Preface     

Santos  F.D. 《Earth, Moon, and Planets》1998,81(1):1-2

Earth, Moon, and Planets -  相似文献   

Arsenic and other Trace Metals in Sediments from the Kara Sea and the Ob and Yenisey Estuaries, Russia     

D.H. Loring  S. Dahle  K. Naes  J. Dos Santos  J.M. Skei  G.G. Matishov 《Aquatic Geochemistry》1998,4(2):233-252

Major (Al and Fe), minor (Mn) andtrace (As, Cd, Co, Cr, Cu, Hg, Li, Mo, Ni, Pb, Sb, Vand Zn) metals along with material of grain size<63 m, TOC and TN have been determined insediment grab and core samples from the Kara Sea, andthe Ob and Yenisey estuaries, Russia. Surprisingly,the levels of trace metals, with the exception of As,were much lower than was anticipated from speculativereports of extensive contamination in the Arcticmarine areas adjacent to the Siberian coastline ofRussia. Lithium normalization indicates that theabundance and distribution of the metals, with theexception of As and Mo, are controlled by theaccumulation of their fine grained aluminosilicatehost minerals at sites determined by hydrodynamicconditions in the Kara Sea and in the estuaries. Metallevels in the Kara Sea and the Ob and Yeniseyestuaries, except for some anomalous As, Cu and Nivalues, are close to natural baseline levels of otherEurasian Arctic shelf sediments. High levels of As,however, occur in surface and subsurface sediments.The accumulation of As, as well as Mo, can beattributed to the post-depositional diagenetic effectsof Fe-Mn cycling both at and near the sediment waterinterface. Subsurface As and Fe maxima and minimasuggest alternating oxic and anoxic water conditionsduring post-glacial rises in sea level. In contrast tothe results from the adjacent Pechora Sea, in the KaraSea there is no correlation between the levels of Asand radionuclides in the sediments.  相似文献   

UV observations of the symbiotic star EG And     

Claudio Bastos Pereira 《Astrophysics and Space Science》1996,235(2):305-318

EG And is a S-type symbiotic star. Here is present UV observations made by IUE from 1978 to 1991. From these observations the electronic density and the electronic temperature were obtained. The size of He II emitting region was estimated as 7.3R . Line and continuum variations confirm the binary nature of EG And.  相似文献   

Thallium in deep-seated crustal rocks     

G.Paolo Sighinolfi  Adelaide M. Santos 《Geochimica et cosmochimica acta》1974,38(4):641-646

A Precambrian granulite terrain of the Brazilian shield presents an average Tl content of 350 ppb, very near to Shaw's figure for the lower continental crust. Thallium, as in other rock types, shows close coherence with Rb and K. The mean Rb/Tl value (193 for 53 samples) falls in the range of the ‘normal’ crustal values, while the K/Tl values (145,000 average) are higher than values for igneous rocks, as are the values for K/Rb. The results support the authors' hypothesis that granulitic rocks have undergone partial melting with contemporaneous depletion of Rb and Tl in relation to K.  相似文献   

A model to describe gastric evacuation in cod (Gadus morhua L.) fed natural prey     

Santos  Jorge Dos; Jobling  Malcolm 《ICES Journal of Marine Science》1992,49(2):145-154

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Short-term environmental impact of clam dredging in coastal waters (south of Portugal): chemical disturbance and subsequent recovery of seabed   总被引：6，自引：0，他引：6  

Falcão M  Gaspar MB  Caetano M  Santos MN  Vale C 《Marine environmental research》2003,56(5):649-664

The physical and chemical changes in sediment and near bottom water caused by clam dredging were examined during July and September 1999, at two locations Vilamoura (VL) and Armona (AR), south coast of Portugal. Sediment cores and near bottom water were collected simultaneously before dredging (control samples) and within short time intervals (min-h) after dredging. After dredging operations, microphytobenthos coming from the path were accumulated in the re-worked sediment (ridge). Chlorophyll a in superficial sediment increased from 1.2 microg x g(-1) before dredging to 1.7 microg x g(-1) after dredging and these higher values remained for a few hours. However, the expected increase of chlorophyll a in near bottom water due to re-suspension was not observed. After sediment disturbance an instantaneous sorption of phosphorus onto iron oxides occurred in the upper sediment layers (from 2 to 3 micromol x g(-1) before dredging to 4-5 micromol x g(-1) after dredging). A microcosm experiment showed that after sediment disturbance HPO(4)(2-) dissolved in pore water decreased from 40 to 10 microM being simultaneously sorbed onto iron oxides formed in the top layer of sediment. The ammonium, nitrates, organic nitrogen, phosphate and silicate dissolved in pore water decreased immediately after dredging activity and simultaneously an increase in near bottom water was sporadically observed. Generally, the re-establishment of seabed was reached within a short time (min-h), at both stations (VL and AR).  相似文献   

Finite element investigation on the static response of a composite catamaran under slamming loads     

Roberto Ojeda  B. Gangadhara Prusty  Marcos Salas   《Ocean Engineering》2004,31(7):901-929

This paper presents the structural response of a fast and relatively small, composite materials catamaran to slamming loads. Finite element method is used to provide valuable information in order to optimise the design of the catamaran. The analysis is carried out using ANSYS 6.0 finite element software.The response of the structure to quasi-static slamming loads according to Det Norske Veritas High Speed and Light Craft crest landing and hollow landing rules [DNV, 1999] has been implemented and studied. An optimisation study for the structural response is carried out by changing the ply orientation in the vessel and suitable recommendations are made.  相似文献   

Test of a food consumption model for the Atlantic cod   总被引：3，自引：0，他引：3  

dos Santos  Jorge; Jobling  Malcolm 《ICES Journal of Marine Science》1995,52(2):209-219

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A Small Autonomous Surface Vehicle for Ocean Color Remote Sensing   总被引：1，自引：0，他引：1  

Desa  E. Maurya  P.K. Pereira  A. Pascoal  A.M. Prabhudesai  R.G. Mascarenhas  A. Madhan  R. Matondkar  S.G.P. Navelkar  G. Prabhudesai  S. Afzulpurkar  S. 《Oceanic Engineering, IEEE Journal of》2007,32(2):353-364

This paper provides a study on the development and the use of a small autonomous surface vehicle (ASV) that automatically follows programmed mission transects, while measuring sensor outputs along the tracks. It discusses the mechanical construction of the ASV, the distributed architecture of controller area network (CAN)-based nodes for science and vehicle payloads, high-speed radio-frequency (RF) communications, the performance of the heading autopilot, global positioning system (GPS)-based guidance algorithm, and the mission programming technique. The field trials of the ASV, performed off the coast of Goa, India, are focused on retrieving the 2-D spatial distribution of surface chlorophyll, which is one of the useful parameters in characterizing the nature of calibration-validation (CALVAL) sites for ocean remote sensing needs. A further benefit of ASVs is that they can be built at a low cost and used in monitoring applications of diverse coastal ecosystems.  相似文献   

Fine-scale distribution of sardine (Sardina pilchardus) eggs and adults during a spawning event   总被引：2，自引：0，他引：2  

Juan Zwolinski  Evan Mason  Paulo B. Oliveira  Yorgos Stratoudakis 《Journal of Sea Research》2006,56(4):294-304

High-resolution acoustic and ichtyoplankton sampling with a ‘continuous under-way fish egg sampler (CUFES)’ was performed in two regions of approximately 100 square nautical miles off southern Iberian Peninsula, with the aim of studying the small scale distribution of sardine (Sardina pilchardus) adults and eggs during a spawning event. Very dense patches (246 eggs m^− 3) of recently spawned eggs with dimensions (up to 3 nautical miles wide) significantly larger than daytime sardine schools were present in both regions. Egg staging and ageing showed very little intra-sample variation, indicating a synchronous spawning period at dusk. The internal structure of the patches evaluated by variography showed very low internal variability, as if they consisted of a single unit. This hypothesis is confirmed by the acoustic finding of large sardine shoals with similar dimensions to those of the patches after sunset and throughout the night. During that period, adults were found near or in contact with the bottom, suggesting that spawning occurred at depth. A distinct patch of older eggs was found in both areas, but with a few nautical miles of horizontal separation. Their characteristics (a larger area, lower egg densities and a more irregular shape) indicate that these patches were exposed to dispersion and ‘stirring’ by physical forces, reshaping their initial appearance, while mesoscale water circulation could have displaced the core of the patches away by several kilometres within a day.  相似文献