Zhang C.,Hohai University |
Liu Q.,BGI Engineering Consultants Co. |
Min F.,Hohai University |
Wang L.,South China Sea Marine Engineering and Environment Institute
15th Asian Regional Conference on Soil Mechanics and Geotechnical Engineering, ARC 2015: New Innovations and Sustainability | Year: 2015
To study the bearing capacity of cemented layer overlaying dredged sediment, a series of plate load tests were carried out by bearing on double-layered systems formed by an artificially cemented top soil layer. And three different top layers overlaying an ultra-soft dredged sediment had been studied. Applied pressure-settlement behavior was observed for tests carried out using circular steel plates ranging from 50 to 150 mm diameter on top of 40 to 80-mm-thick artificially cemented layers. The effects of cemented layer unconfined compressive strength (UCS), thickness, plate size, and the sediment undrained shear strength on the ultimate bearing capacity (UBC) of this foundation were studied. Test results demonstrated the UBC increases linearly with cemented layer UCS strength, cemented layer thickness, DS undrained shear strength, and the ratio of cemented layer thickness to plate diameter. The UBC decreases linearly with the plate diameter. The pressure and settlement curves can be normalized in terms of pressure/pressure at 3% settlement (p/p 3%) versus settlement-to-diameter (d/D). This result can be used to estimate the pressure-settlement curves for footings of different sizes on different thicknesses of a cemented upper layer by a single curve.
Chen M.,Hong Kong University of Science and Technology |
Chen M.,South China Sea Marine Engineering and Environment Institute |
Liu H.,Hong Kong University of Science and Technology |
Li H.,Hong Kong University of Science and Technology
Marine Ecology Progress Series | Year: 2013
An indirect increase in algal abundance that is induced by mesozooplankton predation on intermediate trophic level grazers (microzooplankton) is among the factors that shape the structure of a marine planktonic food web (copepods/cladocerans-ciliates-algae). Marine mesozooplankton include species with diverse feeding strategies, and hence they play different roles in trophic interactions. In this study, we simulated a simple pelagic food web in the laboratory using 3 copepod species and 1 cladoceran as top predators to test the hypothesis that different species with different feeding behaviors will cause different impacts on prey communities. Our results showed that among the 3 crustacean mesozooplankton species, Parvocalanus crassirostris was the most carnivorous species that caused the strongest cascading effect, which led to an increase in algal density as the rate of the cascading effect exceeded the direct consumption of algal prey by intermediate consumers. In contrast, the marine cladoceran Penilia avirostris generally caused a decline in algal density because it created no indirect positive effect on algae since it was incap - able of capturing the intermediate grazers. Temora turbinata fed on ciliates and algal prey at similar rates so that the direct consumption of the algal prey was balanced by the indirect trophic cascade effect. The strength of the cascade effect induced by Acartia erythraea was significantly enhanced by increasing the densities of ciliates. The mechanism was due to a switch in preying behavior from suspension feeding to ambush feeding. Our results imply that mesozooplankton omnivory is important in maintaining the stability of the community structure of microplankton because the effects of direct consumption and the cascading effect balanced each other due to the broad feeding strategies of predators. © Inter-Research 2013.
Cao L.,Guangzhou University |
Cao L.,South China Sea Marine Engineering and Environment Institute |
Huang C.,South China sea marine Environment Monitoring Center |
Wang J.,Guangzhou University |
And 5 more authors.
Journal of Residuals Science and Technology | Year: 2014
Selected metals (Cr, Ni, Cu, Pb, Zn, Cd and As) in surface sediments from the Pearl River Estuary (PRE) and Daya Bay (DYB) were analyzed to observe their total concentrations and chemical phase portioning. It was shown that the amounts of all contents, except Pb, have decreased over the past decade. The mean concentrations in PRE, excluding Pb, were significantly higher than those in DYB. Based on the PLI and mERM-Q, it was revealed that the highest potential ecological risk zones were in the northwest of PRE and sub-basins of DYB. An overwhelming majority of sediments had a 21% probability of toxicity in PRE and 9% probability of toxicity in DYB. The speciation analyzed by the optimized BCR sequential extraction method showed that, in both areas, Cr, As and Ni were present dominantly in the residual fraction and thus of low bioavailability, while Cd and Pb were found to be abundant in the non-residual fraction and thus of high potential availability, indicating significant anthropogenic sources. The partitioning of Cu and Zn showed a significant difference between the two areas. The source analysis shows that the pollutants resulted primarily from anthropogenic material, and secondly from the input of natural weathering products in PRE, while being mainly attributed to natural geological sources of metals, followed by industrial wastewater and aquaculture activity in DYB. © 2014 DEStech Publications, Inc.
He H.-T.,Hohai University |
He H.-T.,China Communications Construction Company Ltd. |
Zhu W.,Hohai University |
Zhang C.-L.,Hohai University |
And 2 more authors.
Yantu Lixue/Rock and Soil Mechanics | Year: 2011
The soil bed formation is a complex process which involves sedimentation and dead-weight consolidation. However, there isn't a simple and feasible method for measuring the water content, density, grain size, pore water pressure and total stress during its physical model test now. An improved laboratory testing method has been carried out. Compared with the available testing methods, the surface settlement, water content (density) distribution, dissipation profiles of excess pore water pressure, and grain size distribution variation of deposition at different depths and times in the process can be obtained by using the improved method. The experimental results show that the measured data are reasonable; and error of consistency test is small; and the improved laboratory testing method is feasible.
Zhang C.-P.,South China Sea Marine Engineering and Environment Institute |
Zhang C.-P.,Sun Yat Sen University |
Chen S.-S.,Sun Yat Sen University |
Chen S.-S.,Guangdong Provincial Key Laboratory |
And 5 more authors.
Pedosphere | Year: 2012
To find new strain in the microbial fuel cell (MFC) for quinoline removal from wastewater and soil, a facultative anaerobic bacterium strain was isolated from the anode of MFC, utilizing quinoline as the carbon source and electron donor. Based on the 16S rRNA sequence analysis, the bacterium strain was Gram-negative and identified as Pseudomonas sp. Q1 according to its morphology and physiochemical properties. The strain was inoculated into a double-chambered MFC using various quinoline concentrations (0, 50, 75, 86, 100, 150, 200 and 300 mg L -1) combining with 300 mg L -1 glucose as the fuel. Results showed that electricity was generated from the MFC, in which quinoline was degraded simultaneously. The values of Coulombic efficiency (CE) increased with the increase of quinoline concentrations from 0 to 100 mg L -1 then decreased with the increase of quinoline concentration from 100 to 300 mg L -1, and the maximum CE 36.7% was obtained at the quinoline concentration of 100 mg L -1. The cyclic voltammetry analysis suggested that the mechanism of electron transfer was through excreting mediators produced by the strain Q1. The MFC should be a potential method for the treatment of quinoline-contaminated water and soil. © 2012 Soil Science Society of China.
Wang P.,South China Sea Marine Engineering and Environment Institute |
Wan Y.C.,Capital Normal University |
Duan F.Z.,Laboratory of 3D Information Acquisition and Application of Beijing
Advances in Energy Science and Equipment Engineering - Proceedings of International Conference on Energy Equipment Science and Engineering, ICEESE 2015 | Year: 2015
Taken the Pearl River Estuary coastline as the research object, this article carried out the Sobel operator and the Normalized Differential Water Index (NDWI) to extract the artificial and natural coastline. It chose the landsat8 ETM+ data as basic date, extracted with the method of visual interpretation and verified the accuracy of the extraction with the coastline of extracting by high resolution image. The results show that NDWI and Sobel operator can enhance the ability of identifying water effectively and confirm the position of coastline accurately. In both types of shoreline extraction, the artificial shoreline is relatively clear and complete, while the natural shoreline is relatively vague. But the accuracy of random points and experienced points reach 83% and 88% respectively. Therefore, taking advantage of this method can effectively extract the Pearl River Estuary coastline. © 2015 Taylor & Francis Group, London.
Huang Y.,Wuhan University |
Li S.,South China Sea Marine Engineering and Environment Institute
Journal of Geomatics | Year: 2010
We introduce the improved fitting algorithm in any inertial systerm by GPS Orbit fitting as an example. This algorithm solves the problems, and is simple, and makes the parameters converge fastly, and makes the precision of orbit fitting is about millimeter.
Zhao M.,CAS Yantai Institute of Coastal Zone Research |
Zhao M.,University of Chinese Academy of Sciences |
Zhao M.,South China Sea Marine Engineering and Environment Institute |
Yang D.,Chinese Institute of Urban Environment |
And 2 more authors.
Ocean and Coastal Management | Year: 2015
The Pearl River estuary is a microcosm of marine sand resource management issues, which are being experienced in many developing coastal regions in China. The increasing demand and inefficient management of marine sand have resulted in a series of environmental problems and raised great challenges for rational utilization of marine sand. In the long term, resolving management conflicts and improving the efficiency of resource utilization will require a shift in management approach from administrative examination and approval (AEA) of sector-based management to market-based approach of cooperation management. This paper concerns a pilot scheme for market-based resource allocation, and illustrates how the involved agencies could work together to push forward the scheme in a sectoral context. Both achievements and inadequacies of the scheme are presented, and enabling factors are identified, which include administrative authorization, institutional support and approach improvement, which facilitate the success of the scheme. We also describe key elements (a clearly defined exchange object, independent third-party trade platform and standardized market rules, rational goals, and cooperation mechanism), which are essential for a market-based approach to manage marine sand. We hope the experience acquired in the Pearl River estuary will be useful for other coastal regions in the world. © 2014 Elsevier Ltd.
Chen J.,Texas A&M University |
Chen J.,Ocean University of China |
Thornton D.C.O.,Texas A&M University |
Thornton D.C.O.,South China Sea Marine Engineering and Environment Institute
Journal of Phycology | Year: 2015
Transparent exopolymer particles (TEP) play an important role in the ocean carbon cycle as they are sticky and affect particle aggregation and the biological carbon pump. We investigated the effect of growth rate on TEP production in nitrogen limited semi-continuous cultures of the diatom Thalassiosira weissflogii (Grunow) G. Fryxell & Hasle. Steady-state diatom concentrations and other indicators of biomass (chl a, and total carbohydrate) were inversely related to growth rate, while individual cell volume increased with growth rate. There was no change in total TEP area with growth rate; however, individual TEP were larger at high growth rates and the number of individual TEP particles was lower. TEP concentration per cell was higher at higher growth rates. SYTOX Green staining showed that <5% of the diatom population had permeable cell membranes, with the proportion increasing at low growth rates. However, TEP production rates were greater at high growth rates, refuting our hypothesis that TEP formation is dependent on dying cells with compromised cell membranes in a diatom population. Measurements of particle size distribution in the cultures using laser scattering showed that they were most aggregated at high growth rates. These results indicate a coupling between TEP production and growth rate in diatoms under N limitation, with fast growing T. weissflogii producing more TEP and aggregates. © 2015 Phycological Society of America.
Zheng S.,CAS South China Sea Institute of Oceanology |
Zheng S.,University of Chinese Academy of Sciences |
Zheng S.,South China Sea Marine Engineering and Environment Institute |
Guan W.,State Oceanic Administration |
And 3 more authors.
Continental Shelf Research | Year: 2014
A three-dimensional numerical model, Estuarine, Coastal and Ocean Modeling System with Sediments (ECOMSED), is employed to study the mechanism of plume front in the Pearl River Estuary (PRE) in detail. The model is forced by winds, tides and river discharges. The modeled results of tidal elevation, current velocity and salinity are in reasonable agreement with observational data in the PRE. By analyzing momentum and saltwater transport balance equations, it is found that the wind stress term, the pressure gradient term and the local time derivative term of velocity are dominant in the momentum equation, while the local time derivative term, the horizontal advective term and the vertical mixing term of salinity are dominant in the salinity transport equation. The residual current at surface along the plume front is seaward and stronger, whilst that in the bottom layer is mainly landward. A series of sensitive experiments is also run to examine the responses of plume front to changes of river discharges at different inlets in Lingdingyang Bay and interannual variation of northeast winds in winter. The location of plume front responds differently to the change of river discharge at different inlets. An increase in the river discharge at Dahu inlet seems to affect the location of plume front most among the four river inlets, it makes the plume front move eastward and southward wholly; the variation of river discharge at Nansha or Fengmamiao inlet on the location of plume front is more local and weaker; whilst the variation of river discharge at Hengmen inlet has little effect on the plume front. The location of plume front also changes in response to the interannual variation of northeast winds in winter, the stronger or the more eastward the winds are, the more westward the plume front moves, and only in the northern PRE, the response of plume front to the variation of wind speeds is largely different from that to the variation of wind directions. © 2013 Elsevier Ltd.