沉积物中多环芳烃在海岸带水域自然环境中的衰减研究     

张勇  庄一廷  张杰  Ka-Fai Poon  Michael H W Lam  洪华生  Rudolf S S Wu 《台湾海峡》2001,20(2):171-176

本文在现场情况下，研究了自然条件下受污染海岸带沉积物中的7种多环芳烃（Polynuclear Aromatic Hydrocarbons，简称PAHs）的解吸动力学行为。结果表明，7种PAHs）的解吸动力学行为。结果表明，7种PAHs的解吸动力学行为可以用二元模型模拟。文中并将所得数据与文献报道的数据进行了比较。  相似文献   

Partitioning of copper among copper-binding proteins in the mussel Mytilus edulis exposed to soluble copper     

F.L. Harrison  J.R. Lam 《Marine environmental research》1985,16(3):151-163

Partitioning of copper among copper-binding proteins was evaluated in digestive glands of Mytilus edulis exposed to soluble copper. Groups of mussels were held in flow-through bioassay systems and exposed to 25 μg Cu liter^?1 for up to 21 weeks. At three-week intervals, groups of 25 mussels were removed and the digestive glands were analyzed for copper-binding proteins by gel-permeation chromatography and atomic absorption spectrometry.Chronic exposure to copper resulted in increased amounts of copper in the low molecular weight (LMW) protein fraction, which contains metallothioneins, and in the high molecular weight (HMW) protein fraction, which contains metalloenzymes. Concentrations of copper in the LMW protein fraction increased and then appeared to plateau with long exposure times, whereas those in the HMW protein fraction continued to increase with exposure time.  相似文献   

Soil–pile–structure interaction under SH wave excitation     

K. K. Koo  K. T. Chau  X. Yang  S. S. Lam  Y. L. Wong 《地震工程与结构动力学》2003,32(3):395-415

A continuum model for the interaction analysis of a fully coupled soil–pile–structure system under seismic excitation is presented in this paper. Only horizontal shaking induced by harmonic SH waves is considered so that the soil–pile–structure system is under anti‐plane deformation. The soil mass, pile and superstructure were all considered as elastic with hysteretic damping, while geometrically both pile and structures were simplified as a beam model. Buildings of various heights in Hong Kong designed to resist wind load were analysed using the present model. It was discovered that the acceleration of the piled‐structures at ground level can, in general, be larger than that of a free‐field shaking of the soil site, depending on the excitation frequency. For typical piled‐structures in Hong Kong, the amplification factor of shaking at the ground level does not show simple trends with the number of storeys of the superstructure, the thickness and the stiffness of soil, and the stiffness of the superstructure if number of storeys is fixed. The effect of pile stiffness on the amplification factor of shaking is, however, insignificant. Thus, simply increasing the pile size or the superstructure stiffness does not necessarily improve the seismic resistance of the soil–pile–structure system; on the contrary, it may lead to excessive amplification of shaking for the whole system. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

Probing the Universe with the Lyα forest — I. Hydrodynamics of the low-density intergalactic medium     

Nickolay Y. Gnedin  & Lam Hui 《Monthly notices of the Royal Astronomical Society》1998,296(1):44-55

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Polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans in sediments from Hong Kong     

Jochen F. Müller  Caroline Gaus  Joelle A. Prange  Olaf Ppke  Ka Fai Poon  M. H. W. Lam  Paul K. S. Lam 《Marine pollution bulletin》2002,45(1-12)

Concentrations of 2,3,7,8-substituted polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) were determined in 14 sediment samples collected from four sites in the Mai Po Marshes Nature Reserve (within a RAMSAR Site) and from another six sites in Victoria Harbour and along the Hong Kong coastline. Elevated levels of PCDDs, and particularly OCDD, were detectable in all samples collected from the Mai Po Marshes and five of the six sites. In contrast to PCDDs, PCDFs were mainly found in sediment samples collected from industrial areas (Kwun Tong and To Kwa Wan) in Victoria Harbour. PCDD/F levels and congener profiles in the samples from the Mai Po Marshes Nature Reserve in particular show strong similarities to those reported in studies which have attributed similar elevated PCDD concentrations to nonanthropogenic PCDD sources.  相似文献   

Displacement‐based seismic analysis for out‐of‐plane bending of unreinforced masonry walls     

K. Doherty  M. C. Griffith  N. Lam  J. Wilson 《地震工程与结构动力学》2002,31(4):833-850

This paper addresses the problem of assessing the seismic resistance of brick masonry walls subject to out‐of‐plane bending. A simplified linearized displacement‐based procedure is presented along with recommendations for the selection of an appropriate substitute structure in order to provide the most representative analytical results. A trilinear relationship is used to characterize the real nonlinear force–displacement relationship for unreinforced brick masonry walls. Predictions of the magnitude of support motion required to cause flexural failure of masonry walls using the linearized displacement‐based procedure and quasi‐static analysis procedures are compared with the results of experiments and non‐linear time‐history analyses. The displacement‐based procedure is shown to give significantly better predictions than the force‐based method. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

Patterns and rates of slopewash on the badlands of Hong Kong     

Kin-Che Lam 《地球表面变化过程与地形》1977,2(4):319-332

Slopewash measurements were made at 449 sites on the badlands of Hong Kong over a 15-month period. The mean amount of ground retreat was 2.17 cm and the spread of data was large (coefficient of variation = 36.6 per cent). This demonstrates a large variation in rates of slopewash in the study area. A large sample size is suggested for any future work to narrow the limits of the sampling error. It is also shown that ground retreat, as conventionally measured in the field, is different and should be distinguished from vertical lowering. In the study of erosion rates and slope evolution, different conclusions are likely to be drawn unless the distinction is realized. Various attempts have been made to account for the observed variations in slopewash rates on the badlands of the study area. It was found that the site to site variations in slopewash rate could not be attributed to the conventional soil, microtopographic and distance parameters. This absence of relationship is probably due to the fact that the sites on the slope profiles are not isolated systems, but are components of a larger functional entity, in which all sites are in some form of adjustment and equilibrium with the others.  相似文献   

The variation of heat flow density with depth in the prairies basin of western Canada     

F.W. Jones  J.A. Majorowicz  H.L. Lam 《Tectonophysics》1985,121(1):35-44

Bottom-hole temperature values from approximately 36,000 wells in Alberta. Saskatchewan and Manitoba, Canada, have been used to study thermal gradients and heat flow density there. It is found that variations of heat flow density with depth occur throughout the Prairies basin. Differences in heat flow density exist between the Mesozoic + Cenozoic and Paleozoic sediments and are related to the hydrodynamics which is controlled by the topography. The heat flow density through the Mesozoic + Cenozoic of the upper part of the section is less than that in the Paleozoic formations of the lower part of the section in recharge areas, but greater in discharge areas. A zone in which heat flow is approximately constant with depth extends down the central part of the basin between the recharge and discharge areas. Heat flowdensity in this zone lies between 60 mW m^?2 and 80 mW m^?2 and is thought to be representative of the deep crustal heat flow density. It is suggested that temperature variations on the Precambrian basement that are not depth related may be associated with anomalous heat flow regimes in the lower crust.  相似文献   

Use of Space-Filling Curves in Generating a National Rural Sampling Frame for HIV/AIDS Research*     

Nina Siu-Ngan Lam  Kam-biu Liu 《The Professional geographer》1996,48(3):321-332

The classical geographic research problem of regionalization and resource allocation is most commonly tackled by means of location-allocation methods. This paper introduces the spatial-order method as an alternative for creating regions or clusters. The spatial-order method utilizes space-filling curves, also known as Peano curves, to determine the nearness or spatial order of areal units, such as counties. Given a capacity constraint, the areal units are grouped consecutively according to their spatial order values. We applied the method to create clusters of rural counties for a national sampling survey of HIV/AIDS patients in the United States. Using the criteria that each cluster had approximately 50 new AIDS cases in 1991–1993 and that contiguity of areal units was maximized, 226 clusters were created from the 1,853 rural counties or health districts. The rural clusters generated by this method have been adopted as the national rural sampling frame in the HIV Cost and Services Utilization Study (HCSUS) being undertaken by RAND. In addition to its simplicity and fast computational speed, the spatial-order method produces satisfactory results. With minor modifications, this method can be an efficient alternative to the location-allocation method for solving a wide variety of locational problems, such as routing, political districting, and facilities location and allocation. This paper also demonstrates how a classical geographic research methodology, with the enhancement of GIS, can contribute to the multidisciplinary study of a pressing societal problem in our nation.  相似文献   

Inter-laboratory comparison of Atlantic and Mediterranean bluefin tuna otolith microconstituents   总被引：1，自引：0，他引：1  

Secor  D. H.; Campana  S. E.; Zdanowicz  V. S.; Lam  J. W. H.; Yang  L.; Rooker  J. R. 《ICES Journal of Marine Science》2002,59(6):1294-1304

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