Spatio-temporal changes of marine macrobenthic community in sub-tropical waters upon recovery from eutrophication. I. Sediment quality and community structure   总被引：1，自引：0，他引：1  

Shin PK  Lam NW  Wu RS  Qian PY  Cheung SG 《Marine pollution bulletin》2008,56(2):282-296

A two-year study was conducted in the vicinity of a harbour in sub-tropical Hong Kong, to examine the progress of improvement in sediment quality and recovery of macrobenthic community upon cessation of organic pollution caused by sewage discharge. Median sediment particle diameter (Mdphi) and levels of total organic carbon (TOC), total Kjeldahl nitrogen (TKN), ammonia-nitrogen (NH(3)-N) and total phosphorus (TP), as well as macrobenthic species composition and abundance were determined bi-monthly at three inside-harbour and two outside-harbour locations. At the two inside-harbour locations, significantly higher levels of TOC, TKN, NH(3)-N and TP in sediments were observed than the outside-harbour locations. However, no significant temporal change of nutrient levels was detected at all sampling locations during the two-year study, except a significant decrease in TKN and NH(3)-N levels at one outside-harbour location and a decline in NH(3)-N content at another outside-harbour location. Spatially, the highest in mean total species number, individual number, species diversity H' and lowest evenness J was found at one outside-harbour location, whereas the other four locations had relatively similar values. H' was negatively correlated with TOC, TKN, NH(3)-N and TP content in sediments while J was positively correlated with MDphi. Across the study period, the patterns of macrobenthic community were significantly different among all samplings and that the spatial difference of benthic community was best correlated with MDphi, TOC, TKN and water depth. A weak sign of recovery in macrobenthic community structure was detected at inside-harbour locations, with replacement of opportunistic by ubiquitous species over the two-year study. The slow recovery of macrobenthic community was related to sediment characteristics. Results of a larval settlement bioassay using the polychaete Capitella sp. I also demonstrated that the inside-harbour sediments were still unfavourable for colonization and larval settlement of species sensitive to pollution. The slow biodegradation of the organic pollutants and continuous presence of heavy metals in the sediment may hinder settlement and colonization of benthic animals. However, increases of H' and J were observed in a longer time scale when comparing the present data with those obtained four years ago. This suggested that a detectable recovery of benthic community in the harbour may take at least three years and a complete recovery may even take longer duration.  相似文献   

A tribute to John Stuart Gray (1941-2007)     

Richardson B  Wu R  Shin P  Lam P  Fleddum A  Elliott M  Sheppard C 《Marine pollution bulletin》2008,56(1):1-4

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Effect of prolonged hypoxia on food consumption, respiration, growth and reproduction in marine scavenging gastropod Nassarius festivus     

Cheung SG  Chan HY  Liu CC  Shin PK 《Marine pollution bulletin》2008,57(6-12):280-286

The effects of prolonged exposure to reduced oxygen levels (3.0 and 1.5 mg O(2)l(-1)) on marine scavenging gastropods Nassarius festivus were studied for 8 weeks. The percentages of individuals engaged in feeding and amount of food consumed were reduced as oxygen level decreased; absorption efficiency, however, did not vary significantly with oxygen level. Oxygen consumption rates and specific oxygen consumption rates were lower at reduced oxygen levels. Reproduction occurred at all oxygen levels with less egg capsules being produced at lower oxygen levels. Egg size and number of eggs per capsule, however, were not significantly affected by oxygen level. The increase in shell length was 12%, 6% and 5% at 6.0 mgO(2)l(-1) (normoxia), 3.0 mgO(2)l(-1) and 1.5 mgO(2)l(-1), respectively. At the end of the experiment, the amount of energy allocated to growth and reproduction decreased at reduced oxygen levels with values obtained at 3.0 mgO(2)l(-1) and 1.5 mgO(2)l(-1) being 48% and 70% lower than those at 6.0 mgO(2)l(-1). At all oxygen levels, most of the accumulated energy was allocated to shell growth and reproduction, and the amount allocated to somatic growth was relatively insignificant. The reduction in energy allocated to reproduction was greater than that to shell growth as the oxygen level was reduced, indicating a strategic energy allocation of marine scavengers under stressful conditions to enhance survival.  相似文献   

Inshore/offshore gradients of imposex and organotin contamination in Nassarius reticulatus (L.) along the Portuguese coast     

Rato M  Gaspar MB  Takahashi S  Yano S  Tanabe S  Barroso C 《Marine pollution bulletin》2008,56(7):1323-1331

Imposex and organotin (OT) tissue contamination of the netted whelk Nassarius reticulatus (L.) were assessed in the continental shelves around the main estuaries of the central coast of Portugal (Lisbon: Tagus estuary; Setúbal: Sado estuary) and the main coastal lagoon in the Southern of Portugal (Faro: Ria Formosa). Pollution levels were higher in areas of more intense boat traffic and shipyard activities and imposex showed a clear decreasing gradient from the estuaries to the offshore, in relation to a similar gradient of tissue contamination by tributyltin. Remarkably, imposex was extensively spread over the adjacent continental shelves of Tagus and Sado estuaries. The current work shows that TBT pollution is undoubtedly a matter of concern not only for the above estuaries where harbours are implanted but also for the adjacent continental shelves, regardless the massive dilution of contaminants that may occur in these deeper areas.  相似文献   

Meiofauna with special reference to nematodes in trawling ground of subtropical Hong Kong   总被引：1，自引：0，他引：1  

Xiao-Shou Liu  Paul K.S. Shin 《Marine pollution bulletin》2009,58(4):607-615

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Development of an Operational Hybrid Data Assimilation System at KIAPS     

In-Hyuk Kwon  Hyo-Jong Song  Ji-Hyun Ha  Hyoung-Wook Chun  Jeon-Ho Kang  Sihye Lee  Sujeong Lim  Youngsoon Jo  Hyun-Jun Han  Hanbyeol Jeong  Hui-Nae Kwon  Seoleun Shin  Tae-Hun Kim 《Asia-Pacific Journal of Atmospheric Sciences》2018,54(1):319-335

This study introduces the operational data assimilation (DA) system at the Korea Institute of Atmospheric Prediction Systems (KIAPS) to the numerical weather prediction community. Its development history and performance are addressed with experimental illustrations and the authors’ previously published studies. Milestones in skill improvements include the initial operational implementation of three-dimensional variational data assimilation (3DVar), the ingestion of additional satellite observations, and changing the DA scheme to a hybrid four-dimensional ensemble-variational DA using forecasts from an ensemble based on the local ensemble transform Kalman filter (LETKF). In the hybrid system, determining the relative contribution of the ensemble-based covariance to the resultant analysis is crucial, particularly for moisture variables including a variety of horizontal scale spectra. Modifications to the humidity control variable, partial rather than full recentering of the ensemble for humidity further improves moisture analysis, and the inclusion of more radiance observations with higher-level peaking channels have significant impacts on stratosphere temperature and wind performance. Recent update of the operational hybrid DA system relative to the previous 3DVar system is described for detailed improvements with interpretation.  相似文献   

Magmatic unmixing in spinel from late Precambrian concentrically-zoned mafic–ultramafic intrusions, Eastern Desert, Egypt     

Ahmed Hassan Ahmed  Hassan Mohamed Helmy  Shoji Arai  Masako Yoshikawa 《Lithos》2008,104(1-4):85-98

Spinel is widespread in the ultramafic core rocks of zoned late Precambrian mafic–ultramafic complexes from the Eastern Desert of Egypt. These complexes; Gabbro Akarem, Genina Gharbia and Abu Hamamid are Precambrian analogues of Alaskan-type complexes, they are not metamorphosed although weakly altered. Each intrusion is composed of a predotite core enveloped by pyroxenites and gabbros at the margin. Silicate mineralogy and chemistry suggest formation by crystal fractionation from a hydrous magma. Relatively high Cr₂O₃ contents are recorded in pyroxenes (up to 1.1 wt.%) and amphiboles (up to 1.4 wt.%) from the three plutons. The chrome spinel crystallized at different stages of melt evolution; as early cumulus inclusions in olivine, inclusions in pyroxenes and amphiboles and late-magmatic intercumulus phase. The intercumulus chrome spinel is homogenous with narrow-range of chemical composition, mainly Fe³⁺-rich spinel. Spinel inclusions in clinopyroxene and amphibole reveal a wide range of Al (27–44 wt.% Al₂O₃) and Mg (6–13 wt.% MgO) contents and are commonly zoned. The different chemistries of those spinels reflect various stages of melt evolution and re-equilibration with the host minerals. The early cumulus chrome spinel reveals a complex unmixing structures and compositions. Three types of unmixed spinels are recognized; crystallographically oriented, irregular and complete separation. Unmixing products are Al-rich (Type I) and Fe³⁺-rich (Type II) spinels with an extensive solid solution between the two end members. The compositions of the unmixed spinels define a miscibility gap with respect to Cr–Al–Fe³⁺, extending from the Fe³⁺–Al join towards the Cr corner. Spinel unmixing occurs in response to cooling and the increase in oxidation state. The chemistry and grain size of the initial spinel and the cooling rate control the type of unmixing and the chemistry of the final products. Causes of spinel unmixing during late-magmatic stage are analogous to those in metamorphosed complexes. The chemistry of the unmixed spinels is completely different from the initial spinel composition and is not useful in petrogenetic interpretations. Spinels from oxidized magmas are likely to re-equilibrate during cooling and are not good tools for genetic considerations.  相似文献   

Seismic behaviour of pile groups by hybrid experiments     

Kenzo Toki  Tadanobu Sato  Junji Kiyono  Nozar Kishi Garmroudi  Susumu Emi  Masaaki Yoshikawa 《地震工程与结构动力学》1991,20(10):895-909

Non-linear seismic soil-pile interaction was studied with a hybrid procedure that used a pseudo-dynamic testing (PDT) method modified to account for frequency dependence and developed for foundation-soil systems. The numerical scheme used in the conventional PDT was improved by the introduction of a time-dependent pseudo-forcing function derived from the frequency-dependent dynamic characteristics of the system by Hilbert transformation in the frequency domain. Single, 2-, 3- and 9-pile group foundation models were used, their mechanical characteristics later being determined from static and forced vibration dynamic tests. Amplitude scaling was used for three recorded accelerograms. Data recorded during an earthquake at the site of the experiments revealed that the proposed methodology predicts well seismic nonlinear interaction and accounts for frequency dependence and non-linearity in the time domain.  相似文献   

Hybrid experiments on non-linear earthquake-induced soil-structure interaction     

Kenzo Toki  Tadanobu Sato  Junji Kiyono  Nozar Kishi Garmroudi  Susumu Emi  Masaaki Yoshikawa 《地震工程与结构动力学》1990,19(5):709-723

Non-linear seismic soil-structure interaction is studied through a hybrid procedure using the pseudo-dynamic testing (PDT) method which is modified to take into account frequency dependence and developed for foundation-soil systems. The numerical scheme used in conventional PDT is improved by introduction of a time-dependent pseudo-forcing function which is derived from frequency-dependent dynamic characteristics of the system by means of Hilbert transformation in the frequency domain. Surface, shallow and caisson foundation models that differed in size and depth of embedment were used. The mechanical characteristics of the systems were determined from static and forced vibration dynamic tests. An amplitude scaling technique was used for three recorded accelerograms.  相似文献   

Asteroids approaching the Earth from directions around the Sun     

Syuzo Isobe  Makoto Yoshikawa 《Earth, Moon, and Planets》1995,71(3):263-266

We have estimated close asteroid encounters with the Earth by numerical integrations of a system with the Sun, 9 planets, and 188 near-earth-asteroids during the period 1994–4600. Asteroids approach the Earth from directions within 30 around the Sun in more than 20% of encounters with the closest distance less than 0.01 AU. Since ground-based observations cannot detect these objects, we should develop space-borne and/or lunar observatories in a short time to allow enough warning time before a catastrophic collision.  相似文献