Regional variations in trace element concentrations in tissues of black tiger shrimp Penaeus monodon (Decapoda: Penaeidae) from South Vietnam     

Nguyen Phuc Cam Tu  Nguyen Ngoc Ha  Tokutaka Ikemoto  Bui Cach Tuyen  Shinsuke Tanabe  Ichiro Takeuchi   《Marine pollution bulletin》2008,57(6-12):858

The goal of the present study was to examine the specific bioaccumulation of 22 trace elements in muscle, exoskeleton and hepatopancreas of black tiger shrimp Penaeus monodon from the Mekong River Delta (MRD), and the South Key Economic Zone (SKEZ), South Vietnam. The general tendency in most trace element concentrations among different tissues were hepatopancreas > exoskeleton > muscle. Comparisons of trace element levels in tissues between the two regions showed that concentrations of Se in muscle and As in all three tissues were higher in SKEZ; whereas in MRD, the higher concentrations of most elements such as Mn, Cu, Cd, Ba, Hg, were observed in tissues. These geographical variations in trace element levels may reflect the differences in human activities between the two regions of South Vietnam. The target hazard quotient (THQ) values for trace elements (<1) indicate that local residents are not exposed to potential health risks via the consumption of shrimp.  相似文献   

Fluorescent Dye and Media Properties Affecting Sorption and Tracer Selection   总被引：4，自引：0，他引：4  

Torez Kasnavia  De Vu  David A. Sabatini 《Ground water》1999,37(3):376-381

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Sediment transport trends and cross-sectional stability of a lagoonal tidal inlet on the Central Coast of Vietnam     

Do Minh Duc  Tran Thanh Tung  Patrick McLaren  Tran Ngoc Anh  Dinh Thi Quynh 《国际泥沙研究》2019,34(4):322-334

Lagoonal tidal inlets are a typical morphology of the Central Coast of Vietnam. Recently, navigation channels in these inlets have become increasingly threatened by siltation. This study analyses the relations between sediment distribution and transport trends (using the technique of Sediment Trend Analysis-STA■) in the lagoonal system of the De Gi inlet and then proposes appropriate countermeasures against sand deposition in the navigation channel. The STA identified three types of transport trends in the De Gi inlet, namely dynamic equilibrium, net accretion, and net erosion. Processes associated with the tidal prism have resulted in trends of sediment transport and deposition across the flood and ebb tidal shoals, which maintain a present cross-sectional area of about 1000m^2. However, longshore sediment transport from north to south resulting from northeast waves cause additional sand deposition in the channel. In addition, the effects of refraction associated with a nearby headland and jetty also increase sedimentation. These processes provide the main reasons for sediment deposition in the De Gi inlet. Short term and regular dredging helps to maintain the navigation channel. A system comprised of three jetties (north, south, and weir) is necessary to ensure the longterm cross-sectional stability of the navigation channel.  相似文献   

Meiobenthos assemblages in the mekong estuarine system with special focus on free-living marine nematodes     

Ngo Xuan Quang  Ann Vanreusel  Nic Smol  Nguyen Ngoc Chau 《Ocean Science Journal》2010,45(4):213-224

Meiobenthos assemblages in eight estuaries of the Mekong river system were investigated in August 2008 (from the Cua Tieu estuary to the Tran De estuary). In each estuary, one sampling station was established for meiobenthos sampling. Twelve major taxa of meiobenthos were recorded in this estuarine system, including Nematoda, Copepoda, Turbellaria, Polychaeta, Oligochaeta, Tardigrada, Bivalvia, Ostracoda, Amphipoda, Cumacea, Gastrotricha, Gastropoda, and Crustacean Nauplii larvae. The densities of the meiobenthos range from 581 to 3168 inds/10 cm². Nematodes always occupy the highest numbers with a percentage ranging from 64–99%. There are 135 nematode genera recorded in this study with the following as dominant genera Desmodora, Leptolaimus, Halalaimus, Thalassomonhystera, Theristus, Daptonema, Rhynchonema, Parodontophora, and Oncholaimus. Although the biodiversity of the meiobenthos at higher taxa level is not high compared to other marine environments, the estimates of nematode biodiversity at the genus level indicates high values. The increase in number of genera with increasing sampling intensity illustrate that the diversity is underestimated and would have been higher if the authors had considered a larger number of individuals, more replicates per station, and more sampling stations.  相似文献   

Time-resolved high-resolution spectroscopy of the pulsating sdB star QQ Vir (PG1325+101)     

J. Telting  R. Østensen  R. Oreiro  U. Heber  M. Vučković  S. Randall  A. Baran 《Astrophysics and Space Science》2010,328(1-2):163-166

In this work, a standard solar model is computed with new reaction rates that take into account the exact astrophysical S-factor, S _e for the ³He(³He,2p)⁴He, ³He(α,γ)⁷Be and ⁷Be(p,γ)⁸B reactions. The exact S-factor which is valid for all energies is an improved version of the S-factor in the lower-energy approximation (Yusof and Kassim in Astrophys. Space Sci., 2009b). The effects of these new nuclear reaction rates on the solar neutrino fluxes are then discussed by comparing this model to a solar model computed with the standard NACRE reaction rates (Angulo et al. in Nucl. Phys. A. 656:3, 1999). The new reaction rates are found to decrease the neutrinos flux for ⁷Be and ⁸B by about 6% and 16%, respectively. A solar model is also computed with the reaction rates of the LUNA collaboration for ¹⁴N(p,γ)¹⁵O (Formicola et al. in Phys. Lett. B 591:61, 2004). In this case, a clear decrease of the fluxes for ¹³N and ¹⁵O is observed to be in good agreement with previous results (see e.g. Bahcall et al. in Astrophys. J. 621:L88, 2005).  相似文献   

Assessment of future stream flow over the Sesan catchment of the Lower Mekong Basin in Vietnam     

Srivatsan V. Raghavan  Minh Tue Vu  Shie‐Yui Liong 《水文研究》2012,26(24):3661-3668

This study used a regional climate model, driven at a resolution of 30 km, to derive climate estimates that were used as input to a hydrological model to determine stream flow in a changing climate. This regional climate model output was derived using the Weather Research and Forecasting model, which was used to downscale the general circulation model ECHAM5 T63 under the A2 greenhouse gas emission scenario for the future. Two river basins, Dakbla and Poko, over the Sesan catchment of the Lower Mekong region were considered for runoff modeling. A 10‐year climatology of the recent past, 1991–2000, was used as the baseline for the present‐day climate, and another 10‐year climate over the period 2091–2100 was chosen for the future time slice. The results from the simulation of future stream flow indicate that, over both Dakbla and Poko river basins, the stream flow is likely to increase, especially during the peak rainfall season. The Dakbla River Basin shows a substantial increase in stream flow when compared with the Poko River Basin. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Thermochronology of the PoSen complex,northern Vietnam: Implications for tectonic evolution in SE Asia     

Pei-Ling Wang  Ching-Hua Lo  Ching-Ying Lan  Sun-Lin Chung  Tung-Yi Lee  Tran Ngoc Nam  Yuji Sano 《Journal of Asian Earth Sciences》2011,40(5):1044-1055

The PoSen complex, located closely adjacent to the southwestern margin of the Red River shear zone represents the uplifted basement of north Vietnam and may record the motion of the shear zone. However, its thermochronological history has not been fully examined yet. Here we applied U–Pb and ⁴⁰Ar/³⁹Ar dating methods to reveal its thermochronological history. U–Pb analysis of composite zircon grains by TIMS yielded an average age of 760 ± 25 Ma, clustering on the concordia line. Twelve SHRIMP U–Pb analyses also yielded a consistent result of 751 ± 7 Ma. Along with the geochemical features, the U–Pb dating results suggest the PoSen complex was a late Proterozoic magmatic complex, which could correspond to the Chengjiang orogeny, a widespread thermal event in southwest China. Results of ⁴⁰Ar/³⁹Ar dating of micas and K-feldspars were in the range of 36–30 Ma, revealing a rapid cooling and exhumation history of the PoSen complex during the late Paleogene. The time span of cooling and exhumation of the PoSen complex is slightly older than the main cooling phases of the Ailao Shan–Red River (ASRR) metamorphic massifs (28–17 Ma), but is synchronous with the early igneous activity stage in the eastern Indo-Asian collision zone of southeast China and north Vietnam. Owing to the ongoing debate about the initiation and offset of the ASRR shear zone, the tectonic force for the late Paleogene cooling of the PoSen complex is still inconclusive. The rapid exhumation of the PoSen complex could be in response to either the detachment of the Neo-Tethyan slab or a transpressional phase of continental subduction along the ASRR shear system in the eastern Indo-Asian collision zone.  相似文献   

An analysis of fog events at Belgrade International Airport     

Katarina Veljović  Dragana Vujović  Lazar Lazić  Vladan Vučković 《Theoretical and Applied Climatology》2015,119(1-2):13-24

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CCD Technology     

Barry Burke  Paul Jorden  Paul Vu 《Experimental Astronomy》2005,19(1-3):69-102

Charge-coupled devices (CCDs) continue to reign supreme in the realm of imaging out to 1 μm, with the steady improvement of performance and the introduction of innovative features. This review is a survey of recent developments in the technology and the current limits on performance. Device packaging for large, tiled focal-plane arrays is also described. Comparisons between CCDs and the emerging CMOS imagers are highlighted in terms of process technology and performance.  相似文献   

Effect of the water/cement ratio on concrete behavior under extreme loading     

Xuan Hong Vu  Yann Malecot  Laurent Daudeville  Eric Buzaud 《国际地质力学数值与分析法杂志》2009,33(17):1867-1888

This study focuses on identifying concrete behavior under severe triaxial loadings (near field detonation or ballistic impacts). In order to reproduce high stress levels with well‐controlled loading paths, static tests have been carried out on concrete samples by mean of a very high‐capacity triaxial press (stress levels on the order of 1 GPa). It is a longstanding fact that the water/cement ratio (W/C), upon entering the concrete composition, is a major parameter affecting the porosity and strength of the cement matrix of hardened concrete. The objective of this article is to quantify the effect of this ratio on concrete behavior under conditions of high confinement. From the composition of a reference ‘ordinary’ concrete (i.e. W/C=0.6), two other concretes have been produced with W/C ratios equal to 0.4 and 0.8, respectively. This article presents experimental results and their analysis regarding the effect of water/cement ratio (W/C) on concrete behavior under high confinement. It shows that when placed under high confinement, concrete behaves like a granular stacking composed of concrete without any influence from the level of cement matrix strength. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献