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71.
The EU Green Paper on Maritime Policy is the European response to the new generation of ocean strategies based on science, technology and innovation aimed at new objectives, such as the strengthening of security and access to new resources. The European character of the proposal is found in the presence of social, cultural and historical elements, what is called the “European vision”. The viability of a European vision of the oceans and the idea of maritime empire as an extension of the current concept of empire within the general context of emerging ocean strategies are the elements offered up for debate on this European Union initiative.  相似文献   
72.
The short-time-scale variability of the remineralization patterns in the domain of Eastern North Atlantic Central Waters (ENACW) off the NW Iberian Peninsula is studied based on biogeochemical data (oxygen, nutrient salts, total alkalinity, pH, dissolved organic matter and fluorescence of dissolved humic substances) collected weekly between May 2001 and April 2002. The temporal variability of inorganic variables points to an intensification of remineralization during the summer and autumn, with an increase of nutrients, total inorganic carbon and fluorescence and a decrease of oxygen. During the subsequent winter mixing, there is a biogeochemical reset of the system, with lower nutrients, total inorganic carbon and fluorescence and higher oxygen. In contrast to inorganic variables, the levels of dissolved organic matter in the ENACW seem to respond to short-term events probably associated with fast sinking particles, where solubilisation of organic matter prevails over remineralization. Applying a previously published stoichiometric model, we observed a vertical fractionation of organic-matter remineralization. Although there is a preferential remineralization of proteins and P compounds in the entire domain of ENACW, the percentage was higher in the upper ENACW (σ<27.10 kg/m3) than in the lower; the percentage of N and P compounds in the oxidised organic matter was >80% for the upper ENACW and 63% for the lower. Likewise, the redissolution of calcareous structures contributes about 6% and 13% to the carbon regenerated in the upper and lower layers of ENACW, respectively.  相似文献   
73.
Abstract. The stomach contents of poor cod, Trisopterus minutus capelanus (Lacepède), were taken at monthly intervals off the eastern coast of the Gulf of Valencia (Spain). A total of 1276 were analyzed to determine diet according to fish size and season. The basic food consists of crustaceans (Mysidacea and Decapoda) and teleosts. Feeding habits varied with size: decapods and fishes were more abundant in the stomachs of larger specimens. Little seasonal variation in food habits was recorded.  相似文献   
74.
The enzymatic activity of alkaline phosphatase (APA) was studied in the transition zone between the African upwelling system and the open ocean waters of the Canary Islands region. This region is recurrently dominated by the presence of upwelling filaments that may transport nutrient-enriched waters out into the open ocean before nutrients become exhausted by plankton. Turnover rates by APA were generally low in the whole region, but detectable in all the measurements carried out. On average, turnover rates were higher in the upwelling stations, and APA in those waters seemed to be mainly generated by heterotrophic bacteria to supply easily assimilable organic C. APA outside the upwelling area showed an inverse hyperbolic relationship with increasing phosphate, suggesting the presence of both constitutive and Pi-inducible APA. In these offshore waters, a threshold of 0.1 μM of phosphate could be defined for the regulatory function of Pi on APA. Thus, APA in nutrient-poor waters seemed to be induced to compensate for Pi-deficiency. Turnover rates in the filaments showed basal (probably constitutive) levels, whereas they increased in the surrounding waters, where phosphate concentration presumably did not satisfy plankton P-demands. The fertilising effect of the filaments and associated cyclonic eddies extended to at least 175 km offshore, where basal alkaline phosphatase activities were still found. The magnitude of this effect depends probably on the intensity of upwelling events and the degree of recirculation of filament water back to the coastal jet.  相似文献   
75.
Practical implementation of Hilbert-Huang Transform algorithm   总被引:12,自引:0,他引:12  
Hilbert-Huang Transform (HHT) is a newly developed powerful method for nonlinear and non-stationary time series analysis. The empirical mode decomposition is the key part of HHT, while its algorithm was protected by NASA as a US patent, which limits the wide application among the scientific community. Two approaches, mirror periodic and extrema extending methods, have been developed for handling the end effects of empirical mode decomposition. The implementation of the HHT is realized in detail to widen the application. The detailed comparison of the results from two methods with that from Huang et al. (1998, 1999), and the comparison between two methods are presented. Generally, both methods reproduce faithful results as those of Huang et al. For mirror periodic method (MPM), the data are extended once forever. Ideally, it is a way for handling the end effects of the HHT, especially for the signal that has symmetric waveform. The extrema extending method (EEM) behaves as good as MPM, and it is better t  相似文献   
76.
通过对南海东北部128个表层沉积样品的定量研究,揭示隆源和矿物碎屑各组分的分布,也显示了组分分析作为一种简单、快速的研究方法在海洋古环境研究中的潜力,研究区生源碎屑的分布明显受与水深相关的深海溶解作用所控制,水深3500-4000m的现代南海CCD以下,钙质生物的含量急剧减少,而硅质生物的含量急剧增加,研究区表层沉积中的碎屑矿物主要来源于亚洲大陆,吕宋镐的风化产物只起次要作用,且其分布主要受与离岸距离远近和海流相关的搬运作用所控制。  相似文献   
77.
The objective of this study was to determine if tamoxifen or an aromatase inhibitor (4-hydroxyandrostenedione; 4-OHA) affected plasma concentrations of o,p' -DDT and its metabolites, o,p'-DDD and o,p'-DDE, in mature tilapia. Male and female tilapia were injected 6 times intraperitoneally with o,p'-DDT (40 mg/kg) alone or in combination with 4-OHA (2 mg/kg) over a 12 day period. An additional group of male fish was injected with tamoxifen (5 mg/kg) plus o,p'-DDT. At the end of the treatment period, plasma samples were extracted and analyzed by GC/ECD. Females injected only with o,p'-DDT had significantly higher levels of o,p'-DDT compared with males. Interestingly, females and males treated concomitantly with o,p'-DDT and 4-OHA or tamoxifen had significantly lower concentrations of plasma o,p'-DDT (about 50%) compared with fish treated with only o,p'-DDT. These initial results suggest that an interaction between endocrine-active compounds occurs in vivo in tilapia and may involve alterations in metabolism of o,p'-DDT.  相似文献   
78.
The Besòs prodelta, located around a highly populated area, receives the discharge of the Besòs River, one of the most contaminated rivers discharging into the Mediterranean sea. The record of heavy metals accumulated in this prodelta is studied to assess the sedimentary behaviour and the history of the anthropogenic heavy metals in the area.

dated sediments have allowed the identification of the sedimentation patterns and the elaboration of dated heavy metals and cenospheres profiles, which reflected the evolution of the anthropogenic impact in this marine environment. Sediments accumulated during the 18th and 19th centuries were already affected by a moderate heavy metal contamination. This contamination increased drastically in the sediments accumulated during the last decades. This data is well correlated with the increase in industrialisation, population and energy consumption in the Besòs drainage basin during the last century.  相似文献   
79.
The Gulf of Cádiz area has been extensively surveyed in recent years and several gas-related fluid escape seafloor structures have been identified. In this study, gravity cores, collected during the ANASTASYA/00 and ANASTASYA/01 cruises, on mud volcanoes, hemipelagic sediments and dredged material from diapiric structures, have been studied. A comparative mineralogical analysis by XRD and SEM of samples from different areas has been performed in order to determine whether there is a characteristic mineralogy related to these fluid escape structures, and also to determine the origin of the mud matrix and constrain the depth of the parent units. The mineralogical analysis reflects the different origins of the different units described in the cores: hemipelagic material of the slope, clays that underlie the mud volcanoes and are discharged at the sea bottom surface, and authigenic and diagenetic minerals possibly involved in the anaerobic oxidation of methane in the mud volcano sediments.  相似文献   
80.
The muricid gastropod Bolinus brandaris exhibited imposex, a phenomenon linked to the use of organotin biocides. Several stages of imposex development (1-5) could be distinguished and were documented with SEM-photographs for the first time in this species. Additional alterations of the genital tract in females (blocked vulva preventing copulation and deposition of egg capsules) and males (excrecences on the penis and vas deferens) were shown. Imposex intensity on the Catalan coast was very high. The frequency of imposex off Barcelona and Vilanova i la Geltrú was 100%, with all females showing stage 4. Imposex frequency off Sant Carles de la Ràpita was 99.7% and the VDS index scored 3.9. Despite regulations of TBT-containing antifouling paints in Spain since 1990, the present study revealed that frequency and intensity of imposex have increased on the Catalan coast, at least since 1997. However, at present, imposex does not apparently affect the population dynamics of B. brandaris in the studied area, since no serious consequences on female reproduction (only one case of female sterilization) were detected. Gonadal activity and oogenesis were not suppressed or supplanted by spermatogenesis. Sex ratios were not male-biased. Possible sources of organotin biocides are examined.  相似文献   
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