Real-time drilling mud gas monitoring for qualitative evaluation of hydrocarbon gas composition during deep sea drilling in the Nankai Trough Kumano Basin     

Hammerschmidt  Sebastian B  Wiersberg  Thomas  Heuer  Verena B  Wendt  Jenny  Erzinger  Jörg  Kopf  Achim 《Geochemical transactions》2014,15(1):1-9

Background

Riverine particles undergo a rapid transformation when they reach estuaries. The rapid succession of hydrodynamic and biogeochemical regimes forces the particles to flocculate, settle and enter the sediment pool. The rates and magnitudes of flocculation depend on the nature of the particles which are primarily affected by the types and quantities of organic matter (OM). Meanwhile, the OM characteristics vary widely between environments, as well as within a single environment due to seasonal climate and land use variability. We investigated the effect of the OM types and quantities through laboratory experiments using natural estuarine particles from the Mississippi Sound and Atchafalaya Bay as well as model mixtures of montmorillonite and organic molecules (i.e., biopolymers (guar/xanthan gums) and humic acid).

Results

Biopolymers promote flocculation but the magnitude depends on the types and quantities. Nonionic guar gum yields much larger flocs than anionic xanthan gum, while both of them exhibit a nonlinear behavior in which the flocculation is the most pronounced at the intermediate OM loading. Moreover, the effect of guar gum is independent of salinity whereas the effect of xanthan gum is pronounced at higher salinity. Meanwhile, humic acid does not affect flocculation at all salinity values tested in this study. These results are echoed in the laboratory manipulation of the natural estuarine particles. Flocculation of the humic acid-rich Mississippi Sound particles is unaffected by the OM, whereas that of biopolymer-rich Atchafalaya Bay particles is enhanced by the OM.

Conclusions

Flocculation is positively influenced by the presence of biopolymers that are produced as the result of marine primary production. Meanwhile, humic acid, which is abundant in the rivers that drain the agricultural soils of Southeastern United States, has little influence on flocculation. Thus, it is expected that humic acid-poor riverine particles (e.g., Mississippi River, and Atchafalaya River, to a lesser degree) may be prone to rapid flocculation and settling in the immediate vicinity of the river mouths when mixed with biopolymer-rich coastal waters. It is also expected that humic acid-rich riverine particles (e.g., Pearl River) may resist immediate flocculation and be transported further away from the river mouth.  相似文献   

Water mass interaction at intermediate depths in the southern Rockall Trough,northeastern North Atlantic     

Jenny E. Ullgren  Martin White 《Deep Sea Research Part I: Oceanographic Research Papers》2010,57(2):248-257

Mooring time series, CTD data, and Argo float data were analysed to investigate some aspects of the circulation at the southern entrance to the Rockall Trough during 2003–2004. The in situ data are used to describe the distribution at intermediate levels of Sub-Arctic Intermediate Water (SAIW) and Mediterranean Water (MW), as well as the temporal variability in the presence of these two water masses. Salty, MW-influenced water was found in the southeastern part of the study area, near the continental slope as far north as Porcupine Bank, consistent with earlier reports. Apart from the main tongue, the distribution of MW is patchy, and MW parcels were found not only adjacent to the slope but also offshore. Further north and west, water at intermediate depths was influenced by the fresher SAIW. Unlike in some earlier studies, SAIW did not extend as far east as the continental shelf. The year-long hydrographic and current time series from a mooring on the western slope of the entrance, at the southern end of Feni Ridge, showed pulses of SAIW influenced water throughout winter and spring. In late spring, the fresh pulses almost completely ceased; throughout summer only a few weak and shortlived fresh anomalies appeared. The weakening of the SAIW signal did not seem to be caused by winter convection, which did not extend to sufficient depth that winter. The relatively weak SAIW presence during most of the study period may be linked to the near neutral state of the NAO index. The warm and saline conditions observed at the southern entrance to Rockall Trough were in agreement with the rising temperatures and salinities found over large parts of the subpolar North Atlantic in the late 1990s and early 2000s.  相似文献   

Heavy metal resistant endophytic fungi isolated from Nypa fruticans in Kuching Wetland National Park     

Choo  Jenny  Sabri  Nuraini Binti Mohd  Tan  Daniel  Mujahid  Aazani  Müller  Moritz 《Ocean Science Journal》2015,50(2):445-453

Heavy metal pollution is an environmental issue globally and the aim of this study was to isolate endophytic fungi from mangrove wetlands of Sarawak to assess and test their ability to grow in the presence of various heavy metals (copper (Cu), zinc (Zn), lead (Pb), and chromium (Cr)). Samples of Nypa fruticans were collected from Kuching Wetland National Park (KWNP) for subsequent endophyte isolation. Ninety-three (93) isolates were obtained and assessed and the most resistant isolates (growing at concentrations up to 1000 ppm) were identified using fungal primers ITS 1 and ITS 4. All of the endophytic fungi were identified to be closely related to Pestalotiopsis sp. and this is to our knowledge the first study reporting the ability of Pestalotiopsis sp. to grow at high concentrations of copper, lead, zinc and chromium. Our results highlight the potential of using endophytic fungi for the treatment of heavy metal pollution, for example as biosorbents.

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Experimental phase equilibria of a Mount St. Helens rhyodacite: a framework for interpreting crystallization paths in degassing silicic magmas     

Jenny M. Riker  Jonathan D. Blundy  Alison C. Rust  Roman E. Botcharnikov  Madeleine C. S. Humphreys 《Contributions to Mineralogy and Petrology》2015,170(1):1-22

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Chironomid‐inferred late‐glacial summer air temperatures from Lough Nadourcan,Co. Donegal,Ireland     

Jenny E. Watson  Stephen J. Brooks  Nicki J. Whitehouse  Paula J. Reimer  H. John B. Birks  Chris Turney 《第四纪科学杂志》2010,25(8):1200-1210

Western Ireland, located adjacent to the North Atlantic, and with a strongly oceanic climate, is potentially sensitive to rapid and extreme climate change. We present the first high‐resolution chironomid‐inferred mean July temperature reconstruction for Ireland, spanning the late‐glacial and early Holocene (LGIT, 15–10 ka BP). The reconstruction suggests an initial rapid warming followed by a short cool phase early in the interstadial. During the interstadial there are oscillations in the inferred temperatures which may relate to Greenland Interstadial events GI‐1a–e. The temperature decrease into the stadial occurs in two stages. This two‐stage drop can also be seen in other late‐glacial chironomid‐inferred temperature records from the British Isles. A stepped rise in temperatures into the Holocene, consistent with present‐day temperatures in Donegal, is inferred. The results show strong similarities with previously published LGIT chironomid‐inferred temperature reconstructions, and with the NGRIP oxygen‐isotope curve, which indicates that the oscillations observed in the NGRIP record are of hemispherical significance. The results also highlight the influence of the North Atlantic on the Irish climate throughout the LGIT. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

Three-dimensional versus conventional volcanic hazard maps     

Charles A. Preppernau  Bernhard Jenny 《Natural Hazards》2015,78(2):1329-1347

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Macroscopic diffusivity in concrete determined by computational homogenization     

Filip Nilenius  Fredrik Larsson  Karin Lundgren  Kenneth Runesson 《国际地质力学数值与分析法杂志》2013,37(11):1535-1551

Effective moisture and chloride ion diffusivity coefficients for concrete are determined by computational homogenization, where concrete is modeled on the mesoscale as a heterogenous three‐phase composite material. By imposing moisture and chloride ion gradients on a representative volume element, effective macroscale properties are obtained through finite element analysis. A parametric study of the effects of the ballast content was carried out. The numerical results correspond well with an estimate of the Hashin–Shtrikman type available in the literature. The computational homogenization strategy proposed here also includes the interfacial transition zone, and its influence on the effective diffusivity coefficients is assessed. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Invited responses to Yiftachel and Yacobi, Planning a bi-national capital: should Jerusalem remain united? (Geoforum Vol. 33, No. 1, pp. 137-145.)     

Jenny Robinson 《Geoforum》2002,33(3):275

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Identifying Major Stressors: The Essential Precursor to Restoring Cultural Ecosystem Services in a Degraded Estuary     

Jenny Davis  Ian M. Kidd 《Estuaries and Coasts》2012,35(4):1007-1017

Worldwide estuaries have been subject to multiple and escalating anthropogenic impacts which have resulted in the loss of many ecosystem goods and services including: commercial activities, navigation and marine transportation, recreational and landscape values, and flood control and biodiversity support. An example of these losses is provided in an urban-industrial region of an estuary in northern Tasmania, Australia, where excessive silt deposition has resulted in almost complete loss of the channel at low tide. The causes of siltation have long been attributed to poor watershed management and high concentrations of flocculated and suspended sediments transported upstream by asymmetrical tides. However, historical analysis of anthropogenic changes in estuarine and riverine processes revealed different stressors. These included the decrease in the tidal prism and hence regime equilibrium, brought about by channel infilling and draining of tidal wetlands to create dry land for urban and agricultural uses, and the reduction and redirection of freshwater inflows for the generation of hydroelectricity. Watershed sediment loads exerted a relatively minor role in the estuarine equilibrium, which is solely dependent on tidal flows and river discharges for maintenance of stable cross-sectional areas. Sustainable remediation measures include increasing the tidal prism through the restoration of dynamic river flows and reconnection and restoration of tidal wetlands. However, the former will not be achievable without changes in major provisioning services, particularly the use of water to generate hydroelectricity. This study emphasises the importance of identifying stressors as the basis for examining the potential to reduce the trade-offs between the multiple ecosystem services provided by an estuary and its tributaries, particularly between provisioning and cultural ecosystem services, within a rehabilitation context.  相似文献   

Hydraulic Conductivity and Coefficient of Consolidation of Two Sulphide Clays in Sweden   总被引：1，自引：0，他引：1  

Rasmus Müller  Stefan Larsson 《Geotechnical and Geological Engineering》2012,30(1):173-186

The variation and anisotropy in hydraulic conductivity and the coefficient of consolidation was investigated for two Swedish sulphide clays. A series of constant rate of strain oedometer tests was performed on samples trimmed in the vertical and horizontal direction. A methodology to evaluate the horizontal coefficients of consolidation c _h via the horizontal hydraulic conductivity k _h and the vertical compression modulus M _v is proposed. Laboratory evaluations of c _h are also compared with determinations of c _h from in situ piezometer measurements in vertically drained sulphide clay. Furthermore, the validity of the empirical correlation between hydraulic conductivity change index C _k and initial void ratio e ₀, C _k  = 0.5e ₀ (Tavenas et al. in Can Geotech J 20(4):645–660, 1983b), was investigated for the sulphide clays. The results from the investigation show large ranges in measured hydraulic conductivities and coefficients of consolidation. However, the results indicate that the correlation C _k  = 0.5e ₀ is valid. The anisotropy in hydraulic conductivity and the coefficient of consolidation of the sulphide clays tested seems to be small. For design purposes, multiple tests for assessment of hydraulic conductivity and the coefficient of consolidation should be made, and a partial factor of safety, depending on the requisite level of safety and the spatial variability of the parameters, should be introduced. For design purposes in this type of clay, k _h  = k _v and c _h  = c _v are suggested.  相似文献