Transgranular Crack Nucleation in Carrara Marble of Brittle Failure     

Yi Cheng  Louis Ngai Yuen Wong  Varun Maruvanchery 《Rock Mechanics and Rock Engineering》2016,49(8):3069-3082

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Size and Geometry Effects on the Mechanical Properties of Carrara Marble Under Dynamic Loadings     

Chunjiang Zou  Louis Ngai Yuen Wong 《Rock Mechanics and Rock Engineering》2016,49(5):1695-1708

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Numerical hindcasting of sea surface pCO₂ at Weathership Station Papa     

D. Archer  S. Emerson  T. Powell  C.S. Wong 《Progress in Oceanography》1993,32(1-4)

A one-dimensional model of temperature, salinity, nutrients, oxygen, carbon, and argon chemistry is used to hindcast the annual cycle of sea surface pCO₂ at weathership Station Papa in the subarctic Pacific (50°N, 145°W), based on recent biological and chemical measurements made in conjunction with the SUPER program. Heat fluxes are calculated from the meteorological time series data from the Canadian weathership program. The Price, Weller and Pinkle (1986) model is used for predicting mixed layer dynamics. The rate of new production in the model is based on sediment trap data (Welschmeyer, personal communication) and a comparison of model oxygen and argon concentrations with the recent data of Emerson, Quay, Stump, Wilbur and Knox (1991). The balances of nutrients and oxygen in the permanent halocline require isopycnal ventilation on a time frame of approximately 10 years; this estimate is consistent with estimate of Van Scoy, Fine and Ostlund (1991) based in tritium data from Geosecs and Long Lines programs. The model results are compared with the 5 year time series data presented by Wong and Chang (1990). The model appears to capture the mean sea surface pCO₂ and the magnitude and timing of the seasonal cycle. The data, howeber, contain much greater high frequency variation than the model results, which we believe is caused by patchiness in the horizontal distribution of NO₃. The model pCO₂ sensitivity to the chemistry of the upwelling water and the rate of biological new production are presented.Although the model simulation of pCO₂ is satisfactory, this study illustrates the limitations of modelling the chemistry of the upper ocean in one dimension. The slow currents and horizontally homogeneous sea surface in the subarctic Pacific make Papa one of the best available candidates for modelling in 1-D. In spite of this, a 1-D formulation is inadequate to address the chemistry of the halocline (a crucial lower boundary condition to the mixed layer) and does not constrain the transport of the nutrients by wind-driven currents in the mixed layer. We conclude that further progress in modelling the upper ocean nutrient and carbon cycles will requires simulation in three dimensions.  相似文献   

Stratigraphy of Quaternary inner-shelf sediments in Tai O Bay, Hong Kong, based on ground-truthed seismic profiles     

A. Bahr  H. K. Wong  W. W.-S. Yim  G. Huang  T. Lüdmann  L. S. Chan  W. N. Ridley Thomas 《Geo-Marine Letters》2005,25(1):20-33

High-resolution boomer profiles from Tai O Bay, Hong Kong SAR, were ground-truthed using ten discontinuously sampled boreholes penetrating bedrock with a maximum length of 82.1 m. The relationship between depth below seabed and seismic profiles was established through the measurement of two borehole compressional-wave velocity profiles. In departure from previous interpretations, nine Quaternary seismic units were identified, which can be divided into eight systems tracts formed by cycles of fourth-order sea-level fluctuations dating back at least to marine isotope stage (MIS) 7 (ca. 190–245 ka). These consist of two lowstand systems tracts, two transgressive systems tracts, and four highstand systems tracts. Secondary unconformities within the highstand deposits are interpreted to document fifth-order sea-level fluctuations. Lowstand deposits are less common because, as soon as the sea level drops by a few metres, Tai O Bay becomes sub-aerially exposed, leading to widespread non-deposition or erosion. At the same time, extensive fluvial erosion and channel incision take place. Filling of the fluvial channels occurs during rising sea level. Lowstand sediments (if present) are generally landslide deposits laid down on a basal alluvial plain. Uncorrected accelerator mass spectrometry (AMS) radiocarbon dates of mollusc shells show that the depositional environment was marine since 6.2 ka, becoming gradually more brackish as a result of progradation of the Pearl River delta. The computed average sedimentation rate for the period 6.2–4.1 ka is 4.4 m/1,000 year, and approximately 1 m/1,000 year since 4.1 ka.  相似文献   

Changes in topography and vegetation near gaps in a protective foredune     

Karl F. Nordstrom  JeanMarie Hartman  Amy L. Freestone  Mark Wong  Nancy L. Jackson 《Ocean & Coastal Management》2007,50(11-12):945-959

Data gathered on a foredune on a nourished beach reveal the relationships between topography and plant communities at gaps in the dune crest. Sand inundation at gaps allows plants in some portions of the dune to rejuvenate to earlier successional stages, while an increase in richness occurs in other portions. Ammophila breviligulata can create an initial dune ridge, colonize new areas of bare sand within the dune field, facilitate growth of other species, and provide a natural alternative to fencing in managing gaps. Foredune mobility can be considered a positive factor if beach width and dune volume provide adequate protection.  相似文献   

The distribution of suspended particles in the Southern Beaufort Sea     

Eiji Matsumoto  C. S. Wong 《Journal of Oceanography》1977,33(4):227-233

The Mackenzie River estuary serves as an avenue for suspended particles to pass seaward. The horizontal distribution of surface suspended particles is compartible with the distribution of low-salinity surface waters. The water structure in the shelf area is highly stratified in summer due to a thin upper layer of low-salinity which has a high concentration of suspended particles. The concentration of suspended particles decreases with depth, but near the bottom a turbid layer had often been observed. It is likely that bottom current energy high enough to erode and maintain in suspension the bottom sediments below 15m in diameter does occur over this shelf area.  相似文献   

Seasonal and Interannual Variability in the Distribution of Surface Nutrients and Dissolved Inorganic Carbon in the Northern North Pacific: Influence of El Niño     

Chi Shing Wong  Nathalie A. D. Waser  Yukihiro Nojiri  Wm. Keith Johnson  Frank A. Whitney  John S. C. Page  Jiye Zeng 《Journal of Oceanography》2002,58(2):227-243

The seasonal and interannual changes in surface nutrients, dissolved inorganic carbon (DIC) and total alkalinity (TA) were recorded in the North Pacific (30–54°N) from 1995 to 2001. This study focuses on the region north of the subarctic boundary (∼40°N) where there was extensive monthly coverage of surface properties. The nutrient cycles showed large interannual variations in the eastern and western subarctic gyres. In the Alaska Gyre the seasonal depletion of nitrate (ΔNO₃) increased from 8–14 μmol kg⁻¹ in 1995–1999 to 21.5 μmol kg⁻¹ in 2000. In the western subarctic the shifts were similar in amplitude but more frequent. The large ΔNO₃ levels were associated with high silicate depletions, indicating enhanced diatom production. The seasonal DIC:NO₃ drawdown ratios were elevated in the eastern and central subarctic due to calcification. In the western subarctic and the central Bering Sea calcification was significant only during 1997 and/or 1998, two El Ni?o years. Regional C/N stoichiometric molar ratios of 5.7 to 7.0 (>40°N) were determined based on the years with negligible or no calcification. The annual new production (NP_a) based on ΔNO₃ and these C/N ratios showed large interannual variations. NP_a was usually higher in the western than in the eastern subarctic. However, values of 84 gC m⁻²yr⁻¹ were found in the Alaska Gyre in 2000 which is similar to that in the most productive provinces of the northern North Pacific. There were also large increases in NP_a around the Alaska Peninsula in 1997 and 1998. Finally, the net removal of carbon by the biological pump was estimated as 0.72 Gt C yr⁻¹ in the North Pacific (>30°N). This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

Novel technology in pollutant removal at source and bioremediation     

N.F.Y. Tam  Y.S. Wong  M.H. Wong 《Ocean & Coastal Management》2009,52(7):368-373

Sewage disposal is a major environmental issue in both developed and developing countries and removal of pollutants such as organic matter, nutrients, heavy metals and persistent organic compounds is required to protect the environment. Novel biological systems using constructed mangrove wetland and immobilized microalgal beads have been developed as alternative systems for treating different types of sewage and pollution at source. The feasibility and efficiency of constructed mangrove wetland to remove organic matter and nutrients from primary settled municipal sewage were demonstrated through a series of greenhouse experiments and a pilot-scale field trial. The treatment efficiency of constructed mangrove wetland was comparable to, or higher than, the conventional constructed wetland. An immobilized microalgal system was developed to remove toxic persistent pollutants from industrial wastewater. Pollutant-resistant microalgal species were selected for culture in domestic wastewater. The harvested biomass was immobilized in alginate beads. Bench-scale experiments showed the algal beads were effective in removing industrial pollutants such as heavy metals (e.g. Cu, Zn, Ni, Cr, etc.), organometallic compounds (e.g. tributyltin, TBT), and persistent organic compounds (e.g. polycyclic aromatic hydrocarbons, PAHs) through biosorption and biodegradation. The adsorbed metals could be recovered by desorption process, and the beads could be used repeatedly for many adsorption–desorption cycles.  相似文献   

Characterization of a hypoxia-responsive leptin receptor (omLepR(L)) cDNA from the marine medaka (Oryzias melastigma)     

Wong MM  Yu RM  Ng PK  Law SH  Tsang AK  Kong RY 《Marine pollution bulletin》2007,54(6):797-803

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Geomorphology: the mechanics and chemistry of landscapes – By Robert S. Anderson and Suzanne P. Anderson     

Vanessa Wong 《New Zealand geographer》2012,68(1):74-75

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