the identity of the Italian specimens. A total of 41 grass snakes were studied for R. aniarum infection. Of 24 snakes sampled between 2009 and 2010, 22 were positive for this parasite. In contrast, all 17 snakes sampled from museum collections between 1983 and 1994 were negative. Our results support the hypothesis that R. aniarum was perhaps introduced into this area during the 1990s by the translocation of the American bullfrog Lithobates (Rana) catesbeianus, a normal second intermediate host of the digenean in its native range in North America. Although the life cycle of R. aniarum is complex and includes 3 host stages, this parasite has found suitable first and second intermediate hosts as well as definitive hosts in Italy. Renifer aniarum was second only to the very common grass snake tapeworm Ophiotaenia europaea in both prevalence and abundance among 9 species of helminths recovered in our study. PMID:21932535

  1. Map showing structural control of breccia pipes on the southern Marble Plateau, north-central Arizona

    SciTech Connect

    Sutphin, H.B.; Wenrich, K.J.

    1988-01-01

    Solution collapse breccia pipes, concentrated throughout the southwestern corner of the Colorado Plateau in Arizona, have been mapped in detail on the southern Marble Plateau. Within the study area, 77 of the 90 (86%) collapse structures fall within northwest-trending and northeast-trending zones that cover only 23% of the total surface area.

  2. Southern Cordilleran Basaltic Andesite suite, southern Chihuahua, Mexico: A link between Tertiary continental arc and flood basalt magmatism in the North America

    SciTech Connect

    Cameron, K. L.; Nimz, G. J.; Kuentz, D.; Niemeyer, S.; Gunn, S.

    1989-06-10

    Mid-Cenozoic orogenic andesites and ignimbrites of western Mexico, southwestern New Mexico, and Arizona are commonly capped by basaltic andesites, most from 29--20 Ma. We refer to these mafic lavas as the Southern Cordilleran Basaltic Andesite (SCORBA) suite, and they may constitute the most extensive Cenozoic basaltic suite in North America. The SCORBA suite has trace element and isotopic characteristics of orogenic (arc) rocks (i.g., Ba/Nb/gt/40), and silica content (53--56% SiO/sub 2/) like the Grande Ronde Basalt, which represents about 80% of the volume of the Columbia River Group. Geochemical and isotopic data are presented on SCORBA lavas and rare mafic lavas (PRE-SCORBA) interlayered with older ignimbrites from a 700-km-long NE-SW transect of southern Chihuahua, Mexico. SCORBA and PRE-SCORBA lavas with relatively low K/P (/lt/7) and differing Ba/Nd (50 versus 18) have similar isotopic compositions, arguing against their isotopic signatures being controlled by crustal assimilation. Along the entire length of the transect, the basaltic rocks have /var epsilon//sub Nd/ and /sup 87/Sr//sup 86/Sr near bulk Earth and /sup 206/Pb//sup 204/Pb and /sup 207/Pb//sup 204/Pb ratios that lie along a 1.7 Ga pseudoisochron. The Pb isotopic variation is geographically controlled, becoming more radiogenic from east to west, reflecting mixing in mantle source regions. The eastern mantle source has low/sup 206/Pb//sup 204/Pb and is a mixture of an enriched, enriched-mantle-like (EMI) component with one or more depleted components, which could include an intraplate component with relatively high Nb/Y (/gt/0.8).

  3. Improved intersection design and monitoring in the Sydney Coalfield

    SciTech Connect

    Corbett, G.R.; Payne, D.A.

    1995-11-01

    The introduction of roof bolts to Phalen Colliery in the Sydney Coalfield, Nova Scotia (annual output of 2Mt) has been successfully implemented in maingate and tailgate entries over the last four years. Monitoring of the roof bolted areas continues to be an integral part of the quality control program as the results are utilized to maintain safety and to aid in long-term design strategies. Although all gateroads in the Phalen Colliery have converted to roof bolts as their primary means of support, the majority of intersections which intersect the main slopes remain supported by large steel structures. Several intersections within the Phalen Colliery were monitored as they were created by the mining process. A comparison is made between intersections supported with only traditional 6.4 to 6.7 m steel structure and intersections supported by 2.44 m fully resin encapsulated roof bolts in conjunction with 7.6 m fully cement grouted cable bolts. Detailed monitoring was conducted using CANMET`s intrinsically safe sonic probe extensometers data logger which has the ability to read up to sixteen probes simultaneously at programmed intervals. The density of the data from the data logger has allowed a better understanding of the deformation of cable bolted intersections than was possible with manual monitoring. Test results have helped mine operators to design safer cable bolted intersections.

  4. First field identification of the Cuonadong dome in southern Tibet: implications for EW extension of the North Himalayan gneiss dome

    NASA Astrophysics Data System (ADS)

    Fu, Jiangang; Li, Guangming; Wang, Genhou; Huang, Yong; Zhang, Linkui; Dong, Suiliang; Liang, Wei

    2016-07-01

    The Cuonadong dome exposes in east-southern margin of the North Himalayan gneiss domes (NHGD), which is reported first time in this study. The Cuonadong dome is located at the southern part of the Zhaxikang ore concentration area, which is divided into three tectono-lithostratigraphic units by two curved faults around the dome geometry from upper to lower (or from outer to inner): the upper unit, middle unit and lower unit, and the outer fault is Nading fault, while the inner fault is Jisong fault. The Cuonadong dome is a magmatic orthogneiss and leucogranite mantled by orthogneiss and metasedimentary rocks, which in turn are overlain by Jurassic metasedimentary and sedimentary rocks. The grades of metamorphism and structural deformation increase towards the core, which is correspondence with the Ridang Formation low-metamorphic schist, tourmaline granitic-biotite gneiss, garnet-mica gneiss and mylonitic quartz-mica gneiss. The Cuonadong dome preserves evidences for four major deformational events: firstly top-to-S thrust (D1), early approximately N-S extensional deformation (D2), main approximately E-W extensional deformation (D3), and late collapse structural deformation (D4) around the core of the Cuonadong dome, which are consistent to three groups lineation: approximately N-S-trending lineation including L1 and L2, E-W trending L3, and L4 with plunging towards outside of the dome, respectively. The formation of the Cuonadong dome was probably resulted from the main E-W extensional deformation which is a result of eastward flow of middle or lower crust from beneath Tibet accommodated by northward oblique underthrusting of Indian crust beneath Tibet. The establishment of the Cuonadong dome enhanced the E-W extension of the NHGD, which is further divided into two structural dome zones according to the different extensional directions: approximately N-S extensional North Himalayan gneiss domes (NS-NHGD) and E-W extensional North Himalayan gneiss domes (EW

  5. Paleomagnetic studies of Carboniferous and Permian in the U. K. Southern North Sea: Core orientation, paleocurrent analysis, and diagenetic application

    SciTech Connect

    Turner, P. ); Hartley, A.J. )

    1991-03-01

    The U.K. southern North Sea is a major gas province with production from Carboniferous and Permian reservoirs. It was a foreland basin in Carboniferous times uplifted to form a Lower Permian desert basin and subsequently deeply buried during the Mesozoic. Paleomagnetic methods have been used for burial analysis, core orientation, and paleocurrent studies. VRM is shown to be of only limited value for core orientation; problems relating to drilling effects and deflection by ChRM will be discussed. Detailed thermal demagnetization studies are most valuable. Blocking temperature spectra can be related to burial history curves, and ChRM directions isolated and compared with Carboniferous and Permian reference directions. ChRM is a valuable parameter for core orientation and thus paleocurrent studies. Examples will be shown from the Carboniferous and Lower Permian.

  6. Prospects for use of lean caking coal from the Kuznetsk coalfield for coking

    SciTech Connect

    Sulimov, G.I.; Agafonov, A.A.; Ol'shanetskii, L.G.

    1983-01-01

    The coals from the Kuznetsk Coalfield were investigated under laboratory and pilot-plant conditions and compared with coals of various rank from the Anzhero Coalfield. The coals from the South of the Kuzbass have a more favorable petrographic composition than the Anzhero coals; their volatile matter depends on the rank; the caking capacity is low; the plastic layer is not measured, and the swelling index is also low. The lean coal types are coked in charges containing Kuznetsk and Pechora coal. The criterion for evaluation of the coking capacity was the coke mechanical strength indices, obtained during testing in the large grate drum. 1 figure, 4 tables.

  7. Evaluation of numerical models by FerryBox and fixed platform in situ data in the southern North Sea

    NASA Astrophysics Data System (ADS)

    Haller, M.; Janssen, F.; Siddorn, J.; Petersen, W.; Dick, S.

    2015-11-01

    For understanding and forecasting of hydrodynamics in coastal regions, numerical models have served as an important tool for many years. In order to assess the model performance, we compared simulations to observational data of water temperature and salinity. Observations were available from FerryBox transects in the southern North Sea and, additionally, from a fixed platform of the MARNET network. More detailed analyses have been made at three different stations, located off the English eastern coast, at the Oyster Ground and in the German Bight. FerryBoxes installed on ships of opportunity (SoO) provide high-frequency surface measurements along selected tracks on a regular basis. The results of two operational hydrodynamic models have been evaluated for two different time periods: BSHcmod v4 (January 2009 to April 2012) and FOAM AMM7 NEMO (April 2011 to April 2012). While they adequately simulate temperature, both models underestimate salinity, especially near the coast in the southern North Sea. Statistical errors differ between the two models and between the measured parameters. The root mean square error (RMSE) of water temperatures amounts to 0.72 °C (BSHcmod v4) and 0.44 °C (AMM7), while for salinity the performance of BSHcmod is slightly better (0.68 compared to 1.1). The study results reveal weaknesses in both models, in terms of variability, absolute levels and limited spatial resolution. Simulation of the transition zone between the coasts and the open sea is still a demanding task for operational modelling. Thus, FerryBox data, combined with other observations with differing temporal and spatial scales, can serve as an invaluable tool not only for model evaluation, but also for model optimization by assimilation of such high-frequency observations.

  8. Seismic structure of the southern Cascadia subduction zone and accretionary prism north of the Mendocino triple junction

    USGS Publications Warehouse

    Gulick, S.P.S.; Meltzer, A.M.; Clarke, S.H., Jr.

    1998-01-01

    Four multichannel-seismic reflection profiles, collected as part of the Mendocino triple junction seismic experiment, image the toe of the southern Cascadia accretionary prism. Today, 250-600 m of sediment is subducting with the Gorda plate, and 1500-3200 m is accreting to the northern California margin. Faults imaged west and east of the deformation front show mixed structural vergence. A north-south trending, 20 km long portion of the central margin is landward vergent for the outer 6-8 km of the toe of the prism. This region of landward vergence exhibits no frontal thrust, is unusually steep and narrow, and is likely caused by a seaward-dipping backstop close to the deformation front. The lack of margin-wide preferred seaward vergence and wedge-taper analysis suggests the prism has low basal shear stress. The three southern lines image wedge-shaped fragments of oceanic crust 1.1-7.3 km in width and 250-700 m thick near the deformation front. These wedges suggest shortening and thickening of the upper oceanic crust. Discontinuities in the seafloor west of the prism provide evidence for mass wasting in the form of slump blocks and debris fans. The southernmost profile extends 75 km west of the prism imaging numerous faults that offset both the Gorda basin oceanic crust and overlying sediments. These high-angle faults, bounding basement highs, are interpreted as strike-slip faults reactivating structures originally formed at the spreading ridge. Northeast or northwest trending strike-slip faults within the basin are consistent with published focal mechanism solutions and are likely caused by north-south Gorda-Pacific plate convergence. Copyright 1998 by the American Geophysical Union.

  9. Seismic structure of the southern Cascadia subduction zone and accretionary prism north of the Mendocino triple junction

    NASA Astrophysics Data System (ADS)

    Gulick, Sean P. S.; Meltzer, Anne M.; Clarke, Samuel H., Jr.

    1998-11-01

    Four multichannel-seismic reflection profiles, collected as part of the Mendocino triple junction seismic experiment, image the toe of the southern Cascadia accretionary prism. Today, 250-600 m of sediment is subducting with the Gorda plate, and 1500-3200 m is accreting to the northern California margin. Faults imaged west and east of the deformation front show mixed structural vergence. A north-south trending, 20 km long portion of the central margin is landward vergent for the outer 6-8 km of the toe of the prism. This region of landward vergence exhibits no frontal thrust, is unusually steep and narrow, and is likely caused by a seaward-dipping backstop close to the deformation front. The lack of margin-wide preferred seaward vergence and wedge-taper analysis suggests the prism has low basal shear stress. The three southern lines image wedge-shaped fragments of oceanic crust 1.1-7.3 km in width and 250-700 m thick near the deformation front. These wedges suggest shortening and thickening of the upper oceanic crust. Discontinuities in the seafloor west of the prism provide evidence for mass wasting in the form of slump blocks and debris fans. The southernmost profile extends 75 km west of the prism imaging numerous faults that offset both the Gorda basin oceanic crust and overlying sediments. These high-angle faults, bounding basement highs, are interpreted as strike-slip faults reactivating structures originally formed at the spreading ridge. Northeast or northwest trending strike-slip faults within the basin are consistent with published focal mechanism solutions and are likely caused by north-south Gorda-Pacific plate convergence.

  10. Mapping total suspended matter from geostationary satellites: a feasibility study with SEVIRI in the Southern North Sea.

    PubMed

    Neukermans, Griet; Ruddick, Kevin; Bernard, Emilien; Ramon, Didier; Nechad, Bouchra; Deschamps, Pierre-Yves

    2009-08-01

    Geostationary ocean colour sensors have not yet been launched into space, but are under consideration by a number of space agencies. This study provides a proof of concept for mapping of Total Suspended Matter (TSM) in turbid coastal waters from geostationary platforms with the existing SEVIRI (Spinning Enhanced Visible and InfraRed Imager) meteorological sensor on the METEOSAT Second Generation platform. Data are available in near real time every 15 minutes. SEVIRI lacks sufficient bands for chlorophyll remote sensing but its spectral resolution is sufficient for quantification of Total Suspended Matter (TSM) in turbid waters, using a single broad red band, combined with a suitable near infrared band. A test data set for mapping of TSM in the Southern North Sea was obtained covering 35 consecutive days from June 28 until July 31 2006. Atmospheric correction of SEVIRI images includes corrections for Rayleigh and aerosol scattering, absorption by atmospheric gases and atmospheric transmittances. The aerosol correction uses assumptions on the ratio of marine reflectances and aerosol reflectances in the red and near-infrared bands. A single band TSM retrieval algorithm, calibrated by non-linear regression of seaborne measurements of TSM and marine reflectance was applied. The effect of the above assumptions on the uncertainty of the marine reflectance and TSM products was analysed. Results show that (1) mapping of TSM in the Southern North Sea is feasible with SEVIRI for turbid waters, though with considerable uncertainties in clearer waters, (2) TSM maps are well correlated with TSM maps obtained from MODIS AQUA and (3) during cloud-free days, high frequency dynamics of TSM are detected. PMID:19654812

  11. Air temperature change in the northern and southern tropical Andes linked to North-Atlantic stadials and Greenland interstadials

    NASA Astrophysics Data System (ADS)

    Urrego, Dunia H.; Hooghiemstra, Henry

    2016-04-01

    We use eight pollen records reflecting climatic and environmental change from northern and southern sites in the tropical Andes. Our analysis focuses on the signature of millennial-scale climate variability during the last 30,000 years, in particular the Younger Dryas (YD), Heinrich stadials (HS) and Greenland interstadials (GI). We identify rapid responses of the vegetation to millennial-scale climate variability in the tropical Andes. The signature of HS and the YD are generally recorded as downslope migrations of the upper forest line (UFL), and are likely linked to air temperature cooling. The GI1 signal is overall comparable between northern and southern records and indicates upslope UFL migrations and warming in the tropical Andes. Our marker for lake level changes indicates a north to south difference that could be related to moisture availability. The direction of air temperature change recorded by the Andean vegetation is consistent with millennial-scale cryosphere and sea surface temperature records from the American tropics, but suggests a potential difference between the magnitude of temperature change in the ocean and the atmosphere.

  12. Institutional Research in Emerging Countries of Southern Africa, Latin America, and the Middle East and North Africa: Global Frameworks and Local Practices

    ERIC Educational Resources Information Center

    Lange, Lis; Saavedra, F. Mauricio; Romano, Jeanine

    2013-01-01

    This chapter presents a synthesis of the conceptualization and practice of institutional research (IR) in higher education (HE) in emerging countries across Southern Africa, Latin America and the Middle East and North Africa (MENA) regions. The chapter contextualizes the growing need for IR in these regions, identifies problems and challenges…

  13. The Practice of Institutional Research. Proceedings of a Joint Conference of the Southern Association for Institutional Research and the North Carolina Association for Institutional Research (Charlotte, North Carolina, October 29-30, 1981).

    ERIC Educational Resources Information Center

    Martin, Mary P., Ed.; Staman, E. Michael, Ed.

    Proceedings of a 1981 joint conference sponsored by the Southern Association for Institutional Research (SAIR) and the North Carolina Association for Institutional Research are presented. The conference theme was the practice of institutional research. Contents include preconference workshop reports, speeches, abstracts of papers, and reports of…

  14. Numerical modelling of physical processes governing larval transport in the southern North Sea

    NASA Astrophysics Data System (ADS)

    Tiessen, M. C. H.; Fernard, L.; Gerkema, T.; van der Molen, J.; Ruardij, P.; van der Veer, H. W.

    2014-05-01

    A three-dimensional hydrodynamic model (GETM) was coupled with a particle tracking routine (GITM) to study the inter-annual variability in transport paths of particles in the North Sea and English Channel. For validation, a comparison with observed drifter trajectories is also presented here. This research investigated to what extent variability in the hydrodynamic conditions alone (reflecting passive particle transport) contributed to inter-annual variability in the transport of eggs and larvae. In this idealised study, no a priori selection of specific spawning grounds or periods was made and no active behaviour (vertical migration) or mortality was included. In this study, egg and larval development towards coastal nursery areas was based solely on sea water temperature, while settlement areas were defined by a threshold water depth. Results showed strong inter-annual variability in drift direction and distance, caused by a combination of wind speed and direction. Strong inter-annual variability was observed both in absolute amount of settlement in several coastal areas, and in the relative importance of the different areas. The effects of wind and temperature variability are minor for settlement along the western shores of the North Sea and in the English Channel, but have a very significant impact on settlement along the eastern shores of the North Sea. Years with strong south-westerly winds across the Dover Straight resulted in higher settlement figures along its eastern shores of the North Sea (standard deviation 37% of the mean annual settlement value). Settlement in the western Dutch Wadden Sea did not only show inter-annual variability, but patterns were also variable within each year and revealed seasonal changes in the origin of particles: during winter, stronger currents along with colder temperatures generally result in particles originating from further away.

  15. Kinematic analysis of a possible suture in the southern Appalachians, northwestern North Carolina

    SciTech Connect

    Mallard, L.D.; Adams, M.G.; Stewart, K.G. . Dept. of Geology)

    1994-03-01

    The contact between Grenville-age basement and the Ashe Metamorphic Suite juxtaposes rocks of the Laurentian continent with rocks of apparent oceanic affinities. The occurrence of ultramafic rocks and recently discovered eclogite along the base of the Ashe Metamorphic Suite suggests the possibility that this contact is a suture. Previous workers have demonstrated that the basement/Ashe Metamorphic suite contact is a northwest-directed thrust fault north of the Grandfather Mountain window. Recent maps published by the North Carolina Geological survey show the contact as a folded thrust fault south of the Grandfather Mountain window. The authors detailed kinematic analyses show that the basement/Ashe Metamorphic Suite contact is not a folded thrust surface; instead, they have identified two distinct northeast-striking fault contacts, one showing strike-slip and the other showing dip-slip motion. Kinematic indicators (asymmetric porphyroclasts, shear bands, mica fish, and S-C fabrics) from mylonites along a portion of the basement/Ashe Metamorphic suite contact from Bakersville to Barnardsville, NC demonstrate dextral strike-slip movement on the eastern fault. Preliminary structural analyses of mylonites on the western fault indicate top-to-the-southeast dip-slip movement. The minerals in these mylonites are partially to totally annealed unlike mylonites from the greenschist facies shear zones along the basement/Ashe Metamorphic Suite contact north of the Grandfather Mountain window.

  16. Hydrological change in Southern Europe responding to increasing North Atlantic overturning during Greenland Stadial 1

    PubMed Central

    Bartolomé, Miguel; Moreno, Ana; Sancho, Carlos; Stoll, Heather M.; Cacho, Isabel; Spötl, Christoph; Belmonte, Ánchel; Edwards, R. Lawrence; Cheng, Hai; Hellstrom, John C.

    2015-01-01

    Greenland Stadial 1 (GS-1) was the last of a long series of severe cooling episodes in the Northern Hemisphere during the last glacial period. Numerous North Atlantic and European records reveal the intense environmental impact of that stadial, whose origin is attributed to an intense weakening of the Atlantic Meridional Overturning Circulation in response to freshening of the North Atlantic. Recent high-resolution studies of European lakes revealed a mid–GS-1 transition in the climatic regimes. The geographical extension of such atmospheric changes and their potential coupling with ocean dynamics still remains unclear. Here we use a subdecadally resolved stalagmite record from the Northern Iberian Peninsula to further investigate the timing and forcing of this transition. A solid interpretation of the environmental changes detected in this new, accurately dated, stalagmite record is based on a parallel cave monitoring exercise. This record reveals a gradual transition from dry to wet conditions starting at 12,500 y before 2000 A.D. in parallel to a progressive warming of the subtropical Atlantic Ocean. The observed atmospheric changes are proposed to be led by a progressive resumption of the North Atlantic convection and highlight the complex regional signature of GS-1, very distinctive from previous stadial events. PMID:25964366

  17. Hydrological change in Southern Europe responding to increasing North Atlantic overturning during Greenland Stadial 1.

    PubMed

    Bartolomé, Miguel; Moreno, Ana; Sancho, Carlos; Stoll, Heather M; Cacho, Isabel; Spötl, Christoph; Belmonte, Ánchel; Edwards, R Lawrence; Cheng, Hai; Hellstrom, John C

    2015-05-26

    Greenland Stadial 1 (GS-1) was the last of a long series of severe cooling episodes in the Northern Hemisphere during the last glacial period. Numerous North Atlantic and European records reveal the intense environmental impact of that stadial, whose origin is attributed to an intense weakening of the Atlantic Meridional Overturning Circulation in response to freshening of the North Atlantic. Recent high-resolution studies of European lakes revealed a mid-GS-1 transition in the climatic regimes. The geographical extension of such atmospheric changes and their potential coupling with ocean dynamics still remains unclear. Here we use a subdecadally resolved stalagmite record from the Northern Iberian Peninsula to further investigate the timing and forcing of this transition. A solid interpretation of the environmental changes detected in this new, accurately dated, stalagmite record is based on a parallel cave monitoring exercise. This record reveals a gradual transition from dry to wet conditions starting at 12,500 y before 2000 A.D. in parallel to a progressive warming of the subtropical Atlantic Ocean. The observed atmospheric changes are proposed to be led by a progressive resumption of the North Atlantic convection and highlight the complex regional signature of GS-1, very distinctive from previous stadial events. PMID:25964366

  18. Investigating crustal deformation associated with the North America-Pacific plate boundary in southern California with GPS geodesy

    NASA Astrophysics Data System (ADS)

    Spinler, Joshua C.

    The three largest earthquakes in the last 25 years in southern California occurred on faults located adjacent to the southern San Andreas fault, with the M7.3 1992 Landers and M7.1 1999 Hector Mine earthquakes occurring in the eastern California shear zone (ECSZ) in the Mojave Desert, and the M7.2 2010 El Mayor-Cucapah earthquake occurring along the Laguna Salada fault in northern Baja California, Mexico. The locations of these events near to but not along the southern San Andreas fault (SSAF) is unusual in that the last major event on the SSAF occurred more than 300 years ago, with an estimated recurrence interval of 215 +/- 25 years. The focus of this dissertation is to address the present-day deformation field along the North America-Pacific plate boundary in southern California and northern Baja California, through the analysis of GPS data, and elastic block and viscoelastic earthquake models to determine fault slip rates and rheological properties of the lithosphere in the plate boundary zone. We accomplish this in three separate studies. The first study looks at how strain is partitioned northwards along-strike from the southern San Andreas fault near the Salton Sea. We find that estimates for slip-rates on the southern San Andreas decrease from ~23 mm/yr in the south to ~8 mm/yr as the fault passes through San Gorgonio Pass to the northwest, while ~13-18 mm/yr of slip is partitioned onto NW-SE trending faults of the ECSZ where the Landers and Hector Mine earthquakes occurred. This speaks directly to San Andreas earthquake hazards, as a reduction in the slip rate would require greater time between events to build up enough slip deficit in order to generate a large magnitude earthquake. The second study focuses on inferring the rheological structure beneath the Salton Trough region. This is accomplished through analysis of postseismic deformation observed using a set of the GPS data collected before and after the 2010 El Mayor-Cucapah earthquake. By

  19. Modelling the seasonal occurrence and distribution of humanpathogenic bacteria within the German Bight, southern North Sea

    NASA Astrophysics Data System (ADS)

    Schakau, Vanessa; Lettmann, Karsten A.; Wolff, Jörg-Olaf

    2015-04-01

    In recent years, the occurrence of human-pathogenic bacteria of the genus Vibrio in the North Sea and the Baltic Sea has come into the focus of many marine research activities, as different Vibrio strains caused harmful infections, especially in summers 2003, 2006, 2010 and 2014. Furthermore, it is anticipated that under global warming conditions, the risk of the occurrence of human-pathogenic in summer season will increase very likely. To present knowledge temperature and salinity are the most powerful predictors of the occurrence of Vibrio spp. in coastal waters. However, studies support the interaction of human-pathogenic Vibrio spp. with different host and vector organisms like chitinous zooplankton or with predator organisms such as Vibrio-specific bacteriophages. A modeling system has been developed to understand and predict the occurrence and distribution of harmful Vibrio spp. within the North Sea with a special focus on the German Bight including the shallower Wadden Sea areas and the estuaries of Ems, Weser and Elbe. On the one hand, this modeling system is based on the unstructured-mesh hydrodynamic model FVCOM, which can predict the oceanic circulation and distributions of temperature and salinity within the German Bight for appropriate present and future climate conditions. On the other hand, a biological module has been attached, which can simulate the distribution and abundances of Vibrio spp.. In detail, apart from specific Vibrio strains, this biological module incorporates functional groups of phyto- and zooplankton and bacteriophages as potential host- and predator-organisms. In a first study, this modeling system has been applied to a hot summer season in 2006. It has been demonstrated that this system can reproduce the valid hydrodynamic conditions within the North Sea region of interest including temperature and salinity distribution patterns. In addition, reasonable temporal and spatial patterns of Vibrio abundances have been obtained.

  20. Towards an integrated view of benthic and pelagic processes in the southern North Sea (German Bight)

    NASA Astrophysics Data System (ADS)

    Friedrich, Jana; van Beusekom, Justus; Neumann, Andreas; Naderipour, Celine

    2015-04-01

    The North Sea can be classified as a semi-enclosed shelf on the western-European continent. Atlantic influences are mainly through the Fair Isle current Channel in the North, and through the Strait of Dover in the South. An anti-clockwise circulation prevails, driven by mainly semi-diurnal tides and winds. The German Bight is located in the south-eastern part of the North Sea, and is strongly influenced by continental rivers. The outflow from the rivers Scheldt, Maas and Rhine is carried towards the German Bight with the residual currents. The German rivers Ems, Weser and Elbe directly debouche into the German Bight. On the shallow shelf, the water column is completely mixed by tidal forces and wind, largely preventing downward flux of particles and instead fostering temporary deposition and resuspension, which influences benthic mineralization. Hence, complex interactions between pelagic and benthic processes occur. Previous budget calculations indicate that the nutrient inventory has to be processed several times to support observed primary production, and, depending on water depth; only 10-20% remineralisation occurs in sediments of the German Bight whereas about 50% of organic matter is remineralised in the sediments of the shallow Wadden Sea. In this presentation, we use in-situ and ex-situ field data on pelagic and benthic oxygen respiration and benthic nutrient fluxes to assess the intense mineralization activity in the German Bight, the partitioning of benthic and pelagic processes and the factors influencing organic matter mineralization. Measurements of pelagic oxygen respiration based on Winkler titration, in-situ benthic oxygen uptake measurements based on flux-chamber landers and ex-situ incubations of intact sediment cores revealed that benthic remineralisation rates are about an order of magnitude smaller than pelagic rates, in agreement with previous budget estimates. Both benthic and pelagic oxygen respiration show a strong seasonality; with higher

  1. Sedimentary response to tectonism in the extensional Chihuahua trough, Cretaceous of Southern North America

    NASA Astrophysics Data System (ADS)

    Budhathoki, P.; Langford, R. P.; Pavlis, T. L.

    2009-12-01

    During the Jurassic and Cretaceous, the Chihuahua Trough formed an extensional basin, extending from the Gulf of Mexico to Southern Arizona, along the Present Border of the United States and Mexico. West of the Big Bend of Texas, Jurassic and Cretaceous sediments are less than 150 m thick, and in many areas are absent. The sedimentary package thickens to over 3km within the trough. The Albian Cox Sandstone is one of the most areally extensive formations and consists of interbedded fluvial coastal and shallow marine sandstones and shales. In this study area, shales (10-70 m) are thicker more than sandstone beds (2-10 m). This unit is overlain by Finlay formation, a fine crystalline gray limestone and underlain by Bluff Mesa formation, a fossiliferous shallow marine limestone. Cross-bedded, brown, fine to medium grained sandstone, interbedded with siltstone, shale and limestone are characteristic lithology of the Cox. The Indio Mountains of Trans-Pecos Texas offer an ideal location to study how this package accommodates the deformation associated with the subsiding Chihuahua trough. A continuous outcrop extends over 30 km oblique to the basin margin and thickens from approximately 375 m on the northern side to 437 m on the southern side of the 10 km section studied so far. One important mechanism is rotation of the strata into the basin, followed by truncation along sequence boundaries. The lower two sequence in the southern Indio mountains are rotated down to the basin relative to Finlay. The lowest sequences thicken from an erosional pinch out towards the South. Shale beds thicken within the rotated strata and accommodate some of the tilting. For example, Thickness of the shale bed varies from 18 m to 70 m within a 2 km distance. However, erosional truncation of the tilted strata accounts for most of the increases in thickness within sequences. The base of the formation has been rotated about 6 degrees south relative to the top of the formation. Another observed

  2. Participation in Lifelong Learning: Reality or Myth? Issues Arising from a United Kingdom Coalfield Closure

    ERIC Educational Resources Information Center

    Thursfield, Denise; Henderson, Roger

    2004-01-01

    In the spring of 2004, the Selby Coalfield, the largest of the remaining coal mines in the United Kingdom (UK) will close and 2071 employees will lose their jobs. The impact of the closure will be severe in the surrounding area, and will present a challenge to local employment services and training agencies. It will also test the UK government's…

  3. Unique organic remains from an upper Permian coal bearing sequence in the Talcher Coalfield, Orissa, India

    SciTech Connect

    Tripathi, A.

    2004-07-01

    The playnological assemblage of coal bearing upper Permian sequence of Talcher Coalfield registers presence of some peculiar organic remains. These are described as Orissiella gen. nov., which is characterized by a vesicle with collar-like structure at the oral end, spines and or corrugations on the body. The affinity and palaeoecological significance of Orissiella is also discussed. 12 refs., 4 figs., 2 plates.

  4. Conservation status of North American freshwater crayfish (Decapoda: Cambaridae) from the southern United States

    USGS Publications Warehouse

    Loughman, Zachary J.; Welsh, Stuart; Fetzner, James W.; Thoma, Roger F.

    2015-01-01

    A list is provided of all crayfishes (family Cambaridae) in the southern United States, which includes common names, global conservation status, an alternative review of the conservation status based on the IUCN red list criteria, and state distribution. This list includes 357 native crayfishes, of which 12 (3.4%) are critically endangered, 37 (10.4%) are endangered, 126 (35.3%) are vulnerable, 181 (50.7%) are lower risk, and 1 (0.3%) is not evaluated. The leading factors causing imperilment are restricted ranges caused by anthropogenic impacts from changes in land use, contaminants, invasion by non-indigenous species, and habitat fragmentation. In order to conserve and manage diversity of native crayfish, consistency is needed in determining conservation status and more complete distribution and life history information are needed for about 60% of species.

  5. Post-Clovis survival of American Mastodon in the southern Great Lakes Region of North America

    NASA Astrophysics Data System (ADS)

    Woodman, Neal; Beavan Athfield, Nancy

    2009-11-01

    The end of the Pleistocene in North America was marked by a wave of extinctions of large mammals, with the last known appearances of many species falling between ca. 11,000-10,000 14C yr BP. Temporally, this period overlaps with the Clovis Paleoindian cultural complex (11,190-10,530 14C yr BP) and with sudden climatic changes that define the beginning of the Younger Dryas chronozone (ca. 11,000-10,000 14C yr BP), both of which have been considered as potential proximal causes of this extinction event. Radiocarbon dating of enamel and filtered bone collagen from an extinct American Mastodon ( Mammut americanum) from northern Indiana, USA, by accelerator mass spectrometer yielded direct dates of 10,055 ± 40 14C yr BP and 10,032 ± 40 14C yr BP, indicating that the animal survived beyond the Clovis time period and into the late Younger Dryas. Although the late survival of this species in mid-continental North America does not remove either humans or climatic change as contributing causes for the late Pleistocene extinctions, neither Clovis hunters nor the climatic perturbations initiating the Younger Dryas chronozone were immediately responsible for driving mastodons to extinction.

  6. Assessment of Coal Geology, Resources, and Reserves in the Gillette Coalfield, Powder River Basin, Wyoming

    USGS Publications Warehouse

    Luppens, James A.; Scott, David C.; Haacke, Jon E.; Osmonson, Lee M.; Rohrbacher, Timothy J.; Ellis, Margaret S.

    2008-01-01

    The Gillette coalfield, within the Powder River Basin in east-central Wyoming, is the most prolific coalfield in the United States. In 2006, production from the coalfield totaled over 431 million short tons of coal, which represented over 37 percent of the Nation's total yearly production. The Anderson and Canyon coal beds in the Gillette coalfield contain some of the largest deposits of low-sulfur subbituminous coal in the world. By utilizing the abundance of new data from recent coalbed methane development in the Powder River Basin, this study represents the most comprehensive evaluation of coal resources and reserves in the Gillette coalfield to date. Eleven coal beds were evaluated to determine the in-place coal resources. Six of the eleven coal beds were evaluated for reserve potential given current technology, economic factors, and restrictions to mining. These restrictions included the presence of railroads, a Federal interstate highway, cities, a gas plant, and alluvial valley floors. Other restrictions, such as thickness of overburden, thickness of coal beds, and areas of burned coal were also considered. The total original coal resource in the Gillette coalfield for all eleven coal beds assessed, and no restrictions applied, was calculated to be 201 billion short tons. Available coal resources, which are part of the original coal resource that is accessible for potential mine development after subtracting all restrictions, are about 164 billion short tons (81 percent of the original coal resource). Recoverable coal, which is the portion of available coal remaining after subtracting mining and processing losses, was determined for a stripping ratio of 10:1 or less. After mining and processing losses were subtracted, a total of 77 billion short tons of coal were calculated (48 percent of the original coal resource). Coal reserves are the portion of the recoverable coal that can be mined, processed, and marketed at a profit at the time of the economic

  7. Reducing coronary heart disease in the Australian Coalfields: evaluation of a 10-year community intervention.

    PubMed

    Higginbotham, N; Heading, G; McElduff, P; Dobson, A; Heller, R

    1999-03-01

    Coronary heart disease is a leading cause of death in Australia with the Coalfields district of New South Wales having one of the country's highest rates. Identification of the Coalfields epidemic in the 1970's led to the formation of a community awareness program in the late 1980's (the healthy heart support group) followed by a more intense community action program in 1990, the Coalfields Healthy Heartbeat (CHHB). CHHB is a coalition of community members, local government officers, health workers and University researchers. We evaluate the CHHB program, examining both the nature and sustainability of heart health activities undertaken, as well as trends in risk factor levels and rates of coronary events in the Coalfields in comparison with nearby local government areas. Process data reveal difficulties mobilising the community as a whole; activities had to be selected for interested subgroups such as families of heart disease patients, school children, retired people and women concerned with family nutrition and body maintenance. Outcome data show a significantly larger reduction in case fatality for Coalfields men (although nonfatal heart attacks did not decline) while changes in risk factors levels were comparable with surrounding areas. We explain positive responses to the CHHB by schools, heart attack survivors and women interested in body maintenance in terms of the meaning these subgroups find in health promotion discourses based on their embodied experiences. When faced with a threat to one's identity, health discourse suddenly becomes meaningful along with the regimens for health improvement. General public disinterest in heart health promotion is examined in the context of historical patterns of outsiders criticising the lifestyle of miners, an orientation toward communal rather than individual responsibility for health (i.e. community 'owned' emergency services and hospitals) and anger about risks from environmental hazards imposed by industrialists

  8. The tectonic crustal stress field and style of faulting along the Pacific North America Plate boundary in Southern California

    NASA Astrophysics Data System (ADS)

    Yang, Wenzheng; Hauksson, Egill

    2013-07-01

    We invert for the state of stress in the southern California crust using a catalogue of high quality earthquake focal mechanisms (1981-2010). The stress field is best resolved where seismicity rates are high and sufficient data are available to constrain the stress field across most of the region. From the stress field, we determine the maximum horizontal compressive stress (SHmax) orientations and the style of faulting across southern California. The trend of SHmax exhibits significant regional and local spatial heterogeneities. The regional trend of SHmax varies from north along the San Andreas system to NNE to the east in the Eastern California Shear Zone as well as to the west, within the Continental Borderland and the Western Transverse Ranges. The transition zones from one state of stress to the other occur over a distance of only a few kilometres, following a trend from Yucca Valley to Imperial Valley to the east, and the western edge of the Peninsular Ranges to the west. The local scale heterogeneities in the SHmax trend include NNW trends along the San Andreas Fault near Cajon Pass, Tejon Pass and the Cucapah Range, as well as NNE trends near the northern San Jacinto Fault and the Wheeler Ridge area. The style of faulting exhibits similar complexity, ranging from predominantly normal faulting in the high Sierra Nevada, to strike-slip faulting along the San Andreas system, to three consecutive bands of thrust faulting in the Wheeler Ridge area and the Western Transverse Ranges. The local variations in the style of faulting include normal faulting at the north end of the San Jacinto Fault and scattered areas of thrust faulting. The regional variations in the SHmax trends are very similar to the pattern of the GPS-measured maximum shortening axes of the surface strain rate tensor field although the strain field tends to be smoother and appears to capture some of the upper-mantle deformation field. The mean trend of SHmax departs about approximately 14° to

  9. Modelling the transport of common sole larvae in the southern North Sea: Influence of hydrodynamics and larval vertical movements

    NASA Astrophysics Data System (ADS)

    Savina, Marie; Lacroix, Geneviève; Ruddick, Kevin

    2010-04-01

    In the present work we used a particle-tracking model coupled to a 3D hydrodynamic model to study the combined effect of hydrodynamic variability and active vertical movements on the transport of sole larvae in the southern North Sea. Larval transport from the 6 main spawning grounds was simulated during 40 day periods starting on 2 plausible spawning dates, the 15/04 and the 01/05, during 2 years, 1995 and 1996. In addition to a "passive" behaviour, 3 types of active vertical movements inspired from previous studies have been tested: (1) Eggs and early larvae float in the surface waters, late larvae migrate toward the bottom and stay there until the end of the simulation; (2 and 3) Eggs float in the surface waters, early larvae perform diel vertical migrations in the surface waters, and (2) Late larvae perform diel vertical migrations in the bottom waters until the end of the simulation; or (3) Late larvae perform tidally synchronised vertical migrations in the bottom waters until the end of the simulation. These behaviours have been implemented in the model with vertical migration rates, positive or negative, which can account for buoyancy or real swimming activity. Variations in larval transport were analysed in terms of mean trajectories, final larvae distribution, larval retention above nurseries, and connectivity. Results suggest that the variations in larval retention above nurseries due to the varying hydrodynamic conditions are not consistent in space i.e. not the same for all the spawning sites. The effect of active vertical movements on larval transport is also not consistent in space: Effects of active vertical movements include decreased retention above nurseries, decreased transport and/or decreased horizontal dispersion of larvae through reduced vertical shear (depending on the zone). The variability in larval retention due to hydrodynamic variability is higher than variability due to differences in the behaviour of larvae. In terms of connectivity

  10. New insights into North America-Pacific Plate boundary deformation from Lake Tahoe, Salton Sea and southern Baja California

    NASA Astrophysics Data System (ADS)

    Brothers, Daniel Stephen

    Five studies along the Pacific-North America (PA-NA) plate boundary offer new insights into continental margin processes, the development of the PA-NA tectonic margin and regional earthquake hazards. This research is based on the collection and analysis of several new marine geophysical and geological datasets. Two studies used seismic CHIRP surveys and sediment coring in Fallen Leaf Lake (FLL) and Lake Tahoe to constrain tectonic and geomorphic processes in the lakes, but also the slip-rate and earthquake history along the West Tahoe-Dollar Point Fault. CHIRP profiles image vertically offset and folded strata that record deformation associated with the most recent event (MRE). Radiocarbon dating of organic material extracted from piston cores constrain the age of the MRE to be between 4.1--4.5 k.y. B.P. Offset of Tioga aged glacial deposits yield a slip rate of 0.4--0.8 mm/yr. An ancillary study in FLL determined that submerged, in situ pine trees that date to between 900-1250 AD are related to a medieval megadrought in the Lake Tahoe Basin. The timing and severity of this event match medieval megadroughts observed in the western United States and in Europe. CHIRP profiles acquired in the Salton Sea, California provide new insights into the processes that control pull-apart basin development and earthquake hazards along the southernmost San Andreas Fault. Differential subsidence (>10 mm/yr) in the southern sea suggests the existence of northwest-dipping basin-bounding faults near the southern shoreline. In contrast to previous models, the rapid subsidence and fault architecture observed in the southern part of the sea are consistent with experimental models for pull-apart basins. Geophysical surveys imaged more than 15 ˜N15°E oriented faults, some of which have produced up to 10 events in the last 2-3 kyr. Potentially 2 of the last 5 events on the southern San Andreas Fault (SAF) were synchronous with rupture on offshore faults, but it appears that ruptures on

  11. Genetic sequence relationships of Winnipegosis platform carbonates, southern Elk Point basin, North Dakota

    SciTech Connect

    Shanley, K.W.; Cross, T.A.

    1988-01-01

    Examination of cores and well log data from the Winnipegosis Formation (Givetian) within a study area of approximately 11,500 mi/sup 2/ (30,000 km/sup 2/) in northern North Dakota allows recognition of seven time-stratigraphic progradational units within the Winnipegosis Formation. Together with the underlying Ashern Formation, these units are arranged in landward-stepping, vertical stacking, and seaward-stepping geometric patterns, which reflect changes in relative sea level. Abrupt juxtaposition of shallow over deeper water lithologies, evidence for subaerial exposure, and onlap geometries further suggest that these progradational units form two larger, Vail-type sequences separated by regionally persistent unconformities or their correlative conformities. Sea level rise during the early Eifelian caused southeastward onlap of the Ashern Formation onto Middle Silurian carbonates of the Interlake Formation. Maximum flooding, expressed by deepest marine facies and a hardground surface, suggests the existence of a condensed section at the top of the Ashern Formation. This was developed during the maximum rate of sea level rise. A decrease in the rate of sea level rise resulted in aggradation of lower Winnipegosis units on a gently dipping ramp. These are represented by nodular and burrowed open marine limestones with scattered stromatoporoid patch reefs and grainstone shoals. During the subsequent sea level fall, represented by Temple units, a shelf margin with pronounced depositional topography and adjacent starved basin were developed. Temple strata include coral-brachiopod-stromatoporoid reefs and productive fore-reef talus deposits along the shelf margin rim.

  12. Influence of palaeotopography on the distribution of coal in the Western Coalfield, Sydney basin, Australia: comparison with South African coals

    NASA Astrophysics Data System (ADS)

    Hutton, A. C.; Feldtmann, R.

    1996-07-01

    The Western Coalfield of New South Wales, centred on the town of Lithgow, is one of several areas of the Sydney Basin (Australia) that produces Permian coals for export and for domestic: use. The lowermost seam of the Illawarra Coal Measures, the Lithgow seam, was deposited in an alluvial fan to proximal braidplain complex. The style of clastic sedimentation and coal seam development was strongly influenced by the palaeotopography, especially basement highs which represent erosional remnants of the pre-Permian erosional cycle. The influence of the palaeotopography is seen in the distribution of the basal conglomerate, the thickness of the basal Shoalhaven Group (which is thinnest on and near the basement highs), the location of the alluvial fan facies of the Illawarra Coal Measures (which are adjacent to the highs and received a large proportion of the clastic detritus from these highs) and the development of the coal seams (which are distal to the basement highs). Of great significance is the location of economic sections of the Lithgow seam with respect to palaeotopographic highs. Adjacent to the highs the Lithgow seam is either too thin or contains too many claystone bands to allow mining. Between the highs: and further to the east and north of the highs, where the precursor peats formed on the floodplain and interfan areas, the seam is of significantly better quality and has been mined.

  13. Evidence of Carboniferous volcanic ash in Pictou Group (West-phalian D), Sydney Coalfield, Nova Scotia, Canada

    SciTech Connect

    Lyons, P.C.; Outerbridge, W.F. ); Hacquebard, P.A. )

    1991-08-01

    Until now, Carboniferous-altered volcanic ash in North America was known only from the Middle Pennsylvanian (upper Westphalian A to lower Westphalian D) of the Appalachian basin. Now, however, mineralogical analysis of thin claystones (8-24 mm thick) in mineable bituminous coal (Hub and Harbour seams) form the P-boreholes in the Donkin submarine areas of the Sydney coalfield, Nova Scotia, indicates the presence of trace amounts of minerals probably derived from a volcanic ash fall of late Westphalian D age. Water-clear to cloudy quartz splinters and euhedral zircon with sharp crystal faces and edges, and length-to-width ratios up to 6:1 - which are typical of Appalachian altered acidic volcanic ash deposits (tonsteins) - were with a dominantly detrital (fluvial ) mineral suite. Fifty to 90% water-laid silt- to sand-size detrital grains of quartz, tourmaline( ), zircon, white mica, and other minerals are found in the HF residum after the removal of the dominant components: clay minerals, pyrite, and coal particles (spores, secretinite, etc.). The fine size of the volcanic minerals and their low concentration indicate a very distant volcanic ash source, perhaps western Europe, where volcanic activity extended into the Stephanian.

  14. Gravity and Magnetic Survey of Southern Oklahoma Alcugen in Texas Panhandle, Near the 2000 earthquake swarm North of Amarillo

    NASA Astrophysics Data System (ADS)

    Manns, S.; Gurrola, H.; Robinson, R.; Horton, M.; Herrmann, M.; Seshhadri, S.; Anderson, H.; Bribiesca, E.; Lindsey, C.; Montalvo, R.; Cyrek, C.; Allen, T.; Hoemberg, J.; Hassan, A.

    2005-12-01

    The Texas panhandle is not a region normally thought of as being prone to seismic activity. Earthquakes with magnitudes of 3 to 4 do however occur in this region every year or so and are felt by residents in the area. There are historical reports of earthquakes of magnitude 5 during the early twentieth century. The earthquakes in this region are most likely associated with displacement on old faults related to the Southern Oklahoma Aulacogen (SOA, 600 Ma) which was deformed during the Ouachita orogeny to form the Wichita Mts. During the summer of 2000 there were an unusually large number of earthquakes for this region, five, all from the same location a few kilometers north of Amarillo Texas, 35.39 degrees north latitude and 101.81 degrees west longitude according to the NEIC catalogue. The non-seismic exploration class at Texas Tech University collected and interpreted gravity and magnetic data along a dirt road crossing the location of this earthquake "swarm" (yes in Texas 5 is a swarm) to determine if the old faults of the SOA coincide with the location of these earthquakes. The survey was conducted along a service road of the Santa Fe Railroad that crosses US 87 approximately 20 miles north of Amarillo, Texas trending in a south-southwest direction. Gravity data were collected every 100m along a 5 km profile using Warden and Lacoste gravity meters with elevation control provided by leveling survey tied to elevation markers on the map. Gravity data were colleted, using GPS elevation location and elevation, on roads over more than 20 km surrounding the local survey to provide regional control. Magnetic data were collected along the 5 km profile. Models derived from these data indicate a 200 m thick layer of poorly consolidated sediments with densities of 2.0 g/cc that can be interpreted as the Ogallala aquifer overlaying a layer with density of 2.6 g/cc. The interface between these layers is very structured and has at least three sharp ridges that we interpret as

  15. Relationships between ground and airborne gamma-ray spectrometric survey data, North Ras Millan, Southern Sinai Peninsula, Egypt.

    PubMed

    Youssef, Mohamed A S

    2016-02-01

    In the last decades of years, there was considerable growth in the use of airborne gamma-ray spectrometry. With this growth, there was an increasing need to standardize airborne measurements, so that they can be independent of survey parameters. Acceptable procedures were developed for converting airborne to ground gamma-ray spectrometric measurements of total-count intensity as well as, potassium, equivalent uranium and equivalent thorium concentrations, due to natural sources of radiation. The present study aims mainly to establish relationships between ground and airborne gamma-ray spectrometric data, North Ras Millan, Southern Sinai Peninsula, Egypt. The relationships between airborne and ground gamma-ray spectrometric data were deduced for the original and separated rock units in the study area. Various rocks in the study area, represented by Quaternary Wadi sediments, Cambro-Ordovician sandstones, basic dykes and granites, are shown on the detailed geologic map. The structures are displayed, which located on the detailed geologic map, are compiled from the integration of previous geophysical and surface geological studies. PMID:26650828

  16. Historical changes in carbon dioxide (CO2) and dimethyl sulphide (DMS) emissions in the eutrophied Southern North Sea

    NASA Astrophysics Data System (ADS)

    Gypens, N.; Borges, A. V.; Lancelot, C.

    2012-04-01

    Anthropogenic activities after the Second World War have severely increased river nutrient [nitrogen (N) and phosphorus (P)] loads to European coastal areas. The resulting N: P: Si imbalance (compared to phytoplankton requirements) stimulated in the Southern North Sea the growth of Phaeocystis colonies modifying the functioning of the ecosystem and, therefore, the carbon but also the biogenic sulphur cycles. Phaeocystis is a significant producer of DMSP (dimethylsulphide propionate), the precursor of DMS. When emitted to the atmosphere the DMS has a cooling effect on the climate contrarily to the CO2 greenhouse gas. Since the late 1990's specific nutrient reduction policies have however considerably reduced P loads while N is maintained. In this application we explore, with a mathematical tool, the effects of changing N and P loads on air-sea CO2 exchanges and DMS marine emissions. The chosen model is the MIRO-CO2-DMS, a complex biogeochemical model describing carbon, biogenic sulphur and nutrient cycles in the marine domain. Model simulations are performed for the contemporary period since 1950, using real forcing fields for sea surface temperature, wind speed and atmospheric CO2 and RIVERSTRAHLER model simulations for river carbon and nutrient loads. Results are discussing the importance of human activities and river inputs of carbon and nutrients on the eutrophication of coastal areas, their ability to absorb atmospheric CO2 and the importance of DMS emissions associated with phytoplankton blooms, especially Phaeocystis.

  17. Impact factors identification of spatial heterogeneity of herbaceous plant diversity on five southern islands of Miaodao Archipelago in North China

    NASA Astrophysics Data System (ADS)

    Chi, Yuan; Shi, Honghua; Wang, Xiaoli; Qin, Xuebo; Zheng, Wei; Peng, Shitao

    2016-09-01

    Herbaceous plants are widely distributed on islands and where they exhibit spatial heterogeneity. Accurately identifying the impact factors that drive spatial heterogeneity can reveal typical island biodiversity patterns. Five southern islands in the Miaodao Archipelago, North China were studied herein. The spatial distribution of herbaceous plant diversity on these islands was analyzed, and the impact factors and their degree of impact on spatial heterogeneity were identified using CCA ordination and ANOVA. The results reveal 114 herbaceous plant species, belonging to 94 genera from 34 families in the 50 plots sampled. The total species numbers on different islands were significantly positively correlated with island area, and the average α diversity was correlated with human activities, while the β diversity among islands was more affected by island area than mutual distances. Spatial heterogeneity within islands indicated that the diversities were generally high in areas with higher altitude, slope, total nitrogen, total carbon, and canopy density, and lower moisture content, pH, total phosphorus, total potassium, and aspect. Among the environmental factors, pH, canopy density, total K, total P, moisture content, altitude, and slope had significant gross effects, but only canopy density exhibited a significant net effect. Terrain affected diversity by restricting plantation, plantation in turn influenced soil properties and the two together affected diversity. Therefore, plantation was ultimately the fundamental driving factor for spatial heterogeneity in herbaceous plant diversity on the five islands.

  18. Distribution of total mercury in surface sediments of the western Jade Bay, Lower Saxonian Wadden Sea, southern North Sea.

    PubMed

    Jin, Huafang; Liebezeit, Gerd; Ziehe, Daniel

    2012-04-01

    A total of 114 surface sediment samples was equidistantly collected in the western part of the Jade Bay, southern North Sea, to analyse total mercury contents as well as grain size distribution and total organic carbon (TOC) contents. Total mercury was determined by oxygen combustion-gold amalgamation. Validation, precision and accuracy of the method were evaluated and controlled with two certified reference materials (HISS-1 and MESS-3). Total mercury contents varied between 8 and 243 ng/g dry sediment with a mean value of 103 ng/g dw. The mercury levels in surface sediments showed an inhomogeneous spatial distribution with higher contents in near-dike areas. The values are mostly in the range of natural background values (50–100 ng/g dw) and positively related to TOC and clay/silt contents (<63 μm). The present total mercury contents are compared to those of previous studies, in order to estimate possible temporal trends of mercury contents in the study area over the last decades. Moreover, the comparison to sediment quality guidelines indicated that the surface sediments of the Jade Bay are not mercury contaminated. These results also suggested that the current mercury contents of Jade Bay surficial sediments are mostly affected by atmospheric deposition and re-emission. PMID:22301998

  19. GPS tracking data of Lesser Black-backed Gulls and Herring Gulls breeding at the southern North Sea coast.

    PubMed

    Stienen, Eric W M; Desmet, Peter; Aelterman, Bart; Courtens, Wouter; Feys, Simon; Vanermen, Nicolas; Verstraete, Hilbran; de Walle, Marc Van; Deneudt, Klaas; Hernandez, Francisco; Houthoofdt, Robin; Vanhoorne, Bart; Bouten, Willem; Buijs, Roland-Jan; Kavelaars, Marwa M; Müller, Wendt; Herman, David; Matheve, Hans; Sotillo, Alejandro; Lens, Luc

    2016-01-01

    In this data paper, Bird tracking - GPS tracking of Lesser Black-backed Gulls and Herring Gulls breeding at the southern North Sea coast is described, a species occurrence dataset published by the Research Institute for Nature and Forest (INBO). The dataset (version 5.5) contains close to 2.5 million occurrences, recorded by 101 GPS trackers mounted on 75 Lesser Black-backed Gulls and 26 Herring Gulls breeding at the Belgian and Dutch coast. The trackers were developed by the University of Amsterdam Bird Tracking System (UvA-BiTS, http://www.uva-bits.nl). These automatically record and transmit bird movements, which allows us and others to study their habitat use and migration behaviour in great detail. Our bird tracking network is operational since 2013. It is funded for LifeWatch by the Hercules Foundation and maintained in collaboration with UvA-BiTS and the Flanders Marine Institute (VLIZ). The recorded data are periodically released in bulk as open data (http://dataset.inbo.be/bird-tracking-gull-occurrences), and are also accessible through CartoDB and the Global Biodiversity Information Facility (GBIF). PMID:26877689

  20. A geophysical overview of the southern continental margin of North America in the Late Precambrian/Cambrian

    SciTech Connect

    Keller, G.R. . Dept. of Geological Sciences)

    1993-02-01

    Recent geophysical studies have shed considerable light on the nature and extent of the southern Continental margin of North America which formed during the Late Precambrian/Cambrian. To the east between Arkansas and Alabama, the PASSCAL/Ouachita seismic experiment and older results in Mississippi indicate that this margin is largely preserved beneath allochthonous rocks emplaced during the Ouachita orogeny. Here the margin is fairly abrupt suggesting transtension was important in this origin. The Wiggins and Sabine blocks appear to be continental fragments which may have formed along this margin. In Texas, the margin extends around the Llano uplift in a sinuous fashion. In this area, Mesozoic extension clouds the picture considerably. However, structural complexities along this portion of he margin can be inferred form gravity data. In West Texas, the margin bends westward and then southward. A very deep oil exploration test which was recently drilled in this area provides valuable constraints for geophysical models of this portion of the margin. Recent results in Mexico allows the authors to trace this margin further south into the state of Chihuahua than previously possible.

  1. Chronic Diseases in North-West Tanzania and Southern Uganda. Public Perceptions of Terminologies, Aetiologies, Symptoms and Preferred Management

    PubMed Central

    Nnko, Soori; Bukenya, Dominic; Kavishe, Bazil Balthazar; Biraro, Samuel; Peck, Robert; Kapiga, Saidi; Grosskurth, Heiner; Seeley, Janet

    2015-01-01

    Background Research has shown that health system utilization is low for chronic diseases (CDs) other than HIV. We describe the knowledge and perceptions of CDs identified from rural and urban communities in north-west Tanzania and southern Uganda. Methods Data were collected through a quantitative population survey, a quantitative health facility survey and focus group discussions (FGDs) and in-depth interviews (IDIs) in subgroups of population survey participants. The main focus of this paper is the findings from the FGDs and IDIs. Results We conducted 24 FGDs, involving approximately 180 adult participants and IDIs with 116 participants (≥18 years). CDs studied included: asthma/chronic obstructive lung disease (COPD), diabetes, epilepsy, hypertension, cardiac failure and HIV- related disease. The understanding of most chronic conditions involved a combination of biomedical information, gleaned from health facility visits, local people who had suffered from a complaint or knew others who had and beliefs drawn from information shared in the community. The biomedical contribution shows some understanding of the aetiology of a condition and the management of that condition. However, local beliefs for certain conditions (such as epilepsy) suggest that biomedical treatment may be futile and therefore work counter to biomedical prescriptions for management. Conclusion Current perceptions of selected CDs may represent a barrier that prevents people from adopting efficacious health and treatment seeking behaviours. Interventions to improve this situation must include efforts to improve the quality of existing health services, so that people can access relevant, reliable and trustworthy services. PMID:26555896

  2. GPS tracking data of Lesser Black-backed Gulls and Herring Gulls breeding at the southern North Sea coast

    PubMed Central

    Stienen, Eric W.M.; Desmet, Peter; Aelterman, Bart; Courtens, Wouter; Feys, Simon; Vanermen, Nicolas; Verstraete, Hilbran; de Walle, Marc Van; Deneudt, Klaas; Hernandez, Francisco; Houthoofdt, Robin; Vanhoorne, Bart; Bouten, Willem; Buijs, Roland-Jan; Kavelaars, Marwa M.; Müller, Wendt; Herman, David; Matheve, Hans; Sotillo, Alejandro; Lens, Luc

    2016-01-01

    Abstract In this data paper, Bird tracking - GPS tracking of Lesser Black-backed Gulls and Herring Gulls breeding at the southern North Sea coast is described, a species occurrence dataset published by the Research Institute for Nature and Forest (INBO). The dataset (version 5.5) contains close to 2.5 million occurrences, recorded by 101 GPS trackers mounted on 75 Lesser Black-backed Gulls and 26 Herring Gulls breeding at the Belgian and Dutch coast. The trackers were developed by the University of Amsterdam Bird Tracking System (UvA-BiTS, http://www.uva-bits.nl). These automatically record and transmit bird movements, which allows us and others to study their habitat use and migration behaviour in great detail. Our bird tracking network is operational since 2013. It is funded for LifeWatch by the Hercules Foundation and maintained in collaboration with UvA-BiTS and the Flanders Marine Institute (VLIZ). The recorded data are periodically released in bulk as open data (http://dataset.inbo.be/bird-tracking-gull-occurrences), and are also accessible through CartoDB and the Global Biodiversity Information Facility (GBIF). PMID:26877689

  3. A Lower Ordovician sponge/algal facies in the southern United States and its counterparts elsewhere in North America

    SciTech Connect

    Alberstadt, L. ); Repetski, J.E. )

    1989-06-01

    Subsurface Ordovician rocks in the Black Warrior Basin, Mississippi Embayment, and the eastern part of the Arkoma Basin reflect a different depositional history than coeval rocks exposed in the Nashville Basin, Ozark Dome, and southern Appalachians. The succession consists of four informal lithologic units. From top to bottom these are: (1) Stones River limestones, (2) upper dolostone, (3) sponge/algal limestones characterized by the presence of Nuia, and (4) lower dolostone. Of these, the sponge/algal limestone unit is the most atypical. It has a conspicuous biotic assemblage which can be recognized petrographically in well cuttings. The diagnostic fossil allochems are: sponges, sponge spicules, Nuia, Girvanella, and Sphaerocodium. Conodonts from the sponge/algal limestones are probably entirely Early Ordovician (Canadian) and include cold- and deep-water species found in the North Atlantic Province, whereas those in the overlying dolostones represent exclusively warm-water, shelf environments. The conodonts in the Black Warrior Basin suggest that an unconformity between Lower and Middle Ordovician carbonates (Knox unconformity) does not exist in much of that region. The sponge/algal limestones represent a different facies than their coeval shelf rocks in the interior of the continent. The limestone contains a distinctive biotic assemblage recognized in Lower Ordovician rocks in Newfoundland, in the Arbuckle and Wichita mountains of Oklahoma, in West Texas, and in the Great Basin of Nevada and Utah.

  4. A 3-D shear velocity model of the southern North American and Caribbean plates from ambient noise and earthquake tomography

    NASA Astrophysics Data System (ADS)

    Gaite, B.; Villaseñor, A.; Iglesias, A.; Herraiz, M.; Jiménez-Munt, I.

    2015-02-01

    We use group velocities from earthquake tomography together with group and phase velocities from ambient noise tomography (ANT) of Rayleigh waves to invert for the 3-D shear-wave velocity structure (5-70 km) of the Caribbean (CAR) and southern North American (NAM) plates. The lithospheric model proposed offers a complete image of the crust and uppermost-mantle with imprints of the tectonic evolution. One of the most striking features inferred is the main role of the Ouachita-Marathon-Sonora orogeny front on the crustal seismic structure of the NAM plate. A new imaged feature is the low crustal velocities along the USA-Mexico border. The model also shows a break of the east-west mantle velocity dichotomy of the NAM and CAR plates beneath the Isthmus of the Tehuantepec and the Yucatan Block. High upper-mantle velocities along the Mesoamerican Subduction Zone coincide with inactive volcanic areas while the lowest velocities correspond to active volcanic arcs and thin lithospheric mantle regions.

  5. Isolation and Screening of Lipolytic Fungi From Coastal Waters of the Southern Caspian Sea (North of Iran)

    PubMed Central

    Sadati, Razieh; Barghi, Amin; Abbasi Larki, Reza

    2015-01-01

    Background: Lipases (acylglycerol acylhydrolase, E. C. 3. 1. 1. 3) are widely distributed among microorganisms, animals and plants, catalyzing the hydrolysis of triglycerides to free fatty acids and glycerol. Their commercial application includes pharmaceutical, chemical, and paper industries. Objectives: This study aimed to isolate and screen lipolytic fungi from coastal waters of the southern Caspian Sea by Internal Transcribed Spacer-Polymerase Chain Reaction (ITS-PCR), and to optimize their lipolytic activity, pH and temperature. The ITS regions possess a high variation among taxonomically distinct fungal species and even within species. Materials and Methods: All fungal were tested to determine their lipolytic activity by the Tributyrin agar plate assay. After DNA extraction, lipase-producing fungi were identified via ITS-PCR of rDNA region with ITS1 and ITS4 primers. Results: Four fungal species were isolated from water samples of the Caspian Sea (north of Iran) between February and June 2011. The nucleotide sequences reported for three of these isolates have been assigned accession numbers from NCBI Gene Bank database. Among these species, Cladosporium langeronii showed maximum lipolytic activity (34 U/mL) and maximum clear zone formation (6 mm) on the Tributyrin agar plates. The optimum pH and temperature for activity were 8.0 and 35°C, respectively. Conclusions: The findings of this study indicated that these isolates were plant pathogenic fungi, which entered seawater from the environment, and were likely to have a suitable lipase activity on plant oils. PMID:26034538

  6. Impact factors identification of spatial heterogeneity of herbaceous plant diversity on five southern islands of Miaodao Archipelago in North China

    NASA Astrophysics Data System (ADS)

    Chi, Yuan; Shi, Honghua; Wang, Xiaoli; Qin, Xuebo; Zheng, Wei; Peng, Shitao

    2016-01-01

    Herbaceous plants are widely distributed on islands and where they exhibit spatial heterogeneity. Accurately identifying the impact factors that drive spatial heterogeneity can reveal typical island biodiversity patterns. Five southern islands in the Miaodao Archipelago, North China were studied herein. The spatial distribution of herbaceous plant diversity on these islands was analyzed, and the impact factors and their degree of impact on spatial heterogeneity were identified using CCA ordination and ANOVA. The results reveal 114 herbaceous plant species, belonging to 94 genera from 34 families in the 50 plots sampled. The total species numbers on different islands were significantly positively correlated with island area, and the average α diversity was correlated with human activities, while the β diversity among islands was more affected by island area than mutual distances. Spatial heterogeneity within islands indicated that the diversities were generally high in areas with higher altitude, slope, total nitrogen, total carbon, and canopy density, and lower moisture content, pH, total phosphorus, total potassium, and aspect. Among the environmental factors, pH, canopy density, total K, total P, moisture content, altitude, and slope had significant gross effects, but only canopy density exhibited a significant net effect. Terrain affected diversity by restricting plantation, plantation in turn influenced soil properties and the two together affected diversity. Therefore, plantation was ultimately the fundamental driving factor for spatial heterogeneity in herbaceous plant diversity on the five islands.

  7. The ebb-tidal delta model of shoreface ridge origin and evolution: Appraisal and applicability along the southern North Sea barrier island coast—a discussion

    NASA Astrophysics Data System (ADS)

    Antia, E. E.

    1994-03-01

    The ebb-tidal delta model of McBride and Moslow is the most comprehensive on the morphogenesis and distribution of shoreface ridges along the US Atlantic seaboard to date. This discussion evaluates the applicability of the above model to the southern North Sea barrier island coast. Results indicate that the characteristics of the North Sea shoreface-connected ridge sediments display a genetic relationship with those of the inlet ebb delta as implied by the ebb-tidal model. By contrast, ridge orientation is not well accounted for by lateral inlet migration and shoreline recession as suggested by the model. A possible reason for the aforementioned discrepancy is discussed.

  8. The age of illite cement growth, Village Fields area, Southern North Sea: Evidence from K-Ar ages and [sup 18]O/[sup 16]O ratios

    SciTech Connect

    Robinson, A.G.; Coleman, M.L.; Gluyas, J.G. )

    1993-01-01

    In this paper we describe K-Ar radiometric ages and oxygen isotope ratio measurements of illite cements from eolian sandstone samples of the Permian lower Leman Sandstone Formation (Rotliegen-des Group). The samples come from a large (about 100 [times] 100 km) part of the Southern North Sea basin (Village Fields area) and from a range of burial depths (2.8-3.4 km subsea bed). Mean illite ages in the gas fields of Ravenspuran North (164 Ma [+-] 20.1 [2[sigma

  9. Ordovician platform, slope, and basin facies in subsurface of southern North America

    SciTech Connect

    Alberstadt, L.P.; Colvin, G.; Sauve, J.

    1986-05-01

    Ordovician carbonates of the Nashville dome and Ozark dome regions have long been considered typical shelf deposits. In the subsurface to the south, in the Black Warrior basin, Mississippi Embayment, and Arkoma basin, these shelf carbonate units changed facies. The most significant change is the occurrence of a thick limestone unit characterized by a faunal and floral assemblage of Nuia, Girvanella (isolated long strands), Sphaerocodium, a delicate stacked-chambered organism (.algal), and sponge spicules and sponge mudstone clumps. In ascending order, the complete Ordovician sequence consists of: a lower dolostone, the Nuia-sponge limestone, a dolostone, and a limestone. The upper part of this four-fold sequence changes character westward into the Arkoma basin. The lower two units maintain their character for long distances along depositional strike and occur in parts of the Appalachians as far north as Newfoundland, and on the opposite side of the continent in Nevada. The Nuia-sponge assemblage is a distinctive petrographic marker and seems to be a persistent Ordovician rock and fossil assemblage of widespread occurrence. In Nevada, it occurs on the surface where it is associated with slump and slide features that suggest that it is an outer shelf or upper slope deposit. Coeval carbonates in the Ouachita Mountains are different and show indications of being deep water (basinal). Biostratigraphic evidence indicates that the succession in the subsurface is continuous; the regional Lower Ordovician-Middle Ordovician unconformity is absent. The Lower Ordovician-Middle Ordovician boundary falls near the top of the Nuia-sponge mudstone unit and not at the top of the underlying thick dolostone unit.

  10. Genetic sequence relationships of Winnipegosis platform carbonates, Southern Elk Point basin, North Dakota

    SciTech Connect

    Shanley, K.W.; Cross, T.A.

    1988-07-01

    Examination of cores and well-log data from the Winnipegosis Formation (Givetian) within a study area of approximately 11,500 mi/sup 2/ (30,000 km/sup 2/) in northern North Dakota allows recognition of seven time-stratigraphic progradational units within the Winnipegosis Formation. Together with the underlying Ashern Formation, these units are arranged in landward-stepping, vertical stacking, and seaward-stepping geometric patterns, which reflect changes in relative sea level. Abrupt juxtaposition of shallow over deeper water lithologies, evidence for subaerial exposure, and onlap geometries further suggest that these progradational units form two larger Vail-type sequences separated by regionally persistent unconformities or their correlative conformities. Sea level rise during the early Eifelian caused southeastward onlap of the Ashern Formation onto Middle Silurian carbonates of the Interlake Formation. Maximum flooding, expressed by deepest marine facies and a hardground surface, suggests the existence of a condensed section at the top of the Ashern Formation. This section was developed during the maximum rate of sea level rise. A decrease in the rate of sea level rise resulted in aggradation of lower Winnipegosis units on a gently dipping ramp. These units are presented by nodular and burrowed open-marine limestones with scattered stromatoporoid patch reefs and grainstone shoals. During the subsequent sea level fall, represented by Temple units, a shelf margin with pronounced depositional topography and adjacent starved basin were developed. Temple strata include coral-brachiopod-stromatoporoid reefs and productive fore-reef talus deposits along the shelf-margin rim. With increased rates of sea level fall, the platform interior and shelf margin were subaerially exposed, slope carbonates were dolomitized, and the E-shale was deposited as a lowstand wedge.

  11. Late Weichselian fluvial evolution on the southern Kara Sea Shelf, North Siberia

    NASA Astrophysics Data System (ADS)

    Dittmers, K.; Niessen, F.; Stein, R.

    2008-02-01

    Glaciations had a profound impact on the global sea-level and particularly on the Arctic environments. One of the key questions related to this topic is, how did the discharge of the Siberian Ob and Yenisei rivers interact with a proximal ice sheet? In order to answer this question high-resolution (1-12 kHz), shallow-penetration seismic profiles were collected on the passive continental margin of the Kara Sea Shelf to study the paleo-drainage pattern of the Ob and Yenisei rivers. Both rivers incised into the recent shelf, leaving filled and unfilled river channels and river canyons/valleys connecting to a complex paleo-drainage network. These channels have been subaerially formed during a regressive phase of the global sea-level during the Last Glacial Maximum. Beyond recent shelf depths of 120 m particle transport is manifested in submarine channel-levee complexes acting as conveyor for fluvial-derived fines. In the NE area, uniform draping sediments are observed. Major morphology determining factors are (1) sea-level fluctuations and (2) LGM ice sheet influence. Most individual channels show geometries typical for meandering rivers and appear to be an order of magnitude larger than recent channel profiles of gauge stations on land. The Yenisei paleo-channels have larger dimensions than the Ob examples and could be originated by additional water release during the melt of LGM Putoran ice masses. Asymmetrical submarine channel-levee complexes with channel depths of 60 m and more developed, in some places bordered by glacially dominated morphology, implying deflection by the LGM ice masses. A total of more than 12,000 km of acoustic profiles reveal no evidence for an ice-dammed lake of greater areal extent postulated by several workers. Furthermore, the existence of the channel-levee complexes is indicative of unhindered sediment flow to the north. Channels situated on the shelf above 120-m water depth exhibit no phases of ponding and or infill during sea

  12. Salinity predicts the distribution of chlorophyll a spring peak in the southern North Sea continental waters

    NASA Astrophysics Data System (ADS)

    Desmit, Xavier; Ruddick, Kevin; Lacroix, Geneviève

    2015-09-01

    In the North Sea, the coastal waters of Belgium and The Netherlands regularly exhibit intense spring phytoplankton blooms where species such as Phaeocystis recurrently form a potential ecological nuisance. In the Belgian and Dutch continental shelves (BCS and DCS), we observe a direct correlation between the chlorophyll a spring maximum (Chlmax) and the nutrients (DIN and DIP) available for the bloom. As the nutrients are themselves strongly correlated with salinity, a rationale is developed to predict Chlmax from winter salinity. The proposed rationale is first tested in a theoretical case with a 3D-biogeochemical model (3D-MIRO&CO). The method is then applied to independent sets of in situ observations over 20 years in the BCS and the DCS, and to continuous FerryBox data in April 2008. Linear regressions explain the relationships between winter nutrients and winter salinity (R2 = 0.88 to 0.97 with model results, and R2 = 0.83 to 0.96 with in situ data). The relationship between Chlmax and the available nutrients across the salinity gradient is also explained by yearly linear regressions (R2 = 0.82 to 0.94 with model results, and R2 = 0.46 to 0.98 with in situ data). Empirical 'DIP requirement' and 'DIN requirement' for the spring biomass bloom formation are derived from the latter relationships. They depend i.a. on the losses from phytoplankton during the spring bloom formation, and therefore show some interannual variability (8-12% for DIP and 13-20% for DIN). The ratio between nutrient requirements allows predicting in winter which nutrient will eventually limit the spring biomass bloom along the salinity gradient. DIP will generally be limiting in the coastal zone, whereas DIN will generally be limiting offshore, the switch occurring typically at salinity 33.5 in the BCS and 33.6 in the DCS. N reduction should be prioritized to limit Phaeocystis in the coastal zone, with target winter DIN:DIP ratios below 34.4 molN molP-1 in the BCS, or 28.6 molN molP- 1 in

  13. North Atlantic Deep Water export to the Southern Ocean over the past 14 Myr: Evidence from Nd and Pb isotopes in ferromanganese crusts

    USGS Publications Warehouse

    Frank, M.; Whiteley, N.; Kasten, S.; Hein, J.R.; O'Nions, K.

    2002-01-01

    The intensity of North Atlantic Deep Water (NADW) production has been one of the most important parameters controlling the global thermohaline ocean circulation system and climate. Here we present a new approach to reconstruct the overall strength of NADW export from the North Atlantic to the Southern Ocean over the past 14 Myr applying the deep water Nd and Pb isotope composition as recorded by ferromanganese crusts and nodules. We present the first long-term Nd and Pb isotope time series for deep Southern Ocean water masses, which are compared with previously published time series for NADW from the NW Atlantic Ocean. These data suggest a continuous and strong export of NADW, or a precursor of it, into the Southern Ocean between 14 and 3 Ma. An increasing difference in Nd and Pb isotope compositions between the NW Atlantic and the Southern Ocean over the past 3 Myr gives evidence for a progressive overall reduction of NADW export since the onset of Northern Hemisphere glaciation (NHG). The Nd isotope data allow us to assess at least semiquantitatively that the amount of this reduction has been in the range between 14 and 37% depending on location.

  14. Southern Cordilleran basaltic andesite suite, southern Chihuahua, Mexico: A link between Tertiary continental arc and flood basalt magmatism in North America

    NASA Astrophysics Data System (ADS)

    Cameron, K. L.; Nimz, G. J.; Kuentz, D.; Niemeyer, S.; Gunn, S.

    1989-06-01

    Mid-Cenozoic orogenic andesites and ignimbrites of western Mexico, southwestern New Mexico, and Arizona are commonly capped by basaltic andesites, most from 29-20 Ma. We refer to these mafic lavas as the Southern Cordilleran Basaltic Andesite (SCORBA) suite, and they may constitute the most extensive Cenozoic basaltic suite in North America. The SCORBA suite has trace element and isotopic characteristics of orogenic (arc) rocks (e.g., Ba/Nb>40), and silica content (53-56% SiO2) like the Grande Ronde Basalt, which represents about 80% of the volume of the Columbia River Group. Geochemical and isotopic data are presented on SCORBA lavas and rare mafic lavas (PRE-SCORBA) interlayered with older ignimbrites from a 700-km-long NE-SW transect of southern Chihuahua, Mexico. SCORBA and PRE-SCORBA lavas with relatively low K/P (<7) and differing Ba/Nb (50 versus 18) have similar isotopic compositions, arguing against their isotopic signatures being controlled by crustal assimilation. Along the entire length of the transect, the basaltic rocks have ɛNd and 87Sr/86Sr near bulk Earth and 206Pb/204Pb and 207Pb/204Pb ratios that lie along a 1.7 Ga pseudoisochron. The Pb isotopic variation is geographically controlled, becoming more radiogenic from east to west, reflecting mixing in mantle source regions. The eastern mantle source has low 206Pb/204Pb and is a mixture of an enriched, enriched-mantle-like (EMI) component with one or more depleted components, which could include an intraplate component with relatively high Nb/Y (>0.8). The western mantle source contains less of the intraplate component and is more oceanic in character. Overprinting both the eastern and western sources is a Cenozoic subduction component that is responsible for the western radiogenic Pb, and this component fades out inland to the east. This transect crosses the inferred position of the Mojave-Sonora megashear, previously proposed to be a major lithospheric boundary, separating Proterozoic basement to

  15. Coupled decadal variability of the North Atlantic Oscillation, regional rainfall and karst spring discharges in the Campania region (southern Italy)

    NASA Astrophysics Data System (ADS)

    De Vita, P.; Allocca, V.; Manna, F.; Fabbrocino, S.

    2012-05-01

    Thus far, studies on climate change have focused mainly on the variability of the atmospheric and surface components of the hydrologic cycle, investigating the impact of this variability on the environment, especially with respect to the risks of desertification, droughts and floods. Conversely, the impacts of climate change on the recharge of aquifers and on the variability of groundwater flow have been less investigated, especially in Mediterranean karst areas whose water supply systems depend heavily upon groundwater exploitation. In this paper, long-term climatic variability and its influence on groundwater recharge were analysed by examining decadal patterns of precipitation, air temperature and spring discharges in the Campania region (southern Italy), coupled with the North Atlantic Oscillation (NAO). The time series of precipitation and air temperature were gathered over 90 yr, from 1921 to 2010, using 18 rain gauges and 9 air temperature stations with the most continuous functioning. The time series of the winter NAO index and of the discharges of 3 karst springs, selected from those feeding the major aqueducts systems, were collected for the same period. Regional normalised indexes of the precipitation, air temperature and karst spring discharges were calculated, and different methods were applied to analyse the related time series, including long-term trend analysis using smoothing numerical techniques, cross-correlation and Fourier analysis. The investigation of the normalised indexes highlighted the existence of long-term complex periodicities, from 2 to more than 30 yr, with differences in average values of up to approximately ±30% for precipitation and karst spring discharges, which were both strongly correlated with the winter NAO index. Although the effects of the North Atlantic Oscillation (NAO) had already been demonstrated in the long-term precipitation and streamflow patterns of different European countries and Mediterranean areas, the results

  16. Pre-Variscan back-arc extension of Avalonia: The genesis of the Southern North Sea Basin

    NASA Astrophysics Data System (ADS)

    Smit, Jeroen; van Wees, Jan-Diederik; Cloetingh, Sierd

    2016-04-01

    The Devonian-Early Carboniferous was a period of intense rifting in the Avalonia microplate in between the Caledonian and the Hercynian-Alleghanian collision phases. This rifting phase created the typical horst-and-graben structure of much of East Avalonia's crust that is best known from the UK and Ireland where the horsts and the graben infill are located at or near the surface. In the Southern North Sea, the Netherlands and northwest Germany, the Late Devonian-Early Carboniferous rift structure and units are obliterated by the thick cover of Late Carboniferous-to-Recent basin fill and by the recurrent fault reactivation. Although this rifting created the basis for 350 Ma of lithospheric memory, its dynamics remains relatively unknown. Major open questions include the mode and total amount of extension as well as the age and origin of the Central Graben and the relation between structures located east and west of it. This study addresses these issues by integrating existing data from lithosphere to basin scales and a map-view restoration. We have revised the crustal map of the Thor Suture Zone. The newly defined northern margin of Avalonia and the Thor Suture Zone are key elements in the reconstruction of Devonian-Carboniferous rifting of Avalonian lithosphere. We present a revised map of Devonian-Carboniferous basin structures including the main horsts and grabens and the governing faults east of the Central Graben. Based on these maps, we present a new paleotectonic reconstruction and a novel geodynamic scenario for the Devonian- Carboniferous rifting. These findings are key for better understanding of long-lived tectonic compartmentalisation and post-rifting deformation phases.

  17. Influences of the El Nino Southern Oscillation and the Pacific Decadal Oscillation on the Timing of the North American Spring

    NASA Technical Reports Server (NTRS)

    McCabe, Gregory J.; Ault, Toby R.; Cook, Benjamin I.; Betancourt, Julio L.; Schwartz, Mark D.

    2012-01-01

    Detrended, modelled first leaf dates for 856 sites across North America for the period 1900-2008 are used to examine how the El Nino Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO) separately and together might influence the timing of spring. Although spring (mean March through April) ENSO and PDO signals are apparent in first leaf dates, the signals are not statistically significant (at a 95% confidence level (p <0.05)) for most sites. The most significant ENSO/PDO signal in first leaf dates occurs for El Nino and positive PDO conditions. An analysis of the spatial distributions of first leaf dates for separate and combined ENSO/PDO conditions features a northwest-southeast dipole that is significantly (at p <0.05) different than the distributions for neutral conditions. The nature of the teleconnection between Pacific SST's and first leaf dates is evident in comparable composites for detrended sea level pressure (SLP) in the spring months. During positive ENSO/PDO, there is an anomalous flow of warm air from the southwestern US into the northwestern US and an anomalous northeasterly flow of cold air from polar regions into the eastern and southeastern US. These flow patterns are reversed during negative ENSO/PDO. Although the magnitudes of first leaf date departures are not necessarily significantly related to ENSO and PDO, the spatial patterns of departures are significantly related to ENSO and PDO. These significant relations and the long-lived persistence of SSTs provide a potential tool for forecasting the tendencies for first leaf dates to be early or late.

  18. Southern Ocean influence on the eastern tropical North Pacific's intermediate-depth circulation during the Last Glacial Maximum

    NASA Astrophysics Data System (ADS)

    Carriquiry, José D.; Sanchez, Alberto; Leduc, Guillaume

    2015-08-01

    The oxygen and carbon isotopic compositions of benthic foraminiferal tests were measured on sedimentary sequences retrieved on the Magdalena Margin, off southern Baja California, Mexico. We reconstruct the hydrographic changes along the water column that occurred in the northeastern tropical Pacific since the Last Glacial Maximum (LGM) and compare those changes to the ones that occurred in the northwest Pacific (NWP, i.e., off Japan and Russia), in the northeast Pacific along the Californian Margin, as well as in the southeast Pacific (off Chile). The foraminiferal δ18O depth profiles across the North and southeast Pacific show similar trends between the LGM and the Holocene, indicating that changes in the oceanographic conditions between ~400 and 2000 m depth were very similar. Changes in the isotopic composition of dissolved inorganic carbon (δ13CDIC) in the Baja California Margin since the Last Glacial Maximum were reconstructed using the δ13C of shallow endobenthic foraminifers U. peregrina and the epibenthic Cibicides mckannai. The most striking result is a marked shift toward more positive δ13C values below 1200 m depth in the northeast Pacific (NEP) during the Holocene (relative to the LGM). This observation suggests that a nutrient-rich water mass ventilated the NEP during the LGM. At a basin scale, the δ13C values of NEP waters at intermediate depths were more negative relative to the NWP and southeast Pacific during the LGM, suggesting that the nutrient-rich water column along the NEP (i.e., Baja California Margin) was confined in that area as observed today.

  19. The Dimethylsulfide Cycle in the Eutrophied Southern North Sea: A Model Study Integrating Phytoplankton and Bacterial Processes

    PubMed Central

    Gypens, Nathalie; Borges, Alberto V.; Speeckaert, Gaelle; Lancelot, Christiane

    2014-01-01

    We developed a module describing the dimethylsulfoniopropionate (DMSP) and dimethylsulfide (DMS) dynamics, including biological transformations by phytoplankton and bacteria, and physico-chemical processes (including DMS air-sea exchange). This module was integrated in the MIRO ecological model and applied in a 0D frame in the Southern North Sea (SNS). The DMS(P) module is built on parameterizations derived from available knowledge on DMS(P) sources, transformations and sinks, and provides an explicit representation of bacterial activity in contrast to most of existing models that only include phytoplankton process (and abiotic transformations). The model is tested in a highly productive coastal ecosystem (the Belgian coastal zone, BCZ) dominated by diatoms and the Haptophyceae Phaeocystis, respectively low and high DMSP producers. On an annual basis, the particulate DMSP (DMSPp) production simulated in 1989 is mainly related to Phaeocystis colonies (78%) rather than diatoms (13%) and nanoflagellates (9%). Accordingly, sensitivity analysis shows that the model responds more to changes in the sulfur:carbon (S:C) quota and lyase yield of Phaeocystis. DMS originates equally from phytoplankton and bacterial DMSP-lyase activity and only 3% of the DMS is emitted to the atmosphere. Model analysis demonstrates the sensitivity of DMS emission towards the atmosphere to the description and parameterization of biological processes emphasizing the need of adequately representing in models both phytoplankton and bacterial processes affecting DMS(P) dynamics. This is particularly important in eutrophied coastal environments such as the SNS dominated by high non-diatom blooms and where empirical models developed from data-sets biased towards open ocean conditions do not satisfactorily predict the timing and amplitude of the DMS seasonal cycle. In order to predict future feedbacks of DMS emissions on climate, it is needed to account for hotspots of DMS emissions from coastal

  20. Centennial-scale vegetation and North Atlantic Oscillation changes during the Late Holocene in the southern Iberia

    NASA Astrophysics Data System (ADS)

    Ramos-Román, M. J.; Jiménez-Moreno, G.; Anderson, R. S.; García-Alix, A.; Toney, J. L.; Jiménez-Espejo, F. J.; Carrión, J. S.

    2016-07-01

    High-reso CE to lution pollen analysis, charcoal, non-pollen palynomorphs and magnetic susceptibility have been analyzed in the sediment record of a peat bog in Sierra Nevada in southern Iberia. The study of these proxies provided the reconstruction of vegetation, climate, fire and human activity of the last ∼4500 cal yr BP. A progressive trend towards aridification during the late Holocene is observed in this record. This trend is interrupted by millennial- and centennial-scale variability of relatively more humid and arid periods. Arid conditions are recorded between ∼4000 and 3100 cal yr BP, being characterized by a decline in arboreal pollen and with a spike in magnetic susceptibility. This is followed by a relatively humid period from ∼3100 to 1600 cal yr BP, coinciding partially with the Iberian-Roman Humid Period, and is indicated by the increase of Pinus and the decrease in xerophytic taxa. The last 1500 cal yr BP are characterized by several centennial-scale climatic oscillations. Generally arid conditions from ∼450 to 1300 CE, depicted by a decrease in Pinus and an increase in Artemisia, comprise the Dark Ages and the Medieval Climate Anomaly. Since ∼ 1300 to 1850 CE pronounced oscillations occur between relatively humid and arid conditions. Four periods depicted by relatively higher Pinus coinciding with the beginning and end of the Little Ice Age are interrupted by three arid events characterized by an increase in Artemisia. These alternating arid and humid shifts could be explained by centennial-scale changes in the North Atlantic Oscillation and solar activity.

  1. Composition and quality of coals in the Huaibei Coalfield, Anhui, China

    USGS Publications Warehouse

    Zheng, Lingyun; Liu, Gaisheng; Wang, L.; Chou, C.-L.

    2008-01-01

    The Huaibei Coalfield, Anhui Province, China, is one of the largest coalfields in China. The coals of Permian age are used mainly for power generation. Coal compositions and 47 trace elements of the No. 10 Coal of the Shanxi Formation, the No. 7, 5, and 4 Coals of the Lower Shihezi Formation, and the No. 3 Coal of the Upper Shihezi Formation from the Huaibei Coalfield were studied. The results indicate that the Huaibei coals have low ash, moisture, and sulfur contents, but high volatile matter and calorific value. The ash yield increases stratigraphically upwards, but the volatile matter and total sulfur contents show a slight decrease from the lower to upper seams. Magmatic intrusion into the No. 5 Coal resulted in high ash, volatile matter, and calorific value, but low moisture value in the coal. Among the studied 47 trace elements, Ba, Co, Cr, Cu, Hg, Mo, Ni, Pb, Sb, Th, U, V, and Zn are of environmental concerns. Four elements Hg, Mo, Zn, and Sb are clearly enriched in the coals as compared with the upper continental crust. ?? 2007 Elsevier B.V. All rights reserved.

  2. Geological characteristics in buried coalfields synthetically using remote sensing and non-remote sensing information

    NASA Astrophysics Data System (ADS)

    Dai, Shifeng; Wang, Silong; Liu, Yurong

    1998-08-01

    With the rapid development of coal industry in China, the emphasis of the geological exploration has been changed from the exposed area to the buried area. Because of the limitation of the geological condition and the exploration methods, it is very difficult to study the geological phenomena in buried coalfield. To the coal geologists in China, to search an effective and practical method has been the important tackle key problem for recent years. In this paper, the authors discussed the characteristics of remote sensing technology in the geological study, and the forming mechanism of remote sensing information in the buried area from the view of agrology and physics, so the important academic evidences were offered for the geological study using remote sensing image in the buried coalfield. The characteristics of the non-remote sensing information, the geophysics information and the basal geological information, were also introduced in the study of buried geological bodies. The authors expounded the general processing method in the investigation of buried geological bodies using remote sensing and non-remote sensing information. At last, the probable distribution area of buried igneous rocks, in Huaibei coalfield in China, were successfully forecasted synthetically using the remote sensing, and non-remote sensing information.

  3. Cooling History in Mabja Dome, Southern Tibet: Implications for the Tectonic Evolution of the North Himalayan Gneiss Domes

    NASA Astrophysics Data System (ADS)

    Lee, J.; Wang, Y.; McWilliams, M.; Hourigan, J.; Blythe, A.; McClelland, W.

    2001-12-01

    The Mabja Dome (MD), southern Tibet, is one of a series of gneiss domes, called the North Himalayan Gneiss Domes, located south of the Indus-Tsangpo suture zone and north of the high Himalaya. The MD consists of an ~25 km diameter doubly plunging antiform cored by migmatitic K-feldspar augen biotite orthogneiss which is mantled by high grade metapelites and granitic orthogneisses. These rocks record two primary deformational events: an older deformational event, D1, characterized by ~EW-trending folds of S0 with an associated moderately N-dipping axial planar foliation, S1, and a younger event, D2, characterized by a domed mylonitic foliation, S2, and associated NS-trending mineral stretching lineation. Peak metamorphism is pre- to early syntectonic with D2 structures and defines a set of isograds that are subparallel to structure. Two-mica granites, one of which yielded an U/Pb monazite age of 14.5+/-0.1 Ma, were emplaced during the latest stages of D2 deformation. Mica and kspar Ar/Ar and apatite fission track (AFT) analyses were completed on orthogneisses, metasediments, and two-mica granites to shed light on the timing and mechanism of cooling of these rocks. Muscovite yielded Ar/Ar cooling ages of ~12.7 Ma on the northern flank of the dome, increasing to ~17.0 Ma in metapelite and orthogneiss at deeper structural levels, and decreasing to ~13.5 Ma within migmatite at the deepest structural levels. Biotites are disturbed and yield total gas ages that are slightly younger than muscovite on the flanks of the dome, but older within the core. Analyses of four kspars from orthogneiss and migmatite yielded complex spectra with old apparent ages at the lowest temperature steps, followed by ages that climb slowly from 12.5-13.0 Ma over the first 30% of 39Ar released, which in turn is followed by ages that climb to 100 Ma (orthogneiss) and 15-18 Ma (migmatite) at high temperature steps. AFT analyses from orthogneiss and migmatite yielded a mean age of 9.5 Ma indicating

  4. Long-term impact of bottom trawling on pelagic-benthic coupling in the southern North Sea (German Bight)

    NASA Astrophysics Data System (ADS)

    Friedrich, Jana; van Beusekom, Justus E. E.; Neumann, Andreas; Naderipour, Celine; Janssen, Felix; Ahmerkamp, Soeren; Holtappels, Moritz; Schueckel, Ulrike

    2016-04-01

    The southern North Sea, and the German Bight, has been systematically bottom-trawled at least since the late 19th century (Christiansen, 2009; Reiss et al., 2009; Kröncke 2011; Emeis et al., 2015, Neumann et al., 2016). As a result, benthic habitats and benthic biogenic structures created by bivalves, polychaetes and hydroids where destroyed or reduced. The parallel removal of hard substrate (gravel and boulders) avoids the resettlement of hard-substrate depended species. For example, the Oyster ground, a huge oyster bank a hundred years ago (Olsen, 1883), turned into a muddy depression today. In addition, shallow depth of max 40 m, strong tidal currents and frequent storms result in a high-energy environment with low sedimentation rates and recurrent sediment resuspension. The decrease in benthic filtering capacity by disturbance in epifauna and bottom roughness (Callaway et al., 2007) apparently influence pelagic-benthic coupling of biogeochemical fluxes. Heip et al. (1995) indicate that benthic respiration at depths prevailing in the German Bight accounts for 10-40% of total respiration, whereas pelagic respiration accounts for 60-90%. Previous estimates are in the middle of this range (Heip et al., 1995). To test these hypotheses and to assess the partitioning of benthic and pelagic processes, and the factors influencing organic matter mineralization, we measured pelagic production and respiration based on Winkler titration, in-situ benthic fluxes using chamber landers, we did ex-situ incubations of intact sediment cores and analysed still images from a towed benthic video sled. In addition, O2 fluxes in permeable sediments were estimated by integrating the volumetric rate measurements of the upper sediment layer over in-situ microsensor-measured O2 penetration depth. Our current results show significant seasonality in benthic respiration, with highest rates in summer and lowest rates in winter. No significant differences in total benthic respiration rates

  5. Millennial scale precipitation changes over Easter Island (Southern Pacific) during MIS 3: Inter-hemispheric connections during North Atlantic abrupt cold events

    NASA Astrophysics Data System (ADS)

    Margalef, Olga; Cacho, Isabel; Pla-Rabes, Sergi; Cañellas-Boltà, Núria; Pueyo, Juan Jose; Sáez, Alberto; Valero-Garcés, Blas L.; Giralt, Santiago

    2013-04-01

    Marine Isotope Stage (MIS) 3 climate has been globally characterized by the occurrence of millennial-scale climate variations defined over North Atlantic as Dansgaard-Oeschger and Heinrich events. Despite climate variability has been broadly explored over North Atlantic records, the response of the tropical and subtropical latitudes, especially in the Southern Hemisphere, still remains as a matter of debate. Rano Aroi peat record (Easter Island, Chile, 27°S) provides a unique opportunity to understand Southern Pacific atmospheric and oceanic changes during these stadial-interstadial transitions because of its exceptional location on the interplay of the South Pacific Convergence Zone (SPCZ), the Intertropical Convergence Zone (ITCZ), the South Pacific Anticyclone (SPA) and the Southern Westerlies (SW). Rano Aroi record contains 8 main enhanced precipitation events between 70 and 40 kyr BP that can be correlated with the timing of Heinrich events 5, 5a and 6 as well as other cold stadials. These humid events are also present in other Southern Hemisphere continental sites and correspond to dry periods on Northern Hemisphere records. This opposite hydrologic trend has been explained by the latitudinal migration of ITCZ and has been supported by several climatic models. As Easter Island precipitation is mainly dependent on SPCZ storm track belt activity, we suggest that the southern migration of the ITCZ is associated to an expansion of SPCZ to the east. This process should be intimately related to a weakening of the Walker circulation, which is further supported by an estimation of d18Osw gradient along the equator for the same time period. Consequently, atmospheric and oceanic responses during these cold stadials and Heinrich events might lead to a configuration that resembles the warm ENSO state over Southern Pacific, as previously suggested by some global climatic models. Rano Aroi record clearly points out that shifts in hydrological cycle in tropical Southern

  6. The influence of eastern North American autumnal migrant monarch butterflies (Danaus plexippus L.) on continuously breeding resident monarch populations in southern Florida.

    PubMed

    Knight, Amy; Brower, Lincoln P

    2009-07-01

    In Florida, the eastern North American population of the monarch butterfly exhibits geographic variability in population structure and dynamics. This includes the occurrence of migrants throughout the peninsula during the autumnal migration, occasional overwintering clusters that form along the Gulf Coast, remigrants from Mexico that breed in north-central Florida during the spring, and what have been assumed to be year-round, resident breeding populations in southern Florida. The work reported here focused on two monarch populations west of Miami and addressed four questions: Are there permanent resident populations of monarchs in southern Florida? Do these breed continuously throughout the year? Do they receive northern monarchs moving south during the autumn migration? Do they receive overwintered monarchs returning via Cuba or the Yucatan during the spring remigration from the Mexican overwintering area? Monthly collections and counts of spermatophores in the bursa copulatrices of females established that a resident population of continuously breeding monarchs exists year-round in southern Florida. It was determined through cardenolide fingerprinting that most of the butterflies had bred on the local southern Florida milkweed species, Asclepias curassavica. During the autumn migration period, however, some monarchs had fed on the northern milkweed, Asclepias syriaca. It appears that instead of migrating to Mexico, these individuals travel south through peninsular Florida, break diapause, mate with and become incorporated into the resident breeding populations. None of the monarchs captured in spring had the A. syriaca cardenolide fingerprint, which is evidence against the southern Florida populations receiving overwintered remigrants from Cuba, Central America or Mexico. PMID:19579046

  7. Community worry about heart disease: a needs survey in the Coalfields and Newcastle areas of the Hunter region.

    PubMed

    Higginbotham, N; Heading, G; Pont, J; Plotnikoff, R; Dobson, A J; Smith, E; Metcalfe, A; Valenti, L; Croce, N

    1993-12-01

    A needs survey was administered by mail in the Coalfields area of the Hunter region (a lower socioeconomic area around Cessnock) and in a higher socioeconomic area of Newcastle. The purpose was to assist planning for Coalfields Healthy Heartbeat--a community-action heart disease prevention program. Response rates from random samples of residents were 435/897 (49 per cent) for the Coalfields and 565/875 (65 per cent) for Newcastle. In both study areas heart attack was ranked eleventh from a list of 17 potential community worries, well below drugs, crime, road safety, the environment, cancer and 'loss of health'. Coalfields respondents were more worried about all issues on the list than were the residents in Newcastle and were less likely to have heard about recent health promotion campaigns. Coalfields respondents felt that heart disease prevention was the responsibility of the individual, the family, and the medical profession, in that order, and much less the responsibility of local community groups. Results suggest that health promotion strategies incorporating values, language and symbols that are meaningful to distinct subgroups may be more successful than disease-specific programs aimed at the general population. PMID:8204711

  8. West Point Melange, remnants of a Lower Paleozoic ophiolitic, eclogite-bearing melange in the Southern Appalachians, Alabama, Georgia, and North Carolina

    SciTech Connect

    Crawford, R.F. III; Higgins, M.W.; Crawford, T.

    1985-01-01

    The lower Paleozoic West Point melange in the West Point thrust sheet is locally preserved beneath and commonly folded with ocean-floor Ropes Creek Metabasalt of the Ropes Creek thrust sheet in the crystalline terrane of Alabama, Georgia, and North Carolina. The melange overlies a calc-alkaline island arc assemblage known as the Paulding volcanic-plutonic complex in the Paulding thrust sheet. The matrix of the melange is generally highly sheared talc-actinolite schist and (or) highly deformed amphibolite, and less commonly sheared scaly pelitic schist. Most clasts in the melange are of a wide variety of mafic and ultramafic rocks, including dunite, coronite troctolite, olivine gabbro, wehrlite, cortlandite, pyroxenite, and olivine-pyroxenite. Eclogite clasts are found at several localities in northern Georgia, southern North Carolina, and in Alabama. The mostly mafic ophiolitic nature of the West Point melange, the clasts of eclogite, and its location between an island-arc assemblage and ocean-ridge basalts suggests that it is the remnants of a subduction melange formed between the mid-Iapetus ridge and the oceanic Paulding island arc. The melange also forms part of the Hillabee Greenstone in Alabama and the Lake Chatuge sill and Shooting Creek complex in northern Georgia and southern North Carolina.

  9. Flame retardants in eggs of American kestrels and European starlings from southern Lake Ontario region (North America).

    PubMed

    Chen, Da; Letcher, Robert J; Martin, Pamela

    2012-11-01

    While a number of studies have extensively investigated flame retardant (FR) contamination in aquatic ecosystems from the Laurentian Great Lakes basin, there remains a dearth of information for terrestrial ecosystems. In the current study, American kestrels (Falco sparverius) (AMKE) and European starlings (Sturnus vulgaris) (EUST) that are terrestrial ecosystem consumers, and from the southern Lake Ontario regions, were investigated as potential terrestrial bio-monitoring species. Egg homogenates were screened for sixteen PBDE congeners and nineteen non-PBDE FRs of established or emerging environmental importance. PBDE congeners dominated the FR burdens in eggs of AMKE and EUST, with total concentrations ranging from 3.4 to 39.8 (median: 13.5) and 1.5 to 117 (median: 4.9) ng g(-1) wet weight (ww), respectively. Although the production and application of the Firemaster FF-1 (a commercial hexabromobiphenyl PBB mixture) has been discontinued for over four decades, its major component, 2,2',4,4',5,5'-hexabromobiphenyl (BB-153), was still frequently detected in AMKE and EUST eggs. Two isomers of the chlorinated FR Dechlorane plus (DP) were mostly detected in eggs collected from Niagara-on-the-Lake in the western portion of Lake Ontario, approximately 15 km from the only North American DP manufacturing site, clearly reflecting point source influences. FR comparisons in eggs from AMKE, EUST and Great Lakes herring gulls revealed species-specific contamination burdens and PBDE congener profiles, likely due to influences from trophic levels and PBDE congener-specific bioaccumulation and biomagnification capacities in terrestrial versus aquatic food chains. Insectivorous birds (e.g. great tit) and relatives of AMKE have also been used as bio-monitoring tools in European and Asian regions, allowing investigation of spatial distribution patterns on a more international scale. AMKE and EUST have also been used as model species for laboratory evaluation of FR toxic effects in

  10. Present-day vertical displacements in the north-western Alps and southern Jura Mountains: Data from leveling comparisons

    NASA Astrophysics Data System (ADS)

    Jouanne, F.; MéNard, G.; Darmendrail, X.

    1995-06-01

    Two high-precision leveling networks were successively surveyed in France, the NGF, measured during the 1886-1907 period, and the IGN69, measured from 1965 to 1979. The accuracy of these levelings (standard deviation of 1.8mm/√km to 3.8mm/√km) allows us to compute the vertical displacements of the benchmarks between two different eras. The results indicate the occurrence of discrete zones of uplift and subsidence: (1) a regional uplift (up to 1.4 mm/yr) of the Subalpine Massifs; (2) an important uplift of the internal Jura (up to 2 mm/yr); (3) a relative subsidence of the southern part of the Jura (0.8 mm/yr); and (4) a relative subsidence of the Bresse Basin with respect to the external Jura. Comparing the spatial distribution of zones of uplift and their respective vertical displacement rates with a regional structural cross section leads to the conclusion that present-day uplift of the Belledonne and Bornes Massifs and of the internal parts of the Jura Mountains, can be explained by crustal shortening along a major basement-involving thrust fault. This fault ramps up under the Bornes Massif from a depth of 12 km to 7 km, turns into a flat under the Molasse Basin, ramps up to the top of the basement at the north-eastern margin of the internal Jura Mountains, and reaches the surface in the external Jura. The Salève ramp-anticline is carried by a bifurcation of this thrust. Horizontal displacement rates of 6 mm/yr at the Bornes ramp, 2 mm/yr at the Salève ramp, and 4 mm/yr at the internal Jura ramp have been determined by inversion of profiles of uplift rates. Whether this basement-involving thrust fault was already active during the Miocene main folding phase of the Jura Mountains or whether it was activated only during Pliocene-Pleistocene times is subject to debate.

  11. Storms, shoreface morphodynamics, sand supply, and the accretion and erosion of coastal dune barriers in the southern North Sea

    NASA Astrophysics Data System (ADS)

    Anthony, Edward J.

    2013-10-01

    The coast of the southern North Sea is bound by dune barriers that have developed adjacent to a shallow storm- and tide-dominated shoreface comprising numerous shore-parallel to sub-shore-parallel tidal sand banks. The banks evolve under the joint control of tide-, wave- and wind-induced shore-parallel currents, which tend to ‘stretch' them, eventually leading to bank division, and to shoaling and breaking storm waves, which tend to drive them ashore. The banks, thus, modulate the delivery of storm wave energy to the coast, redirect currents alongshore and are the sand sources for the accretion of coastal dunes. Foredune accretion occurs where major sand banks have migrated shoreward over the last centuries to be finally driven ashore and weld under the impact of storm waves. Morphological changes in the bank field can impact on shoreline stability through dissipation or enhanced shoreward transmission of storm wave energy and effects on radiation stress, particularly when waves are breaking over the banks. Where banks are close to the shore, mitigation of offshore sediment transport, especially during storms, can occur because of gradients in radiation stress generated by the complex 3D bank structure. These macro-scale mechanisms involve embedded meso-scale interactions that revolve around the mobility of sand waves, mobility of beach bars and troughs and foredune mobility, and micro-scale processes of bedform mobility in the subaqueous and intertidal domains, and of swash and aeolian beach-dune sand transport. These embedded interactions and the morphodynamic feedback loops illustrate the importance of synchroneity of sand transport from shoreface to dune on this coast. Large stretches of the foredunes show either signs of stability, or mild but chronic erosion. Furthermore, a demonstrated lack of a clear relationship occurs between storminess and coastal response over the second half of the 20th century. The present situation may be indicative of conditions

  12. Long-term impact of bottom trawling on pelagic-benthic coupling in the southern North Sea (German Bight)

    NASA Astrophysics Data System (ADS)

    Friedrich, Jana; van Beusekom, Justus E. E.; Neumann, Andreas; Naderipour, Celine; Janssen, Felix; Ahmerkamp, Soeren; Holtappels, Moritz; Schueckel, Ulrike

    2016-04-01

    The southern North Sea, and the German Bight, has been systematically bottom-trawled at least since the late 19th century (Christiansen, 2009; Reiss et al., 2009; Kröncke 2011; Emeis et al., 2015, Neumann et al., 2016). As a result, benthic habitats and benthic biogenic structures created by bivalves, polychaetes and hydroids where destroyed or reduced. The parallel removal of hard substrate (gravel and boulders) avoids the resettlement of hard-substrate depended species. For example, the Oyster ground, a huge oyster bank a hundred years ago (Olsen, 1883), turned into a muddy depression today. In addition, shallow depth of max 40 m, strong tidal currents and frequent storms result in a high-energy environment with low sedimentation rates and recurrent sediment resuspension. The decrease in benthic filtering capacity by disturbance in epifauna and bottom roughness (Callaway et al., 2007) apparently influence pelagic-benthic coupling of biogeochemical fluxes. Heip et al. (1995) indicate that benthic respiration at depths prevailing in the German Bight accounts for 10-40% of total respiration, whereas pelagic respiration accounts for 60-90%. Previous estimates are in the middle of this range (Heip et al., 1995). To test these hypotheses and to assess the partitioning of benthic and pelagic processes, and the factors influencing organic matter mineralization, we measured pelagic production and respiration based on Winkler titration, in-situ benthic fluxes using chamber landers, we did ex-situ incubations of intact sediment cores and analysed still images from a towed benthic video sled. In addition, O2 fluxes in permeable sediments were estimated by integrating the volumetric rate measurements of the upper sediment layer over in-situ microsensor-measured O2 penetration depth. Our current results show significant seasonality in benthic respiration, with highest rates in summer and lowest rates in winter. No significant differences in total benthic respiration rates

  13. Acid deposition sensitivity map of the Southern Appalachian Assessment area; Virginia, North Carolina, South Carolina, Tennessee, Georgia, and Alabama

    USGS Publications Warehouse

    Pepper, John D.; Grosz, Andrew E.; Kress, Thomas H.; Collins, Thomas K.; Kappesser, Gary B.; Huber, Cindy M.; Webb, James R.

    1995-01-01

    Project Summary: The following digital product represents the Acid Deposition Sensitivity of the Southern Appalachian Assessment Area. Areas having various susceptibilities to acid deposition from air pollution are designated on a three tier ranking in the region of the Southern Appalachian Assessment (SAA). The assessment is being conducted by Federal agencies that are members of the Southern Appalachian Man and Biosphere (SAMAB) Cooperative. Sensitivities to acid deposition, ranked high, medium, and low are assigned on the basis of bedrock compositions and their associated soils, and their capacities to neutralize acid precipitation.

  14. Commercial fishing gear modifications to reduce interactions between Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus) and the southern flounder (Paralichthys lethostigma) fishery in North Carolina (USA)

    PubMed Central

    Hager, Christian; Diaddorio, Eric; Dickey, R. Jason

    2016-01-01

    Bycatch of protected species in commercial fishing operations is a primary concern to fishery managers because it threatens the conservation, protection, and recovery of fragile species, such as the Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus). One potential solution to reduce the risk associated with commercial fishing operations is to design commercial fishing gear that is more selective in terms of interactions between Atlantic sturgeon and commercial fisheries. Given this conservation and management need, the overarching goal was to reduce Atlantic sturgeon fishery interactions and maintain southern flounder (Paralichthys lethostigma) catch in North Carolina. The specific objectives of this study were to design and evaluate the effectiveness of a modified gillnet. Overall, the results proved that lowering the profile and amount of webbing had a beneficial impact at reducing Atlantic sturgeon incidental encounters and bycatch. The modified gillnet reduced bycatch and Atlantic sturgeon encounters by 39.6% and 60.9%, respectively. Our design entangled 51.6% fewer southern flounder, which corresponded to a 48.9% reduction in total weight; the modified gear entangled slightly larger southern flounder than the control gear. Our findings showed the number of Atlantic sturgeon encounters was positively associated with mean water depth, with more Atlantic sturgeon encountered in deeper (5.1–6.3 m) than shallower waters; 75% were encountered at depths between 4.6 and 6.1 m. Most southern flounder (n = 518, 39.7%) were taken at a water depth between 3.76 and 5.0 m. This observation suggests that southern flounder prefer slightly shallower waters than Atlantic sturgeon. PMID:27547524

  15. Commercial fishing gear modifications to reduce interactions between Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus) and the southern flounder (Paralichthys lethostigma) fishery in North Carolina (USA).

    PubMed

    Levesque, Juan C; Hager, Christian; Diaddorio, Eric; Dickey, R Jason

    2016-01-01

    Bycatch of protected species in commercial fishing operations is a primary concern to fishery managers because it threatens the conservation, protection, and recovery of fragile species, such as the Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus). One potential solution to reduce the risk associated with commercial fishing operations is to design commercial fishing gear that is more selective in terms of interactions between Atlantic sturgeon and commercial fisheries. Given this conservation and management need, the overarching goal was to reduce Atlantic sturgeon fishery interactions and maintain southern flounder (Paralichthys lethostigma) catch in North Carolina. The specific objectives of this study were to design and evaluate the effectiveness of a modified gillnet. Overall, the results proved that lowering the profile and amount of webbing had a beneficial impact at reducing Atlantic sturgeon incidental encounters and bycatch. The modified gillnet reduced bycatch and Atlantic sturgeon encounters by 39.6% and 60.9%, respectively. Our design entangled 51.6% fewer southern flounder, which corresponded to a 48.9% reduction in total weight; the modified gear entangled slightly larger southern flounder than the control gear. Our findings showed the number of Atlantic sturgeon encounters was positively associated with mean water depth, with more Atlantic sturgeon encountered in deeper (5.1-6.3 m) than shallower waters; 75% were encountered at depths between 4.6 and 6.1 m. Most southern flounder (n = 518, 39.7%) were taken at a water depth between 3.76 and 5.0 m. This observation suggests that southern flounder prefer slightly shallower waters than Atlantic sturgeon. PMID:27547524

  16. Spatio-temporal pattern of eco-environmental parameters in Jharia coalfield, India

    NASA Astrophysics Data System (ADS)

    Saini, V.; Gupta, R. P.; Arora, M. K.

    2015-10-01

    Jharia coal-field holds unequivocal importance in the Indian context as it is the only source of prime coking coal in the country. The coalfield is also known for its infamous coal mine fires which have been burning since last more than a century. Haphazard mining over a century has led to eco-environmental changes to a large extent such as changes in vegetation distribution and widespread development of surface and subsurface fires. This article includes the spatiotemporal study of remote sensing derived eco-environmental parameters like vegetation index (NDVI), tasseled cap transformation (TCT) and temperature distribution in fire areas. In order to have an estimate of the temporal variations of NDVI over the years, a study has been carried out on two subsets of the Jharia coalfield using Landsat images of 1972 (MSS), 1992 (TM), 1999 (ETM+) and 2013 (OLI). To assess the changes in brightness and greenness over the year s, difference images have been calculated using the 1992 (TM) and 2013 (OLI) images. Radiance images derived from thermal bands have been used to calculate at-sensor brightness temperature over a 23 year period from 1991 to 2013. It has been observed that during the years 1972 to 2013, moderate to dense vegetation has decreased drastically due to the intense mining going on in the area. TCT images show the areas that have undergone changes in both brightness and greenness from 1992 to 2013. Surface temperature data obtained shows a constant increase from 1991 to 2013 apparently due to coal fires. The utility of remote sensing data in such EIA studies has been emphasized.

  17. The problems of the kinematic restoration of hyper-extended rifted margins: the example of the southern North-Atlantic

    NASA Astrophysics Data System (ADS)

    Nirrengarten, Michael; Manatschal, Gianreto; Tugend, Julie; Kusznir, Nick

    2016-04-01

    The development in space and time of hyper-extended lithosphere is fundamental to our understanding of the 3D development and propagation of rifting and lithospheric breakup. Hyper-extended domains, consisting of extremely thinned continental crust and exhumed mantle with possible minor magmatic addition, often extend over wide areas, sometimes up to 400 km, continentward of the first unequivocal oceanic crust. Although considerable work has been done in the last decades to describe the evolution of hyper-extended domains, there is yet no generally accepted approach to kinematically restore them. Indeed, in contrast to oceanic crust, where the kinematics can be defined by isochronal magnetic anomalies, in hyper-extended well-defined consistent magnetic anomalies are lacking. Therefore in order to restore these domains, we need to define alternative approaches. The main questions to be addressed to solve this problem are: 1) how can hyper-extended domains be restored, 2) which kinematic markers could be used 3) what are the implications for the 3D propagation of hyper-extended systems. We use the example of the southern North-Atlantic to develop and apply an approach to kinematically analyse the evolution of hyper-extended domains. We combine seismic dataset and drill hole data available with crustal thickness maps determined from gravity inversion to define and map rift domains and rift domain boundaries. We distinguish between the proximal domain (weakly thinned continental crust), thinned continental crust, exhumed mantle, and oceanic crust. From this mapping, we observe that the width of each domain is variable along the margins and that domain boundaries are not always straight lines. It implies that these boundaries, in particular the edge of the continental crust cannot be easily superimposed at a specific time. Therefore, rift domain boundaries cannot be considered as isochrones and do not represent kinematical markers. The restoration of hyper

  18. Atmospheric concentrations and size distributions of aircraft-sampled Cd, Cu, Pb and Zn over the southern bight of the North Sea

    NASA Astrophysics Data System (ADS)

    Injuk, J.; Otten, Ph.; Laane, R.; Maenhaut, W.; Van Grieken, R.

    In an effort to assess the atmospheric input of heavy metals to the Southern Bight of the North Sea, aircraft-based aerosol samplings in the lower troposphere were performed between September 1988 and October 1989. Total atmospheric particulate and size-differentiated concentrations of Cd, Cu, Pb and Zn were determined as a function of altitude, wind direction, air-mass history and season. The obtained data are compared with results of ship-based measurements carried out previously and with literature values of Cu, Pb and Zn, for the marine troposphere of the southern North Sea. The results point out the high variability of the concentrations with the meterological conditions, as well as with time and location. The experimentally found particle size distribution are bimodal with a significant difference in fractions of small and large particles. These large aerosol particles have a direct and essential impact on the air-to-sea transfer of anthropogenic trace metals, in spite of their low numerical abundance and relatively low heavy metal content.

  19. Marine Fouling Assemblages on Offshore Gas Platforms in the Southern North Sea: Effects of Depth and Distance from Shore on Biodiversity

    PubMed Central

    van der Stap, Tim; Coolen, Joop W. P.; Lindeboom, Han J.

    2016-01-01

    Offshore platforms are known to act as artificial reefs, though there is on-going debate on whether this effect is beneficial or harmful for the life in the surrounding marine environment. Knowing what species exist on and around the offshore platforms and what environmental variables influence this species assemblage is crucial for a better understanding of the impact of offshore platforms on marine life. Information on this is limited for offshore platforms in the southern North Sea. This study aims to fill this gap in our knowledge and to determine how the composition and the abundance of species assemblages changes with depth and along a distance-from-shore gradient. The species assemblages on five offshore gas platforms in the southern North Sea have been inventoried using Remotely Operated Vehicles inspection footage. A total of 30 taxa were identified. A Generalised Additive Model of the species richness showed a significant non-linear relation with water depth (p = 0.001): from a low richness in shallow waters it increases with depth until 15–20 m, after which richness decreases again. Using PERMANOVA, water depth (p≤0.001), community age (p≤0.001) and the interaction between distance from shore and community age (p≤0.001) showed a significant effect on the species assemblages. Future research should focus on the effect additional environmental variables have on the species assemblages. PMID:26745870

  20. Marine Fouling Assemblages on Offshore Gas Platforms in the Southern North Sea: Effects of Depth and Distance from Shore on Biodiversity.

    PubMed

    van der Stap, Tim; Coolen, Joop W P; Lindeboom, Han J

    2016-01-01

    Offshore platforms are known to act as artificial reefs, though there is on-going debate on whether this effect is beneficial or harmful for the life in the surrounding marine environment. Knowing what species exist on and around the offshore platforms and what environmental variables influence this species assemblage is crucial for a better understanding of the impact of offshore platforms on marine life. Information on this is limited for offshore platforms in the southern North Sea. This study aims to fill this gap in our knowledge and to determine how the composition and the abundance of species assemblages changes with depth and along a distance-from-shore gradient. The species assemblages on five offshore gas platforms in the southern North Sea have been inventoried using Remotely Operated Vehicles inspection footage. A total of 30 taxa were identified. A Generalised Additive Model of the species richness showed a significant non-linear relation with water depth (p = 0.001): from a low richness in shallow waters it increases with depth until 15-20 m, after which richness decreases again. Using PERMANOVA, water depth (p≤0.001), community age (p≤0.001) and the interaction between distance from shore and community age (p≤0.001) showed a significant effect on the species assemblages. Future research should focus on the effect additional environmental variables have on the species assemblages. PMID:26745870

  1. The Effects of Mountaintop Mines and Valley Fills on Aquatic Ecosystems of the Central Appalachian Coalfields (2011 Final)

    EPA Science Inventory

    Cover of the Mountaintop Mines and Valley Fills Central Appalachian <span class=Coalfields Final Report "> This report assesses the state of the sci...

  2. "Non-Servile Virtuosi" in Insubordinate Spaces: School Disaffection, Refusal and Resistance in a Former English Coalfield

    ERIC Educational Resources Information Center

    Bright, N. Geoffrey

    2011-01-01

    This article reviews excerpts from a body of ethnographic data examining some young people's disaffection from, and refusal of, the education project as a whole in a UK coalfield area. Key examples are used to illustrate intergenerational continuities and disjunctions in attitudes to formal education in these exceptional and sometimes…

  3. The Effects of Mountaintop Mines and Valley Fills on Aquatic Ecosystems of the Central Appalachian Coalfields (External Review Draft)

    EPA Science Inventory

    This report assesses the state of the science on the environmental impacts of mountaintop mines and valley fills (MTM-VF) on streams in the Central Appalachian Coalfields. Our review focused on the aquatic impacts of mountaintop removal coal mining, which, as its name suggests, ...

  4. Ambient Air Quality Assessment with Particular Reference to Particulates in Jharia Coalfield, Eastern India.

    PubMed

    Singh, Gurdeep; Roy, Debananda; Sinha, Sweta

    2014-01-01

    Jharia Coalfield is the critically polluted area with the intense mining and associated industrial activities. There has been widespread concern of particulate pollution with the alarming levels of Suspended Particulate Matter (SPM) and Respirable Particulate Matter (PM10 & PM2.5). Coke oven plants, coal washing, thermal power stations and associated activities coupled with the transportation activities, give rise to critical air pollution levels in the region. This study envisages the assessment of air pollution of the region with particular reference to SPM, PM10 and PM2.5. Eighteen monitoring stations were selected considering various sources of pollution such as mining, industrial, commercial and residential areas apart from siting criteria as per IS: 5182 Part XIV. Air quality monitoring was carried out following standard methodologies and protocols as per Central Pollution Control Board (CPCB)/ National Ambient Air Quality Standard (NAAQS) norms using Respirable Dust Samplers (RDS) and Fine Particulate Samplers (PM2.5 Samplers). This study reveals considerable load of particulates (SPM, PM10, PM 2.5) which exceed not only the NAAQS but also the coal mining areas standards of Jharia coalfield, thus falling under the category of critically polluted area. Air Quality Indexing has also been developed which provides a clear map of the deterioration of air quality and also presenting comparative ranking of all the monitoring locations with respect to air quality status in the study area. PMID:26445752

  5. Geochemistry of environmentally sensitive trace elements in Permian coals from the Huainan coalfield, Anhui, China

    USGS Publications Warehouse

    Chen, J.; Liu, Gaisheng; Jiang, M.; Chou, C.-L.; Li, H.; Wu, B.; Zheng, Lingyun; Jiang, D.

    2011-01-01

    To study the geochemical characteristics of 11 environmentally sensitive trace elements in the coals of the Permian Period from the Huainan coalfield, Anhui province, China, borehole samples of 336 coals, two partings, and four roof and floor mudstones were collected from mineable coal seams. Major elements and selected trace elements were determined by inductively coupled plasma optical emission spectrometry (ICP-OES), inductively coupled plasma mass spectrometry (ICP-MS), and hydride generation atomic absorption spectrometry (HAAS). The depositional environment, abundances, distribution, and modes of occurrence of trace elements were investigated. Results show that clay and carbonate minerals are the principal inorganic constituents in the coals. A lower deltaic plain, where fluvial channel systems developed successively, was the likely depositional environment of the Permian coals in the Huainan coalfield. All major elements have wider variation ranges than those of Chinese coals except for Mg and Fe. The contents of Cr, Co, Ni, and Se are higher than their averages for Chinese coals and world coals. Vertical variations of trace elements in different formations are not significant except for B and Ba. Certain roof and partings are distinctly higher in trace elements than underlying coal bench samples. The modes of occurrence of trace elements vary in different coal seams as a result of different coal-forming environments. Vanadium, Cr, and Th are associated with aluminosilicate minerals, Ba with carbonate minerals, and Cu, Zn, As, Se, and Pb mainly with sulfide minerals. ?? 2011 Elsevier B.V.

  6. The Grenville orogeny in the Llano Uplift, Texas: A record of collision and contraction along the southern margin of North America

    SciTech Connect

    Reese, J.F. . Dept. of Geological Sciences)

    1993-02-01

    Precambrian metamorphic rocks in the SE Llano Uplift record NE-directed ductile thrusting and regional-scale polyphase folding. This deformation is in response to Grenville-age shortening and crustal thickening associated with the collision of a south-lying tectonic block with the southern margin of North America. In the SE Llano Uplift, the most intense and pervasive deformational event, D2, is characterized in the Packsaddle Schist (PS) and Valley Spring Gneiss (VSG) by SSE-plunging, NE-verging isoclinal folds (F2) with an associated SW-dipping axial planar metamorphic layering (S2), and SW-dipping mylonite zones with kinematic indicators showing top-to-the-NE motion. In the Red Mountain and augen-bearing Big Branch gneisses, D2 structures are SW-dipping mylonite zones parallel to S2, and a SW-plunging stretching lineation. Taken together, this suite of structures indicates tectonic transport was to the NE, perpendicular to the NW trending regional structural and metamorphic grain. D2 structures were reoriented by at least two later phases of folding. Timing of all ductile deformation in the SE Llano Uplift is constrained from post-1,215 Ma (deformed PS) to pre-1,098 Ma (undeformed melarhyolite dike). From south to north, metatonalitic, arc-derived Big Branch Gneiss ([approximately] 1,303 Ma) and older mafic schist country rock, previously interpreted as possible ophiolitic melange, structurally overlie much younger, lithologically heterogeneous PS units (1,248-1,215 Ma), previously considered as arc flank deposits. In turn, the PS has been tectonically emplaced above the predominantly felsic VSG (1,270-1,232 Ma). The presence of older zircons in the VSG, of similar age ([approximately]1360 Ma) to Western Granite-Rhyolite Terrane rocks to the north, suggests that the VSG formed in a settling proximal to North America.

  7. Temporal occurrence and community structure of helminth parasites in southern leopard frogs, Rana sphenocephala, from north central Oklahoma.

    PubMed

    Vhora, M Suhail; Bolek, Matthew G

    2015-03-01

    Currently, little information is available about the temporal recruitment of helminth communities in amphibian hosts. We examined the helminth community structure and temporal recruitment of helminth parasites in southern leopard frogs, Rana sphenocephala. Specifically, we were interested in how host life history such as habitat, age and/or size, diet, sex, and temporal variation in abiotic factors (precipitation and temperature) were important in determining monthly infection patterns of helminth populations and communities in southern leopard frogs. From May to September 2011, 74 southern leopard frogs were collected from Teal Ridge in Stillwater Payne County, OK, USA. Sixty-nine (93 %) of 74 frogs were infected with 1 or more helminth species. During our collecting period, the average monthly temperature was lowest in May and highest in July, and monthly precipitation was highest in May and lowest during the first week of September. The component community consisted of 11 species of helminth, including 1 larval and 1 adult cestode, 2 larval and 3 adult trematodes, and 1 juvenile and 3 adult nematodes. Of the 1790 helminths recovered, 51 % (911) were nematodes, 47 % (842) were cestodes, and 2 % (37) were trematodes. There were significant differences in the total abundance and mean species richness of helminths acquired by skin contact or through frog diet in monthly component communities of southern leopard frogs. A positive correlation existed for percentage of all helminths acquired by skin contact and monthly precipitation (r = 0.94, P < 0.01). Conversely, a negative correlation existed for monthly precipitation and percentage of helminths acquired by diet (r = -0.94, P < 0.01). Our results indicate that abiotic conditions such as precipitation have a major influence on the avenues for and constraints on the transmission of helminths with life cycles associated with water/moisture or terrestrial intermediate/paratenic hosts and are important in structuring

  8. The influence of chilling requirement on the southern distribution limit of exotic Russian olive (Elaeagnus angustifolia) in western North America

    USGS Publications Warehouse

    Guilbault, Kimberly R.

    2011-01-01

    If climate change follows a warming trend, it is very likely that the chilling requirement for bud-break of Russian olive trees will not be met in some years and this combined with decreased seed viability at lower latitudes may cause its southern range limit to retreat northward. The retreat of a widespread non-native species, such as Russian olive, may present land managers and ecologists with a unique restoration opportunity.

  9. Monitoring the effects of disposal of fine sediments from maintenance dredging on suspended particulate matter concentration in the Belgian nearshore area (southern North Sea).

    PubMed

    Fettweis, Michael; Baeye, Matthias; Francken, Frederic; Lauwaert, Brigitte; Van den Eynde, Dries; Van Lancker, Vera; Martens, Chantal; Michielsen, Tinne

    2011-02-01

    The impact of continuous disposal of fine-grained sediments from maintenance dredging works on the suspended particulate matter concentration in a shallow nearshore turbidity maximum was investigated during dredging experiment (port of Zeebrugge, southern North Sea). Before, during and after the experiment monitoring of SPM concentration using OBS and ADV altimetry was carried out at a location 5 km west of the disposal site. A statistical analysis, based on the concept of populations and sub-sampling, was applied to evaluate the effect. The data revealed that the SPM concentration near the bed was on average more than two times higher during the dredging experiment. The disposed material was mainly transported in the benthic layer and resulted in a long-term increase of SPM concentration and formation of fluid mud layers. The study shows that SPM concentration can be used as an indicator of environmental changes if representative time series are available. PMID:21122880

  10. Cost assessment and ecological effectiveness of nutrient reduction options for mitigating Phaeocystis colony blooms in the Southern North Sea: an integrated modeling approach.

    PubMed

    Lancelot, Christiane; Thieu, Vincent; Polard, Audrey; Garnier, Josette; Billen, Gilles; Hecq, Walter; Gypens, Nathalie

    2011-05-01

    Nutrient reduction measures have been already taken by wealthier countries to decrease nutrient loads to coastal waters, in most cases however, prior to having properly assessed their ecological effectiveness and their economic costs. In this paper we describe an original integrated impact assessment methodology to estimate the direct cost and the ecological performance of realistic nutrient reduction options to be applied in the Southern North Sea watershed to decrease eutrophication, visible as Phaeocystis blooms and foam deposits on the beaches. The mathematical tool couples the idealized biogeochemical GIS-based model of the river system (SENEQUE-RIVERSTRAHLER) implemented in the Eastern Channel/Southern North Sea watershed to the biogeochemical MIRO model describing Phaeocystis blooms in the marine domain. Model simulations explore how nutrient reduction options regarding diffuse and/or point sources in the watershed would affect the Phaeocystis colony spreading in the coastal area. The reference and prospective simulations are performed for the year 2000 characterized by mean meteorological conditions, and nutrient reduction scenarios include and compare upgrading of wastewater treatment plants and changes in agricultural practices including an idealized shift towards organic farming. A direct cost assessment is performed for each realistic nutrient reduction scenario. Further the reduction obtained for Phaeocystis blooms is assessed by comparison with ecological indicators (bloom magnitude and duration) and the cost for reducing foam events on the beaches is estimated. Uncertainty brought by the added effect of meteorological conditions (rainfall) on coastal eutrophication is discussed. It is concluded that the reduction obtained by implementing realistic environmental measures on the short-term is costly and insufficient to restore well-balanced nutrient conditions in the coastal area while the replacement of conventional agriculture by organic farming

  11. The dimethylsulphide propionate (DMSP) content in microalgae and its influence on DMS emission: Experimental and modelling study in the Southern North Sea

    NASA Astrophysics Data System (ADS)

    Gypens, Nathalie; Borges, Alberto V.; Paulet, Sébastien; Parent, Jean-Yves; Lancelot, Christiane

    2013-04-01

    Dimethylsulphide propionate (DMSP) is the precursor of dimethyl sulphide (DMS), a potentially key player in climate regulation. Current knowledge suggests that DMSP synthesis is restricted to some microalgae (mainly Haptophyceae and Dinophyceae) and varies with environmental conditions. Assessing the species-dependence and regulation mechanisms of DMSP microalgal quotas is the first step towards appraising the role of DMS in climate feedback mechanisms. Here we use a combination of laboratory studies and model simulations to determine to which extent the variations of the microalgal DMSP content might affect marine DMS emissions to the atmosphere. The Southern North Sea is chosen as case study, as it is characterized by diatoms/Phaeocystis successions, two phytoplankters known as contrasted DMSP producers. The DMSP:cell content of Phaeocystis globosa and two diatoms, Skeletonema costatum and Chaetoceros socialis, was measured on pure monospecific cultures. While P. globosa and C. socialis showed respectively expected high and low DMSP content, the cell quota measured for S. costatum was unexpectedly high. Based on these results, the sensitivity of the DMS emissions to the variability of the DMSP content of microalgae was estimated by using the MIRO-DMS model. This model couples a DMSP/DMS module to the ecological MIRO model describing carbon and nutrient cycle in the planktonic and benthic system and includes an explicit description of the diatoms/Phaeocystis successions. The model was implemented in a multi-box 0D frame covering the eutrophied Eastern English Channel and Southern North Sea and shows simulations of DMSP and DMS concentrations and DMS emissions in relationship with species succession along a seasonal cycle. Budget calculations allow to estimate the species contribution to DMS emission and highlight the need of further understanding of factors controlling the species-specific synthesis of DMSP.

  12. New insights into the North American Cordillera forearc: Cretaceous to Eocene tectonic evolution of the Leech River Schist, Southern Vancouver Island, Canada

    NASA Astrophysics Data System (ADS)

    Jakob, Johannes; Johnston, Stephen

    2015-04-01

    The Leech River Complex on southern Vancouver Island is a part of the Pacific Rim Terrane of the North American Cordillera and comprises a series of fault-bounded slices of mainly meta-sedimentary and meta-igneous rocks of Triassic to Cretaceous age. The tectono-metamorphic history of this unit provides important constraints on the history of terrane accretion and the paleogeographic and tectonic evolution of the western North American forearc region. Our focus is on the structures and tectonic fabrics that developed within the western most part of the Leech River Schist from ~88 Ma through ~37 Ma. Similar syn- and post-instrusive structures that developed during emplacement of the ~88 Ma Jordan River meta-granodiorite and the ~51 Ma Walker Creek Intrusions respectively, indicate a consistent stress field during >35 m.y. of northward translation of the outboard Cordilleran terranes. A regional high temperature, Staurolite-Andalusite-grade metamorphic event is recorded in the meta-sedimentary rocks. Subcretion of the Crescent terrane beneath the Leech River Schist at ~51 Ma caused folding of the metamorphic rocks, the development of a system of dextral and sinistral brittle shears, and normal faulting. Related extension to the northwest resulted in the opening of Barkley Sound and the more westerly marine Tofino basin. These multi-faceted deformational structures are most likely a direct consequence of the subcretion of the Crescent terrane and the linked development of the Southern Vancouver Island Orocline. The deposition of sandstones and conglomerates of the Sooke Formation began at ca. 37 Ma. This siliciclastic sequence unconformably overlies the Leech River Schist, records rapid subsidence of the forearc following a preceding uplift and exhumation event, and may be a record of a younger subcretion event.

  13. Does Poseidon Keep the Holy Grail? Changes in Southern Ocean and North Atlantic Deep Water Production as the Driver of the Deglacial CO2 Rise

    NASA Astrophysics Data System (ADS)

    Zeebe, R. E.

    2002-12-01

    The 'Holy Grail' of glacial/interglacial CO2 research is to identify the cause for variations in atmospheric CO2 on this time scale. A simple mechanism has hitherto remained elusive. Here I use an entirely new approach to the problem, namely a global vertical advection-diffusion balance of tracers in the ocean that includes effects of deep water production and the biological pump on atmospheric CO2. The model adequately reproduces modern pCO2 and vertical profiles of temperature, Σ CO2, Alkalinity, PO4, and O2 in the ocean. A reduction of the ocean's deep water production and an associated decrease of O2 and the remineralization efficiency for organic matter in the water column leads to the glacial pCO2 of 200~μatm. Assuming changes in Southern Ocean and North Atlantic deep water production consistent with proxy records over the deglacial transition, model results excellently reproduce the observed temporal evolution of the deglacial atmospheric CO2 rise and deep ocean CaCO3 saturation. The magnitude and timing of the ocean's deep water production rate in the northern and southern hemisphere is hence identified as the dominant driver of glacial/interglacial CO2 variations through its effect on the vertical distribution of heat and elements in the sea.

  14. Late Cretaceous-Oligocene magmatic record in southern Mexico: The case for a temporal slab window along the evolving Caribbean-North America-Farallon triple boundary

    NASA Astrophysics Data System (ADS)

    Ferrari, Luca; Bergomi, Maria; Martini, Michelangelo; Tunesi, Annalisa; Orozco-Esquivel, Teresa; López-Martínez, Margarita

    2014-09-01

    Continental magmatism in southern Mexico is expected to record the eastward displacement of the Farallon-North America-Caribbean triple junction. However, a trench-transversal belt of magmatism in the central western Guerrero State does not fit into a regular pattern of arc migration and reorientation following the formation of the WSW trending Acapulco trench in the Cenozoic. We revised the magmatic pattern of southern Mexico using an updated database and new laser ablation inductively coupled plasma-mass spectrometry sensitive high-resolution ion microprobe, Ar-Ar ages, and geochemical and geologic data for the coastal part of the anomalous Guerrero belt. Our data reveal a persistent magmatic activity between ~75 and 35 Ma, with a changing character at the Paleocene-Eocene boundary (circa 56 Ma). Late Cretaceous-Paleocene granitoids have an adakitic signature imprinted by stable garnet in the source and show no plagioclase fractionation, indicative of wet and oxidized magmas. Eocene rocks consist of an almost bimodal suite of plutonic bodies covered by a succession of mafic lavas. Granitic plutons show plagioclase fractionation and flat middle rare earth element-heavy rare earth element; gabbros have a tholeiitic character, indicative of dryer and more reduced magmas. They appear later and were emplaced at shallow depth in an extensional sedimentary basin. We interpret the magmatic record of the Guerrero belt as the response to two concurrent processes: (1) a temporal window in the Farallon slab induced by the concurrent subduction along the two noncollinear trench segments of southern Mexico (WNW trending) and of the Chortís block (NNW trending) and (2) a scissor-like transtensional rifting associated to counterclockwise rotation and eastward motion of the Chortís block.

  15. Review article. Studying climate effects on ecology through the use of climate indices: the North Atlantic Oscillation, El Niño Southern Oscillation and beyond.

    PubMed

    Stenseth, Nils Chr; Ottersen, Geir; Hurrell, James W; Mysterud, Atle; Lima, Mauricio; Chan, Kung-Sik; Yoccoz, Nigel G; Adlandsvik, Bjørn

    2003-10-22

    Whereas the El Niño Southern Oscillation (ENSO) affects weather and climate variability worldwide, the North Atlantic Oscillation (NAO) represents the dominant climate pattern in the North Atlantic region. Both climate systems have been demonstrated to considerably influence ecological processes. Several other large-scale climate patterns also exist. Although less well known outside the field of climatology, these patterns are also likely to be of ecological interest. We provide an overview of these climate patterns within the context of the ecological effects of climate variability. The application of climate indices by definition reduces complex space and time variability into simple measures, 'packages of weather'. The disadvantages of using global climate indices are all related to the fact that another level of problems are added to the ecology-climate interface, namely the link between global climate indices and local climate. We identify issues related to: (i) spatial variation; (ii) seasonality; (iii) non-stationarity; (iv) nonlinearity; and (v) lack of correlation in the relationship between global and local climate. The main advantages of using global climate indices are: (i) biological effects may be related more strongly to global indices than to any single local climate variable; (ii) it helps to avoid problems of model selection; (iii) it opens the possibility for ecologists to make predictions; and (iv) they are typically readily available on Internet. PMID:14561270

  16. Distribution of chroococcoid cyanobacteria and size-fractionated chlorophyll a biomass in the central and southern north sea waters during June/July 1989

    NASA Astrophysics Data System (ADS)

    Iriarte, Arantza; Purdie, Duncan A.

    The spatial and vertical distribution of phycoerythrin(PE)-containing chroococcoid cyanobacteria and the contribution of the <3 μm size fraction to overall phytoplankton chlorophyll a biomass were investigated in the central and southern North Sea during June and July 1989. PE-containing chroococcoid cyanobacteria cell numbers ranged between 6×10 5 and 4.4×10 7 cells·dm -3 and was typically between 0.5×10 7 and 3×10 7 cells·dm -3, lowest numbers being recorded near the British coast in central North Sea waters. The vertical distribution of these cyanobacteria showed no evidence to suggest a preferential accumulation deep in the euphotic zone. The <3 μm size fraction accounted for 6.6 to 57.5% of the total phytoplankton chlorophyll a biomass (mean 19.7%). In general, the relative significance of the <3 μm size fraction decreased with increasing total chlorophyll a biomass.

  17. Ignimbrite Flare-up in the North-Central Sierra Madre del Sur, Southern Mexico: a Continuation of the Sierra Madre Occidental Ignimbrite Province?

    NASA Astrophysics Data System (ADS)

    Moran-Zenteno, D. J.; Alba-Aldave, L.; Gonzalez-Torres, E. A.; Martiny, B.; Bravo-Diaz, B. A.; Sohn, E.

    2007-05-01

    The north-central Sierra Madre del Sur, immediately south of the Trans Mexican Volcanic Belt, is made up of a series of Eocene silicic volcanic centers distributed along a WNW trending 300 km long belt from Valle de Bravo to Huautla (98°50'-100°30'W longitude). This belt constitutes an inland arc near parallel to, and coeval with, the coastal batholitic belt of southern Mexico. It includes at least 9 exhumed volcanic edifices that display diverse caldera styles controlled by regional fracture zones and rheological contrasts in the host rocks. Initiation of the volcanism ranges from 37 Ma in the west to 32 Ma in the east, and extinction of magmatism was nearly simultaneous in the eastern half of the belt. Southwest of the silicic volcanic belt, andesitic volcanism is slightly younger (33-29 Ma) and the combined effect of post-Eocene uplift and erosion removed most of the extracaldera facies. The remnants of the silicic volcanic cover extend over an area of ~3000 km2. Reactivated fracture zones related to the volcanic activity include NW to W- trending faults that reveal a transition from left lateral to right lateral slip as result of a change in the stress field during the last stages of silicic volcanism. These and other groups of N-S to NNW trending faults accommodated the collapse structures and were the sites of emplacement of massive pyroclastic dikes. Immediately north of the Trans Mexican Volcanic Belt, ignimbrites and related rocks of the Mesa Central and southern Sierra Madre Occidental are slightly younger and display a westward 30 to ~15 Ma migration pattern accompanied by E-W regional extension. These patterns have been attributed to the roll back of the subducted slab, which caused the ascent of asthenospheric mantle and probably triggered ignimbrite flare-up. The distinct tectonic and geochronologic patterns of the arc volcanic rocks in the northern Sierra Madre del Sur and the southern Sierra Madre Occidental-Mesa Central suggests two slab segments

  18. High frequency measurements of dissolved inorganic and organic nutrients using instrumented moorings in the southern and central North Sea

    NASA Astrophysics Data System (ADS)

    Suratman, Suhaimi; Weston, Keith; Greenwood, Naomi; Sivyer, David B.; Pearce, David J.; Jickells, Tim

    2010-05-01

    The aim of this study was to investigate the cycling of dissolved inorganic and organic nutrients using moored instrumented buoys (SmartBuoys) during the spring bloom in the North Sea. The instrumentation on the buoys enabled high frequency measurements of water-column integrated irradiance and in situ chlorophyll to be made, and also preserved water sample collection which were used for dissolved inorganic and organic nutrient analyses. The SmartBuoys were located in the year-round well-mixed plume zone associated with the River Thames and in the summer stratified central North Sea. These site locations allowed comparison of nutrient concentrations and cycling, and spring bloom development at two contrasting sites. The spring bloom was expected to be initiated at both stations due to increasing insolation and decreasing suspended load leading to higher water-column integrated irradiance. Due to differences in suspended load between the sites, the spring bloom started ˜2 months earlier in the central North Sea. The spring bloom in the Thames plume also resulted in higher maximum phytoplankton biomass due to the higher pre-bloom nutrient concentrations associated with riverine input. The use of SmartBuoys is also shown to allow the cycling of dissolved organic nutrients to be examined over the critical, and often undersampled, spring bloom period. Dissolved Organic Nitrogen (DON) clearly increased during the spring bloom in the central North Sea compared to winter concentrations. DON also increased in the Thames plume although showing greater winter variability related to higher riverine and sedimentary dissolved organic matter input at this shallow (˜18 m) coastal site. DON increase during the spring bloom was therefore related to primary production at both sites probably due to active release by phytoplankton. At both stations DON decreased to pre-bloom concentrations as the bloom declined suggesting the released DON was bioavailable and removed due to

  19. Ice core sulfur and methanesulfonic acid (MSA) records from southern Greenland document North American and European air pollution and suggest a decline in regional biogenic sulfur emissions.

    NASA Astrophysics Data System (ADS)

    Pasteris, D. R.; McConnell, J. R.; Burkhart, J. F.; Saltzman, E. S.

    2014-12-01

    Sulfate aerosols have an important cooling effect on the Earth because they scatter sunlight back to space and form cloud condensation nuclei. However, understanding of the atmospheric sulfur cycle is incomplete, leading to uncertainty in the assessment of past, present and future climate forcing. Here we use annually resolved observations of sulfur and methanesulfonic acid (MSA) concentration in an array of precisely dated Southern Greenland ice cores to assess the history of sulfur pollution emitted from North America and Europe and the history of biogenic sulfate aerosol derived from the North Atlantic Ocean over the last 250 years. The ice core sulfur time series is found to closely track sulfur concentrations in North American and European precipitation since records began in 1965, and also closely tracks estimated sulfur emissions since 1850 within the air mass source region as determined by back trajectory analysis. However, a decline to near-preindustrial sulfur concentrations in the ice cores after 1995 that is not so extensive in the source region emissions indicates that there has been a change in sulfur cycling over the last 150 years. The ice core MSA time series shows a decline of 60% since the 1860s, and is well correlated with declining sea ice concentrations around Greenland, suggesting that the phytoplankton source of biogenic sulfur has declined due to a loss of marginal sea ice zone habitat. Incorporating the implied decrease in biogenic sulfur in our analysis improves the match between the ice core sulfur record and the source region emissions throughout the last 150 years, and solves the problem of the recent return to near-preindustrial levels in the Greenland ice. These findings indicate that the transport efficiency of sulfur air pollution has been relatively stable through the industrial era and that biogenic sulfur emissions in the region have declined.

  20. The use of NOSTRADAMUS, a numerical transport model, for simulating concentrations and distributions of chromium, cadmium and lead in the Southern North Sea

    NASA Astrophysics Data System (ADS)

    Tappin, A. D.; Gellers-Barkmann, S.; Burton, J. D.; Statham, P. J.

    1997-09-01

    A numerical transport model, named NOSTRADAMUS, has been developed to simulate concentrations and distributions of a range of EU List I and II metals, including Cr, Cd and Pb in the water column of the southern North Sea. For Cd and Pb, the model takes advantage of data obtained during the observational phase of the Natural Environment Research Council (NERC) North Sea Project (NSP) during 1988 89 to drive the model and to test the results of model simulations. For Cr, there are no water column measurements from the NSP, and so data from other studies, including those from the more recent NERC LandOcean Interaction Study (LOIS), have been used to assess model results. NOSTRADAMUS comprises components for transport of water and inorganic and organic suspended particulate matter (SPM); a primary production module contributes to the latter component. Conservative transport is based on an existing 2-D vertically integrated advection-diffusion model, incorporating a 35x35 km grid, for NW European shelf seas. Sediment resuspension by both the M2 tide and wind-wave interactions is included. Metal exchange between dissolved (water) and total SPM (inorganic + organic) phases is driven by distribution coefficients. Model simulations for both salinity and total SPM show reasonable agreement with depth averaged NSP observations during winter and spring 1989. Simulations of dissolved and particulate Cd and Pb also reproduce the observed concentrations reasonably well. There are, however, clear differences between simulations and observations in some cases, most noticeably for dissolved Cd and Pb during the spring and particulate Pb in winter. There are few measurements of Cr in the North Sea, but simulated concentrations of dissolved and particulate Cr are in good agreement with those reported.

  1. Geochronological and geochemical constraints on the petrogenesis and tectonic significance of Paleozoic dolerite dykes in the southern margin of Alxa Block, North China Craton

    NASA Astrophysics Data System (ADS)

    Duan, Jun; Li, Chusi; Qian, Zhuangzhi; Jiao, Jiangang

    2015-11-01

    Dolerite dykes are common in the southern margin of Alxa Block which is the westernmost part of North China Craton. The ages and petrogenesis of the dolerite dykes, which are important for a better understanding of tectonic-magmatic evolution in the region, are uncertain. This paper reports the results of an integrated geochronological and geochemical study of the dolerite dykes in the Jinchuan area. Previously, these dolerite dykes were considered to be coeval with the ∼831 Ma Jinchuan ultramafic intrusion by some researchers, despite a cross-cutting relationship for the dykes. Our new zircon U-Pb dating indicates that the dolerite dykes were emplaced at ∼424 Ma, >400 Ma younger than the Jinchuan intrusion. The Jinchuan dolerite dykes contain 5-9 wt.% MgO and 47-51 wt.% SiO2, and are characterized by light REE (rare earth elements) enrichments relative to heavy REE, pronounced negative Nb anomaly, elevated initial 87Sr/86Sr from 0.7056 to 0.7068, negative εNd from -2 to -5, and zircon εHf from -2 to -20. The trace element and isotope data are consistent with an asthenosphere-derived parental magma that experienced 10-25% crustal contamination prior to final emplacement. Since the Jinchuan dolerite dykes are 20-40 Ma younger than the subduction-related basaltic volcanic rocks, blueschists and eclogites in the nearby North Qilian orogenic belt to the south, we propose that the Jinchuan dolerite dykes are the products of basaltic magmatism induced by delamination of previously subducted oceanic lithosphere and the associated asthenosphere upwelling in a post-subduction setting. The occurrence of ∼424 Ma post-subduction dolerite dykes in the Jinchuan area and the ∼450 Ma arc basalts to the south indicate that the southwestern margin of North China Craton was an active plate margin in Early Paleozoic.

  2. Paleoseismologic evidence for late Holocene earthquakes on the Southern Panamint Valley fault zone: Implications for earthquake clustering in the Eastern California Shear Zone north of the Garlock fault

    NASA Astrophysics Data System (ADS)

    McAuliffe, L. J.; Dolan, J. F.; Kirby, E.; Haravitch, B.; Alm, S.

    2010-12-01

    New paleoseismological data from two trenches excavated across the southern end of the Panamint Valley fault (PVF), the most active of the three major faults in the eastern California shear zone (ECSZ) north of the Garlock fault, reveal the occurrence of at least two, and probably three, surface ruptures during the late Holocene. These trenches were designed to test the hypothesis that the earthquake clusters and intervening seismic lulls observed in the Mojave section of the ECSZ (Rockwell et al. 2000, Ganev et al. 2010) at 8-9.5 ka, 5-6 ka and during the past ~1-1.5 ka, also involved the fault systems of the ECSZ north of the Garlock fault. Well stratified playa sands, silts and clays exposed in the trench allowed precise identification of two event horizons; a likely third event horizon occurred during a period of soil development across the playa. Calibrated radiocarbon dates from 25 charcoal samples constrain the dates of the most recent event (MRE) to ~1450-1500 AD and the ante-penultimate event at 3.2-3.6 ka. The penultimate event occurred during a period of soil development spanning ~350-1400 AD. The presence of large blocks of soil in what appears to be scarp-derived colluvium in a large fissure opened during this event require that it occurred late during soil development, probably only a few hundred years before the MRE. The timing of the three events indicate that the southern PVF has ruptured at least once, and probably twice during the ongoing seismic cluster in the Mojave region. The PVF earthquakes also are similar in age to the 1872 Owens Valley earthquakes and the geomorphically youthful, but undated MRE in central Death Valley. Although we were unable to excavate deeply enough at this site to expose mid-to lower - Holocene playa strata, the timing of the ante-penultimate earthquake at our site shows that the PVF has ruptured at least once during the well-defined 2-5 ka seismic lull in the Mojave section of the ECSZ. Interestingly the 3.2-3.6 ka

  3. Seasonal and spatial variations of in situ measured benthic fluxes of nutrients and carbon at the sediment water interface of the southern North Sea

    NASA Astrophysics Data System (ADS)

    Oehler, T.; Martinez, R.; Schlueter, M.

    2014-12-01

    Within coastal areas like the North Sea, nutrient and carbon cycles are driven by a close coupling of benthic-pelagic processes. Due to shallow water depths, most of the organic matter which is produced via primary production in surface waters is transferred to the seafloor. Most of the organic matter is degraded within surface sediments and nutrients such as NH4 or PO4are transported back into the water column, whereas only a small amount of organic carbon is buried within the sediment. Consequently, benthic carbon and nutrient fluxes have a direct impact on biological and geological processes such as the availability of nutrients in the water column, nutrient budgets or the storage of carbon within marine sediments. By in situ as well as ex situtechniques, benthic nutrient fluxes and carbon mineralization rates were quantified within the years 2012 to 2014 at different time series sites in the southern North Sea. Benthic nitrogen and carbon fluxes are close to the Redfield ratio of 106 moles of carbon to 16 moles of nitrogen, indicating that mainly marine organic matter is settling at the seafloor. In situ flux measurements by the benthic lander system NuSObs (Nutrient and Suspension Observatory) revealed considerable seasonal and spatial variations of benthic fluxes. For example, benthic mineralization rates of organic carbon are about three to five times higher in summer when compared to winter. Our In situ studies, investigations of pore water and macro fauna, as well as tracer studies revealed that seasonal and spatial variations are dominantly controlled by the activity and abundance of benthic macro fauna. For example, in situasphyxiation experiments during the lander deployments suggests that carbon mineralization rates can be about 20 to 30 times higher when benthic macro fauna is active. Estimated rain rates of organic carbon and organic nitrogen to the seafloor are up to 200 g C m-2 yr-1 and up to 56 g N m-2 yr-1 respectively, while approximately 80

  4. Late Ordovician (post-Sardic) rifting branches in the North Gondwanan Montagne Noire and Mouthoumet massifs of southern France

    NASA Astrophysics Data System (ADS)

    Javier Álvaro, J.; Colmenar, Jorge; Monceret, Eric; Pouclet, André; Vizcaïno, Daniel

    2016-06-01

    Upper Ordovician-Lower Devonian rocks of the Cabrières klippes (southern Montagne Noire) and the Mouthoumet massif in southern France rest paraconformably or with angular discordance on Cambrian-Lower Ordovician strata. Neither Middle-Ordovician volcanism nor associated metamorphism is recorded, and the subsequent Middle-Ordovician stratigraphic gap is related to the Sardic phase. Upper Ordovician sedimentation started in the rifting branches of Cabrières and Mouthoumet with deposition of basaltic lava flows and lahar deposits (Roque de Bandies and Villerouge formations) of continental tholeiite signature (CT), indicative of continental fracturing. The infill of both rifting branches followed with the onset of (1) Katian (Ka1-Ka2) conglomerates and sandstones (Glauzy and Gascagne formations), which have yielded a new brachiopod assemblage representative of the Svobodaina havliceki Community; (2) Katian (Ka2-Ka4) limestones, marlstones, and shales with carbonate nodules, reflecting development of bryozoan-echinoderm meadows with elements of the Nicolella Community (Gabian and Montjoi formations); and (3) the Hirnantian Marmairane Formation in the Mouthoumet massif that has yielded a rich and diverse fossil association representative of the pandemic Hirnantia Fauna. The sealing of the subaerial palaeorelief generated during the Sardic phase is related to Silurian and Early Devonian transgressions leading to onlapping patterns and the record of high-angle discordances.

  5. [Super-low-frequency spectrum analysis for buried faults in coalfield].

    PubMed

    Chen, Li; Qin, Qi-Ming; Zhen, Guang-Wei; Wang, Nan; Bai, Yan-Bing; Chen, Chao

    2013-08-01

    Based on the super-low-frequency (SLF) electromagnetic detection technology, the advanced detection for the buried fault in the coalfield is still at the exploratory stage, while the technology has a strong practical significance for production and design of the coal mine. Firstly, in this paper, the SLF electromagnetic detection signals were collected in study area. Spectrum analysis of SLF signal by wavelet transform can remove high-frequency noise. Secondly, the profile of the measuring line across the fault was analyzed and interpreted geologically. Accordingly SLF spectrum characteristics of the buried fault could be researched. Finally, combined with the geological and seismic data, the characteristics and distribution of fault structures can be verified in the mining area. The results show that: the buried fault could be detected quickly and effectively by SLF electromagnetic detection Hence, SLF electromagnetic detection technology is an effective method for buried fault detection. PMID:24159862

  6. Assessment of trace metal toxicity in soils of Raniganj Coalfield, India.

    PubMed

    Das, Supriyo Kumar; Chakrapani, Govind J

    2011-06-01

    Soil, rock and water samples were collected from India's oldest coalfield Raniganj to investigate trace metal contamination from mining activity. Our data reveal that trace metal concentration in soil samples lies above the average world soil composition; especially, Cr, Cu, Ni and Zn concentrations exceed the maximum allowable concentration proposed by the European Commission for agricultural soils. In particular, Cr, Cu and Ni exceed the ecotoxicological limit, and Ni exceeds the typical value for cultivated soils. Mineral dissolution from overburden material and high adsorption capacity of laterite soil are responsible for the elevated concentrations. This is evident from enrichment factor (E (f)), geoaccumulation index (I (geo)) and metal pollution index values. Sediment quality guideline index indicates toxicity to local biota although enrichment index suggests no threat from consuming crops cultivated in the contaminated soil. PMID:20661770

  7. Study of Internal Dump Stability of Dudhichua Open Cast Project, Northern Coalfields Limited, India

    NASA Astrophysics Data System (ADS)

    Sengupta, S.; Roy, I.

    2015-04-01

    Dudhichua Open Cast Project is one of the prestigious projects of Northern Coalfields Limited, India; with total mineable coal reserves of approximately 400 million tonnes and corresponding 1,700 million m3 volume of waste rock i.e. overburden material. Accommodating this waste dump masses in the limited space of the de-coaled portion of the quarry is considered as one of the major challenges to the mine operators. It has been reported that this mine is facing frequent slope failures of waste rock dumps which is of great concern to the mine management in view of unsafe working condition. To tackle the above problem, a detailed investigation was carried out to propose a stable dump profile which will cater to the land economics and safety aspects of the mine. A detailed investigation along with recommendation of optimum design for dragline dump profile along with shovel-dumper-dump profile is presented in this paper.

  8. Spatio-temporal spawning and larval dynamics of a zebra mussel (Dreissena polymorpha) population in a North Texas Reservoir: implications for invasions in the southern United States

    USGS Publications Warehouse

    Churchill, Christopher John

    2013-01-01

    Zebra mussels were first observed in Texas in 2009 in a reservoir (Lake Texoma) on the Texas-Oklahoma border. In 2012, an established population was found in a near-by reservoir, Ray Roberts Lake, and in June 2013, settled mussels were detected in a third north Texas reservoir, Lake Lewisville. An established population was detected in Belton Lake in September 2013. With the exception of Louisiana, these occurrences in Texas mark the current southern extent of the range of this species in the United States. Previous studies indicate that zebra mussel populations could be affected by environmental conditions, especially increased temperatures and extreme droughts, which are characteristic of surface waters of the southern and southwestern United States. Data collected during the first three years (2010–12) of a long-term monitoring program were analyzed to determine if spatio-temporal zebra mussel spawning and larval dynamics were related to physicochemical water properties in Lake Texoma. Reproductive output of the local population was significantly related to water temperature and lake elevation. Estimated mean date of first spawn in Lake Texoma was approximately 1.5 months earlier and peak veliger densities were observed two months earlier than in Lake Erie. Annual maximum veliger density declined significantly during the study period (p < 0.0001). A population crash occurred as a result of thermal stress and variability of lake elevation. In summer 2011, water temperatures peaked at 34.3°C and lake elevation declined to the lowest level recorded during the previous 18 years, which resulted in desiccation of substantial numbers of settled mussels in littoral zones. Veliger spatial distributions were associated with physicochemical stratification characteristics. Veligers were observed in the deepest oxygenated water after lake stratification, which occurred in late spring. Results of this study indicate environmental conditions can influence variability of

  9. Geochemistry of rare earth elements in Permian coals from the Huaibei Coalfield, China

    USGS Publications Warehouse

    Zheng, Lingyun; Liu, Gaisheng; Chou, C.-L.; Qi, C.; Zhang, Y.

    2007-01-01

    The rare earth elements (REEs) in coals are important because of: (a) REE patterns can be an indicator of the nature of source rocks of the mineral matter as well as sedimentary environments; (b) REEs abundance in coal may have industrial-significance. In this study, a total of thirty-four samples of Permian coal, partings, roof, and floor were collected from the Huaibei Coalfield, Anhui Province, China. Abundances of rare earth elements (REEs) and other elements in the samples were determined by inductively coupled-plasma mass spectrometry (ICP-MS) and inductively coupled-plasma atomic emission spectrometry (ICP-AES). The results show that the REEs are enriched in coals in the Huaibei Coalfield as compared with Chinese and U.S. coals and the world coal average. Coals in the Lower Shihezi Formation (No. 7, 5, and 4 Coals) and Upper Shihezi Formation (No. 3) have higher REE abundances than the coals in Shanxi Formation (No. 10). Magmatic intrusion resulted in high enrichment of REEs concentrations in No. 5 and 7 Coals. The REE abundances are positively correlated with the ash content. The mineral matter in these coals is mainly made up of clay minerals and carbonates. The REEs are positively correlated with lithophile elements including Si, Al, Ti, Fe, and Na, which are mainly distributed in clay minerals, indicating that REEs are contained mainly in clay minerals. The REE abundances in coals normalized by the ash are higher than that in partings. REEs abundances of coals cannot be accounted for by the REE content in the mineral matter, and some REEs associated with organic matter in coals. ?? 2007 Elsevier Ltd. All rights reserved.

  10. Mineralogy and geochemistry of the No. 6 Coal (Pennsylvanian) in the Junger Coalfield, Ordos Basin, China

    USGS Publications Warehouse

    Dai, S.; Ren, D.; Chou, C.-L.; Li, S.; Jiang, Y.

    2006-01-01

    This paper discusses the mineralogy and geochemistry of the No. 6 Coal (Pennsylvanian) in the Junger Coalfield, Ordos Basin, China. The results show that the vitrinite reflectance (0.58%) is lowest and the proportions of inertinite and liptinite (37.4% and 7.1%, respectively) in the No. 6 Coal of the Junger Coalfield are highest among all of the Late Paleozoic coals in the Ordos Basin. The No. 6 Coal may be divided vertically into four sections based on their mineral compositions and elemental concentrations. A high boehmite content (mean 6.1%) was identified in the No. 6 Coal. The minerals associated with the boehmite in the coal include goyazite, rutile, zircon, and Pb-bearing minerals (galena, clausthalite, and selenio-galena). The boehmite is derived from weathered and oxidized bauxite in the weathered crust of the underlying Benxi Formation (Pennsylvanian). A high Pb-bearing mineral content of samples ZG6-2 and ZG6-3 is likely of hydrothermal origin. The No. 6 coal is enriched in Ga (44.8 ??g/g), Se (8.2 ??g/g), Sr (423 ??g/g), Zr (234 ??g/g), REEs (193.3 ??g/g), Hg (0.35 ??g/g), Pb (35.7 ??g/ g), and Th (17.8 ??g/g). Gallium and Th in the No. 6 Coal mainly occur in boehmite, and the Pb-bearing selenide and sulfide minerals contribute not only to Se and Pb contents in the coal, but also probably to Hg content. A high Zr content is attributed to the presence of zircon, and Sr is related to goyazite. The REEs in the coal are supplied from the sediment-source region, and the REEs leached from the adjacent partings by groundwater. ?? 2005 Elsevier B.V. All rights reserved.

  11. American coal miner: a report on community and living conditions in the coalfields

    SciTech Connect

    Not Available

    1980-01-01

    This report represents the first major documentation of coalfield community and living conditions since the Boone Report of 1947, ''A Medical Survey of the Bituminous-Coal Industry'' was published by the Coal Mines Administration of the Department of the Interior in 1947 in response to a demand by John L. Lewis for improvements in public health and medical treatment at the mines and in the coal camps. The situation in 1979 is very different from what it was in 1947. Not only do the coal miners enjoy a much more comfortable lifestyle and significantly improved quality of health care, but also a much higher percentage of miners are employed at surface mines, many of which are now in the western States. During the decade of the 1970s, women entered the mining work force, often after successfully seeking legal action under Federal Equal Employment Opportunity statutes. Many problems remain in the coalfields. There is vast room for improvement in the areas of housing and highways. Health care facilities and services are less extensively available than in more urban areas. Coal mining remains the most dangerous of occupations, despite considerable improvements in coal mine health and safety. The progress achieved by coal miners over their counterparts of earlier generations cannot be denied. Thirty years ago, the miner and his family were still living in coal camps, often in conditions of poverty. Today, mining communities are much more diverse, and the modern miner is, more often than not, among the resident middle class. The reality of that vast change is not widely recognized. This book concentrates on employed miners. (LTN)

  12. The Majorqaq Belt: A record of Neoarchaean orogenesis during final assembly of the North Atlantic Craton, southern West Greenland

    NASA Astrophysics Data System (ADS)

    Dyck, Brendan; Reno, Barry L.; Kokfelt, Thomas F.

    2015-04-01

    Over the past 4.5 billion years (Ga) the Earth has undergone a secular change in tectonic regimes. Archaean tectonics was a markedly different process than observed today, involving a hotter planet with a thinner lithosphere, thicker oceanic crust, and smaller proto-continents. The transition to a more modern type of plate tectonics required the initiation of subduction of oceanic lithosphere. The onset of subduction in the Meso- to Neoarchaean (ca. 3.2 to 2.5 Ga) is shown by geochemical signatures indicative of crustal recycling and petrologic evidence of tectonically driven thickening of the continental crust. This transition is recorded in the rock record of the North Atlantic Craton, which preserves a history of crust formation through to terrane accretion and the collision of crustal blocks. Here we present petrologic, chronologic, chemical and geophysical evidence from the Majorqaq Belt, a ~ 100 km wide east-west striking zone, defined by a high gravity anomaly, voluminous metasedimentary units, olivine-rich ultramafic enclaves, and anomalously high K2O, Ni, and MgO stream-sediment chemistry. We use a 207Pb/206Pb zircon LA-ICP-MS age of 2.557 ± 0.005 Ga (2σ) from an upper-amphibolite facies metapelitic migmatite to propose Neoarchaean suturing of the Maniitsoq crustal block to the North Atlantic Craton. Ti-in-zircon temperatures and zircon-garnet REE distribution coefficients constrain zircon crystallisation to 815-729 °C, which is at, or near the solidus during leucosome crystallisation. Our data reveal a clockwise P-T path with a high-pressure assemblage of garnet-kyanite-plagioclase-rutile-biotite-quartz which grew at an apparent thermal gradient of ~ 660 °C/GPa during subduction-driven compression of surface-derived sediments to a minimum-peak-pressure of ~ 1.15 GPa at ~ 760 °C followed by the growth of gedrite-cordierite-sillimanite-ilmenite at minimum-peak-temperature conditions of ~ 810 °C at ~ 0.94 GPa. We propose the evolution of the Majorqaq

  13. Annual variations of biomass and photosynthesis in Zostera marina at its southern end of distribution in the North Pacific

    USGS Publications Warehouse

    Cabello-Pasini, Alejandro; Munoz-Salazar, R.; Ward, D.H.

    2003-01-01

    Density, biomass, morphology, phenology and photosynthetic characteristics of Zostera marina were related to continuous measurements of in situ irradiance, attenuation coefficient and temperature at three coastal lagoons in Baja California, Mexico. In situ irradiance was approximately two-fold lower at San Quintin Bay (SQ) than at Ojo de Liebre Lagoon (OL) and San Ignacio Lagoon (SI). As a consequence of the greater irradiance, plants at OL and SI were established 1 m deeper within the water column than those at SQ. At SQ, there was a four-fold variation in biomass of Z. marina caused by changes on shoot length and not shoot density, while at OL and SI biomass and shoot length did not fluctuate significantly throughout the year. Reproductive shoot density reached maximum values concomitantly with the greatest irradiance during spring-summer, however, the density was approximately three-fold greater at SQ than at the southern coastal lagoons. While irradiance levels were two-fold greater at the southern lagoons, in general, photosynthetic characteristics were similar among all three lagoons. The hours of light saturated photosynthesis, calculated from their photosynthetic characteristics and irradiance measurements, suggest that photosynthesis of shoots from OL and SI are saturated for more than 6 h per day throughout the year, while shoots from SQ are likely light limited during approximately 15% of the year. Consequently, an increase in attenuation coefficient values in the water column will likely decrease light availability to Z. marina plants at SQ, potentially decreasing their survival. ?? 2003 Elsevier Science B.V. All rights reserved.

  14. Meteorologically-induced mesoscale variability of the North-western Alboran Sea (southern Spain) and related biological patterns

    NASA Astrophysics Data System (ADS)

    Macías, D.; Bruno, M.; Echevarría, F.; Vázquez, A.; García, C. M.

    2008-06-01

    Hydrographic mesoscale structures in the North-western Alboran Sea show a high variability induced by a number of different factors. One of the most important is the differences in atmospheric pressure over the Mediterranean basin when compared to the Gulf of Cádiz. This difference modulates the zonal wind field in the Alboran Sea and the intensity of the Atlantic inflow through the Strait of Gibraltar, also affecting the formation and extension of the Western Alboran Gyre (WAG). When westerly winds are dominant, lower atmospheric pressure in the Mediterranean enhances the inflow of Atlantic waters causing the Atlantic Jet to be located in the vicinity of the Spanish shore, creating a well-defined frontal zone in front of Estepona Cove. In this situation, the coastal upwelling is enhanced, leading to a minimum in sea surface temperature and a maximum of surface nutrient concentrations located in the coastal area. The vertical position of the chlorophyll maximum found in these circumstances appeared to be controlled by the nutrient availability. On the other hand, when easterly winds prevail, higher atmospheric pressure in the Mediterranean leads to a reduced inflow and the oceanographic and biological structures are clearly different. The Atlantic Jet moves southward flowing in a south-eastern direction, changing the structure of the currents, resulting in an enhanced cyclonic circulation extending throughout the North-western Alboran Sea basin. These physical alterations also induce changes in the distribution of biogeochemical variables. Maximum nutrient and chlorophyll concentrations are located further off the coast in the central area of the newly created cyclonic gyre. During these easterlies periods coastal upwelling stops and the distribution of phytoplankton cells seems to be mainly controlled by physical processes such as advection of coastal waters to the open sea.

  15. Late Cretaceous shortening and early Tertiary shearing in the central Sierra Madre del Sur, southern Mexico: Insights into the evolution of the Caribbean-North American plate interaction

    NASA Astrophysics Data System (ADS)

    Cerca, Mariano; Ferrari, Luca; López-MartíNez, Margarita; Martiny, Barbara; Iriondo, Alexander

    2007-06-01

    A wide region in the central part of the Sierra Madre del Sur (SMS), southern Mexico, records two deformational phases between the Late Cretaceous and early Tertiary. The first is a progressive approximately E-W shortening phase that spans from the Coniacian to earliest Paleocene and involves deformation of Cretaceous marine sedimentary units. The second phase corresponds to Paleocene to early Eocene deformation that also affects continental sediments and is characterized by gentle folding and counterclockwise rotation of previous shortening structures associated with strike-slip faulting. Here we present geologic, geochronologic, and structural data of two key areas of the Sierra Madre del Sur, the Guerrero-Morelos Platform (GMP), and the Huajuapan-Tamazulapan area in western Oaxaca to describe the geometry, kinematics, and timing of the Late Cretaceous and early Tertiary deformation. Two regional magmatic episodes constrain the deformational history: (1) the first between the Maastrichtian and the Paleocene (68-57 Ma) documents the end of Late Cretaceous shortening in the GMP; and (2) the second between the late Eocene and early Oligocene (37-29 Ma) has a more regional distribution. The time and space analysis of deformation and magmatism in southern Mexico led us to exclude flat subduction or collision of the Guerrero terrane to the west as the cause for Late Cretaceous shortening in the GMP. Considering the similarity in the time and style of deformation with that of the northern Chortis block, we favor an interpretation in which the tectonic evolution of the central and eastern SMS is the result of progressive interaction of the Caribbean plate with the southernmost edge of North America since the Late Cretaceous.

  16. The application of the Intermittent SBAS (ISBAS) InSAR method to the South Wales Coalfield, UK

    NASA Astrophysics Data System (ADS)

    Bateson, Luke; Cigna, Francesca; Boon, David; Sowter, Andrew

    2015-02-01

    Satellite radar interferometry is a well-documented technique for the characterisation of ground motions over large spatial areas. However, the measurement density is often constrained by the land use, with best results obtained over urban and semi urban areas. We use an implementation of the Small Baseline Subset (SBAS) methodology, whereby areas exhibiting intermittent coherence are considered alongside those displaying full coherence, in the final result, to characterise the ground motion over the South Wales Coalfield, United Kingdom. 55 ERS-1/2 Synthetic Aperture Radar (SAR) C-band images for the period between 1992 and 1999 are processed using the ISBAS (Intermittent Small BAseline Subset) technique, which provides 3.4 times more targets, with associated measurements than a standard SBAS implementation. The dominant feature of the observed motions is a relatively large spatial area of uplift. Uplift rates are as much as 1 cm/yr. and are centred on the part of the coalfield which was most recently exploited. Geological interpretation reveals that this uplift is most likely a result of mine water rebound. Collieries in this part of the coalfield required a ground water to be pumped to enable safe coal extraction; following their closure pumping activity ceased allowing the water levels to return to equilibrium. The ISBAS technique offers significant improvements in measurement density ensuring an increase in detection of surface motions and enabling easier interpretation.

  17. A profound meteoric water influence on genesis in the Permian Waterberg Coalfield, South Africa: Evidence from stable isotopes

    SciTech Connect

    Faure, K.; Harris, C.; Willis, J.P.

    1995-10-02

    The coal, carbonaceous mudrock, and mudrock of the Grootegeluk Formation of the Waterberg Coalfield contain calcite, ankerite, and siderite. The aim of this paper is to use the stable isotope ratios of these minerals to determine the depositional environment of the host rock and the evolution of pore water with burial. In addition, calcite lenses, which are discrete, conformable layers between mudrock and coal seams in the Grootegeluk Formation, allow estimation of the oxygen isotope ratios of ambient meteoric water during diagenesis of the Waterberg Coalfield. Limits on the maximum temperature of formation can be estimated from vitrinite reflectance data of the organic material in the coal and carbonaceous mudrock units. One of the carbonate minerals present in the Grootegeluk Formation is siderite, which does not undergo recrystallization and reequilibration under normal diagenetic conditions. For this reason, the elemental and stable isotope composition of siderite is considered to reflect the sources of carbon and the origin of water and temperature in siderite formation (Mozley 1989; Mozley and Wersin 1992). The carbonates in the Waterberg Coalfield are present in both coal and organic-poor mudrock, thus permitting a comparison of the stable isotope variations of carbonates in these two rock formations.

  18. The 3-D Tectonic Crustal Stress Field and Style of Faulting Along the Pacific North America Plate Boundary in Southern California

    NASA Astrophysics Data System (ADS)

    Yang, W.; Hauksson, E.

    2012-12-01

    We invert for the state of stress in the southern California crust using recent high quality earthquake focal mechanisms catalog (1981-2010). To interpret the stress field we determine the maximum horizontal compressive stress (SHmax) orientations and the style of faulting across southern California at four different scales of resolution, with grid spacing of 5 and 10 km, and with 15 or 30 events per grid. The stress field is best resolved where seismicity rates are high but sufficient data are available to constrain the stress field across most of the region. The trend of SHmax exhibits significant regional and local spatial heterogeneities. The regional trend of SHmax varies from north along the San Andreas system to NNE to the east in the Eastern California Shear Zone as well as to the west, within the Continental Borderland and the western Transverse Ranges. The transition zones from one state of stress to the other are very sharp and occur over a distance of a few kilometers, following a trend from Yucca Valley to Imperial Valley to the east, and the western edge of the Peninsular Ranges to the west. The local scale heterogeneities in the SHmax trend include NNW trends along the San Andreas Fault near Cajon Pass, Tejon Pass, and the Cucapa Range, as well as NNE trends near the northern San Jacinto Fault and the Wheeler Ridge region. The style of faulting exhibits similar complexity, ranging from predominantly normal faulting in the high Sierra Nevada, to strike-slip faulting along the San Andreas system, to three consecutive bands of thrust faulting in the Wheeler Ridge area and the western Transfer Ranges. The local variations in the style of faulting include normal faulting at the north end of the San Jacinto Fault and scattered regions of thrust faulting. We compare the pattern of SHmax trend in the crust with the GPS measured maximum shortening strain rate tensor and upper mantle anisotropy. The regional variations in the SHmax trends are very similar to

  19. Petrologic, geochemical, and geochronologic constraints on the tectonic evolution of the southern Appalachian orogen, Blue Ridge Province of western North Carolina

    NASA Astrophysics Data System (ADS)

    Anderson, Eric Douglas

    2011-07-01

    The Blue Ridge Province of western North Carolina contains a wide variety of metamorphosed igneous and sedimentary rocks that record the tectonic effects of Precambrian and Paleozoic orogenic cycles. Tectonic interpretations of the events that led to the present configuration are varied and often conflicting. This investigation examines metamorphosed mafic rocks that are widely interpreted to have formed during the closure of ocean basins. Metabasites, and specifically eclogites, have a tendency to mark tectonic sutures and frequently preserve pressure (P), temperature (T), and age data (t) that can be gleaned from mineral equilibria and U-Pb isotopic compositions. As such, the examination of the metabasites is considered the key to understanding the orogenic history of the southern Blue Ridge where these metabasites occur. Chapter 2 is an investigation of the retrograde reactions related to the decompression of sodic pyroxenes that react to form diopside-plagioclase-hornblende-quartz symplectites as stability fields are overstepped during isothermal decompression. In Chapter 3 metabasites from the central and eastern Blue Ridge are re-examined and P-T pathways of these lithologies are determined. The argument is made that the Taconic orogeny of the Blue Ridge is the result of a continent-continent collision event that culminated in a mega-melange that coincides with the Cullowhee terrane and the eastern Blue Ridge melange of western North Carolina. Chapter 4 contains the results of a geochronological investigation of the Precambrian basement complex of the eastern Great Smoky Mountains. Chapter 5 is a whole rock geochemical study of the same basement complex. In Chapter 6, a potential lithologic correlation between the southern Blue Ridge basement and the Arequipa-Antofalla block of Peru is discussed. The geologic history of western South America from the Mesoproterozoic through Cambrian is summarized, a potential isotope-based lithologic correlation is proposed

  20. Large Glacitectonic structures on the Dogger Bank, southern North Sea; Implications for glacial dynamics, glacial limits, and interplay between the British and Fennoscandinavian Ice Sheets

    NASA Astrophysics Data System (ADS)

    Dove, Dayton; Cotterill, Carol; Long, Dave; Ruiter, Astrid; Phillips, Emrys; James, Leo; Forsberg, Carl Fredrik

    2013-04-01

    Recently acquired 2D seismic data (sparker) acquired over the Dogger Bank (DB) reveal large glacitectonic structures associated with late-Pleistocene glacial incursion into the southern North Sea. The densely populated survey data (100m line spacing) collected for the purposes of offshore windfarm development on the DB, allow for pseudo-3D interpretation. The sparker data show discrete thrust faults extending from within ~5 m of the seabed to ~200 m depth, and consistently terminate at one of two décollement surfaces. Preliminary mapping and amplitude extraction maps reveal the thrusts to occur in a series of thrust blocks (5-8 faults), with each set encompassing an area of approximately 6 km along-strike and 2 km at right angles. The overall zone of thrusting is up to 16 x 6 km on the western edge of the DB. The strike of the faults indicates ice-flow from the west. Other deformation structures include: open, recumbent, and fault propagation folds, as well as back thrusts, and pop-up structures. The relief of the DB (dimensions) is entirely accounted for by what has historically been termed the 'DB Formation'. These new data reveal that this seismostratigraphic unit likely consists of deposits from a variety of glacially influenced depositional regimes. The observed thrusts penetrate through the 'DB formation', indicating this phase of intense deformation post-dated the initial construction of the bank. Less pronounced glacial deformation affects much of the rest of the DB, and the products of this deformation (push-moraine complexes?) were possibly integral to the construction of the bank itself. While the style and fabric (NS?) of this deformation is less clear, it is likely there were multiple incursions of glacial ice, from different directions (and sources?), into this area where late-Pleistocene glaciation limits are poorly understood. Several mechanisms for forming such glacitectonic features have been proposed, and the thrust blocks here may have been

  1. Communication beyond the Classroom: Dimension 2010. A Thematic Index of "Dimension," 1980-2009. Selected Proceedings of the 2010 Joint Conference of the Southern Conference on Language Teaching, the Foreign Language Association of North Carolina, the North Carolina Chapter of AATSP, and the National Network of Early Language Learning

    ERIC Educational Resources Information Center

    Cherry, C. Maurice, Comp.; Wilkerson, Carol, Comp.

    2010-01-01

    "Dimension" is the annual volume containing the selected, refereed, edited Proceedings of each year's conference. The Southern Conference on Language Teaching (SCOLT), held its annual conference April 15-17, 2010, at the Winston-Salem Marriott in Winston-Salem, North Carolina, in collaboration with the Foreign Language Association of North…

  2. Communication beyond the Classroom. Dimension 2010. Selected Proceedings of the 2010 Joint Conference of the Southern Conference on Language Teaching, the Foreign Language Association of North Carolina, the North Carolina Chapter of AATSP, and the National Network of Early Language Learning

    ERIC Educational Resources Information Center

    Cherry, C. Maurice, Ed.; Wilkerson, Carol, Ed.

    2010-01-01

    "Dimension" is the annual volume containing the selected, refereed, edited Proceedings of each year's conference. "Communication Beyond the Classroom" was the announced theme of the annual conference of the Southern Conference on Language Teaching (SCOLT), held April 15-17, 2010, at the Winston-Salem Marriott in Winston-Salem, North Carolina, in…

  3. Remote Measurements of Carbon Monoxide over North America and Europe during Summer- Fall 2004 and Southern Hemisphere 2006

    NASA Astrophysics Data System (ADS)

    Connors, V. S.; Chen, G.; Pierce, B.; Hopkins, P. E.; Meriwether, T.; Reichle, H. G.; Sachse, Nia, G.; McMillan, W.; Sandy, M.; Companion, J.

    2007-05-01

    The MicroMAPS instrument is a nadir-viewing, gas filter-correlated radiometer which operating in the 4.67 micrometer fundamental band of carbon monoxide. Originally designed and built for a space mission, this CO remote sensor is being flown in support of satellite validation and science instrument demonstrations for potential UAV applications. The MicroMAPS instrument system was integrated and tested at NASA LaRC, in partnership with Scaled Composites and Virginia Space Grant Consortium (VSGC). Full system integration and flight testing was performed at Scaled Composites, in Mojave, in June 2004. Its successful performance enabled participation in four international science missions on Proteus: in 2004, INTEX -NA over eastern North America in July, ADRIEX over the Mediterranean region and EAQUATE over the United Kingdom region in September,and TWP-ICE over Darwin, Australia and the surrounding oceans in Jan-Feb 2006. These flights resulted in nearly 300 hours of data. In parallel with the engineering developments, theoretical radiative transfer models were developed specifically for the MicroMAPS instrument system at the University of Virginia, Mechanical Engineering Department by a combined undergraduate and graduate student team. With technical support from Resonance Ltd. in June 2005, the MicroMAPS instrument was calibrated for the conditions under which the Summer-Fall 2004 flights occurred. The analyses of the calibration data, combined with the theoretical radiative transfer models, provide the first data reduction for the science flights reported here. The influence on widespread fires in Alaska and Canada, coupled with the influence of stratospheric intrusions over the eastern portion of North America during Summer 2004, provides the opportunity to examine the evolution of the tropospheric column and to examine how the transport histories of the air resulted in the CO columns sampled from the Proteus aircraft. These early results and comparisons with

  4. The conductivity structure and dynamic characteristics of Southern-Ningxia arcstructure belt, north-east edge of Qinghai-Tibet Plateau, China

    NASA Astrophysics Data System (ADS)

    Min, G.; Wang, G.; Chen, J.; Zhou, J.; Yin, B.

    2013-12-01

    as strike-slip faults,nor gentle as thrust belt, but take the characteristics of slip and thrust both; we confirmed that a series of thrust nappe structure exist in middle-upper crust, which include Xiangshan nappe structure and the thrust nappe structure in west margin of Ordos with imbricated combination. The depth of their main detachment surface is gradually become deeper from the northeast to the southwest, finally disappear in the low resistance layer in crust; The Paleozoic carboniferous detachment surface, the early Proterozoic or Middle Proterozoic detachment surface and the high conductive layer constitute the main dynamics boundary conditions in study area. Relying on the above boundary conditions, Southern-Ningxia arcstructural belt shows dynamic trend of north Qilian Mountains collision orogenic zone with eastward&northward obduction, Alxa block with southward subduction and Ordos block with westward subduction.

  5. Quaternary magnetic and oxygen isotope stratigraphy in diatom-rich sediments of the southern Gardar Drift (IODP Site U1304, North Atlantic)

    NASA Astrophysics Data System (ADS)

    Xuan, Chuang; Channell, James E. T.; Hodell, David A.

    2016-06-01

    The sediment sequence from Integrated Ocean Drilling Program (IODP) Site U1304 (53°03.40‧N, 33°31.78‧W; water depth, 3024 m) on the southern Gardar Drift, North Atlantic Ocean, covers the last ∼1.8 Myr with a mean sedimentation rate of ∼15 cm/kyr. At Site U1304, paleomagnetic directional and relative paleointensity (RPI) records have been generated for the last ∼1.5 Myr, and benthic oxygen isotope data for the last ∼1 Myr. The age model for Site U1304 was established by matching δ18O and RPI data to calibrated reference records. Prominent intervals of diatom mats at Site U1304 are associated with the latter stages of interglacial marine isotope stages (MIS) 9, 11, 13, 15, 21, 27 and 35, and with the weak glacial of MIS 14. The deposition of diatom mats, and associated diluted magnetic mineral concentrations, leads to weak magnetizations and susceptibilities in these intervals. Comparison of histograms of paleomagnetic directions and RPI from diatom-rich sediments and from surrounding silty clays indicates that, although results from diatom-rich sediments are more scattered, the occurrence of diatom mats does not appreciably distort the paleomagnetic directional and RPI records. Site U1304 sediments record the Matuyama/Brunhes boundary (∼772 ka), the Jaramillo Subchron (∼993-1071 ka) and the Cobb Mountain Subchron (∼1193-1219 ka), as well as three apparent geomagnetic excursions in the Matuyama Chron, interpreted as the "Kamikatsura/Santa Rosa", "Punaruu", and "Gardar" excursions, at ∼888 ka, ∼1124 ka, and ∼1463 ka, respectively. The Site U1304 RPI record can be correlated with the PISO-1500 RPI stack and with other high-resolution RPI records from the North Atlantic Ocean. Wavelet analyses performed on the Site U1304 RPI record and a new high-resolution North Atlantic paleointensity stack for the last 1500 kyr (HINAPIS-1500), comprising Ocean Drilling Program (ODP) Sites 983, 984 and IODP Sites U1306 and U1304, did not reveal significant

  6. Vertically Decoupled Paleocene-Eocene Wrenching in Southern Mexico and its Possible Relation with the Activation of the Caribbean-North America Boundary

    NASA Astrophysics Data System (ADS)

    Cerca Martinez, M.; Ferrari, L.

    2001-12-01

    Recent studies in the eastern part of the Guerrero-Morelos platform and western Mixteco terrane of southern México support the existence of significant strain in a left lateral regime superposed to the late Cretaceous Laramide structures. In the NE part of the study region the most striking evidence is the so-called Papalutla fault and associated contractile structures. In contrast to previous beliefs we documented that this deformation involves rocks as young as 38 Ma and mainly consists of NNE to NE folds that re-fold N-S trending Laramide structures, with a general WNW vergence. In the SW part of the study region the Laramide fold are refolded and broken with an ENE vergence as a result of drag related to the left lateral shear zone bounding the middle to lower crustal rocks of the Xolapa complex. The shear zone and the ductile shear deformation inside the Xolapa predate the 34 Ma Tierra Colorada pluton. Apparently, all the above structures developed during one phase of progressive deformation before the end of Eocene and after the Laramide orogeny. At a regional scale the early Tertiary structures seems to define a 3D strain field characterized by subcircular paths of the maximum strain direction, which can be explained as the result of anticlockwise rotation of blocks about the vertical axis. This deformation appears temporally and kinematically compatible with the ESE motion of the Caribbean plate (Chortis block) and, particularly, with the formation of the left lateral ductile shear zone that bounds to the north the Xolapa complex. However, our study suggests that the early motion of the Caribbean plate was accommodated by a broad zone of shear that extend at least 150 km to the north of the present plate boundary. We speculate that in Paleocene-Eocene times the Caribbean-North America plate boundary was diffuse and characterized by left lateral strain, in agreement with the ductile deformation and migmatization of the same age observed in the Xolapa

  7. Effects of climate warming, North Atlantic Oscillation, and El Niño-Southern Oscillation on thermal conditions and plankton dynamics in northern hemispheric lakes.

    PubMed

    Gerten, Dieter; Adrian, Rita

    2002-03-01

    Impacts of climate warming on freshwater ecosystems have been documented recently for a variety of sites around the globe. Here we provide a review of studies that report long-term (multidecadal) effects of warming trends on thermal properties and plankton dynamics in northern hemispheric lakes. We show that higher lake temperatures, shorter periods with ice cover, and shorter stagnation periods were common trends for lakes across the hemisphere in response to the warmer conditions. Only for shallow dimictic lakes was it observed that deep-water temperatures decreased. Moreover, it became evident that phytoplankton dynamics and primary productivity altered in conjunction with changes in lake physics. Algal spring blooms developed early and were more pronounced in several European lakes after mild winters with short ice cover periods, and primary productivity increased in North American lakes. Effects of elevated temperatures on zooplankton communities were seen in an early development of various species and groups, as is documented for cladocerans, copepods, and rotifers in European lakes. Furthermore, thermophile species reached higher abundance in warmer years. Obviously, the nature of responses is species specific, and depends on the detailed seasonal patterning of warming. Complex responses such as effects propagating across trophic levels are likely, indicating that observed climate-ecosystem relationships are not generally applicable. Nonetheless, the picture emerges that climate-driven changes in freshwater ecosystems may be synchronised to a certain extent among lakes even over great distances if climatic influences are not masked by anthropogenic impacts or differences in lake morphology. Macro-scale climatic fluctuations--such as the North Atlantic Oscillation or the El Niño-Southern Oscillation--were identified as the most important candidates responsible for such coherence, with the former predominating in Europe and the latter in North America. We

  8. Spatial variability in structural and functional aspects of macrofauna communities and their environmental parameters in the Jade Bay (Wadden Sea Lower Saxony, southern North Sea)

    NASA Astrophysics Data System (ADS)

    Schückel, Ulrike; Beck, Melanie; Kröncke, Ingrid

    2013-03-01

    Spatial distribution and functional structure of intertidal benthic macrofauna in relation to environmental variables in the Jade Bay (southern North Sea) were studied and compared with other intertidal areas of the Wadden Sea. A total of 128 stations covering the whole Jade Bay were sampled in summer 2009. A total of 114 taxa were found. Highest species numbers occurred in the subtidal areas, whereas highest mean abundances were found in the upper intertidal areas. Based on species abundance data, six significantly distinct macrofauna communities in the Jade Bay were identified and evaluated with multivariate statistics, univariate correlations and canonical correspondence analysis. Differences in these community patterns were caused by the response of the dominant species ( Hydrobia ulvae, Tubificoides benedii, Pygospio elegans, Caulleriella killariensis, Scoloplos armiger, Urothoe poseidonis, Microprotopus maculatus) to prevailing environmental conditions along the gradient from the lower and exposed sandy intertidal areas via intermediate mixed sediments to the upper mudflat areas. Distribution patterns in relation to tidal zonation were best explained by variability in submergence time, Chlorophyll a (chl a) content and sediment composition (mud content), which are proxies for hydrodynamic conditions and food availability. Species inventory and species richness were comparable with other intertidal areas of the Wadden Sea, but the Jade Bay differs from these areas regarding dominant species. Differences in sediment composition and morphological characteristics (macrotidal versus mesotidal Wadden Sea areas) are discussed for comparison of regional differences.

  9. A novel adaptive biogeochemical model, and its 3-D application for a decadal hindcast simulation of the biogeochemistry of the southern North Sea

    NASA Astrophysics Data System (ADS)

    Kerimoglu, Onur; Hofmeister, Richard; Wirtz, Kai

    2016-04-01

    Adaptation and acclimation processes are often ignored in ecosystem-scale model implementations, despite the long-standing recognition of their importance. Here we present a novel adaptive phytoplankton growth model where acclimation of the community to the changes in external resource ratios is accounted for, using optimality principles and dynamic physiological traits. We show that the model can reproduce the internal stoichiometries obtained at marginal supply ratios in chemostat experiments. The model is applied in a decadal hindcast simulation of the southern North Sea, where it is coupled to a 2-D benthic model and a 3-D hydrodynamic model in an approximately 1.5km horizontal resolution at the German Bight coast. The model is shown to have good skill in capturing the steep, coastal gradients in the German Bight, suggested by the match between the estimated and observed dissolved nutrient and chlorophyll concentrations. We then analyze the differential sensitivity of the coastal and off-shore zones to major drivers of the system, such as riverine nutrient loads. We demonstrate that the relevance of phytoplankton acclimation varies across coastal gradients and can become particularly significant in terms of summer nutrient depletion.

  10. Impact of a phytoplankton bloom on the diversity of the active bacterial community in the southern North Sea as revealed by metatranscriptomic approaches.

    PubMed

    Wemheuer, Bernd; Güllert, Simon; Billerbeck, Sara; Giebel, Helge-Ansgar; Voget, Sonja; Simon, Meinhard; Daniel, Rolf

    2014-02-01

    Despite their importance for ecosystem functioning, little is known about the composition of active marine bacterioplankton communities. Hence, this study was focused on assessing the diversity of these communities in the southern North Sea and examining the impact of a phytoplankton spring bloom on the ambient bacterioplankton community. Community composition in and outside the bloom was assessed in 14 samples by pyrosequencing-based analysis of 16S rRNA gene amplicons generated from environmental RNA. The data set comprised of 211 769 16S rRNA gene sequences. Proteobacteria were the predominant phylogenetic group with Alphaproteobacteria and Gammaproteobacteria as the most abundant classes. Actinobacteria and Bacteroidetes were identified in minor abundances. Active bacterial communities were dominated by few lineages such as the Roseobacter RCA cluster and the SAR92 clade. Community structures of three selected samples were also assessed by direct sequencing of cDNA generated from rRNA-depleted environmental RNA. Generated data sets comprised of 988 202 sequences. Taxonomic assignment of the reads confirmed the predominance of Proteobacteria. The examined phytoplankton spring bloom affected the bacterioplankton community structures significantly. Bacterial richness was reduced in the bloom area, and the abundance of certain bacterial groups was affected by bloom presence. The SAR92 clade and the Roseobacter RCA cluster were significantly more abundant and active in the bloom. Functions affected by the bloom include photosynthesis, protein metabolism, and DNA metabolism. PMID:24111503

  11. A 3-D shear velocity model of the southern North America and the Caribbean plates from ambient noise and earthquake tomography

    NASA Astrophysics Data System (ADS)

    Gaite, B.; Villaseñor, A.; Iglesias, A.; Herraiz, M.; Jiménez-Munt, I.

    2014-10-01

    We use group velocities from earthquake tomography together with group and phase velocities from ambient noise tomography (ANT) of Rayleigh-waves to invert for the 3-D shear-wave velocity structure (5-70 km) of the Caribbean (CAR) and southern North American (NAM) plates. The lithospheric model proposed offers a complete image of the crust and uppermost-mantle with imprints of the tectonic evolution. One of the most striking features inferred is the main role of the Ouachita-Marathon-Sonora orogeny front on the crustal seismic structure of NAM plate. A new imaged feature is the low crustal velocities along USA-Mexico border. The model also shows a break of the E-W mantle velocity dichotomy of the NAM and CAR plates beneath the Isthmus of Tehuantepec and Yucatan Block. High upper-mantle velocities along the Mesoamerican Subduction Zone coincide with inactive volcanic areas while the lowest velocities correspond to active volcanic arcs and thin lithospheric mantle regions.

  12. Impacts of aggregate dredging on sediment composition and associated benthic fauna at an offshore dredge site in the southern North Sea.

    PubMed

    Robinson, J E; Newell, R C; Seiderer, L J; Simpson, N M

    2005-07-01

    Dredging and associated screening at a dredge site in the southern North Sea (Area 408) is associated with areas of well-sorted fine sand that extend for up to 3 km to the south-east of the dredged area and overlay sediments with a more variable particle size composition. This well-sorted fine sand may reflect deposition and transport of material mobilised by the dredging and screening processes at the dredge site. Multivariate analysis of the benthic community structure suggests that marine aggregate dredging, at the level of intensity employed in the study area prior to sample collection, has had a limited impact on benthic community composition compared with that reported from studies elsewhere. This is ascribed to the likely rapid rates of recolonisation by the mobile opportunistic polychaetes and crustaceans that dominate the macrofauna of the sandy gravel deposits at this particular dredge site. Analysis of variance showed, however, that significant differences existed between the sample treatments in terms of species evenness (Pielou's J). Dredged samples were found to have the lowest mean species evenness (0.71) when compared to controls (0.77). The present study highlights the inherent difficulties in the application of general impact/recovery predictions to dredged sites with varying environmental characteristics. PMID:15649527

  13. Temporal variations in 13C and 14C concentrations in particulate organic matter from the southern North Sea

    NASA Astrophysics Data System (ADS)

    Megens, L.; van der Plicht, J.; de Leeuw, J. W.

    2001-09-01

    As a new approach for the characterization and determination of the origin of particulate organic matter (POM) in coastal waters, we measured the 14C activity and 13C/ 12C isotope ratios and applied molecular analysis by means of AMS, IRMS and pyrolysis-GCMS for both bulk samples and isolated fractions of POM from the North Sea off the Dutch coast. The fractions were obtained by a sequence of chemical treatments separating polysaccharides, proteins, lipids and non-hydrolysable resistant compounds. The 13C/ 12C and 14C/ 12C isotope ratios, the 14C activities and the polysaccharide/protein contents were high in the spring and summer samples and significantly lower in the autumn and winter samples. This is explained by the high amount of marine phytoplankton in summer and spring, and the presence of detrital material in autumn and winter. It was noted that phytoplankton as found in the spring and summer samples was ca. 20% enriched in 14C with respect to natural values, very likely caused by 14C contamination of the water from the English Channel by the nuclear fuel reprocessing plant at La Hague, Normandy, France. The 13C/ 12C isotope ratios and 14C activity data show that the winter sample was not a simple mixture of relatively recent marine phytoplankton and POM from the rivers Rhine and Meuse. The main source of both terrestrial and marine organic matter in POM in winter is resuspended organic matter derived from eroded sea floor deposits with relatively low contributions of polysaccharides and proteins.

  14. Hydrologic reconnaissance of the Wasatch Plateau-Book Cliffs coal-fields area, Utah

    USGS Publications Warehouse

    Waddell, Kidd M.; Contratto, P. Kay; Sumsion, C.T.; Butler, J.R.

    1981-01-01

    Data obtained during a hydrologic reconnaissance in 1975-77 in the Wasatch Plateau-Book Cliffs coal-fields area of Utah were correlated with existing long-term data. Maps were prepared showing average precipitation, average streamflow, stream temperature, ground- and surface-water quality, sediment yield, and geology. Recommendations were made for additional study and suggested approaches for continued monitoring in the coalfields areas. During the 1931-75 water years, the minimum discharges for the five major streams that head in the area ranged from about 12,000 to 26,000 acre-feet per year, and the maximum discharges ranged from about 59,000 to 315,000 acre-feet per year. Correlations indicate that 3 years of low-flow records at stream sites in the Wasatch Plateau would allow the development of relationships with long-term sites that can be used to estimate future low-flow records within a standard error of about 20 percent. Most water-quality degradation in streams occurs along the flanks of the Wasatch Plateau and Book Cliffs. In the uplands, dissolved-solids concentrations generally ranged from less than 100 to about 250 milligrams per liter, and in the lowlands, the concentrations ranged from about 250 to more than 6,000 milligrams per liter. Most springs in the Wasatch Plateau and Book Cliffs discharge from the Star Point Sandstone or younger formations, and the water generally contains less than about 1,000 milligrams per liter of dissolved solids. The discharges of 65 springs ranged from about 0.2 to 200 gallons per minute. The Blackhawk Formation, which is the principal coal-bearing formation, produces water in many of the mines. The dissolved-solids concentration in water discharging from springs and mines in the Blackhawk ranged from about 60 to 800 milligrams per liter. In the lowland areas, the Ferron Sandstone Member of the Maneos Shale appears to have the most potential for subsurface development of water of suitable chemical quality for human

  15. The Seasonal Cycles of Temperature, Salinity, Nutrients and Suspended Sediment in the Southern North Sea in 1988 and 1989

    NASA Astrophysics Data System (ADS)

    Prandle, D.; Hydes, D. J.; Jarvis, J.; McManus, J.

    1997-11-01

    Simple statistical analyses are used to summarize the large data set available from the 15 consecutive monthly surveys of the U.K. North Sea Project (NSP). The seasonal cycles of temperature, salinity, phosphate, nitrate, nitrite, silicate, ammonium and suspended particulate matter (SPM) are approximated by a mean value plus a year-long cosine wave. The mean concentrations, with standard deviationcgiven in parentheses, for each of these water quality parameters covering the whole area throughout the 15-month period are: salinity 34·26 (±0·74), ammonia 1·3 (±1·0) μM, nitrate 4·9 (±6·0) μM, nitrite 0·4 (±0·5) μM, phosphate 0·5 (0·3) μM, silicate 2·5 (±2·5) μM and suspended sediment 2·6 (±3·5) mg l-1. This approximate seasonal cycle accounts for most of the variance in temperature and nutrients. The spatially-averaged seasonal amplitudes for both nitrate and silicate are approximately equal to their mean values-this is consistent with these being limiting nutrients. Salinity shows little seasonality. Spatial distributions are shown of the mean values, the seasonal amplitudes and the percentage variances accounted for by a combination of these mean values and seasonal amplitudes. Correlations between the determinands are calculated; these confirm the similarity in the spatial distributions for the nutrients, especially between nitrate, phosphate and silicate. Maximum concentrations are confined to the coastal regions, except for ammonium and nitrite for which they occur offshore. Spatial distributions of the anomalous (non-seasonal) components can be interpreted to indicate the effect of specific riverine and oceanic exchanges. Correlations between nitrate, nitrite and ammonium correspond to the interconversion of these compounds. The oceanic/riverine inflow rates of phosphate, nitrate and silicate are shown to be insufficient to support their seasonal variability, suggesting that internal recycling is required to maintain the seasonal cycle.

  16. A high resolution seismic reflection image for the oceanic LAB (Lithosphere-Asthenosphere Boundary), beneath southern North Island, New Zealand

    NASA Astrophysics Data System (ADS)

    Stern, T. A.; Henrys, S. A.; Okaya, D. A.; Savage, M. K.; Sato, H.; Iwasaki, T.; Louie, J. N.; Lamb, S. H.

    2014-12-01

    We present the first high-resolution, multichannel, seismic-reflection image for the base of an oceanic plate. Our image is based on an 85 km-long, ~ 900 station deployment across the lower North Island of New Zealand. 12 x 500 kg dynamite shots were used as seismic sources. Strong reflections at a two way travel time of 9-12 s define the top of the plate that dips to the NW at ~ 12-15 degrees. Between 27-32 s we identify a pair of reflections on some shot gathers that are interpreted to come from a reflection 90-100 km deep, that dips to the NW at 15 degrees. We interpret the reflection pair as marking a Lithosphere-Asthenosphere Boundary (LAB) zone at the base of the Pacific plate. Using all 12 shots we made a CDP-stacked image (maximum fold = 15) that shows the LAB as a double event (2-3 s apart) dipping roughly parallel to the top of the plate and Benioff zone. Shot quality varies but the highest frequencies we record from the base of the plate are ~ 18 Hz, suggesting a boundary zone < 1 km thick. Seismic amplitude attributes, calibrated to the reflection from the top of the plate, indicate P-wave speed drops off at least 8% across the LAB boundary. The double reflection at the LAB is interpreted to be a 10 km-thick layer of low seismic wave speed. Because it is so sharp it cannot be a thermal boundary and must represent some form of mechanical change. Previous attempts to explain the abruptness of seismic wave speed changes at the LAB have appealed to layered zones of ponded melt, or anelastic relaxation due to water accumulating beneath the LAB. Both mechanisms may explain our observations and both would point to low viscosity below the LAB. However, the fact we see a ~ 10 km thick channel, with strong acoustic impedances each side of the channel, suggests a shear zone where plate motion ( ~ 9 cm/y in hotspot reference frame) is taken up and strain rates of ~3 x 10-13 s-1 are generated. This interpreted, low wave-speed, low-viscosity, shear zone appears to be

  17. 1.4 kyrs of flash flood events in the Southern European Alps: implications for extreme precipitation patterns and forcing over the north-western Mediterranean area

    NASA Astrophysics Data System (ADS)

    Wilhelm, B.; Arnaud, F.; Sabatier, P.; Crouzet, C.; Brisset, E.; Guiter, F.; Reyss, J. L.; Chaumillon, E.; Tachikawa, K.; Bard, E.; Delannoy, J. J.

    2012-04-01

    the general moisture, the hydrology of large rivers and temperature patterns of the south-western European region, i.e. a low flood activity during the warm/dry MCA and conversely during the cold/wet Little Ice Age (LIA). At a sub-centennial scale, a high variability of the flood frequency is superimposed to the general increase during the LIA and appeared in phase with solar maximum. Moreover peaks of flood frequency seem to be correlated with negative autumnal NAO phases, in agreement with previous paleoflood reconstructions of Mediterranean Spanish rivers. Finally the comparison of flood frequency patterns from north-western Mediterranean sites suggests a 50-150 years oscillation mode, probably related to a NAO-like pattern, in two main NW Mediterranean atmospheric circulation patterns triggering extreme precipitations either over the Southern Alps or the Cevennes-Vivarais region.

  18. Early Cretaceous low-Mg# adakitic rocks in the southern margin of the central North China Craton: Partial melting of thickened lower continental crust and tectonic implications

    NASA Astrophysics Data System (ADS)

    Yang, D.

    2015-12-01

    This paper reports new whole-rock geochemical, Sr-Nd-Pb isotopic, and zircon U-Pb and Hf isotopic data for Early Cretaceous intrusive rocks in the Sanmenxia-Houma area of central China, and uses these data to constrain the petrogenesis of low-Mg adakitic rocks (LMAR) and the spatial extent of the influence of the deeply subducted Yangtze slab during the Triassic evolution of this region. New zircon LA-ICP-MS U-Pb data indicate that the early- and late-stage southern Quli, Qiligou, and Gaomiao porphyritic quartz diorites, the Canfang granodiorite, and the northern Wangmao porphyritic quartz monzodiorite were emplaced during the Early Cretaceous (~130 Ma) and the late Early Cretaceous (116 Ma). These rocks are characterized by high Na2O/K2O, Sr/Y, and (La/Yb)n ratios as well as high Sr concentrations, low Mg# values, and low heavy rare earth element and Y concentrations, all of which indicate an LMAR affinity. The samples have relatively high initial 87Sr/86Sr ratios (0.7054-0.7095), and low eNd(t) (-11.90 to -22.20) and eHf(t) (-16.7 to -32.7) values, indicative of a lower continental crust origin. The presence of Neoproterozoic (754-542 Ma) and inherited Late Triassic (220 Ma) metamorphic zircons within the late Early Cretaceous LMAR and the relatively high 206Pb/204Pb ratios of these rocks suggest that they formed from primary magmas derived from partial melting of Yangtze Craton (YC) basement material that had undergone ultrahigh-pressure metamorphism. In contrast, the presence of Paleoproterozoic and Archean inherited zircons within early Early Cretaceous LMAR in this area and the relatively low 206Pb/204Pb ratios of these rocks are indicative of derivation from primary magmas generated by partial melting of the thickened lower continental crust of the North China Craton (NCC). These rocks may have formed in an extensional environment associated with the upwelling of asthenospheric mantle material. The presence of YC basement material within the NCC in the

  19. Fast hydrodynamic model for medium- and long-term dispersion in seawater in the English Channel and southern North Sea, qualitative and quantitative validation by radionuclide tracers

    NASA Astrophysics Data System (ADS)

    du Bois, P. Bailly; Dumas, F.

    The database for medium- and long-term model validation using 125Sb released by the La Hague reprocessing plant includes 1400 measurements performed between 1987 and 1994 in the English Channel and the North Sea and data for each release since 1982. Antimony-125 has a conservative behaviour in water masses over a period of several years. These data can be used qualitatively and quantitatively to compare the measured concentrations with the calculated ones and quantities of tracers. Tritium measurements are also available for model calibration. A two-dimensional hydrodynamic model has been developed to allow repetitive long-term simulations. This model uses a database of residual tidal currents calculated using the Lagrangian barycentric method [Salomon, J.C., Guéguéniat, P., Orbi, A., Baron, Y., 1988. A Lagrangian model for long-term tidally induced transport and mixing. Verification by artificial radionuclide concentrations. In: Guary, J.C., Guéguéniat, P., Pentreath, R.J. (Eds.), Radionuclides: A Tool for Oceanography, Cherbourg 1-5 June, 1987. Elsevier Applied Science Publishers, London, New York, pp. 384-394]. The area covered by the model includes the English Channel, the southern North Sea and the Irish Sea with a mesh size of 1 km. The main adjustment parameters of this model are the sources of wind data used and the calculation method for evaluating wind stress at the sea surface. With these parameters, the fluxes of radionuclides and water masses in the English Channel and the North Sea were balanced for the whole period of field measurements (1987-1994). The correlation factor between individual measurements in seawater and calculation results is 0.88 with an average error of ±54%, the error attributable to the measurement process being 15% on average. The mean flux through the Dover Strait is 126,000 m 3 s -1, close from the one obtained from previous studies [Salomon, J.C., Breton, M., Guéguéniat, P. 1993. Computed residual flow through the Dover

  20. Depositional setting, petrology and chemistry of Permian coals from the Paraná Basin: 2. South Santa Catarina Coalfield, Brazil

    USGS Publications Warehouse

    Kalkreuth, W.; Holz, M.; Mexias, A.; Balbinot, M.; Levandowski, J.; Willett, J.; Finkelman, R.; Burger, H.

    2010-01-01

    In Brazil economically important coal deposits occur in the southern part of the Paran?? Basin, where coal seams occur in the Permian Rio Bonito Formation, with major coal development in the states of Rio Grande de Sul and Santa Catarina. The current paper presents results on sequence stratigraphic interpretation of the coal-bearing strata, and petrological and geochemical coal seam characterization from the South Santa Catarina Coalfield, Paran?? Basin.In terms of sequence stratigraphic interpretation the precursor mires of the Santa Catarina coal seams formed in an estuarine-barrier shoreface depositional environment, with major peat accumulation in a high stand systems tract (Pre-Bonito and Bonito seams), a lowstand systems tract (Ponta Alta seam, seam A, seam B) and a transgressive systems tract (Irapu??, Barro Branco and Treviso seams).Seam thicknesses range from 1.70 to 2.39. m, but high proportions of impure coal (coaly shale and shaley coal), carbonaceous shale and partings reduce the net coal thickness significantly. Coal lithoypes are variable, with banded coal predominant in the Barro Branco seam, and banded dull and dull coal predominantly in Bonito and Irapu?? seams, respectively. Results from petrographic analyses indicate a vitrinite reflectance range from 0.76 to 1.63 %Rrandom (HVB A to LVB coal). Maceral group distribution varies significantly, with the Barro Branco seam having the highest vitrinite content (mean 67.5 vol%), whereas the Irapu?? seam has the highest inertinite content (33.8. vol%). Liptinite mean values range from 7.8. vol% (Barro Branco seam) to 22.5. vol% (Irapu?? seam).Results from proximate analyses indicate for the three seams high ash yields (50.2 - 64.2wt.%). Considering the International Classification of in-Seam Coals, all samples are in fact classified as carbonaceous rocks (>50wt.% ash). Sulfur contents range from 3.4 to 7.7 wt.%, of which the major part occurs as pyritic sulfur. Results of X-ray diffraction indicate the

  1. Modern Pearl River Delta and Permian Huainan coalfield, China: A comparative sedimentary facies study

    USGS Publications Warehouse

    Suping, P.; Flores, R.M.

    1996-01-01

    Sedimentary facies types of the Pleistocene deposits of the Modern Pearl River Delta in Guangdong Province, China and Permian Member D deposits in Huainan coalfield in Anhui Province are exemplified by depositional facies of anastomosing fluvial systems. In both study areas, sand/sandstone and mud/mudstone-dominated facies types formed in diverging and converging, coeval fluvial channels laterally juxtaposed with floodplains containing ponds, lakes, and topogenous mires. The mires accumulated thin to thick peat/coal deposits that vary in vertical and lateral distribution between the two study areas. This difference is probably due to attendant sedimentary processes that affected the floodplain environments. The ancestral floodplains of the Modern Pearl River Delta were reworked by combined fluvial and tidal and estuarine processes. In contrast, the floodplains of the Permian Member D were mainly influenced by freshwater fluvial processes. In addition, the thick, laterally extensive coal zones of the Permian Member D may have formed in topogenous mires that developed on abandoned courses of anastomosing fluvial systems. This is typified by Seam 13-1, which is a blanket-like body that thickens to as much as 8 in but also splits into thinner beds. This seam overlies deposits of diverging and converging, coeval fluvial channels of the Sandstone D, and associated overbank-floodplain deposits. The limited areal extent of lenticular Pleistocene peat deposits of the Modern Pearl River Delta is due to their primary accumulation in topogenous mires in the central floodplains that were restricted by contemporaneous anastomosing channels.

  2. Coal fire mapping of East Basuria Colliery, Jharia coalfield using vertical derivative technique of magnetic data

    NASA Astrophysics Data System (ADS)

    Pal, S. K.; Vaish, Jitendra; Kumar, Sahadev; Bharti, Abhay Kumar

    2016-02-01

    The present study deals with the coal fire mapping of East Basuria Colliery, Jharia coalfield, India, using the magnetic method. It is based on the fact that rise in temperature would result significant changes in magnetic susceptibility and thermo-remanent magnetization (TRM) of the overlying rocks. Magnetism increases slowly with the rise of temperature until the Curie temperature. Generally, rock/ overburden loses magnetization and becomes paramagnetic due to heating to Curie temperature, which results with significant reduction in magnetic susceptibility. However, magnetism increases significantly after cooling below the Curie temperature. Several data processing methods such as diurnal correction, reduction to pole (RTP), first and second vertical derivatives have been used for analysis of magnetic data and their interpretation. It is observed that the total magnetic field intensity anomaly of the area varies approximately from 44850 to 47460 nT and the residual magnetic anomaly varies approximately from -1323 to 1253 nT. The range of the magnetic anomaly after RTP is approximately 1050-1450 nT. About 20 low magnetic anomaly zones have been identified associated with active coal fire regions and 11 high magnetic anomaly zones have been identified associated with non-coal fire regions using vertical derivative techniques.

  3. Arsenic in coal of the Thar coalfield, Pakistan, and its behavior during combustion.

    PubMed

    Ali, Jamshed; Kazi, Tasneem G; Baig, Jameel A; Afridi, Hassan I; Arain, Mariam S; Brahman, Kapil D; Naeemullah; Panhwar, Abdul H

    2015-06-01

    The aim of the current study is to evaluate the occurrence of arsenic in coal collected from Thar coalfield, Pakistan, and its behavior during the combustion. Fractionation of arsenic (As) in coal samples was carried out by Community Bureau of Reference sequential extraction scheme (BCR-SES) and single-step-based BCR method (BCR-SS). These methods are validated using the certified reference material of sediment BCR 701 and standard addition method. The stepwise fractions of As in laboratory-made ash (LMA) have been also investigated. The extractable As content associated with different phases in coal and LMA samples were analyzed by electrothermal atomic absorption spectrophotometer. The extraction efficiency of As by BCR-SS was slightly higher than BCR-SES, while the difference was not significant (p < 0.05). The BCR-SS method is a time-saving method because it can reduce the extraction time from 51 to 22 h. The As contents in LMA revealed that during combustion of the coal, >85 % of As may be released into atmosphere. The relative mobility of As in the coal samples was found in increasing order as follows: oxidizable fraction < reducible fraction < acid soluble fraction. The total and extractable As obtained by BCR-SES and BCR-SS were higher in coal samples of block III as compared to block V (p > 0.05). PMID:25561265

  4. Evaluation of the fate of arsenic-contaminated groundwater at different aquifers of Thar coalfield Pakistan.

    PubMed

    Ali, Jamshed; Kazi, Tasneem G; Baig, Jameel A; Afridi, Hassan I; Arain, Mariam S; Ullah, Naeem; Brahman, Kapil D; Arain, Sadaf S; Panhwar, Abdul H

    2015-12-01

    In present study, the ground water at different aquifers was evaluated for physicochemical parameters, iron, total arsenic, total inorganic arsenic and arsenic species (arsenite and arsenate). The samples of groundwater were collected at different depths, first aquifer (AQ1) 50-60 m, second aquifer (AQ2) 100-120 m, and third aquifer (AQ3) 200-250 m of Thar coalfield, Pakistan. Total inorganic arsenic was determined by solid phase extraction using titanium dioxide as an adsorbent. The arsenite was determined by cloud point extraction using ammonium pyrrolidinedithiocarbamate as a chelating reagent, and resulted complex was extracted by Triton X-114. The resulted data of groundwater were reported in terms of basic statistical parameters, principal component, and cluster analysis. The resulted data indicated that physicochemical parameters of groundwater of different aquifers were exceeded the World Health Organization provisional guideline for drinking water except pH and SO4(2-). The positive correlation was observed between arsenic species and physicochemical parameters of groundwater except F(-) and K(+), which might be caused by geochemical minerals. Results of cluster analysis indicated that groundwater samples of AQ1 was highly contaminated with arsenic species as compared to AQ2 and AQ3 (p > 0.05). PMID:26254562

  5. Distribution, partitioning and fluxes of dissolved and particulate organic C, N and P in the eastern North Pacific and Southern Oceans

    NASA Astrophysics Data System (ADS)

    Loh, Ai Ning; Bauer, James E.

    2000-12-01

    Concurrent distributions of dissolved and suspended particulate organic carbon (DOC and POC susp), nitrogen (DON and PON susp) and phosphorus (DOP and POP susp), and of suspended particulate inorganic phosphorus (PIP susp), are presented for the open ocean water column. Samples were collected along a three-station transect from the upper continental slope to the abyssal plain in the eastern North Pacific and from a single station in the Southern Ocean. The elemental composition of surface sedimentary organic matter (SOM) was also measured at each location, and sinking particulate organic matter (POM sink) was measured with moored sediment traps over a 110-d period at the abyssal site in the eastern North Pacific only. In addition to elemental compositions, C : N, C : P and N : P ratios were also calculated. Surface and deep ocean concentrations of dissolved organic matter (DOM) and inorganic nutrients between the two sites displayed distinct differences, although suspended POM (POM susp) concentrations were similar. Concentrations of DOM and POM susp displayed unique C, N and P distributions, with POM susp concentrations generally about 1-2 orders of magnitude less than the corresponding DOM concentrations. These differences were likely influenced by different biogeochemical factors: whereas the dissolved constituents may have been influenced more by the physical regime of the study site, suspended particulate matter may have been controlled to a greater extent by biological and chemical alteration. Up to 80% of total particulate P in POM susp, POM sink and SOM consisted of PIP. For all organic matter pools measured, elemental ratios reveal that organic P is preferentially remineralized over organic C and organic N at both sites. Increases in C : P and N : P ratios with depth were also observed for DOM at both sites, suggesting that DOP is also preferentially degraded over C and N as a function of depth. A simple one-dimensional vertical eddy diffusion model was

  6. Refined Views of Strike-slip Fault Zones, Seismicity, and State of Stress Associated With the Pacific-North America Plate Boundary in Southern California

    NASA Astrophysics Data System (ADS)

    Hauksson, E.; Nicholson, C.; Shaw, J. H.; Plesch, A.; Shearer, P. M.; Sandwell, D. T.; Yang, W.

    2013-12-01

    The mostly strike-slip plate boundary in southern California is expressed as a system of late Quaternary faults or principal slip zones (PSZs), with numerous adjacent smaller slip surfaces. It is complex, even after large cumulative displacements, and consists of major fault systems with multi-stranded, non-planar fault geometry, including some in close proximity to each other. There are also secondary cross faults and low-angle detachments that interact with the PSZs accommodating main plate boundary motion. The loading of plate-tectonic strain causes the largest earthquakes along PSZs, moderate-sized events in their immediate vicinity, and small earthquakes across the whole region. We apply relocated earthquake and refined focal mechanism (1981-2013) catalogs, as well as other geophysical datasets to provide refined views of the 3D fault geometry of these active fault systems. To determine properties of individual fault zones, we measure the Euclidian distance from every hypocenter to the nearest PSZ. In addition, we assign crustal geophysical parameters such as heat flow value and shear or dilatation strain rates to each epicenter. We investigate seismogenic thickness and fault zone width as well as earthquake source processes. We find that the seismicity rate is a function of location, with the rate dying off exponentially with distance from the PSZ. About 80% of small earthquakes are located within 5 km of a PSZ. For small earthquakes, stress drops increase in size with distance away from the PSZs. The magnitude distribution near the PSZs suggests that large earthquakes are more common close to PSZs, and they are more likely to occur at greater depth than small earthquakes. In contrast, small quakes can occur at any geographical location. An optimal combination of heat flow and strain rate is required to concentrate the strain along rheologically weak fault zones, which accommodate the crustal deformation processes, causing seismicity. The regional trend of

  7. Evolution of the great river systems of southern Asia during the Cenozoic India-Asia collision: Rivers draining north from the Pamir syntaxis

    NASA Astrophysics Data System (ADS)

    Brookfield, M. E.

    2008-08-01

    During uplift of the Tibetan plateau and surrounding ranges, tectonic processes have interacted with climatic change and with local random effects (such as landslides) to determine the development of the major river systems of Asia. Rivers draining northward from the Pamir syntaxis have three distinctive patterns that are controlled by different tectonic and climatic regimes. West of the Pamir, the rivers have moderate but irregular gradients and drain northwards to disappear into arid depressions. Relatively steady uplift of the Hindu Kush in northern Afghanistan allowed rivers to cut across the rising ranges, modified by the shear along the Harirud fault zone, local faulting, and by increasing rain-shadow effects from the rising Makran. In the transition to the Pamir the rivers have steeper but more even gradients suggesting more even flow and downcutting during uplift, possibly related to larger glacial sources. In the central Pamir, only one antecedent river, the Pyandzh appears to have kept its northward course with compression and uplift of the indenter, and its course strangely corresponds with a major geophysical boundary (a distorted subducted slab) but not a geological boundary: the other rivers are subsequent rivers developed along deformation fronts during development and northward displacements of the Pamir structural units. The above areas have sources north of the Cretaceous Karakorum-South Pamir Andean margin. On the eastern flank of the Pamir, in the Kunlun and northern Tibetan plateau, the rivers rise similarly north of the Cretaceous Andean margin of southern Tibet, but then flow with low gradients across the plateau, before cutting and plunging steeply down across the Kunlun to disappear into the arid Tarim. These steep profiles are the result of late Neogene uplift of the northern Tibetan plateau and Kunlun possibly modified by glacial diversion and river capture. The drainage history of the Pamir indenter can be reconstructed by restoring the

  8. The green impact: bacterioplankton response toward a phytoplankton spring bloom in the southern North Sea assessed by comparative metagenomic and metatranscriptomic approaches

    PubMed Central

    Wemheuer, Bernd; Wemheuer, Franziska; Hollensteiner, Jacqueline; Meyer, Frauke-Dorothee; Voget, Sonja; Daniel, Rolf

    2015-01-01

    Phytoplankton blooms exhibit a severe impact on bacterioplankton communities as they change nutrient availabilities and other environmental factors. In the current study, the response of a bacterioplankton community to a Phaeocystis globosa spring bloom was investigated in the southern North Sea. For this purpose, water samples were taken inside and reference samples outside of an algal spring bloom. Structural changes of the bacterioplankton community were assessed by amplicon-based analysis of 16S rRNA genes and transcripts generated from environmental DNA and RNA, respectively. Several marine groups responded to bloom presence. The abundance of the Roseobacter RCA cluster and the SAR92 clade significantly increased in bloom presence in the total and active fraction of the bacterial community. Functional changes were investigated by direct sequencing of environmental DNA and mRNA. The corresponding datasets comprised more than 500 million sequences across all samples. Metatranscriptomic data sets were mapped on representative genomes of abundant marine groups present in the samples and on assembled metagenomic and metatranscriptomic datasets. Differences in gene expression profiles between non-bloom and bloom samples were recorded. The genome-wide gene expression level of Planktomarina temperata, an abundant member of the Roseobacter RCA cluster, was higher inside the bloom. Genes that were differently expressed included transposases, which showed increased expression levels inside the bloom. This might contribute to the adaptation of this organism toward environmental stresses through genome reorganization. In addition, several genes affiliated to the SAR92 clade were significantly upregulated inside the bloom including genes encoding for proteins involved in isoleucine and leucine incorporation. Obtained results provide novel insights into compositional and functional variations of marine bacterioplankton communities as response to a phytoplankton bloom. PMID

  9. The Role of the Sedimentary Regime in Shaping the Distribution of Subtidal Sandbank Environments and the Associated Meiofaunal Nematode Communities: An Example from the Southern North Sea

    PubMed Central

    Schratzberger, Michaela; Larcombe, Piers

    2014-01-01

    We combined sediment and faunal data to explore the role of the sedimentary regime in shaping the distribution of subtidal sandbank environments and the associated meiofaunal nematode communities at Broken Bank and Swarte Bank, in the southern North Sea. A variety of sediment transport processes occur in the area, differing in the frequency and magnitude of sediment mobility, and the continuum between erosion, translation and sediment accumulation. The seabed contained a variety of bedforms, including longitudinal furrows, and small to very large sandwaves. The bed sediments were dominated by fine and medium sands, with admixtures of silt and gravel. Based on sedimentary bedforms and grain size analysis, a total of 11 sedimentary facies were delineated, of which 8 were analysed in detail for their relationships with the meiofauna. The sedimentary facies fell clearly into groups of facies, respectively representing high, high-moderate and moderate, and episodic sediment mobility. For those sedimentary facies where daily movement of sediments and bedforms occurred (‘high’ sediment mobility), the resulting spatially homogeneous environments were dominated by an impoverished nematode community comprising small deposit feeders and large predators. Resistance to sediment movement and the ability to exploit alternative food sources were prominent functional features of the successful colonisers. Those facies characterised by relatively infrequent sediment mobility (‘episodic’ and ‘high-moderate and moderate’ sediment mobility) comprised a heterogeneous suite of benthic habitats, containing taxonomically and functionally diverse assemblages of nematodes of various sizes, feeding types and reproductive potential. Faunal distribution patterns here indicated trade-offs between the resistance to sediment movement, environmental tolerance and competitive abilities. Our focus on diverse assemblages of organisms with high turnover times, inhabiting highly dynamic

  10. Observations on the population dynamics of amphiura filiformis (ophiuroidea: echinodermata) in the southern north sea and its exploitation by the dab, Limanda limanda

    NASA Astrophysics Data System (ADS)

    Duineveld, G. C. A.; Van Noort, G. J.

    Density and growth of an Amphiura filiformis population living at a station in the Oyster Ground (southern North Sea) were monitored during 2 successive years (1982-1984). During this period, the density of adult animals (disk size > 4 mm) was constant and they numerically dominated the 1 mm sieve fraction of the samples. The size distribution of these adults was nearly constant and year classes were not discernable among these larger individuals. Annual recruitment was observed, but growth and survival rates of juveniles were low. During their first year, the disk size of recruits increased from 0.3 to 1.2 mm, and to 2.2 mm in their second year. Approximately 10% of the recruits of the 1982 year class survived the first 8 months. Of the recruits of the 1983 year class only 3% survived after 9 months. Consequently, the contribution by juveniles to the annual production of body tissue was small during the observation period. Adult somatic growth could not be assessed due to the apparent lack of disk growth. Regenerating arms, however, were very common among the larger individuals. Only 4% of the individuals in a sample had intact arms, whereas 55% of the animals (or 20% of all arms) had one or more 'recent' distal regenerations distinguishable by their smaller diameter. These regenerations presumably account for a large part of the annual growth and somatic production. Stomach content analysis of demersal fish in this area suggests that Amphiura arms form an important part of the diet of the dab, Limanda limanda. Annual consumption of Amphiura arms by dab was estimated to be 0.84 g wet weight-m -2, which is equivalent to 420 arms or 6% of the arm population. Considering the large number of adult animals in the population and regeneration capabilities of the species, the grazing by dab will have only little if any effect on the population.