浪流作用下系泊船舶撞击力和系缆力试验研究     

李焱  郑宝友  高峰  孟祥玮 《海洋工程》2007,25(2):57-63

以某25万吨矿石码头工程为例,分别进行了单流、单浪和浪流共同作用下,系泊船舶撞击力和系缆力试验。研究了不同水位、不同船舶载度、不同浪流夹角,单流、单浪和浪流共同作用时对船舶撞击力和系缆力的影响。分析了该码头工程护舷和缆绳的布置情况,为工程设计提供了依据。  相似文献   

Abundance of the introduced seastar, Asterias amurensis, and spatial variability in soft sediment assemblages in SE Tasmania: Clear correlations but complex interpretation     

D. Jeff Ross  Craig R. Johnson  Chad L. Hewitt   《Estuarine, Coastal and Shelf Science》2006,67(4):695-707

The northern Pacific seastar, Asterias amurensis, was first collected in southeast Tasmania in 1986. Mistaken for the endemic asteroid Uniophora granifera, its true identity was not realised until 1992. It is now a conspicuous predator in soft sediment habitats in this region, and is considered a major threat to native assemblages and commercial species. We examined the structure of soft sediment assemblages at different spatial scales in southeast Tasmania, and correlated spatial variation in community composition with seastar abundances. We found that the structure of soft sediment assemblages is highly variable at a range of spatial scales from metres to tens of kilometres. Clear differences in the composition of assemblages and abundances of major taxa were detected between areas with and without seastars and between areas with low and high seastar densities. However, the nature of these patterns suggests that they are more likely due to differences in sediment characteristics than due to impacts of the seastar. Thus, spatial differences in soft sediment assemblages might have been erroneously attributed to seastars without detailed information on important physical factors such as sediment characteristics. A second survey, using larger sampling units (1 m²) but across a more limited spatial extent, targeted bivalves and heart urchins that were identified as important prey of the seastar in observations of feeding and in experimental studies. Large-scale patterns of abundance and size structure were consistent with seastar effects anticipated from small-scale experimental and feeding studies for some, but not all, species. While the field survey ultimately provided evidence about the presence or absence of seastar impacts at large-scales, the identification of key ecological variables in experimental and feeding studies proved crucial to both the design and interpretation of patterns observed in the large-scale surveys. Overall, this work highlighted the necessity to consider multiple lines of evidence rather than relying on a single ‘inferential’ test, in the absence of pre-impact data.  相似文献   

Impact of offshore oil production installations on the benthos of the North Sea   总被引：3，自引：0，他引：3  

Kingston  P. F. 《ICES Journal of Marine Science》1992,49(1):45-53

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Physical and anthropogenic effects on observed long-term nutrient changes in the Irish Sea     

G. L. Evans  P. J. le B. Williams  E. G. Mitchelson-Jacob 《Estuarine, Coastal and Shelf Science》2003,57(5-6):1159-1168

The trend in Irish Sea nutrient concentrations over the last four decades has been considered to reflect changes in anthropogenic loading. Comparison of a long-term database for the Menai Strait, North Wales, with an established historic data set for the Cypris station, Isle of Man, indicates that climate also has a significant influence on observations of nutrient concentrations. Data are presented detailing long-term shifts in nitrate, phosphate and silicate measurements since the 1960s at these two fixed sampling sites in the Irish Sea. Broad systematic changes observed in all three nutrients over the decades show a rise from the 1960s through to the 1980s, followed generally by an overall decline in the 1990s. Decadal-scale salinity changes occur in the opposite sense to nutrient changes. Anthropogenic inputs from freshwater cannot fully account for observed nutrient trends, neither is there evidence for shifts in nutrient concentrations in oceanic waters over the past four decades. Climatically forced movement in the geographical position of the freshwater/seawater mixing zone over a decadal time scale could, however, give rise to the observed shifts in nutrient concentration and salinity. This cannot alter nutrient concentration and salinity per se, but causes the measurements taken at fixed sampling sites to fluctuate inversely over this time scale. It is concluded that there is complex interplay between anthropogenic loading and climate affecting the distribution of nutrients in the Irish Sea.  相似文献   

Vertical distribution of the macrobenthic community and its relationships to trace metals and natural sediment characteristics in the lower Douro estuary, Portugal   总被引：2，自引：0，他引：2  

Ana P. Mucha  M. Teresa S. D. Vasconcelos  Adriano A. Bordalo   《Estuarine, Coastal and Shelf Science》2004,59(4):663

Vertical distribution (0–15 cm) of the macrobenthic community and its relationships to natural sediment characteristics and trace metal contents and bioavailability were studied at five locations in the lower Douro estuary, Portugal. An analysis of vertical metal distribution, for the interpretation of anthropogenic impact on the estuarine sediments, was also investigated. Sediment characterisation included organic matter, grain size, metals (Al, Fe, Cu, Pb, Cr, Ni, Cd, Zn and Mn), acid volatile sulphide (AVS) and simultaneously extracted metals (SEM). The macrobenthic community had low diversity (14 species), was dominated by small size opportunists and seemed to be controlled mainly by natural factors such as grain size distribution, Al and Fe contents and sediment depth. The vertically heterogeneous distribution of macrobenthic community appears to affect redox status of the sediments and consequently metal bioavailability. Despite anthropogenic contamination in terms of Zn, Cu, Pb, Cr and Ni having already been detected in the north bank, the analysis of vertical distribution was essential for the identification of current anthropogenic contamination in terms of Zn, Pb and Cd in the south bank.  相似文献   

The trophic spectrum: theory and application as an ecosystem indicator     

Gascuel  Didier; Bozec  Yves-Marie; Chassot  Emmanuel; Colomb  Audrey; Laurans  Martial 《ICES Journal of Marine Science》2005,62(3):443-452

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Comparing the Benguela and Humboldt marine upwelling ecosystems with indicators derived from inter-calibrated models   总被引：10，自引：0，他引：10  

Moloney  Coleen L.; Jarre  Astrid; Arancibia  Hugo; Bozec  Yves-Marie; Neira  Sergio; Roux  Jean-Paul; Shannon  Lynne J. 《ICES Journal of Marine Science》2005,62(3):493-502

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南四湖湖内浅槽工程施工对水环境的影响及控制措施   总被引：1，自引：0，他引：1  

王茜  王素芳  彭波  邱红  战慧卿 《海洋湖沼通报》2007,(2):80-85

南四湖湖内工程是沂沭泗河洪水东调南下续建工程的单项工程,工程区位于山东省省级自然保护区内;挖泥船施工将对湖内水环境产生一定影响。本文从排泥场回水污染物、生产废水和生活污水三个方面阐述了工程施工对水环境的影响程度,并且提出了相应的控制措施。  相似文献   

Model simulations of carbon sequestration in the northwest Pacific by patch fertilization     

Katsumi Matsumoto 《Journal of Oceanography》2006,62(6):887-902

Iron fertilization of nutrient-rich surface waters of the ocean is one possible way to help slow the rising levels of atmospheric CO₂ by sequestering it in the oceans via biological carbon export. Here, I use an ocean general circulation model to simulate a patch of nutrient depletion in the subpolar northwest Pacific under various scenarios. Model results confirm that surface fertilization is an inefficient way to sequester carbon from the atmosphere (Gnanadesikan et al., 2003), since only about 20% of the exported carbon comes initially from the atmosphere. Fertilization reduces future production and thus CO₂ uptake by utilizing nutrients that would otherwise be available later. Effectively, this can be considered as leakage when compared to a control run. This “effective” leakage and the actual leakage of sequestered CO₂ cause a significant, rapid decrease in carbon retention (only 30–45% retained after 10 years and less than 20% after 50 years). This contrasts markedly with the almost 100% retention efficiency for the same duration using the same model, when carbon is disposed directly into the northwest Pacific (Matsumoto and Mignone, 2005). As a consequence, the economic effectiveness of patch fertilization is poor in two limiting cases of the future price path of carbon. Sequestered carbon in patch fertilization is lost to the atmosphere at increasingly remote places as time passes, which would make monitoring exceedingly difficult. If all organic carbon from one-time fertilization reached the ocean bottom and remineralized there, acidification would be about −0.05 pH unit with O₂ depletion about −20 μmol kg⁻¹. These anomalies are probably too small to seriously threaten deep sea biota, but they are underestimated in the model because of its large grid size. The results from this study offer little to advocate purposeful surface fertilization as a serious means to address the anthropogenic carbon problem.  相似文献   

胶州湾泛亚码头疏浚方案优选及悬浮物影响预测     

李铁军  孙英兰  刘伟峰  付会 《海洋湖沼通报》2007,(4):144-150

采用有限元分步杂交方法,在已建潮流场的基础上,建立了胶州湾疏浚物悬浮泥沙的二维输运-扩散模型,并应用于胶州湾前湾港区泛亚码头工程疏浚区的疏浚物输运扩散的数值模拟预测。根据预测结果分析了泛亚码头疏浚区施工期间悬浮泥沙对附近海域水环境和生态环境的影响,并对不同的疏浚方案进行了优选。  相似文献