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991.
992.
Oracle数据库管理系统已成为我国国家级和省级国土资源基础数据库建设的主流技术平台。该文就国家级和省级数据库的建设,提出了在Oracle数据库技术环境下,如何在物理上合理组织和布局各种类型的数据,如何设置和管理各衍生数据,如何实施数据完整性要求,其目的是实现国土资源基础数据的高效管理和可持续更新支持,更好地满足国土资源基础数据库之上各业务应用系统运转的要求。 相似文献
993.
994.
泉州湾赤潮藻类优势种演替影响因子探讨 总被引:4,自引:1,他引:3
于2006年5—11月对东海泉州湾赤潮监控区设定4个采样站位,进行赤潮常规监测。结果表明,泉州湾藻类优势种由中肋骨条藻(Skeletonema costatum)、太平洋海链藻(Thalassiosira pacifica)、微小原甲藻(Prorocentrum minimum)、尖刺拟菱形藻(Pseudo-nitzschia pungens)、丹麦细柱藻(Leptocylindrus danicus)及旋链角毛藻(Chaetoceros curvisetus)等赤潮生物组成,虽然中肋骨条藻为最主要的优势种,但有3个站位出现了上述优势种的演替。通过深入分析该海域水质营养盐含量及组成结构的动态变化对赤潮藻类优势种演替的影响,发现由于不同的赤潮藻类种群具有各自的生态习性及适应环境的生长增殖策略,海域水质营养盐含量和组成结构的变化,会引起赤潮藻类种群增殖竞争力间强弱的相对变化,而种群增殖竞争力强的种类有可能迅速增殖取代原有的优势种而演替为新的优势种,这是一个动态的过程。 相似文献
995.
Barbara La Porta Monica Targusi Loretta Lattanzi Paola La Valle Daniela Paganelli & Luisa Nicoletti 《Marine Ecology》2009,30(S1):97-104
The aim of this study is to analyse the effects in space and time of relict sand-dredging activities on macrobenthic assemblages, in an area situated offshore Montalto di Castro (central Tyrrhenian Sea, Italy), and to analyse the recolonisation processes of macrobenthos in the dredged areas. The area in question is characterised by relict sand deposits (Holocenic paleo-beaches), used for beach nourishment along the Latium coast. The effects of sand extraction on benthic assemblages were investigated before, during and after three dredging operations. The sites analysed are located within the dredged areas (inside stations) and in neighbouring, not dredged, areas (outside stations). The results showed that the impact of sand extraction was confined to the dredged stations and to the areas in proximity to the dredged areas. During dredging activities, the structure of benthic assemblages within the impacted stations was characterised by low species richness and diversity. Both the direct removal of sediment and the re-suspension and consequent deposition of fine sediment affected benthic assemblages of the impacted stations. A few months after the dredgings, a recolonisation process was still observed at all the impacted stations. A gradual recolonisation process was observed at those stations affected by only one dredging, whereas a different recolonisation was observed at those stations affected by two dredgings over time. This study suggests that differences of re-colonisation processes of benthic assemblages are related to the intensity of dredging operations in terms of dredging frequency. 相似文献
996.
Systematic marine conservation planning in data-poor regions: Socioeconomic data is essential 总被引:1,自引:0,他引:1
Natalie C. Ban Gretchen J.A. Hansen Michael Jones Amanda C.J. Vincent 《Marine Policy》2009,33(5):794-800
Systematic planning for conservation is highly regarded but relies on spatially explicit data that are lacking in many areas of conservation concern. The decision support tool Marxan is applied to a reef system in the central Philippines where 30 marine protected areas (MPAs) have been established in communities without much use of biophysical data. The intent was to explore how Marxan might assist with the legally required expansion to protect 15% of marine waters, and how existing MPAs might affect that process. Results show that biophysical information alone did not provide much guidance in identifying patterns of conservation importance in areas where the data are poor. Socioeconomic data were needed to distinguish among possible areas for protection; but here, as elsewhere in marine environments, the availability of such data was very limited. In the final analysis, local knowledge and integrated understanding of socioeconomic realities may offer the best spatially explicit information. The 30 existing MPAs, which encompassed a small proportion of the reef system, did not limit future options in developing a suite of MPAs on a broader scale. Rather, they appeared to generate the support for MPAs that is obligatory for any larger zoning effort. In summary, establishing MPAs based on community-driven criteria has biological and social value, but efforts should be made to collect ecological and socioeconomic data to guide the continued creation of MPAs. 相似文献
997.
Significant effort has been made to generate a homogeneous database on wave overtopping consisting of more than 10,000 irregular wave overtopping tests from more than 160 independent projects or test series, each described by means of 31 parameters. Many coastal structures, including dikes, rubble mound breakwaters, berm breakwaters, caisson structures and combinations have been considered and have been schematised for inclusion in the database. All these overtopping tests are represented by over 300,000 numbers in the database. 相似文献
998.
A monthly mean climatology of the mixed layer depth (MLD) in the North Pacific has been produced by using Argo observations.
The optimum method and parameter for evaluating the MLD from the Argo data are statistically determined. The MLD and its properties
from each density profile were calculated with the method and parameter. The monthly mean climatology of the MLD is computed
on a 2° × 2° grid with more than 30 profiles for each grid. Two bands of deep mixed layer with more than 200 m depth are found
to the north and south of the Kuroshio Extension in the winter climatology, which cannot be reproduced in some previous climatologies.
Early shoaling of the winter mixed layer between 20–30°N, which has been pointed out by previous studies, is also well recognized.
A notable feature suggested by our climatology is that the deepest mixed layer tends to occur about one month before the mixed
layer density peaks in the middle latitudes, especially in the western region, while they tend to coincide with each other
in higher latitudes. 相似文献
999.
1000.
中国海洋志愿观测船现运行状态及发展 总被引:1,自引:0,他引:1
刘家沂 《海洋通报(英文版)》2009,11(1):90-96
志愿船观测是中国必须履行的国际义务。目前,中国海洋志愿观测船只呈逐年减少趋势,从过去的百余艘船只降至三、四十艘,并且从观测能力上也存在较多问题,比如观测手段比较落后、观测要素单一、观测资料缺乏。从根本上讲,志愿船运行机制缺乏有效的制度化保障,因此难以形成业务化能力,并且不能有效的履行国际义务。本文将对志愿船现运行状态及发展进行论述。 相似文献